Delayed Compressive Angiomatous Degeneration in a Case of Mesial Temporal Lobe Epilepsy Treated by Gamma Knife Radiosurgery: Case Report

OBJECTIVE: Mesial temporal lobe epilepsy (MTLE) is one of the most common causes of intractable partial epilepsy. The conventional treatment of patients with MTLE is surgical excision. Currently, gamma knife (GK) radiosurgery is being explored as an alternative treatment. We report the first delayed major complication related to this treatment. CLINICAL PRESENTATION: A 54-year-old woman with a medical history of a post-viral encephalitis in childhood was treated in April 2001 by GK radiosurgery for a medically refractory MTLE. Her right temporomesial area received a dose of 20 Gy at the 50% marginal isodose line. Unfortunately, the patient continued to experience seizures, although they were of shorter duration and occurred less frequently. She was seen in our department on November 8, 2007, for an intracranial hypertensive syndrome. The imaging work-up showed an expansive hemorrhagic lesion in the right mesiotemporal area. Despite corticosteroid treatment, the patient still complained about headaches on November 13, and surgery was scheduled for November 22. However, the patient returned to the emergency department on November 16 with a temporal herniation syndrome requiring an urgent surgical procedure. INTERVENTION: The expansive lesion was completely removed. Histologic examination revealed lesions of the gray and white matter consisting of severe gliosis, hemorrhagic foci, hyalinized vessels, and neovascularization, giving the brain parenchyma an angiomatous aspect. CONCLUSION: Although reports on GK radiosurgical treatment of MTLE are encouraging, this case stresses the risk of developing 6 years later an angiomatous degeneration of the targeted brain with life-threatening intracranial hypertension.