Failed Hemispheric Disconnection Surgery: What Secondary Treatments Showed

What was studied

This systematic review examined published reports from January 1990 through April 2025 involving people of any age whose seizures returned after hemispheric disconnection surgery, also called hemispherectomy or hemispherotomy.

The review included 25 studies. Reported secondary treatments were repeat hemispheric surgery in 151 patients, laser interstitial thermal therapy in 9, and vagus nerve stimulation in 9. Researchers combined study-level results and also analyzed available individual-patient data over time.

What they found

The pooled estimate indicated that 18% of patients underwent reoperation after failed hemispheric disconnection surgery. After repeat hemispheric surgery, an estimated 50% achieved Engel class I, generally meaning freedom from disabling seizures, and 69% achieved Engel class I or II, meaning freedom from disabling seizures or only rare disabling seizures.

In the individual-patient analysis, median seizure-free survival for an Engel I outcome after repeat surgery was estimated at 4.5 years. Median survival for an Engel I or II outcome was 6.8 years. Engel I duration was significantly longer after repeat surgery than after laser treatment: a median of 4.5 years versus 1.4 years. Information on vagus nerve stimulation was too limited for pooled analysis and was summarized narratively.

Limits of the evidence

This review synthesized previously published studies rather than reporting a randomized comparison, so treatment differences should be interpreted cautiously. Results varied among studies for Engel I outcomes after repeat surgery. Only nine patients each were reported for laser treatment and vagus nerve stimulation, making conclusions about those options especially uncertain. The abstract does not report overall complication rates, functional or developmental outcomes, quality of life, or detailed risk-of-bias findings.

For families and caregivers

The findings suggest that repeat hemispheric surgery may provide meaningful and sometimes durable seizure control for some people whose seizures return after an initial disconnection surgery. Laser treatment is a minimally invasive option, but evidence was based on very few patients and seizure control appeared less durable than after repeat surgery. Vagus nerve stimulation appeared primarily palliative, but the available evidence was too limited for firm conclusions. These results may help inform individualized surgical counseling and decision-making.

What to watch next

Larger comparative studies with longer follow-up and clear reporting of complications, function, development, and quality of life would strengthen the evidence, particularly for laser treatment and vagus nerve stimulation.

Terms in this summary

Hemispheric disconnection surgery

An operation intended to disconnect a brain hemisphere associated with severe seizures from the rest of the brain.

Redo hemispheric surgery

A second operation intended to complete or revise an earlier hemispheric disconnection.

Laser interstitial thermal therapy (LITT)

A minimally invasive procedure that uses laser-generated heat to treat targeted brain tissue.

Vagus nerve stimulation (VNS)

A device-based treatment that sends electrical signals through the vagus nerve and is used to help control seizures.

Engel class I

The best seizure-outcome category, generally meaning no disabling seizures.

Engel class II

An outcome category generally meaning only rare disabling seizures.

Median seizure-free survival

The estimated time by which half of the analyzed group had lost the stated level of seizure control.

Pooled estimate

A result calculated by statistically combining findings from multiple studies.