A 51-year-old man sought care for a 4-month history of generalized seizures. The description of his seizures was consistent with generalized tonic-clonic seizures with focal onset. The patient had no history of head trauma or central nervous system infection and no family history of seizures. The patient reported having visual disturbances for 2 years before the seizures. His medical and surgical history was unremarkable. Brain magnetic resonance imaging showed left temporo-occipital, white matter, T2-signal intensity with gadolinium-enhancing lesions. Brain magnetic resonance imaging showed patchy gadolinium enhancement with T2 hyperintensity in the left parietotemporal and occipital lobes. Brain biopsy of the left temporal lobe showed white matter lesions with necrosis and chronic infiltration with macrophages and CD3-positive T lymphocytes and a predominant perivascular distribution. Focal, secondary vasculitis was present. There was no evidence of lymphoma. A repeated brain biopsy of the parietal lobe after another inflammatory relapse showed pathologic findings identical to the first biopsy. The patient was diagnosed with inflammatory encephalitis without additional defining features on biopsy. The patient received levetiracetam for seizure control, but the seizures remained refractory. He then was treated with high doses of intravenous methylprednisolone and then oral prednisone. Simultaneously, mycophenolate mofetil was initiated. The patient was monitored every 3 months with complete blood cell counts and liver function tests. Three months later, the prednisone dose was slowly tapered. During that process, the patient had no new seizures, and brain magnetic resonance imaging showed no active inflammation. After discontinuation of corticosteroids, the patient had a relapse with a generalized seizure, and brain magnetic resonance imaging showed new gadolinium-enhancing lesions. Prednisone was resumed, with near-remission. He then reinitiated mycophenolate mofetil and continued levetiracetam. With this regimen he remained clinically and radiologically stable, with only occasional visual phenomena that were possibly epileptic, although follow-up electroencephalography when he was symptomatic was normal. Encephalitis of unknown origin represents approximately one-third of cases. This proportion is decreasing over time with the development of novel diagnostic technologies, such as sequencing techniques to identify causative infectious agents and advances in neural autoantibody diagnostics.
Metabolic Strokes in Propionic Acidemia: Transient Hemiplegic Events Without Encephalopathy
