Unilateral subdural motor cortex stimulation improves essential tremor but not Parkinson's disease.

Epidural motor cortex stimulation has been reported to be effective in treating some movement disorders. Nevertheless, clinical results have been variable and no double-blinded evaluations have been reported. The aim of this study was to investigate efficacy and safety of unilateral subdural motor cortex stimulation in patients with essential tremor and Parkinson's disease. Six patients with essential tremor and five parkinsonian patients were selected. Craniotomy was performed under local anaesthesia with conscious sedation. A four contact electrode (Resume II model 3587, Medtronic, Inc) was positioned on the motor cortex, after identification of the area with direct monopolar cortical stimulation. Soon after surgery, a variety of different settings of stimulation were assessed using standard rating scales to select the optimal stimulation parameters. The effects of chronic stimulation were evaluated in both groups of patients after 3 months (double-blinded fashion) and 1 year (open fashion). In essential tremor, contralateral hand tremor scores significantly improved (P = 0.04) with stimulation during the double-blinded study, whereas in Parkinson's disease, there were no changes in the OFF medication/on stimulation motor scores compared with off stimulation. At 1 year, tremor was improved by stimulation in two out of three patients with essential tremor available at follow-up, whereas no improvement was observed in the five parkinsonian patients. One parkinsonian patient had a cortical venous infarct. Three other patients had self-limiting seizures with aggressive trials of stimulation in the period of dosage selection. These findings suggest that unilateral subdural motor cortex stimulation may be useful for contralateral hand tremor in selected patients with essential tremor but was not effective in improving parkinsonian signs in our series.

Unilateral pallidal deep brain stimulation in a patient with cervical dystonia and tremor.

Bilateral deep brain stimulation of the globus pallidus pars interna (GPi) is the favored neuromodulation procedure in cases of cervical dystonia. The authors report on a case of unilateral GPi implantation that resulted in sustained benefit with marked improvement in pain and dystonia.

Levodopa response in long-term bilateral subthalamic stimulation for Parkinson's disease.

Subthalamic nucleus deep brain stimulation (STN-DBS) is effective in advanced Parkinson's disease (PD), but its effects on the levodopa response are unclear. We studied the levodopa response after long-term STN-DBS, STN-DBS efficacy and predictive value of preoperative levodopa response to long-term DBS benefit in 33 PD patients with bilateral STN-DBS. Patients were assessed using the Unified Parkinson's Disease Rating Scale preoperatively (with and without medications) and postoperatively (without medications or stimulation, with only medications or stimulation, and with both medications and stimulation). Levodopa response significantly decreased postoperatively by 31.1% at 3 years and 32.3% at 5 years, possibly related to the reduction in medication requirement, direct STN stimulation effect or PD progression. STN-DBS alone significantly improved motor scores (37.2% at 3 years and 35.1% at 5 years) and activities of daily living scores (27.1% at 3 years and 19.2% at 5 years). Anti-PD drugs were significantly reduced by 47.9% at 3 years and 39.8% at 5 years. However, the magnitude of the preoperative response to levodopa did not predict DBS benefit at 3 and 5 years.

Subthalamic nucleus stimulation: improvements in outcome with reprogramming.

BACKGROUND: Deep brain stimulation (DBS) is currently the most effective surgical treatment for advanced Parkinson disease (PD). Even when the electrode is well positioned in the target, the optimization of clinical results depends on careful programming of electrical parameters and changes in antiparkinsonian drug dosages. OBJECTIVE: To determine whether stable outcomes from subthalamic nucleus DBS for PD can be improved by revising stimulation parameters and drug dosages through "hands-on" involvement of a neurologist expert in both movement disorders and DBS programming. METHODS: In 44 consecutive patients with PD with long-term stable response to subthalamic nucleus DBS (mean +/- SD, 3.5 +/- 1.7 years), we compared scores from the Unified Parkinson's Disease Rating Scale parts II through IV obtained immediately before and following a formal reprogramming of their stimulation. The reprogramming was performed by a neurologist expert in both PD and DBS and accompanied by further medication adjustments. The patients were subsequently followed up for as long as 14 months. RESULTS: In 24 patients (54.6%), the scores on the Unified Parkinson's Disease Rating Scale parts II and III significantly improved by 15.0% and 25.9%, respectively. Anti-PD drugs were significantly reduced (by 25.9%). No improvement was observed in 16 patients (36.4%), and the conditions of 4 patients (9.1%) worsened. CONCLUSIONS: Further improvement of parkinsonian signs can be achieved in the majority of patients even after long-term stable stimulation. Improved patient outcomes from subthalamic nucleus DBS are obtained when postoperative care is personally managed by a neurologist expert in movement disorders and DBS who is directly responsible for stimulation programming and simultaneous drug adjustments based on observed clinical responses to changing stimulation parameters.

Bilateral globus pallidus stimulation for Huntington's disease.

Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) was performed in a patient with Huntington's disease (HD) with severe chorea. Stimulation at 40 and 130 Hz improved chorea. Stimulation at 130 Hz slightly worsened bradykinesia overall, whereas 40 Hz had little effect. A [15O] H2O positron emission tomography showed increased regional cerebral blood flow in motor decision making and execution areas more evident at 40 Hz. Adjustment of stimulation parameters in GPi DBS may have the potential to optimize the motor response in HD, improving chorea without aggravating bradykinesia.