Abstracts

Rationale: We report a healthy 44 year old woman with the simultaneous onset of localization-related epilepsy, ocular myasthenia and characteristic axial muscle contractions consistent with stiff person syndrome (SPS) within one calendar year. Methods: Epilepsy monitoring unit evaluation revealed left temporal spikes on EEG. Brain MRI was normal. Assessment of her intermittent vertical diplopia and ptosis yielded negative anti-acetylcholine receptor antibody titer (0.07nmol/L with reference range 0.00-0.24) and negative Tensilon test. Two consecutive EMG studies demonstrated incomplete relaxation of paraspinal muscles and rectus abdominis, supportive of SPS. Imaging, including PET body imaging, failed to reveal an occult malignancy. Mammography and colonoscopy were negative. Anti-glutamic acid decarboxylase (anti-GAD) antibodies were drawn. Results: Significant elevations of anti-GAD were demonstrated (270.8 U/mL with reference range 0-1.5). The patient is now receiving monthly gamma globulin infusions. Conclusions: Glutamic acid decarboxylase (GAD) catalyzes the conversion of l-glutamic acid to gamma-aminobutyric acid (GABA). Anti-GAD has been associated with intractable epilepsy and myasthenia gravis. Epilepsy with elevated anti-GAD titer has been associated with focal EEG abnormalities but normal brain MRI(McKnight et al. 2005). In studies of intracerebellar and paraspinal administration of anti GAD IgG in rats, Manto et al. (2007) suggest a causative role of Anti-GAD antibody as the autoimmune basis of SPS. Furthermore, Petola et al. (2000) found localization-related epilepsy to be present in 4 of 19 patients with SPS and anti-GAD autoimmunity. Mechanisms include down regulation of GABA production, destruction of GABAergic terminals or altered sensitivity of post-synaptic GABA receptors. This is the first case establishing elevated Anti-GAD with temporal co-emergence of epilepsy, ocular myasthenia and SPS.