|M.Sc Student||Crystal Shoshana|
|Subject||Effect of Lesion Characteristics in Magnetic Resonance|
Guided Focused Ultrasound Surgery (MRgFUS) on
Tremor and Quality of Life - a Clinical,
|Department||Department of Medicine||Supervisor||Professor Menashe Zaaroor|
|Full Thesis text - in Hebrew|
Effect of lesion characteristics in magnetic resonance guided focused ultrasound surgery (MRgFUS) on quality of life and tremor - a clinical, neurophysiological study
Background: Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) is an innovative technology that enables non-invasive Thalamotomy in the ventral intermediate nucleus (VIM) for treatment of medication resistant tremor in patients with essential tremor (ET) and Parkinson's disease (PD). This study examined the effect of lesion characteristics, skull characteristics of patients (skull density ratio (SDR)), and the characteristics of the procedure on the patients’ degree of tremor and adverse events.
Methods: Clinical Measurements were taken the day before the procedure, one day, one week, one month and three months after treatment. Treatment effects on tremor and Quality of Life measured by iSeismometer application, the Clinical Rating Scale for Tremor (CRST) and Quality of Life in Essential Tremor Questionnaire (QUEST)
for ET patients and by the Unified Parkinson's Disease Rating Scale (UPDRS) motor part and by the PD Questionnaire (PDQ-39) for PD and ET-PD patients (ET patients who develop PD many years later). Side-effects were monitored during and after the procedure. Lesion volume (mm3), size (mm), and location (mm) were measured using MRI using the CARESTREAM Vue PACS software.
Results: 21 patients (11 ET patients, 9 PD patients, and 1 ET-PD patient) who underwent unilateral MRgFUS VIM thalamotomy were included in the study. Treatment with MRgFUS improved axial and leg tremor in addition to the treated hand: in Five out of nine patients (55.5%) who suffered from leg tremor, tremor disappearance from ipsilateral leg. Two out of three patients (66.6%) who suffered from axial tremor in the chin prior to surgery, and one patient had an axial tremor in the eyelid (on the same side of the lesion in the brain), showed tremor disappearance from the chin and eyelid after treatment. At 3 month post- treatment, the ET patients' CRST score decreased from 33.6±7.8 (mean±sd) to 4.8±4.5. In PD patients, UPDRS motor score decreased from 26.5±8.7 to 17.2±5.2 3 months post- treatment. Parameters that were associated with tremor improvement in PD patients were total lesion volume (r = 0.640-641, P <0.05), SDR (n =8, r =0.723, p <0.05) and maximal sonication time (r =-0.734, P < 0.05). in ET patients a relationship between the maximal sonication time and improvement in tremor was observed (n =7, r =-0.773, P <0.05). Typical imaging findings were observed in MRI T2-weighted image scanning, which includes three concentric zones around the lesion. Reported adverse event were temporary and passed in all patients three months after the procedure, correspondingly to the disappearance of Perilesional edema. SDR, total lesion volume (one week after the procedure), and maximal energy, predicted adverse effects of instability in gait. In addition, low SDR was associated with an increase of sonication time, energy, and increase in the number of sonications, as well as being associated with a lower therapeutic temperature in the target tissue.
Conclusion: Thalamotomy with MRgFUS is an effective treatment for ET and PD patients with drug-resistant tremor. These findings shed light on the importance of SDR in obtaining therapeutic temperature, the appearance of side effects and impact on reducing tremor.