eLetters

572 e-Letters

  • Reply to “The eye of the beholder and risks of eminence based medicine”

    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...

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  • The eye of the beholder and risks of eminence based medicine

    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...

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  • Paradoxal increased incidence of post-traumatic stress disorder in non-mechanically ventilated Guillain-Barré syndrome patients: the role of resilience?

    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...

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  • Aiding diagnosis of suspected patients with Parkinson's Disease and functional disorders

    Dear 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...

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  • Degeneration of the locus coeruleus in premotor Parkinson's disease could predispose to functional neurological disorders

    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...

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  • Factors influencing EVD related infections: unanswered questions

    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...

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  • Leg stereotypy syndrome

    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...

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  • Dosing regimen of oral prednisolone and prognosis in patients with generalized myasthenia gravis

    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...

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  • Response

    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

  • Classification of respiratory events in amyotrophic lateral sclerosis: diagnostic and therapeutic challenges

    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...

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