The development of an epileptogenic focus. A case study with 99mTc-HMPAO SPECT.

A patient is described who developed complex partial seizures with secondary generalization 3 years after a severe viral encephalitis with a CT and EEG identified lesion in the left insular cortex and its surrounding structures. When the seizures first occurred CT and MRI as well as repeated interictal conventional EEG recordings were entirely normal. Single photon emission computed tomography (SPECT), however, revealed an area of increased 99mTc-hexamethyl propyleneamine oxime (HMPAO) uptake in the left insular cortex. After anticonvulsive therapy the seizures and the SPECT findings disappeared. 99mTc-HMPAO SPECT is a highly sensitive method for the demonstration of functional alterations in brain tissue. It can improve diagnosis of epilepsy and may provide additional information to monitor anticonvulsive therapy.