Clinical relevance of amygdala sclerosis in temporal lobe epilepsy

Object. The goal of this study was to define the incidence and clinical sig nificance of amygdala sclerosis (AS) in patients with temporal lobe epileps y (TLE). Methods. Surgical specimens of the lateral amygdaloid nucleus and the hippo campus excised from 71 patients who were treated for medically intractable TLE were quantitatively evaluated using a computer-assisted image-analysis system and compared with 10 normal autopsy specimens. Densities of neurons and reactive astrocytes in the patients with TLE were correlated with clini cal, neuropsychological, and depth-electroencephalography data. The neuron counts of the lateral amygdaloid nucleus did not correlate with various pre sumed etiological factors of TLE including hereditary seizures, birth compl ications, febrile convulsions, traumatic brain injury, infections, seizure semiology, and epileptological outcome. However, patient age at surgery was significantly higher (mean difference 10 years) when AS was present, as co mpared with patients without AS (p < 0.01). Seizure origin, as determined b y using amygdalohippocampal depth electrodes, did not correlate with the pr esence or absence of AS. Neuropsychologically, there was a significant corr elation between the neuronal densities of the lateral amygdaloid nucleus an d both preoperative visual recognition and postoperative deterioration of s hort-term verbal memory performance (p < 0.05). Conclusions. Except for the relatively long history of epilepsy, the presen ce of AS is not associated with specific clinical or electrocorticographic features of mesial TLE. However, patients without AS are particularly at ri sk for deterioration of short-term verbal memory following amygdalohippocam pectomy.