Neuropsychological and quality of life outcome after thalamic stimulation for essential tremor

OBJECTIVE: To evaluate short-term effects of unilateral thalamic deep brain stimulation (DBS) on cognition, mood state, and quality of life in patients with essential tremor (ET). BACKGROUND: Unilateral thalamotomy and thalamic DBS are effective in alleviating refractory tremor contralateral to the side of surgery. Thalamotomy can lead to cognitive morbidity, and DBS might be a preferable surgical intervention given potential avoidance or reversibility of such morbidity. Although unilateral thalamic DBS is cognitively safe and leads to quality of life improvement in PD, its neurobehavioral effects in ET are unknown. METHODS: Forty patients with ET were administered a broad neuropsychological test battery, measures of mood state, and generic and disease-specific quality of life measures approximately 1 month before and 3 months after surgery (left hemisphere, 38 patients). RESULTS: Unilateral thalamic DBS was associated with significant improvements in tremor and dominant-hand fine visuomotor coordination. Statistically significant but clinically modest gains were observed on tasks of visuoperceptual and constructional ability, visual attention, delayed word list recognition, and prose recall. Only lexical verbal fluency declined significantly after surgery. Patients rated themselves as less anxious after surgery, and they perceived their quality of life as improved significantly. In particular, patients reported improved quality of life with respect to activities of daily living, stigma, emotional well-being, and communication. CONCLUSIONS: Unilateral thalamic DBS for ET is cognitively safe and associated with improvements in anxiety and quality of life in the near term and in the absence of operative complications. Patients were better able to carry out activities of daily living after surgery, and they reported improvement in several psychosocial domains of quality of life.     

Deep brain stimulation of the ventral intermediate thalamic nucleus in the treatment of essential tremor

Essential tremor (ET) is the most common movement disorder. In most patients the course of ET is mild and pharmacological therapy controls postural and kinetic components of tremor. The first-line treatment of ET is pharmacotherapy with propranolol, primidone and gabapentin. In patients with marked head and voice tremor, local botulinum toxin injections have been found to be very effective. Despite optimal drug therapies it is estimated that approximately 50% of patients with ET have medication-resistant tremor. ET can cause more functional impairment than parkinsonian resting tremor because most prominent components of ET are postural and kinetic ones. For patients with drug-resistant debilitating tremor, surgical therapy (thalamotomy) and more recently deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus (VIM) is a viable treatment modality. Several long-term studies have confirmed the high effectiveness rate of ablative surgery and thalamic DBS in the treatment of ET. The most striking advantage of thalamic DBS is the possibility of performing bilateral surgery in one operative session with a significantly lower rate of side effects. Nowadays the bilateral staged thalamotomy is performed rarely because of unacceptable side effects. Moreover, many authors have observed that in bilaterally stimulated patients the head and voice tremor have diminished in postoperative course. Thalamic DBS is a very efficacious and safe procedure in the treatment of ET.     

Comparison of thalamotomy to deep brain stimulation of the thalamus in essential tremor.

OBJECTIVE: To compare outcome in Essential Tremor (ET) patients who have undergone either thalamotomy or Deep Brain Stimulation (DBS) of the thalamus. BACKGROUND: Although both thalamotomy and thalamic DBS are effective surgical treatments of tremor, it is not known if one procedure is superior to the other. DESIGN/METHODS: Thirty-five ET patients underwent thalamotomy between 1994-1998. Data on 18 patients were excluded. The remaining 17 patients were matched for age, sex, side of surgery, and tremor severity to 17 ET patients who underwent thalamic DBS. There were nine men and eight women in each group. The mean age of the thalamotomy group was 74.4 years and that of the thalamic DBS group was 73.1 years. RESULTS: There were no significant differences between any efficacy outcome variables comparing thalamotomy to DBS of the thalamus at baseline or follow-up visits. The surgical complications were higher for the thalamotomy group as compared to the DBS group. However, a larger number of DBS patients underwent repeat surgeries due to problems with the device and the leads. CONCLUSION: Although the efficacy is similar for thalamotomy and DBS of the thalamus for ET, thalamotomy is associated with a higher complication rate. DBS of the thalamus should be the procedure of choice for the surgical treatment of ET in most cases.     

Deep brain stimulation of the Vim nucleus of the thalamus in the treatment of parkinsonian tremor

Deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus (Vim) has been recently introduced by Benabid and his colleagues as a new surgical procedure in the treatment of tremor-dominant Parkinson's disease (PD). The advantage of DBS Vim over lesioning (thalamotomy) is its reversibility and adjustability with the same clinical effect, but without the need to make a destructive thalamic lesion. In this procedure high-frequency stimulation is employed to simulate a thalamic lesion using an implanted electrode connected to a subcutaneously placed neuropacemaker. Four patients with tremor-dominant PD were included in the study. There were 3 men and one women. Three stimulators were implanted in the left and one in the right cerebral hemisphere. The patients were evaluated using clinical scales, before and up to 24 months after surgery. Adverse effects associated with chronic Vim stimulation were mild and reversible. Chronic thalamic stimulation is effective for drug-resistance parkinsonian tremor suppression, with few adverse side-effects. The method results in a significant improvement of function.     

