Deep brain stimulation for tremor [correction of trauma]: patient selection and evaluation

Deep brain stimulation for multiple sclerosis tremor: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aims to evaluate efficacy of deep brain stimulation (DBS) in treating MS-related tremor.

METHODS

We systematically searched PubMed, Web of Science, Embase, Scopus, Google Scholar, and gray literature using a search strategy including the MeSH and text words as (((Brain Stimulations) OR (Deep Brain Stimulations) OR (Deep Brain Stimulations) OR (Deep Brain Brain Stimulation) OR (Deep Electrical Stimulation of the Brain)) AND (Multiple Sclerosis OR Sclerosis, Multiple) OR Sclerosis, Disseminated) OR Disseminated Sclerosis) OR MS (Multiple Sclerosis)) OR Multiple Sclerosis, Acute Fulminating).

RESULTS

The literature search revealed 1663 articles, 1027 of which remained after removing duplicates. Seventeen articles, published between 1999-2018, were included for the meta-analysis, including overall 168 patients. Follow-up time ranged between 6-62 months. The pooled frequency of tremor improvement among the enrolled patients was 73%, (95% CI:64-83%) (I²=84.1%, p<0.001). The pooled standardized mean difference (SMD) (after -before) was -2.9, (95% CI:-4.8, -0.98) (I²=89.8%, p<0.001).

CONCLUSION

The results of this systematic review and meta-analysis demonstrate MS-related tremor improvement after DBS.

Outcomes and Adverse Effects of Deep Brain Stimulation on the Ventral Intermediate Nucleus in Patients with Essential Tremor

Objective

This study was aimed at identifying the potential outcome predictors, comparing the efficacy in patients with different tremor characteristics, and summarizing the adverse effect rates (AERs) of deep brain stimulation on the ventral intermediate nucleus (VIM-DBS) for essential tremor (ET).

Methods

An extensive search of articles published to date in 2019 was conducted, and two main aspects were analyzed. Improvement was calculated as a percentage of change in any objective tremor rating scale (TRS) and analyzed by subgroup analyses of patients' tremor characteristics, laterality, and stimulation parameters. Furthermore, the AERs were analyzed as follows: the adverse effects (AEs) were classified as stimulation-related, surgical-related, or device-related effects. A simple regression analysis was used to identify the potential prognostic factors, and a two-sample mean-comparison test was used to verify the statistical significance of the subgroup analyses.

Results

Forty-six articles involving 1714 patients were included in the meta-analysis. The pooled improvement in any objective TRS score was 61.3% (95% CI: 0.564-0.660) at the mean follow-up visit (20.0 ± 17.3 months). The midline and extremity symptoms showed consistent improvement (P = 0.440), and the results of the comparison of postural and kinetic tremor were the same (P = 0.219). In addition, the improvement in rest tremor was similar to that in action tremor (OR = 2.759, P = 0.120). In the simple regression analysis, the preoperative Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS) scores and follow-up time were negatively correlated with the percentage change in any objective TRS score (P < 0.05). The most common adverse event was dysarthria (10.5%), which is a stimulation-related AE (23.6%), while the rates of the surgical-related and device-related AEs were 6.4% and 11.5%, respectively.

Conclusion

VIM-DBS is an efficient and safe surgical method in ET, and the efficacy was not affected by the body distribution of tremor, age at surgery, and disease duration. Lower preoperative FTM-TRS scores likely indicate greater improvement, and the effect of VIM-DBS declines over time.

Purkinje cell misfiring generates high-amplitude action tremors that are corrected by cerebellar deep brain stimulation

Tremor is currently ranked as the most common movement disorder. The brain regions and neural signals that initiate the debilitating shakiness of different body parts remain unclear. Here, we found that genetically silencing cerebellar Purkinje cell output blocked tremor in mice that were given the tremorgenic drug harmaline. We show in awake behaving mice that the onset of tremor is coincident with rhythmic Purkinje cell firing, which alters the activity of their target cerebellar nuclei cells. We mimic the tremorgenic action of the drug with optogenetics and present evidence that highly patterned Purkinje cell activity drives a powerful tremor in otherwise normal mice. Modulating the altered activity with deep brain stimulation directed to the Purkinje cell output in the cerebellar nuclei reduced tremor in freely moving mice. Together, the data implicate Purkinje cell connectivity as a neural substrate for tremor and a gateway for signals that mediate the disease.

