Total and partial posterior quadrant disconnection for medically refractory epilepsy: A systematic review

Area of Science:

• Neurosurgery
• Epileptology
• Clinical Neuroscience

Background:

• Medically refractory epilepsy (MRE) poses significant challenges when the seizure onset zone (SOZ) is diffuse, particularly in the temporo-parieto-occipital lobes.
• Posterior quadrant disconnection (PQD) is a surgical option for such complex cases, involving extensive resection of posterior brain regions.

Purpose of the Study:

• To compare the factors influencing surgical decisions and the efficacy of total versus partial PQD for MRE.
• To analyze the role of preoperative diagnostic studies in patient selection for different PQD extents.

Main Methods:

• Systematic literature review of studies reporting PQD since 2004.
• Analysis of pooled patient data (n=137) focusing on preoperative assessments, surgical techniques, and patient outcomes.
• Comparison of outcomes between total PQD (66% of patients) and partial PQD (34% of patients).

Main Results:

• Total PQD patients (75%) had higher seizure freedom rates (Engel I/ILAE Class 1) compared to partial PQD patients (63%), though not statistically significant (p=0.078).
• Preoperative studies varied by PQD extent: PET/SPECT common in total PQD (42%), while Wada/fMRI and icEEG more utilized in partial PQD (22% and 30%, respectively).
• Concordance between interictal and ictal EEG findings was a significant predictor of seizure freedom (p=0.048).

Conclusions:

• Both total and partial PQD are effective surgical strategies for MRE with diffuse posterior SOZs.
• Surgical approach (total vs. partial PQD) influences the choice of preoperative diagnostic modalities.
• Concordant EEG findings are crucial for predicting successful seizure control after PQD.