We appreciate Dr. Laura S. Boylan’s interest in our article. However, her viewpoint rather strikingly exemplifies the behaviors that she mistakenly believes we were guilty of in our report, beginning with the “eminence based” statements “in my view” occurring twice in the first paragraph and her conclusion with a personal “old saw I use in teaching”. We strongly disagree with her misinterpretation about our application of “cognitive bias” in the selection of our patients for this case-control study. In fact, most patients with Parkinson’s disease (PD) had functional complications ascertained after several visits –requiring a diagnostic revision once they fulfilled the appropriate positive criteria.1 The diagnostic “delay” in part may have highlighted the absent recognition of functional comorbidities in PD prior to our study, forcing a conservative approach before ascertaining what may be considered a “second” diagnosis in these patients. Furthermore, in contrast to Dr. Boylan’s suggestion, we did not select patients on the basis of comorbid depression, anxiety, cognitive symptoms, pain, nausea, or fatigue. Instead these features segregated more commonly among cases than controls after the patient selection had been completed. She argues that we considered them “supportive” for a diagnosis of functional movement disorder, but we did not. We have instead emphasized the potentially misleading influence of both history and psychiatric features and argued in favor of a diagnos...
We appreciate Dr. Laura S. Boylan’s interest in our article. However, her viewpoint rather strikingly exemplifies the behaviors that she mistakenly believes we were guilty of in our report, beginning with the “eminence based” statements “in my view” occurring twice in the first paragraph and her conclusion with a personal “old saw I use in teaching”. We strongly disagree with her misinterpretation about our application of “cognitive bias” in the selection of our patients for this case-control study. In fact, most patients with Parkinson’s disease (PD) had functional complications ascertained after several visits –requiring a diagnostic revision once they fulfilled the appropriate positive criteria.1 The diagnostic “delay” in part may have highlighted the absent recognition of functional comorbidities in PD prior to our study, forcing a conservative approach before ascertaining what may be considered a “second” diagnosis in these patients. Furthermore, in contrast to Dr. Boylan’s suggestion, we did not select patients on the basis of comorbid depression, anxiety, cognitive symptoms, pain, nausea, or fatigue. Instead these features segregated more commonly among cases than controls after the patient selection had been completed. She argues that we considered them “supportive” for a diagnosis of functional movement disorder, but we did not. We have instead emphasized the potentially misleading influence of both history and psychiatric features and argued in favor of a diagnosis of a functional movement disorder exclusively reliant on neurological examination (i.e., using positive criteria rather than applying a diagnosis of exclusion).2 Importantly, we did not review colleagues' charts; these were our own patients, who had been followed by movement disorders experts over several years. Dr. Boylan exercises far more of her own cognitive bias in highlighting how the diagnosis of functional disorders has been overly considered in females (despite considerable epidemiological evidence that these disorders are more common in women) and in her old teaching saw that “proper diagnosis” of movement disorders (including functional movement disorders) "is the one offered the most senior professor in the vicinity". Her viewpoint ignores modern literature that has shown a very low incidence of misdiagnosis using current evaluations and the application of positive criteria for the diagnosis of functional disorders.3 Thus, in citing old, historical literature and ignoring a growing body of work in the field,4 Dr. Boylan’s letter propagates old thinking and misinformation.
References
1. Gupta A, Lang AE. Psychogenic movement disorders. Curr Opin Neurol. 2009;22(4):430-436.
2. Espay AJ, Lang AE. Phenotype-specific diagnosis of functional (psychogenic) movement disorders. Curr Neurol Neurosci Rep. 2015;15(6):556.
3. Stone J, Carson A, Duncan R, et al. Symptoms 'unexplained by organic disease' in 1144 new neurology out-patients: how often does the diagnosis change at follow-up? Brain. 2009;132(Pt 10):2878-2888.
4. Hallett M, Stone J, Carson A. Functional Neurologic Disorders. Vol 139. Amsterdam, Netherlands. : Handbook of Clinical Neurology, Elsevier. ; 2016.
In my view the data presented in this study (1) which are interpreted as indicating a high prevalence of functional movement disorders (FMD) in PD might also be interpreted as suggesting that diagnostic delay is common in PD, particularly among women patients who present as "high maintenance" patients. The diagnosis of functional movement disorders is a matter of expert opinion and in my view problems with study design and interpretation support rather than minimize cognitive and confirmation bias in this study.
Subjects all met UK brain bank criteria for PD. Subjects diagnosed with FND in this study had high rates of family history of PD. They had depression, anxiety, cognitive symptoms, pain, nausea, fatigue all common complaints among the population in general and most particularly in PD. The presence of these symptoms before or after diagnosis of PD is considered by the authors as supportive for a diagnosis of FMD. However, these same symptoms are known to be associated with PD and might be considered supportive of a PD diagnosis.
Disparities in healthcare for women are well established (2). Neurology has a long history of mistakes distinguishing the "functional" from the "organic" (e.g.3). To choose one example people with blepharospasm, mostly women, were institutionalized long-term as the disease was not recognized as neurologic. Women commonly encounter dismissal in the medical context and this can occasion missed opportuni...
In my view the data presented in this study (1) which are interpreted as indicating a high prevalence of functional movement disorders (FMD) in PD might also be interpreted as suggesting that diagnostic delay is common in PD, particularly among women patients who present as "high maintenance" patients. The diagnosis of functional movement disorders is a matter of expert opinion and in my view problems with study design and interpretation support rather than minimize cognitive and confirmation bias in this study.
Subjects all met UK brain bank criteria for PD. Subjects diagnosed with FND in this study had high rates of family history of PD. They had depression, anxiety, cognitive symptoms, pain, nausea, fatigue all common complaints among the population in general and most particularly in PD. The presence of these symptoms before or after diagnosis of PD is considered by the authors as supportive for a diagnosis of FMD. However, these same symptoms are known to be associated with PD and might be considered supportive of a PD diagnosis.
Disparities in healthcare for women are well established (2). Neurology has a long history of mistakes distinguishing the "functional" from the "organic" (e.g.3). To choose one example people with blepharospasm, mostly women, were institutionalized long-term as the disease was not recognized as neurologic. Women commonly encounter dismissal in the medical context and this can occasion missed opportunities for established clinical interventions (e.g. 4, 5, 6)
Study subjects were selected for assessment for FMD on the basis of their doctors having used language suggesting a suspicion of an FMD in the chart. It sounds as if investigators were reviewing records of colleagues at their own institution. How many, if any, neurologists were considered to have made diagnostic error?
Evidence for the effects of cognitive bias in clinical medicine overshadows evidence for the reliability and validity of expert evaluation of functional movement disorders (4, 7 8).
