Regional Cerebral Blood Flow in Patients with Cerebral Cortical Malformations and Intractable Partial Seizures

Abstract

Purpose: Changes of regional cerebral blood flow (rCBF) in patients with epilepsy with cerebral cortical malformations (CCMs) were studied interictally and ictally, and compared with rCBF in patients with other epileptogenic lesions. Methods: The interictal and ictal rCBF of 66 patients with medically intractable partial seizures with CCMs, identified by magnetic resonance imaging (MRI; 63 cases) or histological study of surgically resected specimens (33 cases) or both were measured by using single photon emission computed tomography (SPECT). The CCMs were classified into cortical dysplasia in 40 patients (34 intralobular and six multilobular), heterotopia in 16 patients (seven double cortex, six sub‐cortical, and three periventricular/subependymal), polymicrogyria in six patients (two bilateral perisylvian polymicrogyria, two unilateral schizencephaly, and two focal polygyric anomaly), hemimegalencephaly in two patients, and pachygyria in two patients. Among the 63 patients with symptomatic partial epilepsy, the localization of their epileptogenic foci was identified in 54 patients (26 frontal, 14 temporal, five occipital, two parietal, and seven multilobular) according to further electroclinical investigation. Three patients with undetermined epilepsies had both partial and generalized seizures. The rCBF‐SPECT findings on static images were evaluated according to the following gradings: hypoperfusion, hyperperfusion, and no remarkable changes. These findings with CCM were compared with those in 59 patients with benign tumors, 10 with angiomas and 117 with medial temporal sclerosis (MTS). Results: Interictal hypoperfusion was recognized in 33 (50%) patients with CCMs, in 86 (73%) with MTS, in 40 (68%) with benign tumors, and in five (50%) with angiomas. Interictal hyperperfusion was seen only in 11 (17%) patients with CCM. Among the 66 patients with CCMs, interictal hypoperfusion was detected in 27 (67%) of 40 cases with cortical dysplasia, in two of two with hemimegalencephaly, and in one of two with pachygyria. In contrast, interictal hypoperfusion was detected only in three (19%) of 16 cases with heterotopia and in none with polymicrogyria. Interictal hyperperfusion was recognized in four patients with heterotopia, in four with polymicrogyria, in two with cortical dysplasia, and in one with pachygyria. An ictal study was performed in 36 patients with CCMs. Increased rCBF at the ictal stage was recognized in 74%, but there was no definite correlation with the different kinds of CCM. Conclusions: Compared with that of other epileptogenic lesions, the frequency of detection of interictal hypoperfusion with SPECT in CCMs is lower, but interictal hyperperfusion was recognized only in CCMs. Moreover, we found some differences concerning the interictal CBF findings between heterotopia/polymicrogyria caused by abnormal neuronal migration and cortical dysplasia caused by abnormal organization. These results suggest that etiology and pathogenesis of CCMs are factors affecting rCBF and revealed that rCBF‐SPECT is effective for detecting the changes of interictal and ictal rCBF closely related to epileptogenesis in patients with CCMs.