Gamma knife thalamotomy for movement disorders: evaluation of the thalamic lesion and clinical results

Abstract

Object. The authors studied the effects of gamma knife thalamotomy (GKT) on Parkinson disease-related tremor and essential tremor before and after reloading of radioactive cobalt. Methods. Based on experience in stereotactic thalamotomy aided by depth microrecording, the target was located at the lateral border of the thalamic ventralis intermedius nucleus (VIM). For more precise targeting, the percentage representation of the thalamic VIM in relation to the entire thalamic length is useful. The location of the target was determined on magnetic resonance (MR) imaging and computerized tomography scanning. A maximum dose of 130 Gy was delivered to the target by using a single isocenter with the 4-mm collimator. In more recent cases, a systematic follow-up examination was performed at 3, 6, 12, 18, and 24 months after GKT. Since 1993, the authors have treated 70 patients with PD. Throughout the series the same dosimetric technique has been used. The course after GKT was compared between the 25 cases with PD treated before reloading and the 35 cases treated after reloading. In the majority (80–85%) treated after reloading, tremor and rigidity were reduced around 6 months after GKT. In the cases treated before reloading this effect took approximately 1 year. The thalamic reaction on MR imaging showed the same two lesion types in both series: a restricted and a diffuse. After reloading the restricted lesion was more frequent and the lesion volume was smaller. Conclusions. The shorter delay in clinical improvement and smaller lesion size may be related to an increased radiation dose.

Gamma Knife Thalamotomy for Disabling Tremor

“…Our findings contrast with other studies reporting marked improvement of resting, postural, and action tremor after GKT. [1][2][3][4] The largest of these series 2 reported on the combined experience at 2 gamma knife radiosurgery centers, but the reliability of their data-even though evaluations were stated to be blinded-has been questioned by others. 6 To our knowledge, no other study has assessed the effectiveness of GKT using physician-blinded assessments or in terms of the effect of tremor on ADL as measured by validated scales.…”

“…Despite some literature claims of significant benefit from GKT, [1][2][3][4][5] proper blinded assessments are necessary to determine how useful the procedure is and the time it takes to benefit. Likewise, adequate assessment of possible complications [6][7][8] needs to take place.…”

Stereotactic radiosurgery for tremor: systematic review

“…All 3 parameters measured by the FTMRS (writing, tremor, and drinking) improved in 66% of cases. Successive studies by Ohye et al, 56,59,60 evaluating between 50 and 85 patients, also reported an improvement in tremor in 80.8% and a decrease in the UPDRS score of 58.9%.…”

“…There were few data on bilateral treatments. 10,12,21,34,58,59,61,83,84 Young et al 84 patient, a PET scan showed lowered metabolism in the region. On autopsy after death due to aspiration pneumonia, the target showed necrosis.…”

Strain fields in histological slices of brain tissue determined by synchrotron radiation-based micro computed tomography

“…Non-invasive magnetic resonance (MR)-guided neurosurgery without intracerebral penetration such as with gamma knife or high-intensity focused ultrasounds (Jolesz et al, 2005;Keep et al, 2005;Kennedy et al, 2003;Ohye et al, 2005;Young, 2002) represents an alternative to deep brain stimulation (DBS) or radiofrequency lesions. The location of the target volume, e.g.…”