Is the target for thalamic deep brain stimulation the same as for thalamotomy?

Deep brain stimulation (DBS) has virtually replaced thalamotomy for the treatment of essential tremor. It is thought that the site for DBS is the same as the optimal lesion site; however, this match has not been investigated previously. We sought to determine whether the location of thalamic DBS matched the site at which thalamotomy would be performed. Eleven patients who had detailed microelectrode recording and stimulation for placement of DBS electrodes and subsequent successful tremor control were analysed. An experienced surgeon, blinded to outcome and final electrode position, selected the ideal thalamotomy site based on the reconstructed maps obtained intraoperatively. When the site of long-term clinically used DBS and theoretical thalamotomy location was calculated in three-dimensional space and compared for each of the x, y, and z axes in stereotactic space, there was no significant difference in the mediolateral location of DBS and theoretical lesion site. There was also no difference between the theoretical lesion site and the placement of the tip of the electrode; however, the active electrodes used for chronic stimulation were significantly more anterior (P = 0.005) and dorsal (P = 0.034) to the ideal thalamotomy target. This mismatch may reflect the compromise required between adverse and beneficial effects with chronic stimulation, but it also suggests different mechanisms of effect of DBS and thalamotomy.     

Comparative effects of unilateral and bilateral subthalamic nucleus deep brain stimulation.

OBJECTIVE: To compare the effects of unilateral subthalamic nucleus (STN) deep brain stimulation (DBS) with bilateral STN DBS in advanced PD. METHODS: Our initial 10 consecutive patients with medication-refractory motor fluctuations and levodopa-induced dyskinesias undergoing chronic bilateral STN DBS underwent a standardized evaluation of unilateral and bilateral STN DBS in the medication-off state 6 to 18 months after electrode implantation. RESULTS: Bilateral STN DBS improved the mean total Unified Parkinson's Disease Rating Scale motor score by 54%, whereas unilateral stimulation improved motor scores only 23%. Unilateral STN DBS improved postural stability and gait 14%, other axial motor features 19%, and overall parkinsonism in limbs contralateral to stimulation by 46%, including an 86% improvement in contralateral tremor. However, bilateral STN DBS resulted in greater improvement in each of these domains, including limb function, i.e., the reduction in scores from the limbs on one side was greater with bilateral than with unilateral stimulation of the contralateral STN. CONCLUSIONS: Bilateral STN DBS improves parkinsonism considerably more than unilateral STN DBS; bilateral simultaneous electrode implantation may be the most appropriate surgical option for patients with significant bilateral disability. Unilateral STN DBS results in moderate improvement in all aspects of off-period parkinsonism and improves tremor as much as is typically reported with DBS of the ventral intermedius nucleus of the thalamus (Vim). For this reason, STN DBS may be a more appropriate choice than Vim DBS or thalamotomy for parkinsonian tremor. Some patients with highly asymmetric tremor-dominant PD might be appropriately treated with unilateral instead of bilateral STN DBS.     

A comparison of neuropsychological effects of thalamotomy and thalamic stimulation

OBJECTIVE: The neuropsychological effects of thalamotomy and thalamic stimulation in patients with severe drug-resistant tremor due to PD, essential tremor (ET), or MS were compared in a randomized trial. METHODS: Complete neuropsychological evaluations at baseline and 6 months after surgery were obtained in 62 patients who underwent thalamotomy (n = 32: 21 PD, 6 ET, 5 MS) or thalamic stimulation (n = 30: 19 PD, 7 ET, 4 MS). RESULTS: Six months after thalamotomy, a decline was seen in the scores of the Stroop Color-Word Test, with the exception of the interference score. In the thalamic stimulation group, no significant changes were found on any of the cognitive tests. Age, diagnosis, disease severity, and baseline cognitive status were not correlated to cognitive changes. A difference in score changes between right- and left-sided surgery was found in verbal fluency and Stroop Test scores after both thalamotomy and thalamic stimulation. CONCLUSIONS: Both thalamotomy and thalamic stimulation are associated with a minimal overall risk of cognitive deterioration. Verbal fluency decreased after both left-sided thalamotomy and thalamic stimulation.     

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.     

