A 25 year old pathologically right-handed man developed focal seizures manifest as left body tonic contraction and jerking at 3.5 years of age. They intensified and worsened in frequency over the next 1-2 years with drop attacks multiple times daily. Interictal left hemiparesis and “brain swelling” was noted on serial MRIs. He underwent a phase 2 evaluation and right frontal topectomy after failing multiple AEDs which was unsuccessful. He then underwent hemispherectomy which rendered him seizure free for the next 12 years. Seizure recurrence prompted re-evaluation. MRI demonstrated the near-complete anatomic hemispherectomy. MPGR sequences for blood demonstrated insular hemosiderosis. Ictal EEG demonstrated left ictal activity during left facial grimace and tonic contraction with and without left arm jerking.
Figure: Brain MRI axial image with near-total anatomically complete hemispherectomy (A) residual hemosiderosis (arrow) in (B) and EEG demonstrating right hemispheric voltage attenuation (C). Recording parameters: longitudinal bipolar montage, sensitivity 7 uv, and filters 1-70 Hz. Hz.
Rasmussen encephalitis (RE) is a chronic progressive inflammation of one hemisphere of the brain. GLUR3 auto-antibodies and activated T-cells found in parenchyma reflect the autoimmunity1. Severe progressive contralateral functional deficits occur. Drug-resistant focal seizures commonly prompt resective surgery. Onset is typically is in childhood (< 10 years of age). Seizures are prolonged and if motor cortex is affected epilepsia partialis continua often results. Hemispherectomy is a standard of care for advanced RE. Long term neurological sequella may be minimized by modified hemispherectomy and hemispherotomy. Minimal cognitive dysfunction or no change is usually evident1. In 33 children and adolescents, hemiplegia was unchanged in 22/33, improved in 5, and worsened in 6 patients2. RE like other progressive and acquired pathology has the best outcome with surgery while developmental lesions have less favorable results. Optimal timing and relationship to pathology is individualized. Our patient had a left hemiparesis that worsened after surgery. His seizures remained lateralized to the left body despite surgical absence of the right hemisphere. Possibilities include remaining tissue with residual connections and transferred function to the intact hemisphere (neuroplasticity) associated with operation at an early age. Immunotherapy with steroids and IVIG is advancing as a primary adjunctive treatment1.
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