Object: The authors report long-term follow-up seizure outcome in patients who underwent corpus callosotomy during the period 1981–2001 at the Montreal Neurological Institute. Methods: The records of 95 patients with a minimum follow-up of 5 years (mean 17.2 years) were retrospectively evaluated with respect to seizure, medication outcomes, and prognostic factors on seizure outcome. Results: All patients had more than one type of seizure, most frequently drop attacks and generalized tonicclonic seizures. The most disabling seizure type was drop attacks, followed by generalized tonic-clonic seizures. Improvement was noted in several seizure types and was most likely for generalized tonic-clonic seizures (77.3%) and drop attacks (77.2%). Simple partial, generalized tonic, and myoclonic seizures also benefited from anterior callosotomy. The extent of the callosal section was correlated with favorable seizure outcome. The complications were mild and transient and no death was seen. Conclusions: This study confirms that anterior callosotomy is an effective treatment in intractable generalized seizures that are not amenable to focal resection. When considering this procedure, the treating physician must thoroughly assess the expected benefits, limitations, likelihood of residual seizures, and the risks, and explain them to the patient, his or her family, and other caregivers.

Object: In this paper the authors aimed to provide information related to major and minor surgical and neurological complications encountered following stereoelectroencephalography and epilepsy surgery. Methods: The authors performed a retrospective review of 491 and 1905 patients who underwent intracranial electrode implantation and epilepsy surgery, respectively, between 1976 and 2006 at the Montreal Neurological Institute. All intracranial electrode implantations and surgical procedures were performed by 1 surgeon (A.O.). Results: A total of 6415 electrode implantations and 2449 surgical procedures were done. There were no deaths related to either procedure. There were no major complications after intracranial electrode implantation, and the risks of infection and intracranial hematoma were found to be 1.8 and 0.8%, respectively. The number of electrodes per lobe (p = 0.05) and number of lobes covered (p = 0.04) were significant risk factors for hematoma and infection. Regarding epilepsy surgery, there were no major surgical complications, and the overall minor complication rate was 2.9%. Infection was the most common complication (1.0%), followed by intracranial hematoma (0.7%). Significant risk factors associated with hematomas and infections were the number of reoperations (p = 0.001) and older patient age (p = 0.03). Minor and major neurological complication rates were 2.7 and 0.5%, respectively, and the rate of overall neurological morbidity was 3.3%. Hemiparesis was the most frequent neurological complication (1.5%). Conclusions: Based on the authors' experience, intracranial electrode implantation is an effective method with an extremely low morbidity rate. Moreover, epilepsy surgery is safe, especially in experienced hands.

Object: Resection strategies for the treatment of temporal lobe epilepsy (TLE) are a matter of discussion, and little information is available. The aim of this study was to compare seizure outcomes at the 5-year follow-up in patients with medically refractory unilateral mesial TLE (MTLE) due to hippocampal sclerosis (HS) who were treated using a cortical amygdalohippocampectomy (CorAH) or a selective AH (SelAH). Methods: The authors obtained data from 100 adult patients who underwent surgery for MTLE. Fifty patients underwent a CorAH and 50 underwent an SelAH. Seizure control achieved with each technique was compared using the Engel classification scheme. Results: Overall, at the 5-year follow-up, favorable (Engel Classes I and II) seizure outcomes were noted in 82 and 90% of patients who had undergone CorAH and SelAH, respectively. Furthermore, 40% of the patients who had undergone a CorAH and 58% of those who had undergone an SelAH were seizure free (Engel Class Ia). There was no statistically significant difference between the 2 surgical approaches in terms of seizure outcome at the 5-year follow-up (p = 0.38). Conclusions: Both CorAH and SelAH can lead to similar favorable seizure control in patients with MTLE/HS. However, the authors suggest that the transcortical selective approach has the great advantage of minimizing or completely abolishing the impact of dividing several venous and arterial adhesions which are tedious, time consuming, and, at times, associated with some degree of cerebral swelling.

Object: The aim of this study was to compare IQ and memory outcomes at the 1-year follow-up in patients with medically refractory mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis. All patients were treated using a corticoamygdalohippocampectomy (CAH) or a selective amygdalohippocampectomy (SelAH). Methods: The data of 256 patients who underwent surgery for MTLE were retrospectively evaluated. One hundred twenty-three patients underwent a CAH (63 [right side] and 60 [left side]), and 133 underwent an SelAH (61 [right side] and 72 [left side]). A comprehensive neuropsychological test battery was assessed before and 1 year after surgery, and the results were compared between the surgical procedures. Furthermore, seizure outcome was compared using the Engel classification scheme. Results: At 1-year follow-up, there was no statistically significant difference between the surgical approaches with respect to seizure outcome. Overall, IQ scores showed improvement, but verbal IQ decreased after left SelAH. Verbal memory impairment was seen after left-sided resections especially in cases of SelAH, and nonverbal memory decreased after right-sided resection, especially for CAH. Left-sided resections produced some improvement in nonverbal memory. Older age at surgery, longer duration of seizures, greater seizure frequency before surgery, and poor seizure control after surgery were associated with poorer memory. Conclusions: Both CAH and SelAH can lead to several cognitive impairments depending on the side of the surgery. The authors suggest that the optimal type of surgical approach should be decided on a case-by-case basis.