pallidotomy

Pallidotomy is a neurosurgical procedure that creates a focal lesion in the globus pallidus interna (GPi) of the brain. It is primarily used to treat movement disorders, most notably Parkinson's disease (PD), as well as dystonia and, less commonly, chorea associated with other conditions. The procedure is usually performed unilaterally in PD to reduce motor symptoms on one side of the body, with bilateral procedures carrying higher risk of speech and cognitive side effects.

The surgery is planned with stereotactic guidance in conjunction with imaging and sometimes microelectrode recording to localize the GPi. The lesion is produced by delivery of heat (radiofrequency ablation) or, more recently, by laser interstitial thermal therapy or radiosurgical methods. Because pallidotomy creates a permanent lesion, accurate targeting and monitoring of neurologic function during the procedure are important.

Mechanistically, GPi output is inhibitory to the thalamus. By lesioning a portion of GPi, pallidotomy reduces this inhibitory drive, thereby disinhibiting thalamocortical pathways. The net effect is improved movement control, with reductions in rigidity, bradykinesia, tremor, and, in some patients, levodopa-induced dyskinesias. Improvements vary among individuals and may take weeks to months to become evident.

Indications include medication-refractory motor fluctuations or tremor in PD and certain dystonias. Risks include stroke or hemorrhage, weakness, sensory changes, speech or cognitive disturbance, and balance problems; many risks are greater with bilateral pallidotomy. The advent of deep brain stimulation (DBS) has largely supplanted pallidotomy in many centers, though pallidotomy remains an option for selected patients or institutions without DBS capabilities.