Introduction: Cavitation-associated adverse events in MR-guided focused ultrasound (MRgFUS) thalamotomy are uncommon but potentially serious. We report a case of acute “electric-shock” sensation during an alignment/verification sonication followed by thalamic T2 hyperintensity/edema after a redo ventral intermediate nucleus (VIM) thalamotomy. We discuss plausible biophysical mechanisms and risk-reduction strategies. Case Presentation: A 53-year-old woman with essential tremor underwent repeat MRgFUS five months after her initial treatment. During the 4th alignment/verification sonication (planned 200 W, 20 s; measured power approximately 192 W), cavitation monitoring triggered a halt at 19.2 seconds after 2037 J was delivered. Despite a maximum target temperature <50 °C, the patient immediately reported an “electric-shock” sensation. Post-procedure, she developed right-sided sensory symptoms, mild dysarthria, and hypogeusia. Early MRI showed irregular thalamic hyperintensity consistent with edema, but without confirmed off-target thermal rise on intra-operative thermometry. Conclusion: The most plausible pathogenesis is mechanically mediated injury from cavitation-related acoustic activity. We hypothesize that substantial overlap with the prior ablation zone was the primary predisposing factor, potentially augmented by calcification-related scattering, No-Pass Region (NPR)-driven aperture distortion, occult skull marrow changes, and standing-wave formation. We discuss biophysical mechanisms and propose physics-guided safeguards for redo procedures.
Introduction: The pallidothalamic tract (PTT), formed by convergence of the ansa lenticularis and fasciculus lenticularis at Forel's field H1, is a major basal ganglia efferent pathway and an emerging functional neurosurgical target. No systematic review has previously synthesised outcomes across PTT-targeted interventions. Methods: This PRISMA 2020-compliant systematic review was registered on PROSPERO (CRD420251248260). PubMed, OVID, and Web of Science were searched for studies reporting functional neurosurgical outcomes targeting the PTT or Forel's fields. Prospective and retrospective studies, case series, and case reports were eligible. Methodological quality was assessed using design-appropriate risk-of-bias tools. Results: Forty studies encompassing 483 patients (1966–2025) were included across five modalities: MR-guided focused ultrasound (n = 143), radiofrequency ablation (n = 167), deep brain stimulation (n = 40), cryogenic lesioning (n = 82), and oil-wax injection (n = 52). Mean follow-up was 21 months. In Parkinson disease (PD; 11 studies; n = 135), mean Unified Parkinson's Disease Rating Scale-III improvement was 39%, with reductions in dyskinesia (Unified Dyskinesia Ratings Scale 90%) and tremor (75%). In dystonia (12 studies; n = 87), Burke Fahn Marsden Dystonia Rating Scale and TWSTRS improved by 57% and 47%, respectively. Dual-target strategies, particularly PTT-VIM combinations, showed additive effects, including greater tremor reduction (77%) and improved rigidity. In drug-resistant epilepsy (6 studies; n = 157), seizure reduction occurred in 71% and seizure freedom in 33%. Conclusion: PTT-targeted interventions yield meaningful motor improvements in PD and dystonia, with preliminary evidence supporting additive dual-target benefits. Seizure-reducing effects in refractory epilepsy have been reported. Evidence remains limited by small uncontrolled studies, heterogeneous outcomes, and inconsistent adverse-event reporting. Prospective trials will elucidate the efficacy, safety, and clinical role of the PTT in neurosurgery.
Background: Focused ultrasound (FUS) thalamotomy has become a common surgical treatment for essential tremor (ET), in some settings partially replacing deep brain stimulation (DBS). However, no randomized comparative studies have been performed. A review directly comparing unilateral FUS thalamotomy and unilateral DBS is therefore warranted. Summary: A systematic literature search identified studies of thalamotomy FUS or thalamic DBS for ET. Eligible studies reported mean values for predefined items of the Clinical Rating Scale for Tremor (CRST) at 6–12 months follow-up. Studies with long-term outcomes (≥5 years) were also considered. Duplicate or overlapping cohorts were excluded. Thirteen short-term FUS studies (427 patients) and six DBS studies (307 patients) met inclusion criteria. Mean age was comparable, though the FUS cohort showed greater gender imbalance. Improvement in total CRST scores did not differ significantly between FUS and DBS (53% vs. 56%). DBS was associated with significantly greater improvement in contralateral hand tremor (86% vs. 72%), combined hand tremor and function (82% vs. 59%), and activities of daily living (71% vs. 65%). Long-term data were limited: two FUS studies (66 patients) and two DBS studies (36 patients) met criteria. Adverse event profiles differed substantially, with complications more frequent and more often persistent following FUS. Key messages: Both treatments provide clinically meaningful tremor reduction, though DBS appears to offer greater overall improvement. Permanent side effects after FUS are relatively common but mostly mild. Randomized trials comparing DBS and FUS are needed, particularly regarding side effects and quality of life.