Stereotactic thalamotomy in the treatment of essential tremor of the upper extremity: reassessment including a blinded measure of outcome

The effectiveness of high frequency stimulation of the thalamic nucleus ventralis intermedius (Vim-HFS) for treatment of tremor has been studied by blinded assessment. The effectiveness of thalamotomy for essential tremor of the upper extremity by use of a blinded measure of outcome is now reported. Thalamotomy was performed in 21 patients (three operated on bilaterally) with medically intractable, essential tremor. Assessments of function, handwriting/drawing, and tremor amplitude were done before and at 3 and 12 months after surgery. The handwriting/drawing score was rated by a neurologist blinded to patient identity, laterality, and operative status. By comparison with baseline, both the total functional score and the total score from blinded assessment of handwriting/drawing improved significantly at 3 and 12 months after surgery. The two scores were significantly correlated, suggesting that the blinded assessment is a good predictor of a total disability from tremor. Complications after unilateral thalamotomy included transient dysarthria, permanent perioral numbness, and permanent mild disequilibrium in one patient each. Permanent mild dysarthria occurred in two of three patients operated bilaterally. Thus a blinded assessment of outcome establishes that unilateral thalamotomy is an effective, safe procedure for the treatment of essential tremor.     

Current therapies for parkinson's disease. Part II: surgical treatment

Surgical treatment of Parkinson's disease (PD) is indicated in patients with severe neurological symptoms (tremor, bradykinesia, rigidity)--who do not benefit from nor tolerate pharmacological therapy. Surgery for PD modifies the motor system function by lesioning or electrostimulation of thalamic, pallidal or subthalamic nuclei. The technological progress together with refined CNS monitoring enabled wider application of deep brain stimulation (DBS). The efficacy of DBS is comparable with lesioning techniques (thalamotomy or pallidotomy) however bears less adverse effects. Both lesioning and DBS are generally well tolerated by patients. The side effects are mostly transient and neurological complications, if occur, usually do not affect quality of patient's life. Unfortunately, the modern surgery for PD is still very expensive and demanding for a large team of specialists and high technology.     

Surgical therapy for tremor in multiple sclerosis: an evaluation of outcome measures.

OBJECTIVE: To assess the reliability, validity, and sensitivity of outcome measures that might be used in a clinical trial of surgery for the treatment of severe tremor associated with MS (MS tremor). METHODS: Nine patients with MS tremor were evaluated before and 3 and 12 months after thalamic surgery (six thalamotomy, three deep brain stimulation). A clinical tremor rating scale (CTRS), a novel quantitative movement analysis technique (QMA), and a variety of measures of disability, neurologic impairment, and quality of life was utilized. RESULTS: Both the CTRS and QMA were reliable measures of tremor and both were sensitive to the improvement in tremor following surgery. However, QMA correlated with disability measures and corresponded better to patient and examiner assessment of surgical results. The disability scales used were insensitive to functional improvements that may follow surgery. The box and blocks test clearly separated three patients who had excellent results from three who had poor results. Baseline QMA values predicted improvement on the box and blocks test. CONCLUSIONS: 1) QMA is a reliable, objective and valid measure of MS tremor that could be used in a clinical trial. 2) The box and blocks test can detect the improvement in prehensile function that follows surgery, but standard disability scales are poorly responsive to this change. 3) Preoperative QMA values may predict which patients are most amenable to functional improvement after surgery.     

Stereotactic ventrolateral thalamotomy in the treatment of essential tremor

BACKGROUND AND PURPOSE: Essential tremor is the most common tremorogenic movement disorder. In the majority of patients the progression of the disease is slow and the pharmacological treatment effectively alleviates tremor. In rare cases of increased essential tremor the surgical treatment (ventrolateral thalamotomy) is indicated. The goal of this study was to assess the effectiveness of unilateral thalamotomy in the treatment of essential tremor. MATERIAL AND METHODS: 10 stereotactic ventrolateral thalamotomies were performed in 9 patients for pharmacologically intractable essential tremor. Right thalamotomy was done in 5 patients and left thalamotomy in 4 patients. The study included five men and four women. Patients were assessed according to the Clinical Rating Scale for Tremor (CRST) before surgery and at 3, 12 and 24 months after thalamotomy. RESULTS: In the postoperative period there was a marked reduction of essential tremor in the contralateral arm and, to a lower extent, in the contralateral leg. The mean presurgery value for contralateral upper extremity postural tremor (scores 5/6 CRST) decreased from 3.5 to mean postsurgery value of 0.6. The tremor reduction contributed to 59% improvement in specific motor tasks of upper extremities (Part B of CRST) at 2 years follow-up. There was also improvement of functional disabilities (Part C of CRST) by 62% when compared to preoperative value 2 years postoperatively. CONCLUSIONS: Ventrolateral thalamotomy is a highly effective method in the treatment of essential tremor. The side effects related to surgery are rare and most of them are transient.     

