Early seizures after clipping of unruptured aneurysms of the anterior circulation: analysis on consecutive 1,000 cases

Seizures occurring after clipping of unruptured cerebral aneurysms have rarely been documented in the literature. The objective of this retrospective study is to clarify whether the frequency of early seizures, i.e., seizures occurring within 14 days of surgery, is influenced by patient- or aneurysm-specific characteristics. Data on 1,000 consecutive patients who underwent clipping of unruptured anterior circulation aneurysms were reviewed. They consisted of 387 men and 613 women with mean age of 59.8 ± 9.7 years. Fifty-one patients (5.1 %) developed early seizures. Interestingly, the frequency was similar to that occurring after clipping of unruptured posterior circulation aneurysms (n = 20, 5.0 %). Multivariate regression analysis revealed that younger age was correlated with early seizures (odds ratio (OR) 0.902; 95 % confidence interval (CI) 0.891–0.989). However, other variables, including aneurysm size and operation length, were not correlated. Although patients with history of epilepsy exhibited relatively high frequency of early seizures, the difference was not statistically significant. The frequency was unaffected by location or multiplicity of aneurysms. Thirty-one patients (61 %) developed seizures within 24 h of clipping. Regarding seizure types, 34 (67 %) developed generalized seizures and the other 17 (33 %) experienced partial seizures. Patients with generalized seizures were significantly more likely to harbor an iatrogenic brain lesion than those with partial seizures (47 vs. 18 %; OR 4.148; 95 % CI 1.005–17.113). Among 40 patients with follow-up period >12 months, seizures were temporary without recurrence in 38 (95 %). Although early seizures are mostly benign, a small possibility of them becoming a permanent morbidity needs to be explained to patients undergoing elective clipping.