Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine
This is a 70-year-old woman with a several year long history of imbalance and stiffness. Exam demonstrated axial and lower extremity stiffness, and ocular motor exam demonstrated gaze-evoked nystagmus (e.g., right-beating in right gaze, left-beating in left gaze, up-beating in up gaze), and mild to moderate slowing of saccades vertically and horizontally. Vestibular function was normal. Evaluation for a posterior fossa syndrome given gaze-evoked nystagmus (GEN, implies dysfunction of cerebellum or its connections) and slow saccades (implies impairment of brainstem burst neurons) demonstrated normal neuroimaging, although she had a very high level of anti-glutamic acid decarboxylase (GAD-65) serum IgG (hers was >300,000 IU/ml where the upper limit of normal is 5 IU/ml). The patient was diagnosed with probable stiff person syndrome, and ocular motor abnormalities were also attributed to the elevated anti-GAD-65 antibody levels. She has not yet received intravenous immunoglobulin. An anti-GAD syndrome with posterior fossa involvement should be considered in any patient with dizziness/vertigo and/or imbalance with central ocular motor signs including GEN and/or slow saccades (both have been reported). It is an important consideration, especially since it can be treated with immunotherapy and benzodiazepines (for stiffness and spasm).
Spencer S. Eccles Health Sciences Library, University of Utah