eLetters

602 e-Letters

  • COVID-19 associated Myasthenic crisis

    We appreciate the authors for describing their patients’ data in myasthenia with COVID-19 which would help clinicians caring for such patients.1 We have the following comments and queries. We would like to point out that, three out of the four patients who had SARS-CoV-2 infection were not having any infiltrates on chest x-ray, suggesting that these patients had mild COVID-19 infection.2 It is also noteworthy that all these patients who had a normal chest radiograph were either on very low dose azathioprine or no immunosuppressant apart from low dose steroids. As the authors rightly point out, the myasthenia disease activity prior to infection with SARS-CoV-2 is an important predictor of the severity of the myasthenic crisis. It is possible that patients with better control of symptoms or those on appropriate immunosuppression don’t develop a crisis with mild COVID-19. Secondly, it would be interesting to know what specific therapy for COVID-19 was offered to these patients. It is possible that steroids given as a part of therapy for COVID-19 could also act to stabilize disease activity in myasthenia. Similarly, IVIg given to manage Myasthenic crisis could have prevented progression in the severity of COVID-19. Likewise, myasthenic patients who receive drugs such as hydroxychloroquine and macrolides can have precipitation of myasthenic crisis.3,4 In case 2, we would also be interested to know if other causes of chest pain and breathlessness like pulmonary thromboembolism w...

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  • Further research required to support a causative association between GBS and COVID-19

    To the Editor

    We were interested to read the study of Filosto et al [1] concluding a significant link between Guillain-Barre Syndrome (GBS) and COVID-19 infection in Northern Italy at the peak of the 1st wave SARS-CoV2 pandemic. We urge caution in accepting such a causative conclusion using a retrospective observational study; causation is not conclusively proven and is drawn from potentially biased data and small case numbers of a rare condition, and a rate calculation without confidence intervals to infer uncertainty.

    Only 34 cases of GBS, of whom 30 were COVID-19 positive, are reported over a 2-month period, with a denominator population of 8,400,107. We calculated the 95% confidence intervals of the incidence rates as 0.08 per 100,000 per month (95% C.I.: 0.04-0.15) in 2019 and 0.2 per 100,000 per month (95% C.I.: 0.14-0.28) in 2020. The overlapping confidence intervals do not support a statistically significant increase in GBS rates from 2019 to 2020. Furthermore, the simple multiplication of the monthly rate by 12 to create an approximate annualised incidence potentially amplifies the inaccuracy. We suggest that the 2.6-fold difference in GBS incidence from 2019 to 2019 is prone to meaningful statistical error.

    During the initial stages of the pandemic the denominator of COVID-19 positive cases will have been under-reported because testing was limited to the symptomatic and presenting populations. We are told that 62,679 inhabitants of the regi...

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  • Vibration therapy for Parkinson's disease: another lesson from Charcot

    We read with great interest the article by Macerollo et al. entitled “Non-invasive intervention for motor signs of Parkinson’s Disease: the effect of vibratory stimuli.”[1] The authors evaluated the use of a wearable device called the "Emma Watch" that produces a constant vibratory stimulus (200 Hz) to the wrist with frequencies of 20 bpm or 60 bpm in terms of motor function of the arms of 16 patients with Parkinson’s disease (PD).[1] Motor performance was assessed through three different tasks: a nine-peg hole test, a STYAR tracing task, and a SPIRAL tracking test.[1] The authors found that patients with PD who used the device with 200 Hz peripheral vibration modulated by 60 bpm as they carried out these tasks performed better in terms of speed and precision.[1] The final conclusion was that vibrotactile stimulation can improve motor function in patients with PD.[1] It is important to comment that the authors did not discuss their results in terms of other studies in the literature, including one systematic review published in 2014 [2] and another with a meta-analysis published in 2020. [3] In these studies, vibratory stimulation in patients with PD was generally seen to yield positive results with regard to balance and gait. [2,3] From a historical point of view, the pioneering and seminal work of Jean-Martin Charcot, who used a vibrating chair to treat patients with PD, should also be noted.[4,5]

    1. Macerollo A, Holz C, Cletheror D, et al. Non-invasiv...

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  • Large data, but what is the implication comparing the aneurysm discovered by bleeding and those by other reasons?

