Ramsay Hunt syndrome: clinical characterization of progressive myoclonus ataxia caused by GOSR2 mutation.

Background: Ramsay Hunt syndrome (progressive myoclonus ataxia) is a descriptive diagnosis characterized by myoclonus, ataxia, and infrequent seizures. Often the etiology cannot be determined. Recently, a mutation in the GOSR2 gene (c.430G>T, p.Gly144Trp) was reported in 6 patients with childhood-onset progressive ataxia and myoclonus.

Methods: We evaluated 5 patients with cortical myoclonus, ataxia, and areflexia.

Results: All 5 patients had the same homozygous mutation in GOSR2. Here we present their clinical and neurophysiological data. Our patients (aged 7-26 years) all originated from the northern Netherlands and showed a remarkably homogeneous phenotype. Myoclonus and ataxia were relentlessly progressive over the years. Electromyography revealed signs of sensory neuronopathy or anterior horn cell involvement, or both, in all patients with absent reflexes.

Conclusions: Based on the presented phenotype, we would advise movement disorder specialists to consider mutation analysis of GOSR2 in patients with Ramsay Hunt syndrome, especially when they also have areflexia.