Deep brain stimulation of the nucleus accumbens for treatment-refractory anorexia nervosa: A long-term follow-up study

BACKGROUND

Given that anorexia nervosa (AN) is a life-threatening mental disorder and has poor clinical outcomes, novel effective treatments are warranted, especially for severe and persistent cases.

OBJECTIVE

To investigate the safety, feasibility, and clinical outcomes of using deep brain stimulation (DBS) of the nucleus accumbens (NAcc) in treatment-refractory AN patients.

METHODS

A total of 28 women with refractory AN underwent NAcc-DBS and completed this 2-year follow-up study. The clinical outcomes, including body mass index (BMI) and mood, anxiety, and obsessive symptoms, were assessed using a series of psychiatric scales at 6 and 24 months post operation.

RESULTS

While no fatalities were reported during this study, 1 patient showed device rejection. The most common short-term side effect observed was varying degrees of pain at the incision sites (n = 22), which usually disappeared 3-4 days following the operation. No severe surgical adverse events were observed. Compared to presurgical levels, significant increases in BMI and improvement in psychiatric scale scores were noted during the 6-month follow-up and were maintained at the 2-year review. Finally, a post-hoc analysis revealed that the NAcc-DBS was less effective for weight restoration in patients with the binge-eating/purge subtype of AN than in those with the restricting subtype (R-AN).

CONCLUSION

Our long-term follow-up study suggests that NAcc-DBS is safe and effective for improving the BMI and psychiatric symptoms of patients with refractory AN. Although NAcc-DBS appears to be more suitable for patients with R-AN, strict inclusion criteria must be applied considering surgery-related complications.

Holmes Tremor Partially Responsive to Topiramate: A Case Report

Background

Holmes tremor is a rare symptomatic movement disorder, characterized by a combination of resting, postural, and intention tremor. It is usually caused by lesions in the brainstem, thalamus, and cerebellum. Despite pharmacological advances, its treatment remains a challenge; many medications have been used with various degrees of effectiveness. Stereotactic thalamotomy and deep brain stimulation in the ventralis intermedius nucleus have been effective surgical procedures in cases refractory to medical treatment.

Case Report

Here we report a young woman with topiramate-responsive Holmes tremor secondary to a brainstem cavernoma.

Discussion

Herein we report a Holmes tremor responsive to Topiramate.

Predictors of deep brain stimulation outcome in tremor patients

BACKGROUND

Deep brain stimulation of the ventro-intermedius nucleus of the thalamus is an established treatment for tremor of differing etiologies but factors that may predict the short- and especially long-term outcome of surgery are still largely unknown.

METHODS

We retrospectively investigated the clinical, pharmacological, electrophysiological and anatomical features that might predict the initial response and preservation of benefit in all patients who underwent deep brain stimulation for tremor. Data were collected at the following time points: baseline (preoperative), one-year post-surgery, and most recent visit. Tremor severity was recorded using the Fahn-Tolosa-Marin Tremor Rating Scale and/or the Unified Parkinson's Disease Rating Scale.

RESULTS

A total of 52 patients were included in the final analysis: 31 with essential tremor, 15 with cerebellar tremor of different etiologies, and 6 with Parkinson's disease. Long-term success (mean follow-up duration 34.7 months, range 1.7-121.1 months) was reported in 63.5%. Predictors of long-term benefit were: underlying tremor etiology (best outcome in Parkinson's disease, worst outcome in cerebellar tremor); age at surgery (the older the better); baseline tremor severity (the greater the better); lack of response to benzodiazepines; a more anterior electrode placement and single-unit beta power (the greater the better).

