Cryptogenic temporal lobe epilepsy. semi-quantitative interictal 99mTc HMPAO SPECT: statistical correlation with clinical data and EEG.

The aim of our work was to identify clinical and electroencephalographic factors that are statistically correlated to 99mTc HMPAO hypofixation in cryptogenic temporal lobe epilepsy. We selected a homogeneous group of patients (28 males and 17 females) affected by temporal lobe epilepsy and having normal results on computed tomography and magnetic resonance imaging. Patients were classified according to semeiological characteristics of the seizures, presence or absence of spikes on electroencephalography (EEG), age at onset, illness duration, and drug resistance. The presence of focal interictal spikes on EEG was statistically correlated to 99mTc HMPAO temporal hypofixation (p = 0.04). The other electroclinical factors considered in this series did not play an important role in modifying radiopharmaceutical fixation in focal epilepsy in interictal phase. We speculate that a possible explanation for focal radiopharmaceutical hypofixation, in addition to hypoperfusion, is an increased permeability of the blood-brain barrier (due to perivascular inflammation or other causes) which can be responsible for 99mTc HMPAO escape with a resultant hypofixation.