Comparative effects of posterior versus total corpus callosotomy in a PTZ-induced rat model of epilepsy: a methodological pilot study.

Corpus callosotomy is a palliative procedure for drug-resistant generalized epilepsy. Posterior callosotomy (PC) may preserve prefrontal fibres while offering seizure control comparable to total callosotomy (TC), but experimental comparisons are scarce. This pilot evaluated the acute behavioural effects of PC versus TC in a pentylenetetrazole (PTZ) kindling rat model. Fourteen adult male Wistar rats (500-700 g) underwent PTZ kindling (37.5 mg/kg, i.p.; seven sessions in two blocks with a 22-day drug-free interval); the eleven survivors were randomized to PC (n = 5) or TC (n = 6). Seizures were graded with the revised Racine scale. One week after surgery, a PTZ rechallenge was performed. Within- and between-group comparisons used t-tests or non-parametric equivalents (α = 0.05); callosal sectioning was verified histologically post-mortem. No significant within- or between-group differences in seizure duration were found for any Racine category (all p > 0.05; between-group p 0.174-0.486); a post-hoc analysis indicated only very large effects (Cohen's d ≈ 1.9) were detectable at 80% power. Histology gave morphological support for an in-vivo callosal lesion (haemorrhage and reactive gliosis) in the transected territory, though prolonged fixation limited evaluation in many specimens. Neither technique produced statistically detectable acute changes in PTZ-evoked seizure duration; given the pilot's limited sensitivity, the findings are exploratory and hypothesis-generating. Because PTZ generalization depends largely on subcortical pathways, this model appears suboptimal for isolating callosal contributions; adequately powered studies in chronic focal epilepsy models, with electrophysiological monitoring and longer follow-up, are needed.