Vo Thalamotomy Research Articles

Radiofrequency Lesioning Surgery for Movement Disorders

Radiofrequency lesioning surgery is primarily performed to treat Parkinson's disease, dystonia, and tremor. Its effects are similar to those of deep brain stimulation (DBS). However, Radiofrequency lesioning surgery has not been popularized, possibly due to the over-evaluation of its risks. The current most available targets for the treatment of movement disorders include ventral intermediate (Vim) nucleus, ventral oral (Vo) nucleus, and globus pallidus internus (GPi). Vim thalamotomy is available for Parkinsonian tremor, essential tremor, dystonic tremor, and other various kinds of tremor, and it is highly effective. Bilateral vim thalamotomy is feasible when properly performed on tiny lesions on the bilateral vim nucleus. Vo thalamotomy is mainly available for focal hand dystonia. The safety profile of bilateral Vo thalamotomy has not yet been established, but it is thought that it may lead to irreversible hypophonia and dysarthria. Pallidotomy is selected for treatment of dystonia and Parkinson's disease. Although unilateral pallidotomy is a safe procedure, it can cause medically refractory parkinsonism including postural reflex disturbance and gait disorder. Delayed infarction on the posterior limb of internal capsule is another major concern associated with pallidotomy and can lead to hemiparesis. Correct understanding is absolutely essential to ensure the safety of radiofrequency lesioning surgery.

Ventro-oral Thalamotomy as a Treatment for Focal Hand Dystonia

Investigators retrospectively report on the safety and long-term efficacy of unilateral ventro-oral (vo) thalamotomy on 171 consecutive patients

Stereotactic Lesioning of the Thalamic Vo Nucleus for the Treatment of Writer's Cramp (Focal Hand Dystonia).

Writer's cramp (focal hand dystonia) is a sporadic focal dystonia that affects a specific part of the upper limb causing excessive co-contraction of antagonistic muscles. It usually presents as a task-specific dystonia, including, among others, writing of a character or playing a musical instrument. Although treatments for writer's cramp exist, medical therapy often results in unsatisfactory outcomes in patients with this type of dystonia. However, accumulating evidence suggests that long-term and complete remission of various types of focal hand dystonia can be achieved with stereotactic ablation or deep brain stimulation of the thalamic ventral-oralis complex (Vo) nucleus, which includes both the ventralis oralis posterior and anterior nuclei of the thalamus. Following the striking therapeutic success of Vo thalamotomy in patients with medically-refractory writer's cramp, we here introduce the use of stereotactic lesioning of the thalamic Vo nucleus for the treatment of this focal type of dystonia. Our findings identified patients with disabling writer's cramp (i.e., it prevents their success in their professional careers) to be good candidates for positive outcome with this surgical technique.

Stereotactic Selective Thalamotomy for Focal Dystonia with Aid of Depth Microrecording

Long-term effectiveness of selective ventralis intermedius nucleus (VIM)-ventralis oralis nucleus (VO) thalamotomy with depth microrecording for the treatment of focal dystonia was evaluated. The optimal thalamic areas for controlling focal dystonia were studied based on the electrophysiologic and anatomic data. Stereotactic selective VIM-VO thalamotomy with depth microrecording was carried out in 8 patients with focal arm and hand dystonia and in 1 patient with cervical dystonia. Electrophysiologic data on the lateral part of thalamic VIM were studied in patients with focal dystonia. A very small and narrow therapeutic lesion was formed in the shape of a square on the sagittal plane and ofan I, rotated V, Y, or inverse Y on the axial plane in the VIM-VO, which covered the kinesthetic response area topographically related to focal dystonia. Patients with armand hand dystonia were followed up for 4.7 ± 3.0 years and 1 patient with cervical dystonia was followed up for 18.2 years. Marked improvement of focal dystonia was shown by functional assessment using the Unified Dystonia Rating Scale. Transient dysarthria was recognized in 1 patient. The sequence of body localization of kinesthetic response in the VIM was clearly shown in patients with focal dystonia. Decreases in the amplitude and amplitude ratio of electromyography on the forearm muscles were markedly significant after VIM thalamotomy, but insignificant after VO thalamotomy immediately after VIM thalamotomy. Marked reduction of electromyographic tonic discharges of focal dystonia was shown after VIM lesioning. Selective VIM-VO thalamotomy showed good and long-term stable effects for focal dystonia.