CONCLUSIONS

Specific patients' features (including single unit beta activity) and electrode locations may predict the short- and long-term benefit of thalamic stimulation for tremor. Future prospective studies enrolling a much larger sample of patients are needed to substantiate the associations detected by this retrospective study.

Developing a Deep Brain Stimulation Neuromodulation Network for Parkinson Disease, Essential Tremor, and Dystonia: Report of a Quality Improvement Project

Objective

To develop a process to improve patient outcomes from deep brain stimulation (DBS) surgery for Parkinson disease (PD), essential tremor (ET), and dystonia.

Methods

We employed standard quality improvement methodology using the Plan-Do-Study-Act process to improve patient selection, surgical DBS lead implantation, postoperative programming, and ongoing assessment of patient outcomes.

Results

The result of this quality improvement process was the development of a neuromodulation network. The key aspect of this program is rigorous patient assessment of both motor and non-motor outcomes tracked longitudinally using a REDCap database. We describe how this information is used to identify problems and to initiate Plan-Do-Study-Act cycles to address them. Preliminary outcomes data is presented for the cohort of PD and ET patients who have received surgery since the creation of the neuromodulation network.

Conclusions

Careful outcomes tracking is essential to ensure quality in a complex therapeutic endeavor like DBS surgery for movement disorders. The REDCap database system is well suited to store outcomes data for the purpose of ongoing quality assurance monitoring.

Eligibility Criteria for Deep Brain Stimulation in Parkinson’s Disease, Tremor, and Dystonia

In this review, the available evidence to guide clinicians regarding eligibility for deep brain stimulation (DBS) in the main conditions in which these forms of therapy are generally indicated—Parkinson’s disease (PD), tremor, and dystonia—is presented. In general, the literature shows that DBS is effective for PD, essential tremor, and idiopathic dystonia. In these cases, key points in patient selection must include the level of disability and inability to manage symptoms using the best available medical therapy. Results are, however, still not optimal when dealing with other aetiologies, such as secondary tremors and symptomatic dystonia. Also, in PD, issues such as age and neuropsychiatric profile are still debatable parameters. Overall, currently available literature is able to guide physicians on basic aspects of patient selection and indications for DBS; however, a few points are still debatable and controversial. These issues should be refined and clarified in future studies.

Practical considerations and nuances in anesthesia for patients undergoing deep brain stimulation implantation surgery

The field of functional neurosurgery has expanded in last decade to include newer indications, new devices, and new methods. This advancement has challenged anesthesia providers to adapt to these new requirements. This review aims to discuss the nuances and practical issues that are faced while administering anesthesia for deep brain stimulation surgery.

[The use of neuromodulation for the treatment of tremor]

BACKGROUND

Tremor may be a disabling disorder and pharmacologic treatment is the first-line therapy for these patients. Nevertheless, this treatment may lead to a satisfactory tremor reduction in only 50% of patients with essential tremor. Thalamotomy was the treatment of choice for tremor refractory to medical therapy until deep brain stimulation (DBS) of the ventral intermedius nucleus (Vim) of the thalamus has started being used. Nowadays, thalamotomy is rarely performed.

METHODS

This article is a non-systematic review of the indications, results, programming parameters and surgical technique of DBS of the Vim for the treatment of tremor.

RESULTS

In spite of the fact that it is possible to achieve similar clinical results using thalamotomy or DBS of the Vim, the former causes more adverse effects than the latter. Furthermore, DBS can be used bilaterally, whereas thalamotomy has a high risk of causing disartria when it is performed in both sides. DBS of the Vim achieved an adequate tremor improvement in several series of patients with tremor caused by essential tremor, Parkinson's disease or multiple sclerosis. Besides the Vim, there are other targets, which are being used by some authors, such as the zona incerta and the prelemniscal radiations.

CONCLUSION

DBS of the Vim is a useful treatment for disabling tremor refractory to medical therapy. It is essential to carry out an accurate patient selection as well as to use a proper surgical technique. The best stereotactic target for tremor is still unknown, although the Vim is the most used one.

