Neurosurgery. 2012 Mar;70(3):526-35; discussion 535-6. Gamma knife thalamotomy for Parkinson disease and essential tremor: a prospective multicenter study. Ohye C(1), Higuchi Y, Shibazaki T, Hashimoto T, Koyama T, Hirai T, Matsuda S, Serizawa T, Hori T, Hayashi M, Ochiai T, Samura H, Yamashiro K. Author information: (1)Functional and Gamma Knife Surgery Center, Hidaka Hospital, Takasaki, Japan.
OBJECTIVE: To clarify the safety and optimally effective conditions for performing unilateral gamma knife (GK) thalamotomy for tremors of Parkinson disease (PD) and essential tremor (ET), a systematic postirradiation 24-month follow-up study was conducted at 6 institutions. We present the results of this multicenter collaborative trial.
METHODS: 72 patients (PD characterized by tremor, n = 59; ET, n = 13) were registered at 6 Japanese institutions. Following our selective thalamotomy procedure, the lateral part of the ventralis intermedius nucleus, 45% of the thalamic length from the anterior tip, was selected as the GK isocenter. A single 130-Gy shot was applied using a 4-mm collimator. Evaluation included neurological examination, magnetic resonance imaging and/or computerized tomography, the unified Parkinson's disease rating scale (UPDRS), electromyography, medication change, and video observations.
RESULTS: Final clinical effects were favorable. Of 53 patients who completed 24 months of follow-up, 43 were evaluated as having excellent or good results (81.1%). UPDRS scores showed tremor improvement (parts II and III). Thalamic lesion size fluctuated but converged to either an almost spherical shape (65.6%), a sphere with streaking (23.4%), or an extended high-signal zone (10.9%). No permanent clinical complications were observed.
CONCLUSION: GK thalamotomy is an alternative treatment for intractable tremors of PD as well as for ET. Less invasive intervention may be beneficial to patients.
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J Neurosurg. 1998 Jun;88(6):1044-9. Gamma knife radiosurgery for thalamotomy in parkinsonian tremor: a five-year experience. Duma CM(1), Jacques DB, Kopyov OV, Mark RJ, Copcutt B, Farokhi HK. Author information: (1)The Neurosciences Institute and Department of Radiation Oncology, Good Samaritan Hospital, Los Angeles, California 90017, USA. Comment in J Neurosurg. 1998 Jun;88(6):1121-2.
OBJECT: Certain patients, for example, elderly high-risk surgical patients, may be unfit for radiofrequency thalamotomy to treat parkinsonian tremor. Some patients, when given the opportunity, may choose to avoid an invasive surgical procedure. The authors retrospectively reviewed their experience using gamma knife radiosurgery for thalamotomies in this patient subpopulation: 1) to determine the efficacy of the procedure; 2) to see if there is a dose-response relationship; 3) to review radiological findings of radiosurgical lesioning; and 4) to assess the risks of complications.
METHODS: Radiosurgical nucleus ventralis intermedius thalamotomy using the gamma knife unit was performed to make 38 lesions in 24 men and 10 women (median age 73 years, range 58-87 years) over a 5-year period. A median radiation dose of 130 Gy (range 100-165 Gy) was delivered to 38 nuclei (four patients underwent bilateral thalamotomy) using a single 4-mm collimator following classic anatomical landmarks. 29 lesions were made in the left nucleus ventralis intermedius thalamus for right-sided tremor. Patients were followed for a median of 28 months (range 6-58 months). Independent neurological evaluation of tremor based on the change in the Unified Parkinson's Disease Rating Scale tremor score was correlated with subjective patient evaluation. Comparison was made between a subgroup of patients in whom "low-dose" lesions were made (range 110-135 Gy, mean 120 Gy) and those in whom "high-dose" lesions were made (range 140-165 Gy, mean 160 Gy) for purposes of dose-response information. 4 thalamotomies (10.5%) failed, 4 (10.5%) produced mild improvement, 11 (29%) produced good improvement, and 10 (26%) produced excellent relief of tremor. In 9 thalamotomies (24%) the tremor was eliminated completely. The median time to onset of improvement was 2 months (range 1 week-8 months). Concordance between an independent neurologist's evaluation and that of the patient was statistically significant (p < 0.001). Two patients who underwent unilateral thalamotomy experienced bilateral improvement in their tremor. There were no neurological complications. There was better tremor reduction in the high-dose group than in the low-dose group (p < 0.04).
CONCLUSIONS: Although less effective than other stereotactic techniques, gamma knife radiosurgery for thalamotomy offers tremor control with minimal risk to patients unsuited for open surgery.
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J Neurosurg. 2000 Dec;93 Suppl 3:128-35. Gamma knife thalamotomy for treatment of tremor: long-term results. Young RF(1), Jacques S, Mark R, Kopyov O, Copcutt B, Posewitz A, Li F. Author information: (1)Neuroscience Institute and Gamma Knife Centers, Good Samaritan Hospital, Los Angeles, California, USA.
OBJECT: The purpose of this study was to investigate the long-term effects of gamma knife thalamotomy for treatment of disabling tremor.
METHODS: 158 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.
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