External laryngeal tremor in adult-onset Alexander disease: a case report

Abstract

Introduction: Alexander disease is caused by mutations in GFAP, the glial fibrillary acidic protein gene. External laryngeal tremor has not been reported in adult-onset Alexander disease (AOAxD). The aims of this work were to report one such case and to review the literature on palatopharyngeal tremor and AOAxD. Case Presentation: A 43-year-old man experienced involuntary movements at the front of his neck. Continuous, rhythmic vertical movements of the laryngeal skeleton, soft palate and tongue, and lower limb dysmetria were observed. The pathogenic GFAP variant c.994G>A; p.(Glu332Lys) was found. MRI demonstrated spinal cord and medulla oblongata atrophy and hyperintensities at the cerebellum and cerebral white matter. Conclusion: External laryngeal, palatopharyngeal tremor and cerebellar ataxia constituted a mild phenotype, as expected from this variant, herein reported in isolation for the third time. Imaging was consistent with AOAxD, including the so-called tadpole sign. Additional studies are necessary to define this infrequent disease.