Gamma knife thalamotomy for treatment of tremor: long-term results

Abstract

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.

Management of essential tremor

“…Although it has been suggested that gamma knife VIM thalamotomy provides tremor relief equivalent to that provided by thalamotomy or deep brain stimulation and may be a safer procedure [77], a recent report by Siderowf et al [78] noted that gamma knife thalamotomy led to a complex, disabling movement disorder in a 59-year-old ET patient who underwent the procedure.…”

Essential tremor: Treatment options

“…Thalamotomy is faster, cheaper, requires only minimal subsequent care, and is generally equally effective, especially for unilateral procedures. • Gamma knife thalamotomy techniques are also being explored but suffer from their inability to record thalamic electrical activity, thus making exact localization difficult [63]. The procedure has the tremendous advantage of being noninvasive, but to date, results have been inconsistent.…”

Functional lesional neurosurgery for tremor: back to the future?

“…Microelectrode recordings from a limited number of patients suggest that the T2-hypointense core region represents the directly irradiated zone, while the surrounding irregular T2-hyperintense region is not functionally damaged 77. Tissue reaction can vary, and delayed effects months after the actual treatment have been repeatedly reported, resulting in drastically different lesion sizes between 188 mm 3 and 871 mm 3 97 with exceptional cases as large as 2030 mm 3 after 36 months98 or >6000 mm 3 after 18 months95 (see figure 3). After GK VIM thalamotomy cases without side effects showed smaller lesion sizes of 188±224 mm 3 (n=157 procedures) than cases with side effects: 871±742 mm 3 97.…”