In the 19th century there was debate over whether Parkinson's disease itself was functional or organic (9). While some cases are clear cut, an old saw I use in teaching is that the proper movement disorder diagnosis is the one offered by the most senior professor in the vicinity.
References:
(1) Wissel BD, Dwivedi AK, Merola A, et al. Functional neurological disorders in Parkinson disease. J Neurol Neurosurg Psychiatry. 2018 Jun;89(6):566-571.
(2) Hornbuckle LM, Amutah-Onukagha N, Bryan A, et al. Health Disparities in Women. Clinical Medicine Insights Women’s Health. 2017.
(3) Hamill EB, Yen MT. The History of Blepharospasm in Medicine. Int Ophthalmol
Clin. 2018 Winter;58(1):3-10.
(4) Schulman KA, Berlin JA, Harless W, et al. The effect of race and sex on physicians' recommendations for cardiac catheterization. N Engl J Med. 1999 Feb 25;340(8):618-26.
(5) Faigle R, Urrutia VC, Cooper LA, Gottesman RF. Individual and System
Contributions to Race and Sex Disparities in Thrombolysis Use for Stroke Patients in the United States. Stroke. 2017 Apr;48(4):990-997
(6) Dusenbery M. Doing harm. Harper Collins 2018.
(7) Vickrey BG, Samuels MA, Ropper AH. How neurologists think: A cognitive psychology perspective on missed diagnoses. Ann Neurol. 2010 Apr;67(4):425-33.
(8) Saposnik G, Redelmeier D, Ruff CC, Tobler PN. Cognitive biases associated with medical decisions: a systematic review. BMC Med Inform Decis Mak. 2016 Nov 3;16(1):138.
(9) Bechet E. Contribution a l'etude clinique des formes de la maladie de parkinson. Paris. Ancienne Maison Delahaye. 1892.
Conflict of Interest
Dr. Laura Boylan does medicolegal consulting work.
We read with interest the study presented by Berg et al [1] that showed that prolonged mechanical ventilation (more than 2 months) in Guillain-Barre syndrome (GBS) was associated with poorer outcome and more residual deficits compared to non-ventilated GBS patients.
We recently found very similar results in the same population of patients. Nevertheless, it should be precised that despite this, we could not found any difference in quality of life compared to the general French population [2]. Berg et al. also found that ventilated patients were less likely to have residual fatigue symptoms compared to non-ventilated GBS patients, respectively 20% versus 54% (p=0.007). Among 13 prolonged mechanically ventilated GBS, we could show that 22% of patients displayed DSM IV criteria for long-term post-traumatic stress disorder (PTSD) [2]. Since one of our main hypothesis was that PTSD symptoms were mainly related to the mechanical ventilation, we assessed long-term PTSD in 20 non-ventilated GBS patients (Table). Unexpectedly, 65% of these non-ventilated patients had PTSD as compared to 22% in the ventilated group found in our previous study (Table). As for fatigue, we would have expected a correlation between the severity of the disease (especially mechanical ventilation), and the incidence of PTSD.
One explanation of these unexpected results could be that the acute stress induced by the temporary paralysis, the traumatic aspects of intubation an...
We read with interest the study presented by Berg et al [1] that showed that prolonged mechanical ventilation (more than 2 months) in Guillain-Barre syndrome (GBS) was associated with poorer outcome and more residual deficits compared to non-ventilated GBS patients.
We recently found very similar results in the same population of patients. Nevertheless, it should be precised that despite this, we could not found any difference in quality of life compared to the general French population [2]. Berg et al. also found that ventilated patients were less likely to have residual fatigue symptoms compared to non-ventilated GBS patients, respectively 20% versus 54% (p=0.007). Among 13 prolonged mechanically ventilated GBS, we could show that 22% of patients displayed DSM IV criteria for long-term post-traumatic stress disorder (PTSD) [2]. Since one of our main hypothesis was that PTSD symptoms were mainly related to the mechanical ventilation, we assessed long-term PTSD in 20 non-ventilated GBS patients (Table). Unexpectedly, 65% of these non-ventilated patients had PTSD as compared to 22% in the ventilated group found in our previous study (Table). As for fatigue, we would have expected a correlation between the severity of the disease (especially mechanical ventilation), and the incidence of PTSD.
One explanation of these unexpected results could be that the acute stress induced by the temporary paralysis, the traumatic aspects of intubation and the need for prolonged mechanical ventilation (MV) could promote a stronger resilience process, a mental ability which enables adaption to a stressful event [3], in severe GBS patients compared to milder ones. Nevertheless, to our knowledge, no study has shown that the length of stay or the severity of a traumatic event could be associated to higher resilience. In our studies, median length of stay (LOS) was longer in ventilated versus non-ventilated GBS patient, respectively at 102 days [72-126] and 12 days [11-16) (p<0.0001). In the contrary of most ICU patients, GBS patients with prolonged MV are admitted for a transitory impairment of the peripheral nervous system responsible of respiratory failure, without multiple organ dysfunctions. During their LOS, they are, with full consciousness, hostages to their paralyzed bodies, before the recovering. We can make the hypothesis that this uncommon stressful experience could promote in some patients a resilience process in order to deal transiently with they’re inexorable status, with the hypothesis that higher LOS could promote this resilience process. Such changes in mental status have been described in war prisoners and hostages with prolonged captivity [4, 5].
We totally agree with the authors that based on the actual available studies the prediction of which patients with prolonged mechanical ventilation may reach good outcome is impossible and that prospective studies are mandatory. In such studies, detailed psychological and psychiatric evaluation focusing on PTSD and resilence processes would be valuable.
Figure Legend:
Table : Characteristics of the patients.
References
1. van den Berg, B., et al., Clinical outcome of Guillain-Barre syndrome after prolonged mechanical ventilation. J Neurol Neurosurg Psychiatry, 2018. 7(317968): p. 2018-317968.
2. Le Guennec, L., et al., Post-traumatic stress symptoms in Guillain-Barre syndrome patients after prolonged mechanical ventilation in ICU: a preliminary report. J Peripher Nerv Syst., 2014. 19(3): p. 218-23. doi: 10.1111/jns.12087.
3. Wagnild, G.M. and H.M. Young, Development and psychometric evaluation of the Resilience Scale. J Nurs Meas, 1993. 1(2): p. 165-78.
4. Ranscombe, P., Fear, resilience, and tunnel vision. Lancet Neurol, 2015. 14(12): p. 1158.
5. Park, C.L., et al., Does Wartime Captivity Affect Late-life Mental Health? A Study of Vietnam-era Repatriated Prisoners of War. Res Hum Dev, 2012. 9(3): p. 191-209.