Deep brain stimulation: indications and evidence

Deep brain stimulation is a minimally invasive targeted neurosurgical intervention that enables structures deep in the brain to be stimulated electrically by an implanted pacemaker. It has become the treatment of choice for Parkinson's disease, refractory to, or complicated by, drug therapy. Its efficacy has been demonstrated robustly by randomized, controlled clinical trials, with multiple novel brain targets having been discovered in the last 20 years. Multifarious clinical indications for deep brain stimulation now exist, including dystonia and tremor in movement disorders; depression, obsessive-compulsive disorder and Tourette's syndrome in psychiatry; epilepsy, cluster headache and chronic pain, including pain from stroke, amputation, trigeminal neuralgia and multiple sclerosis. Current research argues for novel indications, including hypertension and orthostatic hypotension. The development, principles, indications and effectiveness of the technique are reviewed here. While deep brain stimulation is a standard and widely accepted treatment for Parkinson's disease after 20 years of experience, in chronic pain it remains restricted to a handful of experienced, specialist centers willing to publish outcomes despite its use for over 50 years. Reasons are reviewed and novel approaches to appraising clinical evidence in functional neurosurgery are suggested.

Rationale and clinical pearls for primary care doctors referring patients for deep brain stimulation

BACKGROUND

Deep brain stimulation (DBS) is a surgical treatment involving the implantation of a brain lead connected to a chest-based neurostimulator similar to a cardiac pacemaker. The device can be programmed to deliver electrical impulses to neuromodulate abnormal brain circuitry in disorders such as Parkinson's disease (PD), essential tremor (ET), and dystonia. As the number of patients receiving DBS surgery increases, it will be important for primary care doctors to identify reasonable DBS candidates for referral to an experienced center.

OBJECTIVE

To provide primary care physicians with a rationale and also to provide clinically useful pearls for referral of potential DBS candidates.

METHODS

A complete PubMed review of the literature.

RESULTS

This review will be focused on PD and ET and will address the following issues: what are the common motor and nonmotor symptoms? What is the evidence supporting the use of DBS in PD and ET? What is the importance of a multi- or interdisciplinary DBS team for patient selection? What can be done to improve success in identifying and referring potential DBS candidates?

CONCLUSION

DBS is a highly effective therapy for select candidates with PD and ET. The most important factor influencing DBS outcome is proper patient selection. It will be critical as DBS continues to be more commonly employed for primary care doctors to select candidates from their practices as appropriate referrals to specialized centers.

Neuropsychological safety of nucleus accumbens deep brain stimulation for major depression: effects of 12-month stimulation

OBJECTIVES

Deep brain stimulation (DBS) to the nucleus accumbens (NAcc-DBS) has antidepressant effects in patients suffering from treatment-resistant depression (TRD). However, limited information exists regarding the impact of NAcc-DBS on cognitive functioning. The aim of this study was to examine whether NAcc-DBS in patients with TRD has any cognitive effects.

METHODS

A comprehensive neuropsychological battery was administered to 10 patients with TRD before onset of bilateral NAcc-DBS and after 1 year of DBS stimulation. Neuropsychological testing covered the domains of attention, learning and memory, executive functions, visual perception, and language. Performance was analyzed at baseline and after 1 year of continuous DBS.

RESULTS

No evidence was found for cognitive decline following NAcc-DBS comparing test results after 1 year of NAcc-DBS with baseline. However, significantly improved cognitive performance on tests of attention, learning and memory, executive functions and visual perception was found. In addition, there was a general trend towards cognitive enhancement from below average to average performance. These procognitive effects were independent of the antidepressant effects of NAcc-DBS or changes in NAcc-DBS parameters.

CONCLUSIONS

These results not only support cognitive safety of NAcc-DBS but also stress its beneficial role in augmenting cognitive performance in patients with TRD.

