Thalamotomy and Pallidotomy

Indications

• Pallidotomy

  • Parkinson disease : Complications of advancing disease and medical therapy including tremor, wearing off, motor fluctuations, and dyskinesia in patients with a good response to levodopa therapy. Pallidotomy should preferably be unilateral in Parkinson’s disease patients.

  • Dystonia : Disabling symptoms nonresponsive to medical therapy, including anticholinergics, benzodiazepines, and botulinum toxin. In certain cases, pallidotomy may be performed bilaterally in dystonic patients.

• Thalamotomy

  • Essential tremor: Disabling, predominantly upper extremity, unilateral kinetic tremor despite optimum medical therapy, including beta blockers, primidone, and benzodiazepines.

  • Parkinson disease: Unilateral rest tremor resistant to medical therapy in tremor-dominant disease.

  • Cerebellar outflow tremor: Medically intractable unilateral kinetic, postural, or rest tremor secondary to multiple sclerosis or traumatic brain injury

• Contralateral to deep brain stimulation (DBS) system

  • In patients requiring bilateral surgery (e.g., patients with Parkinson disease, essential tremor), pallidotomy and thalamotomy may be performed contralateral to a DBS system.

  • Dystonia may be treated with bilateral pallidotomy or unilateral pallidotomy contralateral to a globus pallidus internus (GPi) DBS system.

• In place of DBS system

  • In patients who have undergone DBS (GPi, ventralis intermedius [Vim], possibly subthalamic nucleus), but in whom there have been hardware-related complications, such as chronic infection, the DBS may be removed and radiofrequency lesioning performed.

Contraindications

• Unstable medical condition precluding awake stereotactic surgery.

• Neuropsychiatric conditions, including untreated depression, psychotic symptoms (unless resulting from medical therapy such as dopamine agonists), and cognitive decline.

• Multisystem atrophy in parkinsonian patients.

• Poor response to levodopa therapy in Parkinson disease (except tremor).

• Contralateral homotopic lesion (except for dystonia).

• Need for general anesthesia during surgery.

  • With rare exception, radiofrequency lesions should be created with constant neurologic evaluation, necessitating an awake patient.

  • General anesthesia can be used and the patient reversed for the lesioning part of the procedure if necessary.

Planning and positioning