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Background and ObjectiveMyotonic dystrophy types 1 and 2 are progressive multisystem genetic disorders whose core clinical feature is myotonia. Mexiletine, an antagonist of voltage-gated sodium channels, is a recommended antimyotonic agent in the nondystrophic myotonias, but its use in myotonic dystrophy is limited because of lack of data regarding its long-term efficacy and safety profile.MethodsTo address this issue, this study retrospectively evaluated patients with myotonic dystrophy receiving mexiletine over a mean time period of 32.9 months (range 0.1–216 months).ResultsThis study demonstrated that 96% of patients reported some improvement in myotonia symptoms with mexiletine treatment. No clinically relevant cardiac adverse events were associated with the long-term use of mexiletine.ConclusionsThese findings support that mexiletine is both safe and effective when used long-term in myotonic dystrophy.Classification of EvidenceThis study provides Class IV evidence that mexiletine is a well-tolerated and effective treatment for myotonic dystrophy types 1 and 2.

Reports of Guillain-Barré syndrome (GBS) have emerged during the Coronavirus disease 2019 (COVID-19) pandemic. This epidemiological and cohort study sought to investigate any causative association between COVID-19 infection and GBS. The epidemiology of GBS cases reported to the UK National Immunoglobulin Database was studied from 2016 to 2019 and compared to cases reported during the COVID-19 pandemic. Data were stratified by hospital trust and region, with numbers of reported cases per month. UK population data for COVID-19 infection were collated from UK public health bodies. In parallel, but separately, members of the British Peripheral Nerve Society prospectively reported incident cases of GBS during the pandemic at their hospitals to a central register. The clinical features, investigation findings and outcomes of COVID-19 (definite or probable) and non-COVID-19 associated GBS cases in this cohort were compared. The incidence of GBS treated in UK hospitals from 2016 to 2019 was 1.65–1.88 per 100 000 individuals per year. GBS incidence fell between March and May 2020 compared to the same months of 2016–19. GBS and COVID-19 incidences during the pandemic also varied between regions and did not correlate with one another (r = 0.06, 95% confidence interval: −0.56 to 0.63, P = 0.86). In the independent cohort study, 47 GBS cases were reported (COVID-19 status: 13 definite, 12 probable, 22 non-COVID-19). There were no significant differences in the pattern of weakness, time to nadir, neurophysiology, CSF findings or outcome between these groups. Intubation was more frequent in the COVID-19 affected cohort (7/13, 54% versus 5/22, 23% in COVID-19-negative) attributed to COVID-19 pulmonary involvement. Although it is not possible to entirely rule out the possibility of a link, this study finds no epidemiological or phenotypic clues of SARS-CoV-2 being causative of GBS. GBS incidence has fallen during the pandemic, which may be the influence of lockdown measures reducing transmission of GBS inducing pathogens such as Campylobacter jejuni and respiratory viruses.

BackgroundReports of Guillain-Barré Syndrome (GBS) have emerged during the Coronavirus Disease 2019 (COVID-19) pandemic. This epidemiological and cohort study sought to investigate any causative association between COVID-19 infection and GBS.MethodsThe epidemiology of GBS cases reported via the UK National Immunoglobulin Database were studied from 2016-2019 and compared to cases reported during the COVID-19 pandemic. For the cohort study, members of the British Peripheral Nerve Society reported all cases of GBS during the pandemic. The clinical features, investigation findings and outcomes of COVID-19 (definite or probable) and non-COVID-19 associated GBS cases were compared.ResultsThe UK GBS incidence from 2016-2019 was 1.65-1.88 per 100,000 people per year. GBS and COVID-19 incidence varied between regions and did not correlate (r = 0.06, 95% CI −0.56 to 0.63, p=0.86). GBS incidence fell between March and May 2020 compared to the same months of 2016-2019. Forty-seven GBS cases were included in the cohort study (13 definite, 12 probable COVID-19 and 22 non-COVID-19). There were no significant differences in the pattern of weakness, time to nadir, neurophysiology, CSF findings or outcome. Intubation was more frequent in the COVID-19+ve cohort (7/13, 54% vs 5/22, 23% in COVID negative) thought to be related directly to COVID-19 pulmonary involvement.ConclusionsThis study finds no epidemiological or phenotypic clues of SARS-CoV-2 being causative of GBS. GBS incidence has fallen during the pandemic which may be the influence of lockdown measures reducing transmission of GBS inducing pathogens such as Campylobacter jejuni and respiratory viruses.

Context: Syringobulbia is a very rare progressive disorder of central nervous system, with several possible underlying conditions. Rarely, it is also encountered as a late complication of syringomyelia. Findings: In the present manuscript, a case of a paraplegic patient, due to traumatic spinal cord injury (thoracolumbar fracture), presenting after years progressively developing symptoms of the lower cranial nerves and upper extremities, owed to syringomyelia and syringobulbia, the surgical treatment applied and its outcomes are described. We performed a syringo-peritoneal shunting procedure using a T-tube. The patient's symptoms resolved postoperatively and the cavity's size was reduced to a great degree. Conclusion/Clinical Relevance: The late appearance of cranial nerve deficits or symptoms—signs of the upper extremities in a patient with traumatic thoracic spinal cord injury should raise suspicion that post-traumatic syringomyelia or syringobulbia has occurred. In such cases, radiologic evaluation and early surgical drainage of the cyst as a means of preventing significant delayed neurologic deficit is advocated.

Background Olfactory loss is common in Parkinson’s disease (PD), can distinguish PD from other disorders, and may even identify prodromal PD. However, olfaction worsens with ageing, and is poorer in men than women, so clear definitions are required to interpret olfaction test results. Objectives To collate types of olfaction identification tests used in the assessment of PD, and the definitions for hyposmia that were used. Methods Published papers with original data using olfaction identification tests in patients with PD, or possible prodromal PD, were categorised according to the methods used. Results Four main methods of commercially produced olfaction testing were reported. Analysis methods varied as follows: (1) Raw score values (number of items correct/total number of items), sometimes using age/sex matching with controls, or applying age and/or sex as a covariate in statistical analysis; (2) Cut-offs from score values to categorise as normosmic/hyposmic, although different cut-points were applied between some studies; or (3) Values below age- and sex-derived centiles or standard deviations. Conclusions Significant variations in methods for testing olfaction and defining hyposmia are problematic. However, standardisation of the definition of hyposmia in PD in future studies is feasible, based on a minimum set of age and sex stratification criteria.