Unilateral stimulation of the subthalamic nucleus in Parkinson disease: a double-blind 12-month evaluation study.

OBJECT: Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been established as an effective treatment for Parkinson disease (PD). Nevertheless, bilateral surgical procedures can be associated with frequent and severe complications. The aim in the present study was to assess the safety and efficacy of unilateral STN stimulation, and the need for a second procedure. METHODS: Twelve patients with PD underwent unilateral DBS of the STN and were followed up for 12 months. Patients were assessed at baseline and at each visit in a double-blind fashion by analyzing the Unified PD Rating Scale (UPDRS), ambulation speed, and home diaries. Levodopa-off/stimulation-on UPDRS motor scores were improved by 26 +/- 8% (p < 0.05, mean +/- standard deviation [SD]) compared with the baseline levodopa-off score; there was a 50% improvement in contralateral features, a 17% improvement ipsilaterally, and a 36% improvement in axial features. The mean ambulation speed increased by 83 +/- 44% (p < 0.01, mean +/- SD). The medication-on time with dyskinesias was significantly reduced (p < 0.01) and the daily levodopa dose was reduced by 19 +/- 6% (p < 0.05, mean +/- SD). There were no clinically significant side effects. CONCLUSIONS: Unilateral DBS of the STN is safe and well tolerated, and may provide sufficient benefit so that additional surgery is not required.

Benefits and risks of pharmacological treatments for essential tremor.

Essential tremor can cause significant functional disability in some patients. The arms are the most common body part affected and cause the most functional disability. The treatment of essential tremor includes medications, surgical options and other forms of therapy. Presently there is no cure for essential tremor nor are there any medications that can slow the progression of tremor. Treatment for essential tremor is recommended if the tremor causes functional disability. If the tremor is disabling only during periods of stress and anxiety, propranolol and benzodiazepines can be used during those periods when the tremor causes functional disability. The currently available medications can improve tremor in approximately 50% of the patients. If the tremor is disabling, treatment should be initiated with either primidone or propranolol. If either primidone or propranolol do not provide adequate control of the tremor, then the medications can be used in combination. If patients experience adverse effects with propranolol, occasionally other beta-adrenoceptor antagonists (such as atenolol or metoprolol) can be used. If primidone and propranolol do not provide adequate control of tremor, occasionally the use of benzodiazepines (such as clonazepam) can provide benefit. Other medications that may be helpful include gabapentin or topiramate. If a patient has disabling head or voice tremor, botulinum toxin injections into the muscles may provide relief from the tremor. Botulinum toxin in the hand muscles for hand tremor can result in bothersome hand weakness and is not widely used. There are other medications that have been tried in essential tremor and have questionable efficacy. These drugs include carbonic anhydrase inhibitors (e.g. methazolamide), phenobarbital, calcium channel antagonists (e.g. nimodipine), isoniazid, clonidine, clozapine and mirtazapine. If the patient still has disabling tremor after medication trials, surgical options are usually considered. Surgical options include thalamotomy and deep brain stimulation of the thalamus. These surgical options provide adequate tremor control in approximately 90% of the patients. Surgical morbidity and mortality for these procedures is low. Deep brain stimulation and thalamotomy have been shown to have comparable efficacy but fewer complications have been reported with deep brain stimulation. In patients undergoing bilateral procedures deep brain stimulation of the thalamus is the procedure of choice to avoid adverse effects seen with bilateral ablative procedures. The use of medication and/or surgery can provide adequate tremor control in the majority of the patients.

Effect of motor improvement on quality of life following subthalamic stimulation is mediated by changes in depressive symptomatology.

BACKGROUND/AIMS: Subthalamic deep brain stimulation (STN-DBS) for Parkinson's disease (PD) improves motor symptoms and quality of life (QOL). Because depression is a potent correlate of QOL, and STN-DBS may be associated with changes in mood, this study sought to determine whether QOL improvement is a direct or indirect consequence of motor improvement. METHODS: 26 patients with PD, free of dementia and major depression, who consecutively underwent bilateral, microelectrode-guided STN-DBS, underwent preoperative and 3-month postoperative neuropsychological evaluation, including measures of QOL (PD Questionnaire -39) and depressive symptoms (Beck Depression Inventory). RESULTS: Motor score in the Unified Parkinson's Disease Rating Scale (UPDRS Part III) improved significantly with STN-DBS relative to preoperative 'on' and 'off' scores, as did QOL and depressive symptoms. Extent of QOL improvement tended to be associated with improvement in motor score from presurgical on to postsurgical on stimulation and on medication state. QOL improvement was significantly related to amelioration of depressive symptoms. Partial correlations revealed that the association between QOL improvement and depression remained significant when influence of motor improvement on QOL and depression was controlled for. The motor-QOL association was no longer significant when effects of depression were controlled for. CONCLUSIONS: Significant QOL improvements after STN-DBS are associated with improved motor 'on' state and depressive symptoms. The influence of motor improvement on QOL may be largely indirect by reducing depression.

Thalamic stimulation for midbrain tremor after partial hemangioma resection.

We describe a patient with disabling medication-resistant midbrain tremor developed after partial hemangioma resection, who responded to deep brain stimulation of the thalamus.