I read the article entitled "Patients with Parkinson disease are prone to functional neurological disorders" by Hallett M published in the Journal of Neurology, Neurosurgery and Psychiatry (Published Online First: 16 March 2018. doi: 10.1136/jnnp-2017-317684). I want to congratulate the author for this successful article, and make some contributions.
The article particularly mentions certain aspects of the clinical presentation, medical history and examination of patients, which should raise the suspicion of a functional disorder (1). I think it is important to remember patients with functional disorders will not always adhere to these criteria and clinicians should perhaps consider trialling suspected patients on either cognitive behavioural therapy (CBT) or physiotherapy to assess if they experience any improvement with these strategies. There is increasing evidence to show CBT and physiotherapy are beneficial for patients with functional disorders, hence they may be useful in confirming the diagnosis (2)(3).
Furthermore, the author suggests patients with functional symptoms and no sign of Parkinson's Disease should not be pursued further for a diagnosis of Parkinson's Disease. I think a difficulty is often deciding what classifies as a sign of Parkinson's Disease. The cardinal symptoms of bradykinesia, resting tremor, muscular rigidity and postural instability are commonly subtle within patients, making...
I read the article entitled "Patients with Parkinson disease are prone to functional neurological disorders" by Hallett M published in the Journal of Neurology, Neurosurgery and Psychiatry (Published Online First: 16 March 2018. doi: 10.1136/jnnp-2017-317684). I want to congratulate the author for this successful article, and make some contributions.
The article particularly mentions certain aspects of the clinical presentation, medical history and examination of patients, which should raise the suspicion of a functional disorder (1). I think it is important to remember patients with functional disorders will not always adhere to these criteria and clinicians should perhaps consider trialling suspected patients on either cognitive behavioural therapy (CBT) or physiotherapy to assess if they experience any improvement with these strategies. There is increasing evidence to show CBT and physiotherapy are beneficial for patients with functional disorders, hence they may be useful in confirming the diagnosis (2)(3).
Furthermore, the author suggests patients with functional symptoms and no sign of Parkinson's Disease should not be pursued further for a diagnosis of Parkinson's Disease. I think a difficulty is often deciding what classifies as a sign of Parkinson's Disease. The cardinal symptoms of bradykinesia, resting tremor, muscular rigidity and postural instability are commonly subtle within patients, making them a challenge to distinguish from normal limits. This is made even more difficult if a functional disorder is also suspected. Clinicians should therefore consider demonstrating reduced levels of the presynaptic dopamine active transporter (DAT) using a DaTscan, if available, to aid their diagnosis of Parkinson's Disease as the author suggests in another of their articles (4). Guidance surrounding the use of a DaTscan from the National Institute for Health and Care Excellence (NICE) does not currently account for this indication, however it may be worth considering for future recommendations (5).
References:
1. Wissel BD, Dwivedi AK, Merola A, et al Functional neurological disorders in Parkinson disease J Neurol Neurosurg Psychiatry Published Online First: 16 March 2018. doi: 10.1136/jnnp-2017-317378.
2. Nielsen G, Stone J, Matthews A, et al Physiotherapy for functional motor disorders: a consensus recommendation J Neurol Neurosurg Psychiatry 2015;86:1113-1119.
3. Conwill M, Oakley L, Evans K, Cavanna A. CBT-based group therapy intervention for nonepileptic attacks and other functional neurological symptoms: A pilot study. Epilepsy & Behavior. 2014;34:68-72.
4. Hallett M. Psychogenic Parkinsonism. Journal of the neurological sciences. 2011;310(1-2):163-165. doi:10.1016/j.jns.2011.03.019.
5. National Institute for Health and Care Excellence. Parkinson’s disease in adults NICE guideline NG71 [Internet]. Nice.org.uk. 2017 [cited 12 April 2018]. Available from: https://www.nice.org.uk/guidance/ng71/chapter/Recommendations#diagnosing....
Wissel and colleagues recently reported on a large retrospective case series of patients with functional neurological disorder (FND) and Parkinson's disease (PD) [1]. The authors only briefly touched upon the question of shared pathophysiology, noting that in principle certain structural brain diseases may predispose to FND. The study was not designed to tease out any shared or causal pathways between FND and PD, but some speculation based on the presented data could help formulate useful hypotheses concerning this interesting comorbidity. I propose that a disruption of the central noradrenergic system due to degeneration of the locus loeruleus (LC), the sole source of noradrenaline in the brain with far-reaching projections, is a good candidate for a causal link between FND and (prodromal) PD.
In the study by Wissel and colleagues FND antedated the diagnosis of PD in 26% of cases, often by several years [1]. This is significant, because it nearly eliminates the possibility that the comorbidity is entirely a matter of symptom modelling or functional overlay in all cases. Considering the typical neuroanatomical progression of Lewy pathology in PD, this suggests that neurodegenerative effects within the lower brainstem (Braak stage 1 or 2) are likely structural candidates for a causal pathway. Early LC pathology has been associated with other premotor manifestations of Lewy pathology and PD such as REM sleep behaviour disorder and cognitive decline. A study using...
Wissel and colleagues recently reported on a large retrospective case series of patients with functional neurological disorder (FND) and Parkinson's disease (PD) [1]. The authors only briefly touched upon the question of shared pathophysiology, noting that in principle certain structural brain diseases may predispose to FND. The study was not designed to tease out any shared or causal pathways between FND and PD, but some speculation based on the presented data could help formulate useful hypotheses concerning this interesting comorbidity. I propose that a disruption of the central noradrenergic system due to degeneration of the locus loeruleus (LC), the sole source of noradrenaline in the brain with far-reaching projections, is a good candidate for a causal link between FND and (prodromal) PD.
In the study by Wissel and colleagues FND antedated the diagnosis of PD in 26% of cases, often by several years [1]. This is significant, because it nearly eliminates the possibility that the comorbidity is entirely a matter of symptom modelling or functional overlay in all cases. Considering the typical neuroanatomical progression of Lewy pathology in PD, this suggests that neurodegenerative effects within the lower brainstem (Braak stage 1 or 2) are likely structural candidates for a causal pathway. Early LC pathology has been associated with other premotor manifestations of Lewy pathology and PD such as REM sleep behaviour disorder and cognitive decline. A study using neuromelanin-sensitive MRI sequences recently confirmed in vivo that degeneration of the LC is indeed closely associated with (and likely responsible for) the occurrence of REM sleep behaviour disorder, cognitive impairment, EEG slowing and ortostatic hypotension in PD patients [2]. So in terms of premotor progression of pathology, neuroanatomy and functional relevance of neurodegeneration, the LC seems to be a good candidate. But why should central noradrenergic dysfunction predispose to FND?
