Bilateral dorsolateral subthalamotomy for advanced Parkinson's disease

Abstract

Functional surgery for Parkinson's disease has undergone a resurgence since the motor complications of chronic levodopa use have become apparent. Laitinen et al showed a beneficial effect on dyskinesia, bradykinesia, and rigidity with unilateral pallidotomy. Limousin and co-workers 2 Limousin P Pollak P Benazzouz A et al. Effect on parkinsonian signs and symptoms of bilateral subthalamic nucleus stimulation. Lancet. 1995; 345: 91-95 Summary PubMed Google Scholar have presented evidence that bilateral implantation of deep brain stimulators into the central portion of the subthalamic nuclei (STN) can be undertaken safely and will improve all features of parkinsonism. The caudomedial aspect of STN is thought to be the origin of excitatory tracts to the globus pallidus interna (GPi) and the substantia nigra reticulata (SNR) via the subthalamic fasciculus. 3 Carpenter MB Batton RB Carleton SC Keller JT Interconnections and organisation of pallidal and subthalamic nucleus neurons in the monkey. J Comparative Neurol. 1981; 197: 579-603 Crossref PubMed Scopus (136) Google Scholar A discrete lesion in this area should have an effect equivalent to STN stimulation. Lesions of STN carry a risk of hemiballismus. Surgical targets for treating hemiballism are the zona incerta and the ventral intermediate nucleus (VIM). 4 Krauss KJ Mundinger F Functional stereotactic surgery for hemiballism. J Neurosurg. 1996; 85: 278-285 Crossref PubMed Scopus (50) Google Scholar These structures lie immediately above the dorsolateral STN. If a lesion in the dorsolateral STN were to produce hemiballism, then extending the lesion 2–3 mm ventrally should suppress it. Stimulators are bulky and costly, require regular adjustment, and patients may develop tolerance. They preclude further magnetic resonance imaging (MRI) scans and the stimulator units need to be replaced every 3–5 years. Lesions do not have these problems, but unlike stimulators side-effects may not be reversible. Unilateral STN lesions are reported in 5 patients by Obeso et al. 5 Obeso JA Alvarez LM Macias RJ et al. Lesion of the subthalamic nucleus in Parkinson's disease. Neurology. 1997; 48: A138 Google Scholar We report two cases of safe and so far effective bilateral STN lesions.