Abstracts

Rationale: Rasmussen encephalitis (RE) is a rare inflammatory brain disease in children. It presents with intractable epilepsy, often associated with epilepsia partialis continua and unilateral motor and speech deficits. EEG changes are seen in contralateral hemisphere along with unilateral cerebral atrophy on Neuroimaging. RE leads to progressive hemispheric damage and surgical excision of the affected hemisphere is needed to control the symptoms of the disease. The underlying pathogenic mechanism is poorly understood. However proposed mechanisms include viral infection, humoral and cytotoxic T-cell mediated auto-immunity. Methods: Case report with EMG, MRI and acetlycholine receptor antibody studies Results: An 11 year-old girl had a history of intractable epilepsy since 3 years of age and was later diagnosed with Rasmussen's encephalitis. She had intractable epilepsy requiring three anti-epileptic drugs and immunomodulation with IVIG every four weeks. She developed generalized muscle weakness, bulbar weakness with dysphonia. Further diagnostic testing was pursued and included an EMG with repetitive stimulation. Results revealed a postsynaptic decrement. A thymoma panel revealed elevated acetylcholine receptor binding and modulation antibodies. MRI of the mediastinum revealed a cystic lesion within the right aspect of the thymus. Conclusions: The coexistence of Rasmussen encephalitis and myasthenia gravis has not previously been reported. Myasthenia gravis is commonly associated with other immune-mediated diseases such as thyroiditis and multiple sclerosis. The association here suggests that in this case RE and myasthenia gravis may share a common autoimmune etiology.