The LC noradrenergic system is critically involved in three interconnected cognitive domains that are highly relevant for FND: arousal, attention and affective learning [3]. The LC projects directly to the prefrontal cortex, where it is involved in selective attention and attentional shifts, as well as to various limbic structures including the hippocampus and amygdala, where it mediates arousal and affective learning. A persistent dysregulation of attention, arousal and affective learning can lead to abnormal stress responsivity and maladaptive behavioural changes. General hyperarousal is common in many forms of FND, and is assumed to be pivotal in the emergence and maintainance of functional and dissociative symptoms [4]. Dysregulated attentional control can lead to increased self-directed attention (attentional biases) and dissociative experiences, both common in FND [4]. Furthermore, current mechanistic frameworks of FND predict that disproportionate attentional weighting of sensory expectations and illness beliefs can distort or even override contradictory sensory inputs to produce functional symptoms beyond volitional control [5]. To summarize, if Lewy pathology critically disrupts LC function (possibly years before the dopaminergic system is affected) the resulting dysregulation of attentional control, arousal and affective learning can directly predispose to the development of functional sensory or motor symptoms. The additional findings by Wissel and colleagues that PD-FND patients had worse depression and anxiety than PD without FND, and that FND presented nearly always on the PD-affected side are also in line with the potential role of LC pathology.
Future studies could test this proposition by investigating the effect of noradrenergic medication on FND, and by prospectively evaluating patients with isolated/idiopathic REM sleep behaviour disorder (and no dopaminergic dysfunction) for FND.
References
1. Wissel BD, Dwivedi AK, Merola A, et al. Functional neurological disorders in Parkinson disease. J Neurol Neurosurg Psychiatry. Published Online First: 16 March 2018. doi: 10.1136/jnnp-2017-317378
2. Sommerauer M, Fedorova TD, Hansen AK, Knudsen K, Otto M, Jeppesen J, Frederiksen Y, Blicher JU, Geday J, Nahimi A, Damholdt MF, Brooks DJ, Borghammer P. Evaluation of the noradrenergic system in Parkinson's disease: an 11C-MeNER PET and neuromelanin MRI study. Brain. 2018 Feb 1;141(2):496-504. doi: 10.1093/brain/awx348.
3. Sara SJ. The locus coeruleus and noradrenergic modulation of cognition. Nat Rev Neurosci. 2009 Mar;10(3):211-23. doi: 10.1038/nrn2573. Epub 2009 Feb 4.
4. Roelofs K, Pasman J. Stress, childhood trauma, and cognitive functions in functional neurologic disorders. Handb Clin Neurol. 2016;139:139-155. doi: 10.1016/B978-0-12-801772-2.00013-8.
5. Edwards MJ, Adams RA, Brown H, Pareés I, Friston KJ. A Bayesian account of 'hysteria'. Brain. 2012 Nov;135(Pt 11):3495-512. doi: 10.1093/brain/aws129. Epub 2012 May 28.
I read with great interest the paper by Jamjoom et al.[1] The authors have done commendable work in establishing a national external ventricular drain related infection (ERI) rate and elucidating the factors influencing it in the largest prospective multicentre study. However, some questions have been left unanswered in this respect.
One of the contributing factors to a low ERI rate in the study could have been the fact that majority (98.6%) of EVDs were inserted in the operating theatre. In their single centre retrospective study of 84 patients, Arabi et al[2] found that placement outside operating rooms was associated with a trend towards higher ERIs. Clark et al[3], in their retrospective review of complications of intracranial pressure monitoring in 140 trauma patients, noted that the incidence of major infectious complications (eg. clinical ventriculitis, subdural empyema, brain abscesses) was higher in the groups in which the catheter was placed in the intensive care unit. A randomised control trial would better examine the importance of this finding.
In this study by Jamjoom et al[1], the authors found no significant difference between infected and uninfected cases with regard to the length of tunnelling. However, recent evidence although weak, points towards a preventive benefit of long tunnel EVDs over short tunnel EVDs.[4,5] Hence, a discussion about the role of tunnelling length in ERIs is felt missing in the paper.
Korinek et al, in their stud...
I read with great interest the paper by Jamjoom et al.[1] The authors have done commendable work in establishing a national external ventricular drain related infection (ERI) rate and elucidating the factors influencing it in the largest prospective multicentre study. However, some questions have been left unanswered in this respect.
One of the contributing factors to a low ERI rate in the study could have been the fact that majority (98.6%) of EVDs were inserted in the operating theatre. In their single centre retrospective study of 84 patients, Arabi et al[2] found that placement outside operating rooms was associated with a trend towards higher ERIs. Clark et al[3], in their retrospective review of complications of intracranial pressure monitoring in 140 trauma patients, noted that the incidence of major infectious complications (eg. clinical ventriculitis, subdural empyema, brain abscesses) was higher in the groups in which the catheter was placed in the intensive care unit. A randomised control trial would better examine the importance of this finding.
In this study by Jamjoom et al[1], the authors found no significant difference between infected and uninfected cases with regard to the length of tunnelling. However, recent evidence although weak, points towards a preventive benefit of long tunnel EVDs over short tunnel EVDs.[4,5] Hence, a discussion about the role of tunnelling length in ERIs is felt missing in the paper.
Korinek et al, in their study to test the effect of a strict protocol of care on ERI, have postulated that frequent manipulation of EVD increases the risk of related infections.[6] Since the study by Jamjoom et al[1] was a prospective study, this strength could have been utilised in determining the role of frequent manipulation of EVD (eg. dressing, flushing the system, administering intrathecal drugs) for purposes other than CSF sampling.
Lastly, an analysis of the role of perioperative systemic antibiotics as a preventive measure in ERI could have been done as the evidence is still controversial in this regard.[6]
REFERENCES
1 Jamjoom AAB, Joannides AJ, Poon MT-C, et al. Prospective, multicentre study of external ventricular drainage-related infections in the UK and Ireland. J Neurol Neurosurg Psychiatry 2018;89:120–6. doi:10.1136/jnnp-2017-316415
2 Arabi Y, Memish ZA, Balkhy HH, et al. Ventriculostomy-associated infections: incidence and risk factors. Am J Infect Control 2005;33:137–43. doi:10.1016/j.ajic.2004.11.008
3 Clark WC, Muhlbauer MS, Lowrey R, et al. Complications of intracranial pressure monitoring in trauma patients. Neurosurgery 1989;25:20-4.