Surgery for movement disorders

Movement disorders, such as Parkinson's disease, tremor, and dystonia, are among the most common neurological conditions and affect millions of patients. Although medications are the mainstay of therapy for movement disorders, neurosurgery has played an important role in their management for the past 50 years. Surgery is now a viable and safe option for patients with medically intractable Parkinson's disease, essential tremor, and dystonia. In this article, we provide a review of the history, neurocircuitry, indication, technical aspects, outcomes, complications, and emerging neurosurgical approaches for the treatment of movement disorders.

Deep brain stimulation and tremor

Deep brain stimulation (DBS) has been used to treat various tremor disorders for several decades. Medication-resistant, disabling essential tremor (ET) is the most common tremor disorder treated with DBS. The treatment has been consistently reported to result in significant benefit in upper extremity, as well as head and voice tremor, all of which were improved more dramatically with bilateral procedures. These benefits have been demonstrated to be sustained for up to 7 years. DBS has also been shown to be beneficial for the tremor associated with multiple sclerosis and post-traumatic tremor; however, fewer cases have been reported and the benefit is less consistent, less dramatic, and more transient than that seen with ET. The ventral intermediate nucleus of the thalamus is the most common DBS target for tremor disorders, but more recent studies have demonstrated benefits in tremor from DBS of the subthalamic area, primarily the zona incerta. Surgical complications are relatively uncommon and are generally less frequent than those seen with thalamotomy. Stimulation-related effects are usually mild and resolve with adjustment of stimulation parameters. DBS is thus a relatively safe and effective treatment for tremor disorders, particularly for medication-resistant, disabling ET, but may also have some role in medication-resistant, disabling tremor associated with multiple sclerosis and traumatic head injury.

Deep brain stimulation to reward circuitry alleviates anhedonia in refractory major depression

Deep brain stimulation (DBS) to different sites allows interfering with dysfunctional network function implicated in major depression. Because a prominent clinical feature of depression is anhedonia--the inability to experience pleasure from previously pleasurable activities--and because there is clear evidence of dysfunctions of the reward system in depression, DBS to the nucleus accumbens might offer a new possibility to target depressive symptomatology in otherwise treatment-resistant depression. Three patients suffering from extremely resistant forms of depression, who did not respond to pharmacotherapy, psychotherapy, and electroconvulsive therapy, were implanted with bilateral DBS electrodes in the nucleus accumbens. Stimulation parameters were modified in a double-blind manner, and clinical ratings were assessed at each modification. Additionally, brain metabolism was assessed 1 week before and 1 week after stimulation onset. Clinical ratings improved in all three patients when the stimulator was on, and worsened in all three patients when the stimulator was turned off. Effects were observable immediately, and no side effects occurred in any of the patients. Using FDG-PET, significant changes in brain metabolism as a function of the stimulation in fronto-striatal networks were observed. No unwanted effects of DBS other than those directly related to the surgical procedure (eg pain at sites of implantation) were observed. Dysfunctions of the reward system--in which the nucleus accumbens is a key structure--are implicated in the neurobiology of major depression and might be responsible for impaired reward processing, as evidenced by the symptom of anhedonia. These preliminary findings suggest that DBS to the nucleus accumbens might be a hypothesis-guided approach for refractory major depression.

Mood improvement after deep brain stimulation of the internal globus pallidus for tardive dyskinesia in a patient suffering from major depression

Deep brain stimulation (DBS) has the unique characteristic to very precisely target brain structures being part of functional brain circuits in order to reversibly modulate their function. It is an established adjunctive treatment of advanced Parkinson's disease and has virtually replaced ablative techniques in this indication. Several cases have been published relating effectiveness in neuroleptics-induced tardive dyskinesia. It is also investigated as a potential treatment of mood disorders. We report on the case of a 62 years old female suffering from a treatment refractory major depressive episode with comorbid neuroleptic-induced tardive dyskinesia. She was implanted a deep brain stimulation treatment system bilaterally in the globus pallidus internus and stimulated for 18 months. As well the dyskinesia as also the symptoms of depression improved substantially as measured by the Hamilton Rating Scale of Depression (HRSD) score and the Burke-Fahn-Marsden-Dystonia-Rating-Scale (BFMDRS) score. Scores dropped for HRSD from 26 at baseline preoperatively to 13 after 18 months; and for BFMDRS from 27 to 17.5. This case illustrates the potential of deep brain stimulation as a technique to be investigated in the treatment of severe and disabling psychiatric and movement disorders. DBS at different intracerebral targets being actually investigated for major depression might have similar antidepressant properties because they interact with the same cortico-basal ganglia-thalamocortical network found to be dysfunctional in major depression.

