Interictal temporal hypoperfusion is related to early-onset temporal lobe epilepsy

Previous studies of interictal regional cerebral blood flow (rCBF) in temporal lobe epilepsy have shown variable correlations with clinical measures. We used high spatial resolution hexamethyl propyleneamine oxime single photon emission computed tomography (HMPAO SPECT) in 80 consecutive patients with complex partial seizures (CPS), comparing results with those from a large series of normal subjects. Visual image analysis detected abnormalities of rCBF in 41 of 80 (51%; numeric analysis detected abnormalities in 38 of 80). Age at epilepsy onset was significantly younger in patients with temporal hypoperfusion (p = 0.002), and the frequency distribution of hypoperfusion versus age at epilepsy onset was reverse exponential. The results of numerical image analysis showed that degree of hypoperfusion did not vary with age at epilepsy onset. These data suggest a single insult operating early in life as a cause of temporal hypoperfusion, as has been shown for mesial temporal sclerosis (MTS). We could not demonstrate relationships with other clinical variables, including time since last seizure.