Nicole Poulin

Long-term seizure outcome after mesial temporal lobe epilepsy surgery: corticalamygdalohippocampectomy versus selective amygdalohippocampectomy

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.

Long-term seizure outcome after corpus callosotomy: a retrospective analysis of 95 patients.

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 tonic-clonic 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.

Memory outcome after temporal lobe epilepsy surgery: corticoamygdalohippocampectomy versus selective amygdalohippocampectomy

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.

Life 12 years after temporal lobe epilepsy surgery: A long-term, prospective clinical study

It has been suggested that aim of the temporal lobe epilepsy surgery is twofold: first is to decrease seizure frequency and second is to improve quality of life without causing intolerable complications. The aim of this prospective, longitudinal clinical study is to report outcomes with respect to seizure, medication, employment and quality of life in short- and long-term follow-ups after resective temporal lobe epilepsy surgery. Consecutively 63 patients who underwent resective temporal lobe epilepsy surgery between 1993 and 1994 were enrolled. Outcomes at 6 months, 2 and 12 years were evaluated and compared with pre-operative status. The mean follow-up of this study was 12.3+/-0.6 years. Results showed that rates of seizure freedom were 82.5, 76.2, and 70.8% at 6 months, 2 and 12 years, respectively. Significant reduction in antiepileptic drug dose at long-term follow-up was found when compared to baseline. Patients after surgery had net gain of employment and improved quality of life was seen in all seizure outcome groups after surgery. Seizure-free patients showed better quality of life than those who continued to have seizure. Our results suggest that surgery leads to improvement in both seizure outcome and quality of life. Even years after the surgery, patients are still working, have reduced their medication load and have nearly normal life.

Superficial Anastomotic Veins : Neurosurgical View Depending on 251 Craniotomies

BACKGROUND Superficial anastomotic veins (SAVs) have been studied extensively but little attention has been paid to clinical studies. The aim of this study is to provide variations in the drainage patterns of SAVs depending on the intraoperative findings. METHODS A total of 251 craniotomies due to intractable temporal lobe epilepsy were performed between 1972 and 1987 at the Montreal Neurological Institute. The courses of the three largest SAVs including the vein of Trolard (VT), vein of Labbe (VL) and superficial Sylvian vein (SSV) were studied. RESULTS All three veins showed variable courses. The most common predominant vein was the combination of the VL + SSV. The VT and VL were frequently coursed at the level of the central vein and middle temporal vein, respectively. On the right hemisphere the SSV was the predominant type while the VL tended to be predominant on the left hemisphere. A combination of VL and SSV was predominant in patients with right and/or left hemispheric dominance. CONCLUSIONS The SAVs showed considerable variation in their courses and it is difficult to define an exact pattern although some courses showed constant directions. Attention should be paid not to damage these veins since in a considerable number of cases a single dominant vein may be responsible for draining a majority of the lateral surface of cerebral hemisphere.

Functional results of electrical cortical stimulation of the lower sensory strip

The aim of this paper is to provide functional results obtained from electrical cortical stimulation of the lower postcentral gyrus in patients who underwent either lesional or non-lesional epilepsy surgery. Group I (n=393) included those patients with gliosis or normal tissue and Group II (n=107) included patients with space-occupying lesions. For cortical stimulation, a unipolar voltage-controlled electrode was used. The tongue, lip, and hand/finger sequences over the lower postcentral gyrus lateromedially in both groups were in agreement with classic teaching. The presence of structural lesions, such as tumors and dysplasia, did not affect the vertical representation of the body parts on the lower sensory strip. Individual variations, which included mosaicism over the sensory strip, were frequent. Whether the functional variability and mosaicism within the sensory cortex result from a pathological condition or not remains to be elucidated in healthy humans using advanced non-invasive brain mapping techniques.

Atypical speech activations: PET results of 92 patients with left-hemispheric epilepsy.

PurposeLanguage lateralization and factors that may influence language lateralization were investigated using positron emission tomography.MethodsNinety-two right-handed patients who had left-sided lesions (tumors, focal cortical dysplasia, and vascular lesions) and 19 right-handed normal subjects were included and synonym generation task was used for evaluation of language lateralization.ResultsAs expected, the majority of individuals in both groups showed left hemisphere dominance. Lesions in the vicinity of language-related areas did not alter patterns of activation responses. However, atypical inferior frontal gyrus (IFG) activations (33.6%) were more commonly observed in the patient group than in the control group (21%). There were no clear right-sided IFG activations in the control group but almost 28% of the patients showed clear right-sided IFG activations. Atypical language lateralization was strongly correlated with duration of seizure (p = 0.01) and early age at onset (p = 0.03).ConclusionsOur data provide evidence for inter-hemispheric plasticity related to language function as a response to lesions involving the left hemisphere. A better understanding of the dynamic organization of the brain and about the interaction between the lesion and reactional plasticity will lead to changes in surgical strategy, which will enable us to perform a total removal of the lesion involving eloquent brain areas with improved functional outcome.