Long-term clinical outcomes of the Adams modification to the anatomical hemispherectomy for refractory epilepsy: A case series and global systematic review.

Background

Although contemporary hemispheric epilepsy surgery has largely shifted towards functional disconnection and hemispherotomy, complete anatomical approaches may retain a role in selected patients, including as rescue procedures after failed disconnection. In the 1980s, a modified anatomical hemispherectomy was developed at the Radcliffe Infirmary at the University of Oxford, incorporating an extended extradural dissection to reduce delayed haemorrhagic complications. The long-term efficacy of this approach in refractory epilepsy and related comorbidities has not previously been evaluated.

Methods

We performed a retrospective observational study and systematic review. Clinical data were obtained from patients undergoing modified hemispherectomy at our institution between 1983 and 1996. A systematic search of MEDLINE, EMBASE, and Scopus (inception-December 2024) was conducted according to PRISMA guidelines. Studies including ≥ 10 patients with postoperative seizure outcomes reported after ≥ 5 years' mean or median follow-up were included. Epilepsy aetiology and surgical techniques were categorised using predefined criteria. Outcomes focused on seizure freedom at final follow-up, complications and neurocognitive outcomes were reported. Statistical analyses employed parametric or non-parametric testing with significance set at p ≤ 0.05.

Results

In our patient cohort (n = 49), most patients presented with focal onset seizures with secondary generalisation (59%) and an acquired aetiology (65%). Within five years of surgery, 63% achieved seizure freedom. Anti-seizure medications were discontinued in 51%, of whom 80% remained seizure-free at long-term follow-up. Neurodevelopmental improvement was observed in 69% and behavioural improvement in 80% of individuals. Seizure freedom was significantly associated with gains in neurocognitive (OR 9.6, 95%:CI 2.36-32.70) and behavioural (OR 6.5, 95%:CI 1.48-25.59) outcomes. Postoperative complications occurred in 16 patients (33%), more than half of which were wound infections (9, 56%). The systematic review included 58 studies, 77% from high-income countries, and demonstrated a median seizure freedom rate of 74% at last follow-up (median 5.7 years, IQR 5.1-7.0), with functional hemispherectomies showing superior outcomes.

Conclusions

This study presents the largest systematic review of hemispherectomies to date and provides new insight into a surgical modification that influenced the evolution of modern epilepsy surgery.