Abstracts

Rationale: Corpus callosotomy (CC) is a palliative procedure for management of medically intractable seizures. CC is efficacious in generalized epilepsies (especially tonic/atonic), and focal onset seizures, particularly with rapid secondary generalization. Two widely used approaches are partial (anterior two-thirds) and total (complete) CC. A criterion for patient selection for either of the two procedures has not been clearly defined in literature. We reviewed our experience at Minnesota Epilepsy Group, comparing seizure control post-operatively (including partial and/or complete CC) to the pre-operative period. Methods: Since 1990, 98 CC have been performed. All patients initially had partial CC, and 67 later went for CC completion. Data collected included: age of onset of epilepsy, age at surgery, epilepsy syndromes, MRI, EEG findings, IQ, frequency of seizures and seizure semiology [tonic or atonic (type 1) and others (type 2)] prior to CC, following partial and after total CC. We defined success as Engel class I or II. Results: Prior to surgery, 74% had type 1 seizures. After partial CC, 8% had success. Type 1 seizures were still present in 74% (n= 73) of patients after partial CC. Though statistically insignificant, increased age of epilepsy onset was associated with better outcomes. Age at partial surgery was statistically significant (p= 0.02), with increasing age associated with improved outcomes. Patients with type 2 seizures performed better after partial CC (p= 0.01). Though statistically insignificant, increased frequency of seizures was associated with better outcomes. Other characteristics did not show any associations with outcomes (Table 1). 66 patients (73%) went for a total CC. 42% (n= 28) of patients going to CC completion had success in seizure outcomes. 93% (n= 62) had class I success in Type 1 seizures. Having type 1 seizures was associated with better outcome after a complete CC (p value = 0.01). Though statistically insignificant, a modest association was shown in patients having a higher IQ with better outcomes after a complete CC. There were no reports of disconnection syndromes after complete CC. Other characteristics did not show any association with outcomes (Table 2). Next, comparing the data between patients with partial and complete CC showed a modest association with higher IQ associated with better outcomes after the complete CC. Conclusions: We conclude that increasing age at time of partial CC surgery and seizure semiology (type 2) are associated with a statistically significant better outcome, and higher age of epilepsy onset is associated with a statistically insignificant modest association with good outcomes. For patients who went for total CC after having partial CC surgery, the seizure semiology (type 1) and higher IQ was associated with better outcomes. There were greater seizure reductions after total CC in comparison to partial CC, and there were no related disconnection syndromes. Other characteristics failed to show any significant associations