4 Omar MA, Mohd Haspani MS. The Risk Factors of External Ventricular Drainage-Related Infection at Hospital Kuala Lumpur: An Observational Study. Malays J Med Sci MJMS 2010;17:48–54.
5 Rafiq MFA, Ahmed N, Ali S. Effect of tunnel length on infection rate in patients with external ventricular drain. J Ayub Med Coll Abbottabad JAMC 2011;23:106–7.
6 Korinek A-M, Reina M, Boch AL, et al. Prevention of external ventricular drain--related ventriculitis. Acta Neurochir (Wien) 2005;147:39-45; discussion 45-46. doi:10.1007/s00701-004-0416-z
We read with great interest the research paper published recently by Lotia et al. entitled “Leg stereotypy syndrome: phenomenology and prevalence”. 1 The study brings important new information about an intriguing newly identified condition, previously designated by the same group as leg stereotypy disorder2, defined as repetitive, rhythmical, stereotypic leg movements, particularly noticeable while sitting.1,2 The authors describe the phenomenology and prevalence of leg stereotypy syndrome (LSS) by evaluating a total of 92 individuals, 57 from the general population (control group) and 35 with different movement disorders (Parkinson´s disease, restless legs syndrome, Tourette´s syndrome, and tardive dyskinesia).1 LSS was found in 7% of the control group and 17% of the movement disorders group, concluding that in terms of prevalence, this is a common condition.1 Another interesting finding was that all but one (83 %) of the patients with LSS from the movement disorders group also had a diagnosis of attention deficit hyperactivity disorder (ADHD).1 Lotia and colleagues do not believe in a relationship between ADHD and LSS1 stating in the discussion that “while certain movements or fidgetiness can be observed in individuals with anxiety or ADHD, the presence of typical stereotyped movements has not been previously described with ADHD”.1 Our group is currently studying the frequency of abnormal involuntary movements in patients with ADHD, compared a control group, and our pre...
We read with great interest the research paper published recently by Lotia et al. entitled “Leg stereotypy syndrome: phenomenology and prevalence”. 1 The study brings important new information about an intriguing newly identified condition, previously designated by the same group as leg stereotypy disorder2, defined as repetitive, rhythmical, stereotypic leg movements, particularly noticeable while sitting.1,2 The authors describe the phenomenology and prevalence of leg stereotypy syndrome (LSS) by evaluating a total of 92 individuals, 57 from the general population (control group) and 35 with different movement disorders (Parkinson´s disease, restless legs syndrome, Tourette´s syndrome, and tardive dyskinesia).1 LSS was found in 7% of the control group and 17% of the movement disorders group, concluding that in terms of prevalence, this is a common condition.1 Another interesting finding was that all but one (83 %) of the patients with LSS from the movement disorders group also had a diagnosis of attention deficit hyperactivity disorder (ADHD).1 Lotia and colleagues do not believe in a relationship between ADHD and LSS1 stating in the discussion that “while certain movements or fidgetiness can be observed in individuals with anxiety or ADHD, the presence of typical stereotyped movements has not been previously described with ADHD”.1 Our group is currently studying the frequency of abnormal involuntary movements in patients with ADHD, compared a control group, and our preliminary results have demonstrated that legs and foot stereotypies are actually very common in patients with ADHD (30 % ) (Teive et al., unpublished data). In fact, lower limbs stereotypies, such as fidgeting and foot movements (crossed-knee jiggle and uni or bilateral toe tap) was previously characterized by Wender, as a suggestive sign of ADHD in adult patients, often referred to as Wender´s sign.3 We believe that these findings may contribute to the understanding and phenomenological characterization of the new neurological syndrome described by Lotia et al.
References:
1. Lotia M, York MK, Strutt AM, Jankovic J. Leg stereotypy syndrome: phenomenology and prevalence. J Neurol Neurosurg Psychiatry 2018; 0: 1-4. Doi: 10.1136/jnnp-2017-317057
2. Jankovic J. Leg stereotypy disorder. J Neurol Neurosurg Psychiatry 2016; 87: 220-221.
3. Wender PH. Attention deficit hyperactivity disorder in adults. Oxford University Press, New York, 1995, pp. 23
Imai et al. examined the association between the dosing regimen of oral prednisolone (PSL) and the achievement of minimal manifestation status or better on PSL <=5 mg/day lasting >6 months in patients with generalized myasthenia gravis (1). The authors classified 590 patients into high-dose, intermediate-dose and low-dose (n=166) groups, and logistic regression analysis was applied to know the prognosis of patients in low-dose group, by splitting observational period into 1 to 3 years of treatment. The authors concluded that a low-dose PSL regimen with early combination of other treatment options was significantly associated with good prognosis. I have two concerns about their study.
First, the dosing regimen of oral PSL should be considered with caution. Namely, the authors set the maximum dose of oral PSL in each group, and standard treatment schedule was selected after each patient was allocated. Mean daily dose of PSL does not become highest in high-dose group in the study, which happens in the study protocol. In addition, there is a possibility of higher frequency in patients with combination of other treatment options, when patients were registered into low-dose group. As the age of onset was higher and disease duration was shorter in patients with low-dose group, randomized allocation should be strictly conducted in further study.
Second, the number of events was not enough after 1 year observation, and higher odds ratios with wide ranges of con...
Imai et al. examined the association between the dosing regimen of oral prednisolone (PSL) and the achievement of minimal manifestation status or better on PSL <=5 mg/day lasting >6 months in patients with generalized myasthenia gravis (1). The authors classified 590 patients into high-dose, intermediate-dose and low-dose (n=166) groups, and logistic regression analysis was applied to know the prognosis of patients in low-dose group, by splitting observational period into 1 to 3 years of treatment. The authors concluded that a low-dose PSL regimen with early combination of other treatment options was significantly associated with good prognosis. I have two concerns about their study.
First, the dosing regimen of oral PSL should be considered with caution. Namely, the authors set the maximum dose of oral PSL in each group, and standard treatment schedule was selected after each patient was allocated. Mean daily dose of PSL does not become highest in high-dose group in the study, which happens in the study protocol. In addition, there is a possibility of higher frequency in patients with combination of other treatment options, when patients were registered into low-dose group. As the age of onset was higher and disease duration was shorter in patients with low-dose group, randomized allocation should be strictly conducted in further study.
Second, the number of events was not enough after 1 year observation, and higher odds ratios with wide ranges of confidence interval were observed. As the follow-up period become longer, odds ratios become small, although significance disappeared in comparison between low-dose and high-dose groups after 3 year observation. I suppose that confounders for the prognosis were not completely adjusted, and there is a limitation of study design in multicentre cross-sectional study.