Neurophysiologic intervention in deep brain stimulation treatment for movement disorders: a practical framework

Clinical neurophysiology has always played an important interventional role throughout the perioperative stages in functional neurosurgery. On the one hand, some neurophysiologic procedures have become an integrated part of neurosurgery. On the other hand, in deep brain stimulation, although the surgical electrode implantation is an essential step, the therapeutic effects are actually produced by electrically modulating the physiologic activity of the brain. We review the topic of neurophysiologic intervention in the deep brain stimulation for movement disorders by presenting the evidence derived from our own experiences based on an integrated group located at two hospitals in London and Oxford, UK, and mainly covering tremor caused by multiple sclerosis, Parkinson's disease and dystonia.

Deep brain stimulation: Preoperative issues

Numerous factors need to be taken into account in deciding whether a patient with Parkinson's disease (PD) is a candidate for deep brain stimulation. Patient-related personal factors including age and the presence of other comorbid disorders need to be considered. Neuropsychological and neuropsychiatric concerns relate both to the presurgical status of the patient and to the potential for surgery to result in new problems postoperatively. A number of factors related to the underlying PD need to be considered, including the specific parkinsonian motor indications (e.g., tremor, bradykinesia, gait dysfunction), previous medical therapies, including benefit from current therapy and adverse effects, and past surgical treatments. Definable causes of Parkinsonism, particularly atypical Parkinsonisms, should be considered. Finally, methods of evaluating outcomes should be defined and formalized. This is a report from the Consensus on Deep Brain Stimulation for Parkinson's Disease, a project commissioned by the Congress of Neurological Surgeons and the Movement Disorder Society (MDS). The report has been endorsed by the Scientific Issues Committee of the MDS and the American Society of Stereotactic and Functional Neurosurgery. It outlines answers to a series of questions developed to address all aspects of deep brain stimulation preoperative decision-making.

Brain stimulation techniques in the treatment of obsessive-compulsive disorder: current and future directions

Recent studies on the epidemiology of obsessive-compulsive disorder (OCD) estimate 50 million patients suffer from OCD worldwide, thus making it a global problem. The treatment of OCD has changed substantially over the last 2 decades following the introduction of selective serotonin reuptake inhibitors, which provide symptom improvement in approximately 60% of patients. However, some patients remain resistant to the standard pharmacologic and behavioral treatments. Although some treatment-resistant patients respond to pharmacologic augmentations, others do not, and there is evidence that some of the most severe cases benefit from treatment with neurosurgical interventions. Besides pharmacologic, behavioral, and neurosurgical approaches, different brain stimulation methods-transcranial magnetic stimulation, deep brain stimulation, and electroconvulsive therapy-have been investigated in treatment-resistant patients with OCD. However, available data about the use of these techniques in OCD treatment are quite limited in terms of sample size and study design, given the difficulty in conducting standard blinded trials for these procedures. In addition, none of the mentioned treatments have received Food and Drug Administration approval for the treatment of OCD. Nevertheless, promising findings regarding efficacy, tolerability, and non-invasiveness and/or reversibility of these techniques have increased interest in investigating their use in treatment-resistant OCD.

