Typical and atypical perfusion patterns in periictal SPECT of patients with unilateral temporal lobe epilepsy

Purpose: To characterize perfusion patterns of periictal single-photon emis sion tomography (SPECT) in patients with unilateral temporal lobe epilepsy (TLE) and to determine their relationship to the epileptogenic zone (EZ). Methods: We studied periictal SPECT scans of 53 patients after anterior mes ial temporal lobectomy who had good seizure outcome after surgery. Ictal SP ECT scans were performed during video-EEG monitoring. Typical SPECT pattern s consisted of ipsilateral ictal hyperperfusion or ipsilateral postictal hy poperfusion. Atypical ictal patterns included normal scans, bilateral tempo ral hyperperfusion, or contralateral patterns. These perfusion patterns wer e retrospectively analyzed searching for concordance rate with the EZ. Results: We obtained 51 ictal and two early postictal scans. In the typical group. 40 (75.4%) patients had ipsilateral ictal temporal lobe hyperperfus ion. and one (1.9%) patient had ipsilateral postictal temporal lobe hypoper fusion. Twelve (22.7%) patients exhibited atypical perfusion patterns: seve n (13.2%) patients had bitemporal ictal hyperperfusion (four cases showed a symmetric temporal lobe changes), four (7.6%) patients had contralateral hy perperfusion. and one (1.9%) patient had a normal SPECT scan. All four pati ents with bitemporal asymmetric hyperperfusions showed greater perfusion la teralized to the side of the EZ. Three of the four patients who had contral ateral hyperperfusion also had a complex postictal-like pattern in the ipsi lateral temporal lobe consisting of anteromeasial hyperperfusion with adjac ent lateral hypoperfusion. Conclusions: This study analyzed typical and atypical perfusion patterns in unilateral TLE, and suggested that not only typical, but also some atypica l perfusion patterns may contribute to the lateralization of EZ.