Functional stereotactic surgery for treatment of cervical dystonia: review of the experience from the lesional era.

BACKGROUND: Functional stereotactic neurosurgery has been rediscovered as a powerful tool to treat various manifestations of medically refractory dystonia. The purpose of this study was to provide the first systematic review of previous experience with thalamic and basal ganglia surgery in the treatment of cervical dystonia (CD). METHODS: A comprehensive review of the literature published between 1950 and 1990 was performed. In addition, data from an unpublished doctoral thesis on 162 patients with CD operated on by Mundinger between 1972 and 1986 were analyzed. RESULTS: Overall, there is published documentation of experience with more than 300 patients with CD who underwent functional stereotactic surgery between the late 1950s and the early 1980s. In general, amelioration of CD was achieved in about 50-70% of patients in most studies. Bilateral surgery generally provided better outcomes than unilateral surgery. Postoperative benefit was reported to become evident only after a delay in several studies. Some reports demonstrated sustained benefit after follow-up of more than 5 years. Bilateral procedures, in particular bilateral thalamotomies, were clearly associated with a higher rate of postoperative side effects, such as dysarthria, dysphagia and ataxia, ranging from 20 to 70%. In the first decade after its introduction, thalamotomy was the preferred procedure. Later, the subthalamic area was targeted more frequently in order to affect pallidal outflow. Experience with targeting the pallidum proper was limited. Functional stereotactic surgery for CD was abandoned in the late 1970s for several reasons, including the general decline in movement disorder surgery at that time, the introduction of selective peripheral denervation and the widespread and beneficial use of botulinum toxin soon thereafter. CONCLUSIONS: Functional stereotactic surgery for treatment of CD has a rich history. There are several lessons to be learned from review of earlier experience. Contemporary techniques have led to a significant improvement in the benefit to risk ratio, in particular regarding bilateral surgery.

Thalamic stimulation for tremor. Subtle changes in episodic memory are related to stimulation per se and not to a microthalamotomy effect.

The aim of this study was to investigate the impact of unilateral deep brain stimulation (DBS) of the ventrointermediate (Vim) thalamic nucleus on neuropsychological functioning comparing stimulation-on with stimulation-off conditions. Nine patients [five patients with Parkinson's Disease (PD), two patients with essential tremor (ET) and 2 patients with multiple sclerosis (MS)] underwent comprehensive neuropsychological testing for cognitive functions, including general mental impairment, aphasia, agnosia, executive and constructional abilities, learning, memory, cognitive processing speed and attention as well as depression. The neuropsychological assessments were performed at least 6 months postoperatively (mean 9 months). Testing in the stimulation-on and stimulation-off condition was obtained within a period of 3 to 4 weeks. Unilateral DBS resulted in improvement of tremor in all patients. There were no significant differences between the stimulation-on and the stimulation-off condition with the exception of a decrement of word-recall in the short delay free-recall subtest of the Rey Auditory-Verbal Learning Test (RAVLT). Subgroup analysis indicated that the impairment in word-recall was related to left-sided thalamic stimulation. Our study confirms that chronic unilateral DBS is a safe method with regard to cognitive function. The subtle changes in episodic memory are related to stimulation per se and not to a microthalamotomy effect.

Long-term pallidal deep brain stimulation in patients with advanced Parkinson disease: 1-year follow-up study.

OBJECT: The goal of this study was to investigate the efficacy of long-term deep brain stimulation (DBS) of the posteroventral lateral globus pallidus internus (GPi) accomplished using a single-contact monopolar electrode in patients with advanced Parkinson disease (PD). METHODS: Sixteen patients suffering from severe PD and levodopa-induced side effects such as dyskinesias and on-off fluctuations were enrolled in a prospective study protocol. There were six women and 10 men and their mean age at surgery was 65 years. All patients underwent implantation of a monopolar electrode in the posteroventral lateral GPi. Initially, nine patients received unilateral stimulation. Three of these patients underwent contralateral surgery at a later time. Ten patients received bilateral stimulation (contemporaneous bilateral surgery was performed in seven patients and staged bilateral surgery in the three patients who had received unilateral stimulation initially). Formal assessments were performed during both off-medication and on-medication (levodopa) periods preoperatively, and at 3 and 12 months postoperatively. There were no serious complications related to surgery or to DBS. Two transient adverse events occurred: in one patient a small pallidal hematoma developed, resulting in a prolonged micropallidotomy effect, and in another patient a subcutaneous hemorrhage occurred at the site of the pacemaker. In patients who received unilateral DBS, the Unified Parkinson's Disease Rating Scale activities of daily living (ADL) score during the off-levodopa period decreased from 30.8 at baseline to 20.4 at 3 months (34% improvement) and 20.6 at 12 months (33% improvement) postoperatively. The motor score during the off period improved from 57.2 at baseline to 35.2 at 3 months (38% improvement) and 35.3 at 12 months (38% improvement) postoperatively. Bilateral DBS resulted in a reduction in the ADL score during the off period from 34.9 at baseline to 22.3 at 3 months (36% improvement) and 22.9 at 12 months (34% improvement). The motor score for the off period changed from 63.4 at baseline to 40.3 at 3 months (36% improvement) and 37.5 at 12 months (41% improvement). In addition, there were significant improvements in patients' symptoms during the on period and in on-off motor fluctuations. CONCLUSIONS: Pallidal DBS accomplished using a monopolar electrode is a safe and effective procedure for treatment of advanced PD. Compared with pallidotomy, the advantages of pallidal DBS lie in its reversibility and the option to perform bilateral surgery in one session. Comparative studies in which DBS is applied to other targets are needed.