Association of the C677T and A1298C polymorphisms of methylenetetrahydrofolate reductase gene in patients with essential tremor in Turkey

Essential tremor (ET) is a most common human movement disorder of unknown etiology. Previous reports have shown that the C677T polymorphism of methylenetetrahydrofolate reductase gene has been associated with neurodegenerative disorders. To investigate the role of methylenetetrahydrofolate reductase gene polymorphisms in essential tremor, we analyzed the alleles and genotypes of methylenetetrahydrofolate reductase (MTHFR) C677T and MTHFR A1298C in a total of 158 unrelated essential tremor patients and compared them with those of 246 unrelated healthy control subjects, using a polymerase chain reaction restriction fragment length polymorphism method. The allele frequency of MTHFR 677T was 35.76% in the essential tremor cases and 30.08% in the controls. We obtained statistically significant results for MTHFR677 and also for MTHFR1298. The MTHFR T677T genotype was overrepresented and was statistically significant. The T677T/A1298A and C677C/C1298C compound genotypes were similarly statistically significant. The C677C/A1298A compound genotype provided protection for essential tremor. In conclusion, the MTHFR 677T, 1298C alleles and MTHFR T677T genotype and T677T/A1298A, and C677C/C1298C compound genotypes are genetic risk factors for essential tremor in Turkey.

Mechanical Injury of the Subthalamic Area During Stereotactic Surgery Followed by Improvement of Trunk, Neck, and Face Tremor-Case Report-

A 50-year-old man had undergone right nucleus ventrointermedius (Vim) thalamotomy 1 year previously, resulting in the disappearance of left hand tremor. However, he presented with right distal and proximal tremor including the axial trunk, neck, and head. Deep brain stimulation (DBS) of the left Vim for these symptoms was unsuccessful. Attempts were made to stimulate the left Vim, nucleus ventralis lateralis, and subthalamic nucleus (STN), but no significant improvement was obtained after repeat surgery. However, subsequent improvement of the symptoms including proximal tremor was very marked even without DBS stimulation. Brain magnetic resonance imaging demonstrated lesion and edema in the posteromedial area of the STN. Mechanical injury of the area caused by the surgical procedures may have contributed to the improvement in his persistent symptoms.

Surgical treatment for Parkinson's disease

Since the early 1930s, physicians have developed and refined various surgical therapies for the treatment of Parkinson's disease. In this review we examine some of the problems associated with early surgical therapies, the development of new techniques and targets, and the results of clinical trials examining the safety and efficacy of these techniques. Ablative techniques include pallidotomy, thalamotomy, and, more recently, subthalamotomy. Because of concern over the high incidence of side-effects associated with bilateral ablative procedures, alternative approaches were explored. Deep brain stimulation (DBS) was subsequently developed and successfully applied in the internal globus pallidus, subthalamic nucleus, and thalamus for the treatment of Parkinson's disease. Recent approaches include biological neurorestorative techniques--surgical therapies with transplantation, gene therapy, and growth factors are all being studied. Although a great deal of work remains to be done, advances in surgical therapies for the treatment of Parkinson's disease are moving forward at an unprecedented pace.

Deep brain stimulation of the nucleus ventralis intermedius for Holmes (rubral) tremor and associated dystonia caused by upper brainstem lesions

✓Holmes tremor is caused by structural lesions in the perirubral area of the midbrain. Patients often present with associated symptoms such as dystonia and paresis, which are usually refractory to medical therapy. Here, the authors describe two patients in whom both tremor and associated dystonia improved markedly following unilateral stimulation of the thalamic nucleus ventralis intermedius.

Deep brain stimulation of the nucleus ventralis intermedius for Holmes (rubral) tremor and associated dystonia caused by upper brainstem lesions. Report of two cases

Holmes tremor is caused by structural lesions in the perirubral area of the midbrain. Patients often present with associated symptoms such as dystonia and paresis, which are usually refractory to medical therapy. Here, the authors describe two patients in whom both tremor and associated dystonia improved markedly following unilateral stimulation of the thalamic nucleus ventralis intermedius.