    Dear editor,
    We read with great interest the article by Rousseau et al. “Location of intracranial aneurysms is the main factor associated with rupture in the ICAN population.”1
    They compared ruptured intracranial aneurysms (RIAs) with unruptured cerebral aneurysms (UCAs) in the ICAN registry, and analyzed factors that were considered associated with subarachnoid hemorrhage in previous literature. As a result, they found the location of the aneurysm showed the largest hazard ratio as much as 6.05 and showed their result with beautiful info-graphic.
    We should be careful that their result is derived from comparisons between the aneurysms, which caused subarachnoid hemorrhage and UCAs that was found without bleeding. Hence, the meaning is different from that of ISUIA2, UCAS Japan3, and other studies, which investigated the risk of bleeding from the known UCAs. As noted in the discussion of the headache, which prefers UCAs to RIAs, the factors examined may be seeing factors, which lead to brain examination without causing subarachnoid hemorrhage in France.
    As in the title, they focused on the location of the aneurysm, and found ACA and posterior circulation aneurysms have high odds ratio of 4.99 and 6.05 respectively comparing with ICA aneurysms. As in ISUIA study, they included internal carotid- posterior communicating artery (IC-Pcom) aneurysms in the posterior circulation aneurysms, and “ICA” includes other aneurysms occurring on the ICA. However...

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  • Parkinson's disease determinants, prediction and gene-environment interactions

    Jacobs et al. investigated the association of environmental factors and prodromal features with incident Parkinson's disease (PD) with special reference to the interaction of genetic factors [1]. The authors constructed polygenic risk scores (PRSs) for the risk assessment. Family history of PD, family history of dementia, non-smoking, low alcohol consumption, depression, daytime somnolence, epilepsy and earlier menarche were selected as PD risk factors. The adjusted odds ratio (OR) (95% confidence interval [CI]) of the highest 10% of PRSs for the risk of PD was 3.37 (2.41 to 4.70). I have some concerns about their study.

    Regarding risk/protective factors of PD, Daniele et al. conducted a case-control study to performed a simultaneous evaluation of potential factors of PD [2]. Among 31 environmental and lifestyle factors, 9 factors were extracted by multivariate analysis. The adjusted OR (95% CI) of coffee consumption, smoking, physical activity, family history of PD, dyspepsia, exposure to pesticides, metals, and general anesthesia were 0.6 (0.4-0.9), 0.7 (0.6-0.9), 0.8 (0.7-0.9), 3.2 (2.2- 4.8), 1.8 (1.3-2.4), 2.3 (1.3- 4.2), 5.6 (2.3-13.7), 2.8 (1.5-5.4), and 6.1 (2.9-12.7), respectively. Family history of PD and non-smoking were common risk factors, which had also been reported by several prospective studies.

    Regarding smoking, Angelopoulou et al. investigated the association between environmental factors and PD subtypes (early-onset, mid-and-late on...

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  • Pain Responsiveness: A Useful Clinical Tool?

    The recently published paper ‘Abnormal pain perception is associated with thalamo-cortico-striatal atrophy in C9orf72 expansion carriers in the GENFI cohort’ by Convery et al.[1] draws attention to a topic of great importance in the field of frontotemporal dementia (FTD) research. In this study, Convery and colleagues investigated differences in pain responsiveness within a group of patients with genetic FTD. Changes in pain responsiveness compared to baseline were captured using a scale designed by the group, and patients were scored from 0-3 (0 = no change, 0.5 = questionable or very mild change, 1 = mild change, 2 = moderate change, 3 = severe change). Within the sample, symptomatic C9orf72 mutation carriers (9/31) experienced greater changes in pain responsiveness than symptomatic MAPT (1/10) and GRN (1/24) mutation-carriers or normal controls (1/181). Within the C9orf72 mutation carriers, these changes were associated with thalamo-cortico-striatal atrophy.
    This research brings attention to an important but little-investigated clinical feature of FTD. Changes in pain responsiveness, including both increases and decreases, have now been reported in both sporadic and genetic FTD, along with other somatic complaints.[1–4] However, the changes are not widely captured in either clinical or research settings, and the field lacks standardized and objective measurements to do so. The ability to measure changes in pain responsiveness may be a useful clinical marker to di...

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  • Reply to: Mental health and suicide in former professional soccer players

    We thank White and colleagues for their correspondence on our article(1) and note many of the observations raised are already addressed by our robust study design and discussed in the original manuscript text. Importantly, we are quite clear throughout that this is a study designed to investigate whether there is higher risk of common mental health disorder in former professional soccer players than anticipated from general population controls.

