Surgical treatment of essential tremor

Surgical treatment for essential tremor (ET) has been used since the early 1950s. Initially, different areas were targeted for tremor control. However , the optimal target was eventually determined to be the ventralis intermed ius (VIM) nucleus of the thalamus. Thalamotomy improves contralateral tremo r in more than 90% of patients. Long-term studies of thalamotomy indicate t hat the benefits continue in most patients. Persistent morbidity associated with thalamotomy, which occurs in less than 10% of patients, includes dysa rthria, dysequilibrium, weakness, and cognitive impairment. Bilateral thala motomy is associated with substantial morbidity and is usually avoided. Stu dies demonstrate that chronic stimulation of the VIM is safe and effective for tremor. Adverse effects of chronic stimulation include paresthesia, dys arthria, dysequilibrium, and localized pain. In many patients, bilateral th alamic stimulation is performed without a substantial increase in morbidity . ET patients with disabling medication-resistant tremor are reasonable can didates for these stereotactic procedures.