Gamma Knife® stereotactic radiosurgery as a treatment for essential and parkinsonian tremor: long-term experience

Stereotatic radiosurgery for the treatment of motor symptoms in Parkinson's disease: A systematic review

BACKGROUND

Stereotaxic Radiosurgery (SRS) is a non-invasive lesioning technique for movement disorders when patients cannot undergo DBS due to medical comorbidities.

OBJECTIVE

To describe and summarize the literature on SRS's application and physical parameters for Parkinson's disease (PD) motor symptoms.

METHODS

The MEDLINE/PUBMED and EMBASE databases were searched in July 2022 following the PRISMA guideline. Two independent reviewers screened data from 425 articles. The level of evidence followed the Oxford Centre for Evidence-Based Medicine. Pertinent details for each study regarding participants, physical parameters, and results were extracted.

RESULTS

Twelve studies reported that 454 PD patients underwent Gamma KnifeⓇ (GK). The mean improvement time of the treated symptoms was three months after GK. Tremor is the most common symptom investigated, with success rates ranging from 47.5% to 93.9%. Few studies were conducted for caudatotomy (GKC) and pallidotomy (GKP), which presented an improvement for dyskinesia and bradykinesia. Physical parameters were similar with doses ranging from 110 to 200 Gy, use of a 4-mm collimator with an advanced imaging locator system, and coordinates were obtained from available stereotactic atlases.

CONCLUSIONS

GK thalamotomy is a good alternative for treating tremor; however, its effects are delayed, and there are cases in which it can regress after years. The outcomes of GKC and GKP seem to be promising. The existing studies are more limited, and effects need to be better investigated.

The Effectiveness and Toxicity of Frameless CyberKnife Based Radiosurgery for Parkinson's Disease-Phase II Study

Frame-based stereotactic radiosurgery (SRS) has an established role in the treatment of tremor in patients with Parkinson's disease (PD). The low numbers of studies of frameless approaches led to our prospective phase 2 open-label single-arm clinical trial (NCT02406105), which aimed to evaluate the safety and efficacy of CyberKnife frameless SRS. Twenty-three PD patients were irradiated on the area of the thalamic ventral nuclei complex with gradually increasing doses of 70 to 105 Gy delivered in a single fraction. After SRS, patients were monitored for tremor severity and the toxicity of the treatment. Both subjective improvement and dose-dependent efficacy were analysed using standard statistical tests. The median follow-up was 23 months, and one patient died after COVID-19 infection. Another two patients were lost from follow-up. Hyper-response resulting in vascular toxicity and neurologic complications was observed in two patients irradiated with doses of 95 and 100 Gy, respectively. A reduction in tremor severity was observed in fifteen patients, and six experienced stagnation. A constant response during the whole follow-up was observed in 67% patients. A longer median response time was achieved in patients irradiated with doses equal to or less than 85 Gy. Only two patients declared no improvement after SRS. The efficacy of frameless SRS is high and could improve tremor control in a majority of patients. The complication rate is low, especially when doses below 90 Gy are applied. Frameless SRS could be offered as an alternative for patients ineligible for deep brain stimulation; however, studies regarding optimal dose are required.

Rodent Model of Brain Radionecrosis using Clinical LINAC-based Stereotactic Radiosurgery

Purpose

Methods and Materials

Results

Conclusions