Reference
1. Imai T, Utsugisawa K, Murai H, et al. Oral corticosteroid dosing regimen and long-term prognosis in generalised myasthenia gravis: a multicentre cross-sectional study in Japan. J Neurol Neurosurg Psychiatry 2017 Nov 24. doi: 10.1136/jnnp-2017-316625
Ryuji Kaji MD, PhD
Department of Neurology, Tokushima University
I appreciate Dr Popkirov’s unique and interesting views and comments related to our paper [1]. This reminds me of the gating of sensory inputs at various levels of the nervous system, and their perception is not a passive but is a very active process. In addition to the fact that it is not possible to tickle oneself, other sensory phenomena associated with abnormal movements deserve mention. Restless legs syndrome is characterized by constant urge to move legs, and is successfully managed by dopamine agonists. Tics are also preceded by sensory symptoms. These could be examples of aberrant sensory inputs coming to the conscious level, which would normally be handled at subconscious pathways. At this moment, the exact role of the cerebellar pathway in these conditions is not clear, but should be investigated in the future aside from dystonia.
1. Kaji R, Bhatia K, Graybiel AM. Pathogenesis of dystonia: is it of cerebellar or basal ganglia origin? J Neurol Neurosurg Psychiatry. 2017 Oct 31. pii: jnnp-2017-316250. doi: 10.1136/jnnp-2017-316250. [Epub ahead of print]
No conflict of interest declared
Dear Editor,
We read with great interest the article of Boentert et al.1 recently published on this journal. In their paper, the authors describe polysomnographic findings in a large series of non-ventilated patients with amyotrophic lateral sclerosis (ALS). One of the points the authors underscore is that in their patients most respiratory events during sleep were of the obstructive, and not of the central type. This finding is in agreement with what described by Kimura,2 but not by several other authors who found that most respiratory events were of the central type.3 Furthermore, the authors of this paper did not find that obstructive apneas were preferentially associated with bulbar ALS, similarly to David et al.4 but unlike what described by Santos et al.5 However, the tables in the article show that most of the respiratory events were hypopneas, whose type was not specified.
Criteria for scoring sleep disordered breathing events have changed over time, especially as regards hypopneas. Only recently a general rule for type of hypopnea, central or obstructive has been proposed. Obstructive hypopneas are those where at least one of three criteria is met during the event: presence of snoring, flow limitation demonstrated by a flattening of the nasal pressure derived flow signal, opposing thoracic and abdominal movements. Absence of all these criteria characterizes central hypopneas.6 However, standard criteria for apneas and hypopneas fit well to patients wi...
Dear Editor,
We read with great interest the article of Boentert et al.1 recently published on this journal. In their paper, the authors describe polysomnographic findings in a large series of non-ventilated patients with amyotrophic lateral sclerosis (ALS). One of the points the authors underscore is that in their patients most respiratory events during sleep were of the obstructive, and not of the central type. This finding is in agreement with what described by Kimura,2 but not by several other authors who found that most respiratory events were of the central type.3 Furthermore, the authors of this paper did not find that obstructive apneas were preferentially associated with bulbar ALS, similarly to David et al.4 but unlike what described by Santos et al.5 However, the tables in the article show that most of the respiratory events were hypopneas, whose type was not specified.
Criteria for scoring sleep disordered breathing events have changed over time, especially as regards hypopneas. Only recently a general rule for type of hypopnea, central or obstructive has been proposed. Obstructive hypopneas are those where at least one of three criteria is met during the event: presence of snoring, flow limitation demonstrated by a flattening of the nasal pressure derived flow signal, opposing thoracic and abdominal movements. Absence of all these criteria characterizes central hypopneas.6 However, standard criteria for apneas and hypopneas fit well to patients with sleep apnea syndromes, but may be difficult to use in patients with other disorders, and in particular in those with neuromuscular diseases.
The separate occurrence of central and obstructive hypopneas was reported in some ALS studies, although standard criteria were not applied. However, a sharp separation of obstructive and central hypopneas in patients with ALS may be difficult, either using standard criteria or not, and often factitious. A clear flattening of the flow signal may not be clearly identified with a weak flow signal. Paradoxical thoraco-abdominal movements may be the effect not only of upper airway narrowing but also of respiratory muscle weakness. Finally, perhaps most importantly, presence of obstruction during a hypopnea does not exclude a simultaneous reduction of respiratory drive, thus a concomitant central genesis of the event.
Even when dealing with apneas, the precise nature of an event in neuromuscular patients is often dubious based on its polygraphic appearance. In the International Classification of Sleep Disorders, central apneas are indicated as the result of a failure of ventilatory control centers to initiate ventilatory effort.7 However, in common practice central apneas are identified by the absence of respiratory movements on polygraphic recordings, although it may not be always easy to precisely identify the pathogenesis of an event based on its polygraphic expression. In neuromuscular patients, many apneas are associated with very small movements. That may lead different scorers to classify them as either central or obstructive. Some authors suggested to introduce the new category of “pseudocentral apneas” to indicate events occurring when the contraction of respiratory muscles is too weak to maintain breathing, which may be more often seen in phasic REM sleep.8 During these events, deflections in the traces of the respiratory movements are very small. Despite their polygraphic aspect resembles apneas more often of the central type, their pathogenesis depends more on peripheral that on central causes. This category of events is not taken in consideration by most authors studying neuromuscular patients. Probably, a non-uniform way to score respiratory events in ALS is one reason for some discrepancies among studies.
We are aware that a correct identification of central and obstructive events is important, because they require different ventilatory approaches that may have a strong influence on sleep quality, therapy acceptance and, in the long-term, disease evolution and survival. Use of positive expiratory pressure, which is mandatory when obstructive events are present, is not only useless, but also questionable in case of absence of upper airway obstruction, as it enhances patient-ventilator asynchronies and sympathetic nervous system tone during sleep.9
Possibly, criteria for scoring sleep disordered breathing events in non-ventilated patients with neuromuscular diseases should be better standardized. They could be useful to have a better agreement among physicians who evaluate polysomnographic recordings, and to better guide in the choice of an appropriate therapeutic strategy.
REFERENCES
1 Boentert M, Glatz C, Helmle C, et al. Prevalence of sleep apnoea and capnographic detection of nocturnal hypoventilation in amyotrophic lateral sclerosis. J Neurol Neurosurg Psychiatry 2017 doi: 10.1136/jnnp-2017-316515.
2 Kimura K, Tachibana N, Kimura J, et al. Sleep-disordered breathing at an early stage of amyotrophic lateral sclerosis. J Neurol Sci 1999;164:37-43.