Unilateral thalamotomy for the treatment of tremor dominant Parkinson's disease

BACKGROUND AND PURPOSE: To assess the effectiveness of unilateral thalamotomy for the treatment of parkinsonian tremor and other motor signs of Parkinson's disease (PD). MATERIAL AND METHODS: Between 1999 and 2004, 41 patients with idiopathic tremor dominant PD were treated surgically in the Neurosurgical Department of Postgraduate Medical Center in Warsaw. Stereotactic thalamotomy was performed with Leksell stereotactic frame (model G) using intraoperative macrostimulation. The patients were assessed according to the Unified Parkinson's Disease Rating Scale version 3. (UPDRS) before and after thalamotomy in the off state. The progression of PD was also evaluated according to the Hoehn and Yahr scale in the off state and also Schwab and England was used to assess the disability of the patients. The patients were evaluated before thalamotomy in the off state, and 3, 12, 24 and 36 months after surgery, according to the above mentioned clinical rating scales. RESULTS: The authors report their results among 41 patients who underwent stereotactic thalamotomy 3 years postoperatively. At 3 years follow-up (in the group of 19 patients) the contralateral tremor from the presurgical value of 11.2 (items 20 - 21 UPDRS) decreased to 2.6. The rigidity in contralateral limbs at 3 years follow-up was 1.7 (item 22 UPDRS) when compared to 2.8 (item 22 UPDRS) preoperative value. Thalamotomy had no effect on bradykinesia or other manifestations of PD such as balance or gait disturbance. There were 13 transient and 6 permanent complications. CONCLUSIONS: Thalamotomy using intraoperative macrostimulation in carefully selected patients is a beneficial operation for the control of medically refractory parkinsonian resting and postural tremor. The effect of unilateral thalamotomy on tremor is long lasting.     

Combined deep brain stimulation and thalamotomy for tremor-dominant Parkinson’s disease

Although deep brain stimulation (DBS) is an established treatment for Parkinson’s disease, the long-term suppression of tremor is still a challenging issue. We report two patients with tremor-dominant Parkinson’s disease (PD) treated with unilateral thalamotomy of the ventralis intermedius nucleus (Vim) combined with the subthalamic nucleus (STN)-DBS or the posterior subthalamic area (PSA)-DBS. One year after the surgery, thalamotomy of the area from the Vim to the PSA showed improvement not only in tremor but also in rigidity and akinesia. PSA- or STN-DBS with low intensity stimulation eliminated residual PD symptoms. Combined DBS and thalamotomy may provide long-term improvement of the majority of PD symptoms using lower therapeutic stimulation voltages.     

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.     

Difference in surgical strategies between thalamotomy and thalamic deep brain stimulation for tremor control

Journal of Neurology - Stereotactic targeting strategies differ between thalamotomy and thalamic deep brain stimulation (DBS) for tremor control. In thalamotomy, a minimal radiofrequency lesion...     

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     

刺激术和毁损术在双侧立体定向手术治疗帕金森病中的比较

目的比较脑深部刺激术和毁损术在双侧立体定向手术治疗帕金森病中的优缺点。方法69例帕金森病病人进行了双侧手术治疗,其中同期双侧丘脑底核(STN)脑深部刺激术(DBS)11例,同期一侧苍白球腹后部毁损术(PVP),另一侧STNDBS3例,分期一侧PVP或腹中间核(Vim)毁损术、另一侧STN或VimDBS9例;分期双侧PVP或Vim毁损术41例,同期双侧PVP5例。平均随访9.3个月。结果UPDRS评分显示刺激术和毁损术均能显著改善对侧肢体震颤、僵硬和运动迟缓症状,双侧刺激术还能改善步态和姿势症状,但双侧毁损术可加重语言、吞咽及流涎等症状,并发症较高。结论双侧DBS是具有双侧症状的帕金森病病人手术治疗的最佳术式,双侧毁损术并发症较高,应严格慎重采用。     

Difference in surgical strategies between thalamotomy and thalamic deep brain stimulation for tremor control

Stereotactic targeting strategies differ between thalamotomy and thalamic deep brain stimulation (DBS) for tremor control. In thalamotomy, a minimal radiofrequency lesion created within the lateral portion of the nucleus ventralis intermedius (Vim) often affords the best control of parkinsonian tremor, supporting the assumption that there is a concentrated cluster of cells within this area which is responsible for tremor. However, this assumption may not always be true; such neural elements sometimes appear to spread out across wide areas. Cells with tremor-frequency activity are widely distributed over the areas extending from the Vim to the nuclei ventralis oralis posterior and anterior (Vop and Voa). All of these cells appear to be more or less involved in tremor generation, especially in patients with essential tremor and post-stroke tremor. In contrast to radiofrequency lesions for thalamotomy, electrodes for DBS can be arranged in such a way that wide areas can be stimulated, if necessary. For this purpose, it is critically important to determine optimal placement and orientation of DBS leads for arranging the electrodes to yield maximal benefits in patients with tremor.