Uncommon Epiloptogenic Lesions Affecting the Temporal Lobe

There are several processes implicated as uncommon causes of temporal lobe epilepsy. Trauma is the leading cause of epilepsy in young adults, intracerebral blood collection being the most consistent risk factor of seizures, especially subdural hematomas and brain contusions. Infarction is the entity most commonly related to epilepsy in the elderly population. Seizures usually present as complex seizures with high recurrence between 6 months and 2 years after stroke. There are some radiological characteristics of the affectation associated with high risk of early and late seizures. Noninfectious limbic encephalitis is a syndrome characterized by seizures, memory loss, and confusion. It includes paraneoplasic and non-paraneoplasic limbic encephalitis, both presenting as hyperintense lesion affecting temporobasal regions more evident with fluid-attenuated inversion recovery sequences. Paraneoplasic limbic encephalitis is associated with several types of tumor-induced autoimmunity against the nervous system. The tumors most frequently implicated are the lungs, testis, and breast, including Hodgkin’s lymphoma, teratoma, and thymoma in young patients. Once a tumor is excluded, non-paraneoplasic limbic encephalitis has to be considered by investigating the presence of antibodies against voltage-gated potassium channels. It is associated with hyponatremia and responds to regimens of steroids, plasma exchange, and intravenous immunoglobulins. Finally, herpetic limbic encephalitis is also associated with seizures, accompanied by fever and neurologic symptoms. It presents characteristic findings and distribution on magnetic resonance imaging, which shows abnormalities in more than 90% of patients with proven Herpes simplex virus type 1.