3 Aboussouan LS, Mireles-Cabodevila E. Sleep-Disordered Breathing in Neuromuscular Disease: Diagnostic and Therapeutic Challenges. Chest 2017;152:880-892.
4 David WS, Bundlie SR, Mahdavi Z. Polysomnographic studies in amyotrophic lateral sclerosis. J Neurol Sci 1997;152:29-35
5 Santos C, Braghiroli A, Mazzini L, et al. Sleep-related breathing disorders in amyotrophic lateral sclerosis. Monaldi Arch Chest Dis 2003;59:160-5.
6 Berry RB, Budhiraja R, Gottlieb DJ, et al. American Academy of Sleep Medicine. Rules for scoring respiratory events in sleep: update of the 2007 AASM Manual for the Scoring of Sleep and Associated Events. Deliberations of the Sleep Apnea Definitions Task Force of the American Academy of Sleep Medicine. J Clin Sleep Med 2012;8:597-619
7 American Academy of Sleep Medicine . International Classification of Sleep Disorders . 3rd ed. Darien, IL : American Academy of Sleep Medicine; 2014.
8 Gould GA, Gugger M, Molloy J, et al. Breathing pattern and eye movement density during REM sleep in humans. Am Rev Respir Dis 1988;138:874-7
9 Crescimanno G, Greco F, Arrisicato S, et al. Effects of positive end expiratory pressure administration during non-invasive ventilation inpatients affected by amyotrophic lateral sclerosis: A randomized crossover study. Respirology 2016;21:1307-13
We appreciate Dr. Laura S. Boylan’s interest in our article. However, her viewpoint rather strikingly exemplifies the behaviors that she mistakenly believes we were guilty of in our report, beginning with the “eminence based” statements “in my view” occurring twice in the first paragraph and her conclusion with a personal “old saw I use in teaching”. We strongly disagree with her misinterpretation about our application of “cognitive bias” in the selection of our patients for this case-control study. In fact, most patients with Parkinson’s disease (PD) had functional complications ascertained after several visits –requiring a diagnostic revision once they fulfilled the appropriate positive criteria.1 The diagnostic “delay” in part may have highlighted the absent recognition of functional comorbidities in PD prior to our study, forcing a conservative approach before ascertaining what may be considered a “second” diagnosis in these patients. Furthermore, in contrast to Dr. Boylan’s suggestion, we did not select patients on the basis of comorbid depression, anxiety, cognitive symptoms, pain, nausea, or fatigue. Instead these features segregated more commonly among cases than controls after the patient selection had been completed. She argues that we considered them “supportive” for a diagnosis of functional movement disorder, but we did not. We have instead emphasized the potentially misleading influence of both history and psychiatric features and argued in favor of a diagnos...
Show MoreIn my view the data presented in this study (1) which are interpreted as indicating a high prevalence of functional movement disorders (FMD) in PD might also be interpreted as suggesting that diagnostic delay is common in PD, particularly among women patients who present as "high maintenance" patients. The diagnosis of functional movement disorders is a matter of expert opinion and in my view problems with study design and interpretation support rather than minimize cognitive and confirmation bias in this study.
Show MoreSubjects all met UK brain bank criteria for PD. Subjects diagnosed with FND in this study had high rates of family history of PD. They had depression, anxiety, cognitive symptoms, pain, nausea, fatigue all common complaints among the population in general and most particularly in PD. The presence of these symptoms before or after diagnosis of PD is considered by the authors as supportive for a diagnosis of FMD. However, these same symptoms are known to be associated with PD and might be considered supportive of a PD diagnosis.
Disparities in healthcare for women are well established (2). Neurology has a long history of mistakes distinguishing the "functional" from the "organic" (e.g.3). To choose one example people with blepharospasm, mostly women, were institutionalized long-term as the disease was not recognized as neurologic. Women commonly encounter dismissal in the medical context and this can occasion missed opportuni...
Dear Editor,
We read with interest the study presented by Berg et al [1] that showed that prolonged mechanical ventilation (more than 2 months) in Guillain-Barre syndrome (GBS) was associated with poorer outcome and more residual deficits compared to non-ventilated GBS patients.
We recently found very similar results in the same population of patients. Nevertheless, it should be precised that despite this, we could not found any difference in quality of life compared to the general French population [2]. Berg et al. also found that ventilated patients were less likely to have residual fatigue symptoms compared to non-ventilated GBS patients, respectively 20% versus 54% (p=0.007). Among 13 prolonged mechanically ventilated GBS, we could show that 22% of patients displayed DSM IV criteria for long-term post-traumatic stress disorder (PTSD) [2]. Since one of our main hypothesis was that PTSD symptoms were mainly related to the mechanical ventilation, we assessed long-term PTSD in 20 non-ventilated GBS patients (Table). Unexpectedly, 65% of these non-ventilated patients had PTSD as compared to 22% in the ventilated group found in our previous study (Table). As for fatigue, we would have expected a correlation between the severity of the disease (especially mechanical ventilation), and the incidence of PTSD.
One explanation of these unexpected results could be that the acute stress induced by the temporary paralysis, the traumatic aspects of intubation an...
Show MoreDear Editor,
I read the article entitled "Patients with Parkinson disease are prone to functional neurological disorders" by Hallett M published in the Journal of Neurology, Neurosurgery and Psychiatry (Published Online First: 16 March 2018. doi: 10.1136/jnnp-2017-317684). I want to congratulate the author for this successful article, and make some contributions.
The article particularly mentions certain aspects of the clinical presentation, medical history and examination of patients, which should raise the suspicion of a functional disorder (1). I think it is important to remember patients with functional disorders will not always adhere to these criteria and clinicians should perhaps consider trialling suspected patients on either cognitive behavioural therapy (CBT) or physiotherapy to assess if they experience any improvement with these strategies. There is increasing evidence to show CBT and physiotherapy are beneficial for patients with functional disorders, hence they may be useful in confirming the diagnosis (2)(3).
Furthermore, the author suggests patients with functional symptoms and no sign of Parkinson's Disease should not be pursued further for a diagnosis of Parkinson's Disease. I think a difficulty is often deciding what classifies as a sign of Parkinson's Disease. The cardinal symptoms of bradykinesia, resting tremor, muscular rigidity and postural instability are commonly subtle within patients, making...
Show MoreWissel and colleagues recently reported on a large retrospective case series of patients with functional neurological disorder (FND) and Parkinson's disease (PD) [1]. The authors only briefly touched upon the question of shared pathophysiology, noting that in principle certain structural brain diseases may predispose to FND. The study was not designed to tease out any shared or causal pathways between FND and PD, but some speculation based on the presented data could help formulate useful hypotheses concerning this interesting comorbidity. I propose that a disruption of the central noradrenergic system due to degeneration of the locus loeruleus (LC), the sole source of noradrenaline in the brain with far-reaching projections, is a good candidate for a causal link between FND and (prodromal) PD.