Introduction: Ventral intermediate nucleus (Vim) thalamotomy effectively suppresses essential tremor (ET); however, improvements in tremor severity do not necessarily translate into enhanced upper-limb dexterity or quality of life (QOL). In this study, we aimed to characterize postoperative changes in line-drawing trajectories and explore their functional correlates following Vim thalamotomy. Methods: Thirty patients with ET who underwent unilateral Vim thalamotomy and 13 healthy controls (HC) were included. The ET group was assessed preoperatively and at 1 week and 1 month postoperatively using The Essential Tremor Rating Assessment Scale (TETRAS; tremor severity [performance subscale; PS] and activities of daily living [ADL]), Purdue Pegboard Test (PPT), Box and Block Test (BBT), and Quality of Life in Essential Tremor Questionnaire (QUEST [QOL]). Line-drawing trajectories were quantitatively analyzed using the proportion of upward-direction deviation area (upper %) as an exploratory descriptor of trajectory characteristics. Longitudinal changes, comparisons with HC, and regression analyses of QOL were performed. Results: Tremor severity and ADL impairment improved significantly after surgery (both p < 0.001), accompanied by significant improvement in QOL (p < 0.001). In contrast, PPT and BBT scores showed no significant postoperative improvement. Upper % was significantly higher at 1 month than at 1 week postoperatively (p = 0.047) and exceeded the level observed in HC (p = 0.034). Sensitivity analysis demonstrated that increases in upper % occurred more frequently than decreases (20 vs. 6 patients, p = 0.009). TETRAS ADL was the only independent predictor of QOL (B = -1.565, p = 0.001). Conclusion: Vim thalamotomy improved tremor severity, ADL, and QOL, whereas objective dexterity remained unchanged. Exploratory trajectory analysis identified delayed postoperative alterations in line-drawing characteristics. These trajectory changes may provide complementary information regarding upper-limb performance beyond conventional tremor measures and warrant further longitudinal investigation.
Introduction Severe self-injurious behavior (SIB) is a potentially life-threatening condition that is often treatment refractory, particularly in patients with severe psychiatric illness. Limbic leucotomy, which combines anterior cingulotomy and subcaudate tractotomy, has shown benefit in select patients with severe, treatment-refractory SIB as an intervention of last resort. However, long-term outcome data beyond a few years is essentially absent from present literature. We report the longest follow-up to date in two patients after limbic leucotomy for severe refractory SIB. Case Presentations Two chronically institutionalized female patients (ages 23 and 31 at surgery) with longstanding, refractory SIB underwent MRI-guided stereotactic limbic leucotomy at Massachusetts General Hospital. In one patient, the procedure was staged (anterior cingulotomy followed 13 months later by subcaudate tractotomy), and in the other patient the limbic leucotomy was performed in a single procedure. Both had extensive prior treatment including pharmacotherapy, psychotherapy, and electroconvulsive therapy, without sustained benefit. Outcomes were assessed longitudinally by an independent psychiatrist using validated measures, including the Clinical Global Impression (CGI), Current Global Psychiatric-Social Status (CGPS), Global Assessment of Functioning (GAF), Beck Depression Inventory (BDI), and neuropsychological testing through 47 months in one patient and 11 years in the other patient. Both patients demonstrated marked and sustained reductions in SIB and overall psychiatric symptom burden following surgery. Improvements were gradual and continued over extended follow-up. Functional outcomes improved substantially, with significant increases in GAF scores. Last follow-up exceeded 18 years for both patients (18 and 23 years) which were descriptive and did not include validated instruments. However, both patients transitioned from long-term institutionalization to independent living, pursued higher education, and obtained employment. No long-term adverse effects attributable to surgery were observed. Conclusions We present two cases of sustained clinical and functional improvement of 18 and 23 years after limbic leucotomy, the longest follow-up reported to date.
