[Surgical treatment of Parkinson disease and essential tremor].

Recognition of the often failing effect of levodopa treatment as Parkinson's disease (PD) progresses has led to the resumption of surgical treatment. In the 1950'ies and 1960'ies pallidotomy and thalamotomy were commonly performed to reduce parkinsonian symptoms, whilst today these permanent lesions are replaced by Deep Brain Stimulation (DBS) of implanted leads. The advantages of DBS in either the subthalamic nuclei (STN) or the internal part of the globus pallidus are that implantation of leads into these nuclei can be performed bilaterally, and that DBS is a reversible treatment. Pallidotomy and thalamotomy are permanent lesions and if performed bilaterally these lesions often cause unacceptable complications. Bilateral stimulation of the STN is often preferred due to the reduction of rigidity, hypokinesia and tremor as well as the significant reduction of dyskinesias and off-periods. The motor functions are significantly improved and stabilized.