To explore the abnormal brain metabolic pattern and connectivity in temporal lobe epilepsy (TLE) patients.

¹⁸F-FDG PET images of 75 patients diagnosed as drug resistant unilateral TLE from January 2014 to December 2016 in Huashan Hospital of Fudan University were collected retrospectively, including 41 (22 males, 19 females, age (28.4±8.7) years) left TLE (LTLE) and 34 (13 males, 21 females, age (28.5±8.8) years) right TLE (RTLE). Forty-four healthy controls (24 males, 20 females, age (31.2±6.2) years) were also enrolled. The cerebral glucose metabolism in TLE patients and the controls were analyzed with statistical parametric mapping (SPM) 12. The brain connectivity based on glucose metabolism were analyzed with bilateral hippocampus and amygdala as seeds. Permutation test with 1 000 permutations was used to analyze data.

Compared to control group, in both LTLE and RTLE groups, hypometabolism was found in affected hippocampus, amygdala, insula and temporal gyrus and hypermetabolism was observed in health hippocampus, parahippocampal gyrus, amygdala, lenticular nucleus and thalamus. In addition, hypometabolism was also found in affected superior/middle frontal gyrus and hypermetabolism was also found in bilateral frontal-orbital gyrus, bilateral cerebellum, affected lenticular nucleus and thalamus in LTLE group. In both TLE groups, affected seeds exhibited increased connectivity with affected superior frontal gyrus, lingual gyrus, fusiform gyrus, superior/middle temporal gyrus and temporal pole (all P<0.05); affected seeds exhibited increased connectivity with health superior frontal gyrus (P=0.005), lingual gyrus (P=0.018) and transverse temporal gyrus (P=0.016) in RTLE group in addition. Besides, affected seeds exhibited decreased connectivity with bilateral default mode network (DMN) (all P<0.05), affected caudate nucleus (P=0.015) and health thalamus (P=0.008), in a uniform distribution pattern in LTLE group, and with bilateral cerebral cortex in an irregular distribution pattern in RTLE group (all P<0.05). In LTLE group, health seeds exhibited more increased connections with superior (P=0.005)/middle frontal gyrus (P=0.042), health hippocampus (P=0.038), parahippocampal gyrus (P=0.019), amygdala (P=0.038), posterior cingulate gyrus (P=0.004), and bilateral fusiform gyrusand (P=0.048) compared with RTLE group; while, in RTLE group, health seeds exhibited more decreased connections with health superior (P=0.047), inferior frontal gyrus (P<0.001), orbital frontal gyrus (P<0.001) and rectus gyrus (P=0.016) compared with LTLE group.

Altered brain glucose metabolism and connectivity pattern are found and will elucidate the underlying metabolic pattern of TLE.

Epilepsy, temporal lobe; Metabolism; Nerve net; Positron-emission tomography; Tomography, X-ray computed; Fluorodeoxyglucose F18