The diagnostic spectrum of ATP1A3-related disorders: 3 new patients.

BACKGROUND: ATP1A3-related disorders are rare but increasingly recognized syndromes with overlapping phenotypes. CLINICAL OBSERVATIONS: A male child and his mother with c.2452G>A (p.Glu818Lys) mutation and an unrelated child with c.2428A>T (p.Ile810Phe) mutation in the ATP1A3 gene are reported. RESULTS: The first child presented with fever-induced flaccid unresponsiveness and the diagnosis was made after extensive negative workup except for abnormal EMG showing low amplitude motor responses with acute denervation; his symptomatic mother went undiagnosed for thirty years until his diagnosis. An unrelated male child presented with symptoms most consistent with the rapid-onset dystonia-Parkinsonism (RDP) phenotype but with intermediate features of alternating dystonia with choreoathetoid movements two years after a c.2428A>T (p.Ile810Phe) mutation was found. CONCLUSION: ATP1A3-related disorders have variable manifestations and can remain undiagnosed for decades. Treatment remains mostly supportive. With the increasing use of genetic testing for broad indications, further research into effective therapies is necessary.

Infarction of the Splenium of the Corpus Callosum in the Age of COVID-19: A Snapshot in Time.

BACKGROUND AND PURPOSE: Ischemic infarction of the corpus callosum is rare and infarction isolated to the corpus callosum alone rarer still, accounting for much <1% of ischemic stroke in most stroke registries. About half of callosal infarctions affect the splenium. METHODS: During a 2-week period, at the height of the coronavirus disease 2019 (COVID-19) pandemic in New York City, 4 patients at Montefiore Medical Center in the Bronx were found to have ischemic lesions of the splenium of the corpus callosum, 2 with infarction isolated to the corpus callosum. RESULTS: All patients tested positive for COVID-19 and 3 had prolonged periods of intubation. All had cardiovascular risk factors. Clinically, all presented with encephalopathy and had evidence of coagulopathy and raised inflammatory markers. CONCLUSIONS: Infarction of the splenium of the corpus callosum is exceedingly rare and a cluster of such cases suggests COVID-19 as an inciting agent, with the mechanisms to be elucidated.

Nerve entrapments related to muscle herniation.

BACKGROUND: Muscle herniation is a muscle protrusion through a fascial defect. It is a rarely reported cause of nerve entrapment. METHODS: We present a case of superficial fibular (peroneal) neuropathy associated with a fibularis (peroneus) brevis muscle herniation and a review of the literature on nerve entrapments secondary to muscle herniation unrelated to compartment syndrome. RESULTS: Eleven cases of nerve entrapments secondary to muscle herniation were identified. The superficial fibular nerve (SFN) was the most commonly entrapped nerve by fibularis muscle herniation. Patients presented with pain, numbness, or paresthesias, and an often tender, small palpable mass with a Tinel sign. Muscle MRI or ultrasound identified the lesion, and patients responded well to fasciotomy. CONCLUSIONS: The most commonly reported nerve entrapped by muscle herniation is the SFN secondary to fibularis muscle herniation. Characteristic clinical and imaging (MRI or ultrasound) features are diagnostic, and there is a salutary response to fasciotomy.

Optic neuritis and palatal dysarthria as presenting features of post-infectious GQ1b antibody syndrome.

A 31-year-old man had optic neuritis 2 weeks after a diarrheal illness, followed by several deficits including palatal dysarthria, diplopia, ataxia, sensory dysfunction, and mild dysautonomia. Brain MRI and CSF were normal. Nerve conduction studies were initially normal and subsequently showed mild reduction in sensory amplitudes. Anti-GQ1b IgG titer was positive. Deficits resolved after treatment with IVIg. This clinical constellation represents an overlap between Miller Fisher syndrome (MFS) and the pharyngeal-cervical-brachial (PCB) variant of Guillain-Barre syndrome (GBS), along with the infrequently reported central feature of optic neuritis. Campylobacter jejuni enteritis may have triggered the syndrome by molecular mimicry. GQ1b antibodies are associated with MFS, GBS, Bickerstaff brainstem encephalitis and PCB; they form an overlapping spectrum of features, hence the anti-GQ1b syndrome.

Blood gammadelta T cells, Campylobacter jejuni, and GM1 titers in Guillain-Barré syndrome.

The gammadelta T cells participate in microbial defense, are prevalent in intestinal epithelia, and are activated in autoimmune diseases. We studied whether peripheral blood gammadelta cells and gammadelta subsets are increased in Guillain-Barré syndrome (GBS) and whether elevations are associated with Campylobacter jejuni infection or GM1 elevations. In 20 GBS patients, we performed serial flow cytometry studies of blood gammadelta, Vdelta1, and Vdelta2 cells (+/- CD8+), C jejuni, and ganglioside titers. There was no significant difference in median gammadelta T-cell percentages between GBS patients and controls at onset and at convalescence. However, 5 patients had marked Vdelta1/CD8+ elevations. Elevated Vdelta1 or Vdelta1/CD8+ cells occurred in 3 of 6 patients with C jejuni or GM1 titer elevations. A minority of GBS patients have elevations of Vdelta1/CD8+ cells, possibly associated with elevated C jejuni or GM1 titers. The gammadelta T cells may have a cytotoxic (or suppressor) role in the disease.