Movement Disorders After Head Injury

Head injury can cause extrapyramidal movement disorders such as tremors, parkinsonism, dystonia, chorea, myoclonus, and tics. Pure adventitious movements are rare, but combinations with paresis, spasticity, apraxia, or ataxia occur in approximately 20% of cases of severe head injury, in many cases appearing or evolving in the months following the injury. Tremors may improve in time but many of the other syndromes tend to persist. Reversible causes such as medications or metabolic derangements are occasionally identifiable. Some of these adventitious movements can be improved using neuroactive drugs, botulinum toxin injections, or stereotactic brain surgery.

Body weight gain rate in patients with Parkinson's disease and deep brain stimulation

We evaluated body weight changes in patients with Parkinson's disease (PD) after electrode implantation for deep brain stimulation (DBS) in the subthalamic nucleus (STN) in relation to clinical improvement. Thirty PD patients who received STN DBS were included (22 men, 8 women; mean age, 60.0 +/- 7.1 years; mean PD duration, 13.5 +/- 3.7 years; mean body mass index [BMI], 21.6 +/- 3.0 kg/m2). Body weight, physical activity, and Unified Parkinson's Disease Rating Scale (UPDRS) scores were noted before and 3 and 12 months after the procedure. Significant weight gain occurred in 29 patients; the mean increase was 14.8 +/- 9.8% of initial body weight in 1 year. Of the patients, 46.5% reported weight gain in the first 3 months, 21.4% gradual weight gain in the first 6 months, and 32.1% a slow increase for 1 year. Mean BMI increased up to 24.7 +/- 3.7 kg/m2. After 1 year, mean UPDRS motor score improved significantly in off and in on; and therapy complications improved by 91.0 +/- 17.0%. BMI changes at 3 and 12 months were significantly correlated to dyskinesia score changes, and levodopa dosage was not. In PD, STN DBS produces not only symptom control, but also weight gain. DBS candidates should be given nutritional counseling before the intervention to prevent rapid and/or excessive weight gain.

Mechanisms and the current state of deep brain stimulation in neuropsychiatry

Deep brain stimulation (DBS) is established as a therapy for movement disorders, and it is an investigational treatment in other neurologic conditions. DBS precisely targets neuroanatomical targets deep within the brain that are proposed to be centrally involved in the pathophysiology of some neuropsychiatric illnesses. DBS is nonablative, offering the advantages of reversibility and adjustability. This might permit therapeutic effectiveness to be enhanced or side effects to be minimized. Preclinical and clinical studies have shown effects of DBS locally, at the stimulation target, and at a distance, via actions on fibers of passage or across synapses. Although its mechanisms of action are not fully elucidated, several effects have been proposed to underlie the therapeutic effects of DBS in movement disorders, and potentially in other conditions as well. The mechanisms of action of DBS are the focus of active investigation in a number of clinical and preclinical laboratories. As in severe movement disorders, DBS may offer a degree of hope for patients with intractable neuropsychiatric illness. It is already clear that research intended to realize this potential will require a very considerable commitment of resources, energy, and time across disciplines including psychiatry, neurosurgery neurology, neuropsychology, bioengineering, and bioethics. These investigations should proceed cautiously.

Update on deep brain stimulation

Deep brain stimulation (DBS) is an established therapy for movement disorders and an investigational treatment in other neurologic conditions and in neuropsychiatry. DBS can target with precision neuroanatomical targets deep within the brain that are proposed, on the basis of increasing evidence from functional neuroimaging and other methods, to be centrally involved in the pathophysiology of some neuropsychiatric illnesses. DBS is nonablative, offering the advantages of reversibility and adjustability. In theory, this characteristic might permit therapeutic effectiveness to be enhanced or side effects to be minimized. Although its mechanisms of action are unknown, several possible effects have been proposed to underlie the therapeutic effects of DBS in movement disorders, and potentially in other conditions as well. This issue is the subject of very active investigation in a number of clinical and preclinical laboratories. DBS may offer a degree of hope for patients with intractable neuropsychiatric illness. Research intended to realize this potential will require a very considerable commitment of resources, energy, and time across disciplines including psychiatry, neurosurgery, neurology, neuropsychology, and bioethics. Investigations in this area should proceed cautiously.