    Undoubtedly, there will be physically active individuals in our general population control group, including a number who might have participated in some form of contact sport. However, we would suggest this does not define our over 23,000 matched general population controls as a cohort of ‘non-elite’ athletes, as proposed by White et al. Instead, we would assert this merely underlines their legitimacy as a general population control cohort for comparison with our cohort of almost 8000 former professional soccer players.

    Potential study limitations regarding healthy worker effect, illness behavior in former professional soccer players and use of hospitalization datasets are addressed in detail in our manuscript text. Regarding data on duration of hospital stay and therapy, while these might indeed be of interest in follow-on studies regarding illness severity, we would suggest that they are not immediately relevant to a study designed to address risk of common mental health disorder.

    As White et al observe, wh...

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  • Response to: Mental health and suicide in former professional soccer players

    Russell et al. (1) published a retrospective cohort study with a population of former professional soccer players with known high neurodegenerative mortality. Findings showed that they are at lower risk of common mental health disorders and have lower rates of suicide than a matched general population. These findings are surprising and different from previous studies, which have used first-hand clinical accounts of ex-athletes who have lived with neurodegeneration (1). We suggest there may be reasons for this disparity and welcome critical dialogue with the authors of this research.

    Cohort Comparison
    Russell et al. has compared their soccer cohort with a matched population cohort. However, the matched cohort may also include those who have experienced repetitive head impacts, such as amateur soccer players, rugby players or boxers. Therefore, the study represents differences of elite versus non-elite rather than sport versus non-sport. While Russell recognises the healthy worker effect (2), it may have a greater influence in this study than presented.

    Soccer Stoicism
    Men’s engagement in health-seeking behaviours has been a long-standing concern in health care and is often attributed to factors such as stigma, hypermasculinity and stoicism (3). Furthermore, working-class sports such as soccer, require the acceptance of pain, suffering, and physical risk, so these players are more likely to ‘suffer in silence’ than the general population (4). Give...

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  • Guillain-Barre syndrome and other neurological complication in SARS-CoV-2: Role of antiganglioside antibodies and treatment option

    I read an interesting case report of GBS with antiganglioside antibodies in SARS-CoV-2 by Civardi et al1. We are also seeing various complications like GBS, pseudotumorcerebri, precipitation of stroke, seizures etc2 but do not have the access to antiganglioside antibodies but, all those who can afford and get it done we should try for that and get it documented for academic and research purpose in this pandemic of modern time of advanced technology. We may screen for ganglioside antibodies to assess autoimmunity in Covid-19 patients3. The gangliosides are particularly abundant in the brain and in the nervous system; they participate in maintenance and repair of neuronal cells, memory formation and synaptic transmission4. So we have to be watchful in this regard towards impairment of these neurological functions i.e. new autoimmune disorder like GBS, multiple sclerosis(MS), neuromyelitis optica spectrum disorders(NMO-SD), chronic inflammatory demyelinating neuropathy(CIDP) etc. and precipitation of neurodegenerative and cognitive disorders in acute, convalescent ant post recovery follow up. Of course the paediatric population is less affected but as the gangliodides also take part in the development and regeneration of neurons the SARS-CoV-2 may affect the growth and development of paediatric population.
    As the intravenous immunoglobulins(IVIg) and plasmapharesis are useful in the treatment of GBS with antiganglioside antibodies the trial of IVIg, and monoclonal a...

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  • Response to Larrabee et al

    We read Larrabee and colleagues’ e-letter response to our systematic review on Performance Validity Testing (PVT). Whilst we welcome debate, and we recognize that some clinicians will disagree with our conclusions, we were disappointed that they misrepresented our paper in formulating their response:

    1. The authors state “Throughout the paper, the authors refer to PVTs as “effort tests”, a characterization that is no longer in use in the United States..”. In reality we used the term “effort test” only twice in our paper; in the introduction: “(PVTs), also historically called effort tests” and once in the methods in describing our search terms. By contrast we use the term PVT on 45 occasions.

    2. We are concerned that they then go on to misrepresent the results of our review. We found a wide variation in results in different clinical groups and in different tests. We noted that failure rates for some groups and some tests exceeds 25%. We did not conclude that all failure rates were as high as this, but rather that failing a PVT was not a rare phenomenon but was reasonably common in a range of clinical groups.

    We presented results to support our conclusion that the PVT literature is problematic with regards to blinding to diagnosis and potential for selection bias.

    We also uphold our speculation that an alternate explanation for failure on forced choice tests at above chance cutoffs may result from attentional deficit related to other symptoms. W...

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