A case of neuromyotonia and axonal motor neuropathy: A report of a HINT1 mutation in the United States.

INTRODUCTION: HINT1 mutations cause an autosomal recessive distal hereditary motor axonal neuropathy with neuromyotonia. This is a case report of a HINT1 mutation in the United States. METHODS: A 30-year-old man of Slovenian heritage and no significant family history presented with scoliosis as a child and later developed neuromyotonia and distal weakness. Electrodiagnostic testing revealed an axonal motor neuropathy and neuromyotonic discharges. Previous diagnostic work-up, including testing for Cx32, MPZ, PMP-22, NF-L, EGR2, CLCN1, DM1, DM2, SMN exon 7/8, emerin, LMNA, MPK, SCNA4, acid maltase gene, paraneoplastic disorder, and a sural nerve biopsy, was negative. RESULTS: Genetic testing for a HINT1 mutation was performed and revealed a homozygous mutation at p.Arg37Pro. CONCLUSION: This entity should be distinguished clinically and genetically from myotonic dystrophy and channelopathies with the clinical features of neuromyotonia and an axonal neuropathy. This case illustrates the importance of identifying the correct phenotype to avoid unnecessary and costly evaluations.

Veni, Vidi, Scribivi: I Came, I Saw, I Wrote

Narrative medicine talks at the American Academy of Neurology Annual Meeting have included writing prompts to inspire and promote wellness among attendees. The 6-word writing exercise at the 2023 Annual Meeting prompted pithy and powerful stories, which we share in this article.

The illusion of severe carpal tunnel syndrome (CTS).

Thenar atrophy occurs in patients with severe carpal tunnel syndrome (CTS) of long-standing duration. In this report we present a young woman with mild bilateral CTS, based on electrophysiological studies, in whom marked thenar atrophy was on a congenital basis related to the VATER association (vertebral anomalies, anal atresia, tracheoesophageal fistula, and radial or renal abnormalities).

Continued efficacy and safety of subcutaneous apomorphine in patients with advanced Parkinson's disease.

The study purpose was to assess the efficacy of intermittent subcutaneous apomorphine (APO) as acute therapy for off episodes in advanced Parkinson's disease (PD) patients who had previously received APO for 3 months. Patients (n=62) were randomized to receive double-blind treatment with APO at their typically effective dose (TED; APO), APO at their TED+0.2mL (2.0mg; APO+2), placebo at volume equal to their TED (PL), or placebo at volume equal to their TED+0.2mL (PL+2), for a single off episode. Significantly greater improvement in mean Unified PD rating scale motor scores was seen with pooled APO versus pooled placebo 20min after administration (-24.2 vs. -7.4; p<0.0001); the difference was also significant at 10min (p<0.0001). Overall adverse event incidence did not significantly differ between pooled APO and pooled PL. This study supports the long-term use of intermittent APO as effective acute therapy for off episodes in advanced PD patients.

Pancytopenia related to dental adhesive in a young patient.

Copper deficiency resulting in hypocupremia is a rare cause of pancytopenia associated with a neurological syndrome. Hypocupremia may also occur as a consequence of excessive oral zinc consumption as described by Brewer et al and several other groups. Dental fixatives have been described as a potential source of hyperzincemia in patients. Despite the recently modified dental fixatives with safer zinc content, zinc poisoning results in hypocupremia secondary to inappropriate use of them can still happen and more likely be misdiagnosed. We describe a case of a patient with pancytopenia who was diagnosed with severe aplastic anemia and hypocellular myelodysplastic syndrome and was referred to us for consideration of bone marrow transplantation.

Creation of an open-access, mutation-defined fibroblast resource for neurological disease research.

Our understanding of the molecular mechanisms of many neurological disorders has been greatly enhanced by the discovery of mutations in genes linked to familial forms of these diseases. These have facilitated the generation of cell and animal models that can be used to understand the underlying molecular pathology. Recently, there has been a surge of interest in the use of patient-derived cells, due to the development of induced pluripotent stem cells and their subsequent differentiation into neurons and glia. Access to patient cell lines carrying the relevant mutations is a limiting factor for many centres wishing to pursue this research. We have therefore generated an open-access collection of fibroblast lines from patients carrying mutations linked to neurological disease. These cell lines have been deposited in the National Institute for Neurological Disorders and Stroke (NINDS) Repository at the Coriell Institute for Medical Research and can be requested by any research group for use in in vitro disease modelling. There are currently 71 mutation-defined cell lines available for request from a wide range of neurological disorders and this collection will be continually expanded. This represents a significant resource that will advance the use of patient cells as disease models by the scientific community.