Somatostatin concentrations in cerebrospinal fluid and brain tissue of patients with refractory epilepsy

The somatostatin concentrations of cerebrospinal fluid (CSF) and brain tissue in 16 refractory epileptic patients were measured simultaneously by a radioimmunoassay (RIA) method. An increased level of somatostatin was found in the epileptic foci of cerebral cortex, determined by the cortical EEG. There were significant differences among the epileptic foci (75.58 +/- 6.58 pg/mg wet wt, +/- SEM), nonfocal tissues (37.04 +/- 6.55 pg/mg), and normal tissues of control patients (47.69 +/- 10.12 pg/mg), p < 0.001 and p < 0.05, respectively. The somatostatin concentrations of CSF in 11 epileptic patients were determined before (257.78 +/- 19.11 pg/mL) and after (178.36 +/- 8.78 pg/mL) the removal of epileptic focal area, and a dramatic decrease of the CSF somatostatin concentration after operation was detected (p < 0.01). We also found that the somatostatin level of cerebral scar induced by head injury in cases of posttraumatic epilepsy was highest (106.39 +/- 12.41 pg/mg). The results suggested that the surgical removal of the epileptic focal area in refractory epileptic patients may reduce the increased central somatostatin level, which could play an important part in the pathophysiological process of refractory epilepsy.