Neurosurgical treatment of tremor in mitochondrial encephalopathy

A 53‐year‐old woman underwent several ischemic stroke‐like episodes and later developed incomplete, bilateral ophthalmoplegia, left vision deterioration, and bilateral tremor. The clinical course, laboratory data, and muscle histology led to a diagnosis of mitochondrial encephalomyopathy. No other etiology could be identified in the background of her disabling bilateral postural–kinetic tremor. As this tremor did not respond to pharmacological therapy, left thalamotomy and subsequently right thalamic deep brain stimulator (DBS) implantation were performed, which resulted in an excellent clinical outcome. The Fahn–Tolosa–Marin Tremor Rating Scale improved from 110 to 11 points. This case suggests that the rare tremor caused by mitochondrial encephalopathy may be treated long‐term with either thalamotomy or thalamic DBS implantation. © 2006 Movement Disorder Society     

Staged lesions through implanted deep brain stimulating electrodes: a new surgical procedure for treating tremor or dyskinesias.

Thalamotomy and pallidotomy have been shown to have some efficacy for treating some movement disorders such as disabling tremor or parkinsonian levodopa-induced dyskinesias (LID). Compared to continuous deep brain stimulation (DBS), this surgical procedure has the disadvantage of irreversibility and a lack of adaptability. Making a lesion involves a risk of inducing permanent side effects, especially if the lesion is large, or of observing a resurgence of the symptoms if the lesion is too small. We performed unilateral pallidotomy in one patient suffering from LID and unilateral thalamotomy in two patients suffering from tremor through the lead classically used for DBS. The technique of lead implantation was similar to that used for DBS treatment but, instead of connecting the lead to a pulse generator, it was left in place and used to make a radiofrequency lesion. This technique allowed the lesion to be kept as small as possible, thereby minimizing the risk of permanent side effects and made possible to extend the lesion if the symptoms reappeared. One lesioning session was enough to relieve tremor in the two patients treated by thalamotomy; three lesioning sessions over a 7-month period were required to relieve drug-induced dyskinesias in the patient treated by pallidotomy. In all 3 patients, disabling symptoms were still relieved without any permanent side effects 6 months after the last lesion was performed.     

Surgical therapy for multiple sclerosis tremor: a 12‐year follow‐up study

Background and purpose: Severe multiple sclerosis (MS) tremor causes disability poorly responsive to medication. Deep brain stimulation (DBS) or thalamotomy can suppress tremor, but long‐term outcomes are unclear. Methods: Nine patients with MS tremor underwent disability measures at baseline and 12 months post‐surgery (six thalamotomy, three DBS) in 1997–1998 (previously reported, Matsumoto et al., Neurology 2001;57:1876–82). We report the prospective 12‐year follow‐up of this cohort for tremor, disability, and death. Results: Surgery was initially successful in all. Tremor recurred in all patients within median 3 months, although two DBS patients were tremor‐free for 5 years. Median tremor‐free survival (tremor‐free time/survival time) was 4.3%. At 12‐year follow‐up, four survivors (two thalamotomy, two DBS) (Expanded Disability Status Scale scores 8–8.5) were severely disabled. Five patients were dead (four thalamotomy, one DBS) median 5.8 years post‐operative. Conclusions: Surgery benefit for severe tremor was overall short‐lived (median 3 months), with long‐term poor prognosis. Although two DBS patients had sustained 5‐year tremor‐suppression, the observed progressive disability and death in this cohort bear importance for long‐term success in future MS tremor surgery trials.     

Deep brain stimulation for essential tremor: A systematic review

Deep brain stimulation (DBS) is a neurosurgical treatment, which has proven useful in treating Parkinson's disease. This systematic review assessed the safety and effectiveness of DBS for another movement disorder, essential tremor. All studies concerning the use of DBS in patients with essential tremor were identified through searching of electronic databases and hand searching of reference lists. Studies were categorized as before/after DBS or DBS stimulation on/off to allow the effect of the stimulation to be analyzed separately to that of the surgery itself. A total of 430 patients who had received DBS for essential tremor were identified. Most of the reported adverse events were mild and could be treated through changing the stimulation settings. Generally, in all studies, there was a significant improvement in outcomes after DBS compared with baseline scores. In addition, DBS was significantly better in testing when the stimulation was turned on, compared with stimulation turned off or baseline. Based on Level IV evidence, DBS is possibly a safe and effective therapy for essential tremor. © 2010 Movement Disorders Society     

