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Introduction/aims: Hyperexcitable peripheral nerve disorders (HPNDs) are rare. Although their clinical and laboratory features have been well studied, information on treatment and follow-up is limited. The aim of this study is to explore the long-term clinical, investigative, and therapeutic profile of patients with acquired HPNDs., Methods: This study retrospectively analyzed patients from a single tertiary care center with HPND (January 2012 to January 2022). Patients were recruited according to published inclusion and exclusion criteria. Details of clinical features, diagnostic tests, therapeutic interventions, and follow-up were recorded. This study included patients with follow-up of 2 or more years., Results: A total of 32 patients (M = 26, F = 6) were studied. The common clinical features included myokymia, neuropathic or shock-like pain, cramps, sleep disturbances, encephalopathy, cerebellar ataxia, and seizures. A total of 81.25% of patients responded favorably to corticosteroids and membrane stabilizers. Among the nonresponders, five received intravenous immunoglobulin (IVIG), and one received plasma exchange (PLEX). Two patients required rituximab due to poor responses to the above treatments. The mean duration of response was 6 weeks (4-24 weeks) from the initiation of treatment. All patients had favorable outcomes, reaching clinical remission within 1-5 years from the initiation of treatment. Only two patients had relapses. Immunotherapy could be stopped in 78% of patients within 3 years and 100% by 5 years., Discussion: Chronic immunosuppression starting with corticosteroids is required for satisfactory outcomes of HPNDs. These disorders usually run a monophasic course, and relapses are uncommon., (© 2023 Wiley Periodicals LLC.)

Background: GNE myopathy is widely regarded as a distal myopathy. Involvement of proximal musculature in this condition has not been systematically studied., Methods: The phenotype of genetically confirmed patients with GNE myopathy was analyzed. Fourteen groups of muscles were evaluated with Medical Research Council (MRC) grading and the average muscle scores (AMS:1-10) were calculated., Results: Fully documented AMS data was available in 31 of 65 patients. It showed a consistent pattern of severe weakness of hip adductors, hip flexors, knee flexors, and foot dorsiflexors, with milder weakness of the hip extensors and abductors. The knee extensors were largely unaffected. The proximal weakness appeared early in the course of the disease. Proximal muscle weakness was also present in the remaining 34 patients in whom the data were limited. A variant in exon 13 (c.2179G > A) was very common (81.5%)., Conclusions: The GNE phenotype in this Indian cohort exhibited mixed proximal and distal involvement. Weakness of adductors and flexors of the hip formed an integral part of the phenotype., (© 2020 Wiley Periodicals LLC.)

Introduction: Chronic immune polyradiculopathies (sensory, motor, and mixed) are uncommon., Methods: In this single-center, retrospective study, the inclusion criteria for participants were progressive sensory ataxia and/or areflexic limb weakness; tibial somatosensory evoked potential (SSEP) abnormalities of the N22 and P40 potentials with normal sensory and motor nerve conduction studies or root involvement, according to magnetic resonance imaging (MRI); and albuminocytological dissociation., Results: Eight patients were included in our study. Two had weakness, two had sensory ataxia, and four had both weakness and ataxia. Patients with weakness had abnormal SSEPs and patients with sensory ataxia also had absent F waves. Electromyography showed chronic denervation. MRI scans confirmed thickening and enhancement of roots. The patients responded to corticosteroid treatment., Discussion: The overlapping clinicoelectrophysiological findings and similarities in radiological and therapeutic responses suggest that these entities are clinical variants of the same disease. The terms CIS(m)P, CI(s)MP, and CISMP (for chronic immune sensory motor polyradiculopathy) could be used to denote the predominant clinical involvement., (© 2020 Wiley Periodicals LLC.)

Introduction: Clinical heterogeneity of limb-girdle muscular dystrophies (LGMDs, 24 known subtypes), which includes overlapping phenotypes and varying ages of onset and morbidity, adds complexity to clinical and molecular diagnoses., Methods: To diagnose LGMD subtype, protein analysis, using immunohistochemistry (IHC) and immunoblotting, was followed by gene sequencing through a panel approach (simultaneous sequencing of known LGMD genes) in 9 patients from unrelated families of the Indian Agarwal community. Haplotype studies were performed by targeted SNP genotyping to establish mutation segregation., Results: We identified 2 founder mutations in CAPN3, a missense (c.2338G>C; p.D780H) and a splice-site (c.2099-1G>T) mutation, on 2 different haplotype backgrounds. The patients were either heterozygous for both or homozygous for either of these mutations., Conclusions: Founder mutations have immediate clinical application, at least in selected population groups. Clinically available gene panels may provide a definitive molecular diagnosis for heterogeneous disorders such as LGMD., (Copyright © 2012 Wiley Periodicals, Inc.)

Pyridostigmine relieved episodic weakness in a family with paramyotonia congenita resulting from the R1448C mutation in the sodium channel gene. The transmission was autosomal dominant and the patients had paradoxical myotonia and exercise-induced weakness. On electrophysiological studies there were myotonic potentials, and there was progressive reduction of compound muscle action potential (CMAP) amplitudes after short exercise associated with clinical weakness. Pyridostigmine in doses of 60 mg three times daily abolished the drop in the postexercise CMAP amplitude and reduced the amplitude decrement to slow rate repetitive stimulation, but there continued to be a drop in amplitude on exposure to cold. The decline of the CMAP amplitude on exposure to cold was controlled by treatment with phenytoin. The clinical and electrophysiological features are discussed in relation to therapy with pyridostigmine and phenytoin.