Full recovery from drummer’s dystonia with foot and arm symptoms after stereotactic ventro-oral thalamotomy: a case report

Ventro-oral (Vo) thalamotomy is effective in patients with focal task-specific dystonias (FTSDs), but only in those with upper-limb symptoms. We describe a patient with drummer's dystonia who completely recovered after Vo thalamotomy. A 37-year-old man who started playing drums at 14 began having difficulty performing fine movements with his right foot when drumming at 22. He experienced right hand cramps while drumming 3months before visiting our hospital. He was diagnosed with FTSD. Left Vo thalamotomy was performed, which led to complete improvement of symptoms. Vo thalamotomy may be effective for FTSD patients with upper- and lower-extremity symptoms.

Surgical Interventions for Task-specific Dystonia (Writer's Dystonia).

Objectives:Writer's cramp is a focal dystonia producing abnormal postures during selective motor activities. Thalamotomy or globus pallidus internus deep brain stimulation (GPi DBS) has been used as a surgical treatment in patients not responding to medical treatment.Materials and Methods:Eight patients (all men, age 16–47 years) with refractory focal hand dystonia underwent either ventrooralis (Vo) thalamotomy (seven patients) or GPi DBS (one patient) using stereotactic techniques. Preoperative video recordings, Writing movment score for dystonic posture and latency of dystonia (WMS), and symptom severity scores (SSSs) were evaluated at baseline and latest follow-up ranging from 1 to 4 years.Results:All patients had difficulty in performing their most common tasks. The duration of symptoms ranged from 6 months to 12 years. All patients obtained immediate postoperative relief from the dystonic symptoms, and the effect was sustained during the follow-up period. The WMS (range 0–28) improved from a mean of 14.5 before surgery to 2, whereas the SSS (maximum 43 and minimum 10) improved from a mean of 15.3 before surgery to 2 at the last follow-up. There were no surgical complications, morbidity, or mortality.Conclusion:Vo thalamotomy or GPi DBS offers successful symptom relief in patients with task-specific dystonia.

The Effect of Bilateral Globus Pallidus Internus Deep Brain Stimulation plus Ventralis Oralis Thalamotomy on Patients with Cerebral Palsy

Objective: We compared bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) with bilateral GPi DBS plus ventralis oralis (Vo) thalamotomy to analyze the effect of the combined Vo thalamotomy. Methods: Between March 2003 and December 2008, 10 patients underwent DBS and/or Vo thalamotomy for treatment of cerebral palsy in our institute of neurosurgery and rehabilitation medicine. Four patients received bilateral posteroventral GPi DBS as group I and 6 patients received GPi DBS plus unilateral thalamotomy as group II. Results: The movement and disability scores of group I improved by 32 and 14.3%, respectively, at the last follow-up compared with baseline. The movement and disability scores of group II improved by 31.5 and 0.18%. The BFMDRS-movement subscores of group II demonstrated statistically significant improvement in the contralateral arm compared to group I (p = 0.042). Body pain, vitality and mental health seemed to improve in group II, in terms of health-related quality of life. Conclusions: Contrary to our expectations, we were unable to demonstrate clear improvements in overall BFMDRS scores between group I and group II. However, movements of the contralateral upper extremities improved and health-related quality of life in group II showed satisfactory results.

Stereotactic Ventrooralis Thalamotomy for Task-Specific Focal Hand Dystonia (Writer’s Cramp)

Background: Writer’s cramp is a type of focal dystonia due to dysfunction of the pallido-thalamo-cortical circuit. The symptom is refractory to most conservative treatment, though botulinum toxin injection is generally used for symptomatic relief. As a surgical treatment of dystonia, we performed stereotactic nucleus ventrooralis (Vo) thalamotomy for dystonic cramp of the hand. Methods: Twelve patients (5 men, 3 women; age 26–40 years, mean 32.1 years) with medically intractable task-specific focal dystonia of the hand underwent Vo thalamotomy. The stereotactic target was chosen at the junction of the anterior and posterior Vo nuclei. Results: The mean duration of the symptom ranged from 3 to 6 years (mean 4.5 years.) All patients had complained of difficulty in writing. Seven patients were professionals, such as a comic artist, guitarist and barber, and, because of the dystonic symptoms occurring during their work, they had stopped pursuing their profession. All patients showed immediate postoperative disappearance of dystonic symptoms, and the effect was sustained during the follow-up period (3–33 months, mean 13.1 months), except in one case. Two patients showed partial recurrence of the symptom and underwent second thalamotomy 5 months after the initial surgery with satisfactory results. The score on the writer’s cramp rating scale decreased significantly (p < 0.001) after Vo thalamotomy. There were no permanent operative complications. There was no mortality or permanent morbidity. Conclusion: Although a longer follow-up is needed, stereotactic Vo thalamotomy is a useful and safe therapeutic option for writer’s cramp.