Show MoreIn the study by Wissel and colleagues FND antedated the diagnosis of PD in 26% of cases, often by several years [1]. This is significant, because it nearly eliminates the possibility that the comorbidity is entirely a matter of symptom modelling or functional overlay in all cases. Considering the typical neuroanatomical progression of Lewy pathology in PD, this suggests that neurodegenerative effects within the lower brainstem (Braak stage 1 or 2) are likely structural candidates for a causal pathway. Early LC pathology has been associated with other premotor manifestations of Lewy pathology and PD such as REM sleep behaviour disorder and cognitive decline. A study using...
I read with great interest the paper by Jamjoom et al.[1] The authors have done commendable work in establishing a national external ventricular drain related infection (ERI) rate and elucidating the factors influencing it in the largest prospective multicentre study. However, some questions have been left unanswered in this respect.
Show MoreOne of the contributing factors to a low ERI rate in the study could have been the fact that majority (98.6%) of EVDs were inserted in the operating theatre. In their single centre retrospective study of 84 patients, Arabi et al[2] found that placement outside operating rooms was associated with a trend towards higher ERIs. Clark et al[3], in their retrospective review of complications of intracranial pressure monitoring in 140 trauma patients, noted that the incidence of major infectious complications (eg. clinical ventriculitis, subdural empyema, brain abscesses) was higher in the groups in which the catheter was placed in the intensive care unit. A randomised control trial would better examine the importance of this finding.
In this study by Jamjoom et al[1], the authors found no significant difference between infected and uninfected cases with regard to the length of tunnelling. However, recent evidence although weak, points towards a preventive benefit of long tunnel EVDs over short tunnel EVDs.[4,5] Hence, a discussion about the role of tunnelling length in ERIs is felt missing in the paper.
Korinek et al, in their stud...
We read with great interest the research paper published recently by Lotia et al. entitled “Leg stereotypy syndrome: phenomenology and prevalence”. 1 The study brings important new information about an intriguing newly identified condition, previously designated by the same group as leg stereotypy disorder2, defined as repetitive, rhythmical, stereotypic leg movements, particularly noticeable while sitting.1,2 The authors describe the phenomenology and prevalence of leg stereotypy syndrome (LSS) by evaluating a total of 92 individuals, 57 from the general population (control group) and 35 with different movement disorders (Parkinson´s disease, restless legs syndrome, Tourette´s syndrome, and tardive dyskinesia).1 LSS was found in 7% of the control group and 17% of the movement disorders group, concluding that in terms of prevalence, this is a common condition.1 Another interesting finding was that all but one (83 %) of the patients with LSS from the movement disorders group also had a diagnosis of attention deficit hyperactivity disorder (ADHD).1 Lotia and colleagues do not believe in a relationship between ADHD and LSS1 stating in the discussion that “while certain movements or fidgetiness can be observed in individuals with anxiety or ADHD, the presence of typical stereotyped movements has not been previously described with ADHD”.1 Our group is currently studying the frequency of abnormal involuntary movements in patients with ADHD, compared a control group, and our pre...
Show MoreImai et al. examined the association between the dosing regimen of oral prednisolone (PSL) and the achievement of minimal manifestation status or better on PSL <=5 mg/day lasting >6 months in patients with generalized myasthenia gravis (1). The authors classified 590 patients into high-dose, intermediate-dose and low-dose (n=166) groups, and logistic regression analysis was applied to know the prognosis of patients in low-dose group, by splitting observational period into 1 to 3 years of treatment. The authors concluded that a low-dose PSL regimen with early combination of other treatment options was significantly associated with good prognosis. I have two concerns about their study.
First, the dosing regimen of oral PSL should be considered with caution. Namely, the authors set the maximum dose of oral PSL in each group, and standard treatment schedule was selected after each patient was allocated. Mean daily dose of PSL does not become highest in high-dose group in the study, which happens in the study protocol. In addition, there is a possibility of higher frequency in patients with combination of other treatment options, when patients were registered into low-dose group. As the age of onset was higher and disease duration was shorter in patients with low-dose group, randomized allocation should be strictly conducted in further study.
Second, the number of events was not enough after 1 year observation, and higher odds ratios with wide ranges of con...
Show MoreRyuji Kaji MD, PhD
Department of Neurology, Tokushima University
I appreciate Dr Popkirov’s unique and interesting views and comments related to our paper [1]. This reminds me of the gating of sensory inputs at various levels of the nervous system, and their perception is not a passive but is a very active process. In addition to the fact that it is not possible to tickle oneself, other sensory phenomena associated with abnormal movements deserve mention. Restless legs syndrome is characterized by constant urge to move legs, and is successfully managed by dopamine agonists. Tics are also preceded by sensory symptoms. These could be examples of aberrant sensory inputs coming to the conscious level, which would normally be handled at subconscious pathways. At this moment, the exact role of the cerebellar pathway in these conditions is not clear, but should be investigated in the future aside from dystonia.
1. Kaji R, Bhatia K, Graybiel AM. Pathogenesis of dystonia: is it of cerebellar or basal ganglia origin? J Neurol Neurosurg Psychiatry. 2017 Oct 31. pii: jnnp-2017-316250. doi: 10.1136/jnnp-2017-316250. [Epub ahead of print]
No conflict of interest declared
Dear Editor,
Show MoreWe read with great interest the article of Boentert et al.1 recently published on this journal. In their paper, the authors describe polysomnographic findings in a large series of non-ventilated patients with amyotrophic lateral sclerosis (ALS). One of the points the authors underscore is that in their patients most respiratory events during sleep were of the obstructive, and not of the central type. This finding is in agreement with what described by Kimura,2 but not by several other authors who found that most respiratory events were of the central type.3 Furthermore, the authors of this paper did not find that obstructive apneas were preferentially associated with bulbar ALS, similarly to David et al.4 but unlike what described by Santos et al.5 However, the tables in the article show that most of the respiratory events were hypopneas, whose type was not specified.
Criteria for scoring sleep disordered breathing events have changed over time, especially as regards hypopneas. Only recently a general rule for type of hypopnea, central or obstructive has been proposed. Obstructive hypopneas are those where at least one of three criteria is met during the event: presence of snoring, flow limitation demonstrated by a flattening of the nasal pressure derived flow signal, opposing thoracic and abdominal movements. Absence of all these criteria characterizes central hypopneas.6 However, standard criteria for apneas and hypopneas fit well to patients wi...
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