A VIM thalamotomy with the Leksell GK offers a safe and effective alternative for surgical treatment of ET. It is particularly applicable to patients who are not ideal candidates for deep brain stimulation but can be offered to all patients who are considering surgical intervention for ET.

Object. The purpose of this study was to investigate the long-term effects of gamma knife thalamotomy for treatment of disabling tremor. Methods. One hundred fifty-eight patients underwent magnetic resonance imaging—guided radiosurgical nucleus ventralis intermedius (VIM) thalamotomy for the treatment of parkinsonian tremor (102 patients), essential tremor (52 patients), or tremor due to stroke, encephalitis, or cerebral trauma (four patients). Preoperative and postoperative blinded assessments were performed by a team of independent examiners skilled in the evolution of movement disorders. A single isocenter exposure with the 4-mm collimator helmet of the Leksell gamma knife unit was used to make the lesions. In patients with Parkinson's disease 88.3% became fully or nearly tremor free, with a mean follow up of 52.5 months. Statistically significant improvements were seen in Unified Parkinson's Disease Rating Scale tremor scores and rigidity scores, and these improvements were maintained in 74 patients followed 4 years or longer. In patients with essential tremor, 92.1% were fully or nearly tremor free postoperatively, but only 88.2% remained tremor free by 4 years or more post-GKS. Statistically significant improvements were seen in the Clinical Rating Scale for tremor in essential tremor patients and these improvements were well maintained in the 17 patients, followed 4 years or longer. Only 50% of patients with tremor of other origins improved significantly. One patient sustained a transient complication and two patients sustained mild permanent side effects from the treatments. Conclusions. Gamma knife VIM thalamotomy provides relief from tremor equivalent to that provided by radiofrequency thalamotomy or deep brain stimulation, but it is safer than either of these alternatives. Long-term follow up indicates that relief of tremor is well maintained. No long-term radiation-induced complications have been observed.

No abstract

Deep brain stimulation (DBS) has been widely accepted as a tool for treating many symptoms of Parkinson's disease (PD); pallidotomy has been nearly abandoned. Concerns about both the safety and efficacy of pallidotomy are based on small series, isolated case reports, and techniques that would now be considered obsolete. The senior author recently reviewed long-term follow-up of a series of patients who had gamma knife pallidotomy (GKP) for advanced PD. GKP leads to durable, clinically significant benefit. Bilateral GKP adds incremental improvement. The complication rate was 4% when calculated on a per lesion basis. GKP is not quite as effective as DBS for tremor and bradykinesia; the results of GKP and DBS are equivalent for dyskinesia. GKP should be considered in patients who are not candidates for DBS. GKP is not as invasive as radiofrequency pallidotomy and avoids the problems and expenses associated with DBS. Patients on anticoagulants, with cognitive deficits or with other contraindications to DBS can be offered GKP to alleviate many of the motor symptoms of PD.

No abstract