Radiosurgical treatment of medically refractory Parkinson’s tremor

Abstract

Introduction. In spite of medication treatment being today the basic form of treatment for Parkinson’s disease, surgical methods may be preferable to improve symptoms of the disease. Radiosurgery is one of them, but in Russia, to date, there are no publications summarizing data about the experience of using this method throughout the country.The study objective is to evaluate the effect of radiosurgical thalamotomy (destruction of the intermediate ventral nucleus of the thalamus) on the severity of tremor in patients with Parkinson’s disease, as well as to estimate the frequency of complications of this intervention, the frequency of different variants of radiological and clinical-neurological response.Materials and methods. One hundred and one (101) patients with medically refractory Parkinson’s tremor received Gamma Knife radiosurgery in our centre over a 10‑year period, of whom 10 patients were treated bilaterally. Pre-treatment evaluation was done using tremor assessment scales and video recordings of tremor intensity. Gamma Knife radiosurgery was provided with Leksell Gamma Knife 4C and Leksell Gamma Knife Perfexion (Elekta AB, Sweden) preceded by magnetic resonance tractography the day before treatment. The same planning protocol was used for all patients, the target was ventral intermediate nucleus and the prescription dose of 130 Gy was delivered with a 4 mm isocenter. After treatment, patients were evaluated radiologically and neurologically at regular 6‑month intervals, as well as through telephone interviews and video recordings.Results. Ninety-two (92) patients were included in the analysis of the results of radiosurgical treatment. Median follow-up time after radiosurgery was 26 months, from 6 to 113 months. Tremor reduction was achieved in 76 % of the patients, 61 % of whom had almost complete tremor arrest. Decreased tremors were observed from 1 to 6 months after treatment, with a mean of 4 months. Three (3) patients experienced tremor resurgence after 3–7 years. Complications were observed in 6.5 % of patients and were transient in character. Some of the patients developed severe depression. Only 1 patient had a serious complication in the form of thalamic haemorrhage (at 22 months after treatment). Ten (10) patients who were treated bilaterally all showed considerable clinical improvement and absence of complications.Conclusion. Gamma Knife radiosurgery is a safe and effective functional neurosurgical procedure for tremor correction to improve patients’ quality of life, especially when deep brain stimulation is not accessible. Patients with severe medically refractory tremors are good candidates for Gamma Knife treatment, which showed high efficacy and a low risk of complications.