Bilateral effects of unilateral thalamic deep brain stimulation: A case report

A recent study has proved that unilateral deep brain stimulation (DBS) of the subthalamic nucleus has bilateral effects. However, it is still unclear whether unilateral ventral intermediate thalamic nucleus (Vim) DBS exerts exclusively contralateral or bilateral effects on tremor. Previous studies demonstrated a clinically irrelevant improvement on the nontarget side after thalamic stimulator implantation, which was considered to be solely the result of mechanical effects. We report here the case of a 55‐year‐old woman in whom unilateral thalamic DBS can stop the disabling postural‐kinetic tremor in both hands. Simultaneous surface electromyography (sEMG), accelerometry, and video recordings were obtained to evaluate the underlying mechanism. After the right Vim DBS was turned off, moderate rest tremor appeared in both hands accompanied by bilateral bursts on sEMG. Because right hand tremor cannot simply reflect the mechanical overflow of the left side, the bilateral improvement caused by right Vim DBS is probably due to an active tremor reduction in this particular case. © 2007 Movement Disorder Society     

Gait and balance in essential tremor: Variable effects of bilateral thalamic stimulation

Essential tremor (ET) is a multi‐faceted condition best known for postural and action tremor but also may include disordered gait and postural instability. Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus provides substantial tremor reduction yet some patients with bilateral VIM DBS have gait and balance impairment. This study examines gait and balance performance in 13 participants with ET who have bilateral VIM DBS compared with a matched control group. Participants with ET were tested with their stimulators off (DBS OFF) and on (DBS ON). For both standard and tandem walking, participants with ET walked significantly more slowly than controls, with significantly lower cadence, spending a lower percentage of the gait cycle in single limb support and a higher percentage in double support compared with controls. Participants with ET also had significantly lower tandem and one leg stance times, Berg balance scores, balance confidence, and required significantly greater time to perform the Timed Up‐and‐Go relative to controls. There were no significant differences in any gait or balance measures in the DBS OFF versus DBS ON conditions, but the effects of DBS on gait and balance were highly variable among individuals. Future studies are needed to determine why some individuals experience gait and balance difficulties after bilateral thalamic DBS and others do not. A better understanding of the mechanisms underlying gait and balance impairments in those with bilateral DBS is critical to reduce falls and fractures in this group. © 2008 Movement Disorder Society     

Long‐term deep brain stimulation for essential tremor: 12‐year clinicopathologic follow‐up

We describe the clinical course and postmortem pathological findings in a patient with essential tremor (ET) treated with deep brain stimulation (DBS) for 12 years. This 75 year old woman had a 13‐year history of progressive ET prior to implantation of bilateral quadripolar DBS electrodes in the region of her ventral intermediate thalamic nuclei in 1996, producing immediate relief of arm tremor. Histopathological examination of the brain, performed 12 years after the initial implantation, demonstrated electrode catheter tracts rimmed by 20‐25 micron fibrous sheaths, with multinucleated giant cells and reactive gliosis. Lymphocytic infiltration was seen by L26 immunoreactivity with CD3 (T cells) staining predominating over CD20 (B cells). Cerebellar axonal spheroids and Purkinje cell loss were found. The minimal foreign body reaction and gliosis around the electrodes 12 years after implantation supports the long‐term safety of DBS. The case represents the longest reported follow‐up with autopsy examination after DBS and confirmed histological changes associated with ET. © 2009 Movement Disorder Society     

Mood and motor effects of thalamic deep brain stimulation surgery for essential tremor

Purpose: The aim of this study was to evaluate the effects of unilateral and bilateral ventralis intermedius (Vim) deep brain stimulation (DBS) on mood and motor function. Methods: Thirty‐one consecutive medication refractory patients with essential tremor who underwent unilateral or bilateral Vim DBS at University of Florida and returned for at least 6 ‐month follow‐up completed the Visual Analog Mood (VAMS), the Beck Depression Inventory (BDI), and the Tremor Rating Scale (TRS) before and after surgery. We excluded all patients who were implanted at other institutions. Results: The tense subscale of the VAMS improved significantly in both the unilateral and bilateral DBS groups (P < 0.001). On the VAMS afraid subscale, only the bilateral group trended toward improvement (P = 0.075). There were no significant changes for either group for the happy, confused, sad, angry, energetic or tired VAMS scores. TRS subscale scores all improved after unilateral and bilateral Vim DBS surgery (P < 0.001). Conclusions: Feelings of tenseness, tremor severity and ADLs improved following unilateral or bilateral Vim DBS for ET.     

特发性震颤的微电极导向射频治疗

目的探讨丘脑Vim核中神经细胞的电活动与特发性震颤（ET）的关系,总结Vim核射频毁损（切开）术治疗ET的可行性、并发症及疗效。方法对72例ET行CT定位微电极导向Vim核射频,并进行FAHN评分。结果Vim核中存在与肢体震颤节律一致的细胞电活动,毁损这些细胞后震颤立即消失,有效率100％。整体评分改善率60．2％;震颤程度和部位改善率53．1％;特殊动作和功能改善率51．6％;功能残疾改善率76．2％。暂时性并发症19例,3—36个月随访疗效稳定。结论丘脑Vim核中存在与ET密切相关的细胞,射频毁损Vim核是治疗ET安全有效措施。