Magnetic resonance-guided focused ultrasound central lateral thalamotomy against chronic and therapy-resistant neuropathic pain: retrospective long-term follow-up analysis of 63 interventions.

OBJECTIVE: Medial thalamotomies were introduced in the late 1940s. Pain relief was shown to be achieved for all body locations. With some exceptions, these early relatively small series showed frequent, more or less complete recurrence of the original pain. The posterior part of the central lateral nucleus in the human medial thalamus was identified in the 1990s using multiarchitectonic studies and intraoperative single-cell recordings and was confirmed as a surgical target. This retrospective patient series extended over 11 years. Its goal was to demonstrate the efficacy and risk profile of the MR-guided focused ultrasound (MRgFUS) central lateral thalamotomy (CLT) against chronic and therapy-resistant neuropathic (i.e., neurogenic) pain. METHODS: In this single-center, nonrandomized retrospective cross-sectional analysis of consecutive patients, 63 consecutive MRgFUS CLT interventions were performed in 55 patients. RESULTS: The mean follow-up duration was 55 months. A total of 112 CLT targets were performed, and the CLT was applied bilaterally in 48 patients and contralateral to their pain in 7 patients. Repeat MRgFUS interventions were performed in 8 patients. One serious adverse event with numbness of the upper lip was recorded. The mean pain relief rated by patients was 42% ± 32% at 3 months, 43% ± 36% at 1 year, and 42% ± 37% at the last follow-up (n = 63). The proportions of cases with ≥ 30% pain relief were 65% at 3 months, 63% at 1 year, and 61% at the last follow-up. Good outcomes (≥ 50% pain relief) were found in 54% of patients at 3 months, 49% at 1 year, and 51% at the last follow-up. The reduction in mean VAS scores showed similar percentage reductions as those for pain relief (-41% for continuous pain and -49% for pain attacks) at the 1-year follow-up. The mean frequency of pain attacks was reduced by 92%. Allodynia was reduced or suppressed in 68% of patients and never appeared de novo after MRgFUS CLT. CONCLUSIONS: These results suggest that MRgFUS CLT against neuropathic pain is a safe approach and its results are stable over time. At a mean follow-up duration of 55 months, the mean pain relief was 42% and more than 50% of patients still reported ≥ 50% pain relief. Patients with classical and idiopathic trigeminal neuralgia reported a higher mean pain relief compared with the whole patient group.

Complete resolution of chronic cluster headache following central lateral thalamotomy using incisionless MRI-guided focused ultrasound with 6 years of follow-up: illustrative case.

BACKGROUND: The authors reported the case of a 66-year-old male patient with a 14-year history of right-sided severe episodic and therapy-resistant cluster headache (CH) who underwent bilateral central lateral thalamotomy (CLT) using incisionless transcranial magnetic resonance imaging-guided focused ultrasound (MRgFUS). OBSERVATIONS: The patient experienced a single cluster headache attack 5 weeks after the procedure. There were no more pain attacks over the next 6 years of follow-up. LESSONS: This treatment success may indicate a common pathophysiology for CH and neurogenic (neuropathic) pain, which has been treated with CLT for more than 30 years. Further experience is needed to assess the reproducibility of this case.

Bilateral MR-Guided Focused Ultrasound Pallidothalamic Tractotomy for Parkinson's Disease With 1-Year Follow-Up.

Objective: Bilateral stereotactic neurosurgery for advanced Parkinson's disease (PD) has a long history beginning in the late 1940s. In view of improved lesioning accuracy and reduced bleeding risk and in spite of long-standing caveats about bilateral approaches, there is a need to investigate bilateral MR-guided focused ultrasound (MRgFUS) interventions. We hereby present the clinical results of bilateral pallidothalamic tractotomy (PTT), i.e., targeting of pallidal efferent fibers below the thalamus at the level of Forel's field H1, followed for 1 year after operation of the second side. Methods: Ten patients suffering from chronic and therapy-resistant PD having received bilateral PTT were followed for 1 year after operation of the second side. The primary endpoints included the Unified Parkinson's Disease Rating Scale (UPDRS) scores in on- and off-medication states, dyskinesias, dystonia, sleep disturbances, pain, reduction in drug intake, and assessment by the patient of her/his global symptom relief as well as tremor control. Results: The time frame between baseline UPDRS score and 1 year after the second side was 36 ± 15 months. The total UPDRS score off-medication at 1 year after the second PTT was reduced by 52% compared to that at baseline on-medication (p < 0.007). Percentage reductions of the mean scores comparing 1 year off- with baseline on-medication examinations were 91% for tremor (p = 0.006), 67% for distal rigidity (p = 0.006), and 54% for distal hypobradykinesia (p = 0.01). Gait and postural instability were globally unchanged to baseline (13% improvement of the mean, p = 0.67, and 5.3% mean reduction, p = 0.83). Speech difficulties, namely, hypophonia, tachyphemia, and initiation of speech, were increased by 58% (p = 0.06). Dyskinesias were suppressed in four over four, dystonia in four over five, and sleep disorders in three over four patients. There was 89% pain reduction. Mean L-Dopa intake was reduced from 690 ± 250 to 110 ± 190. Conclusions: Our results suggest an efficiency of bilateral PTT in controlling tremor, distal rigidity, distal hypobradykinesia, dyskinesias, dystonia, and pain when compared to best medical treatment at baseline. Larger series are of course needed.

MRgFUS Pallidothalamic Tractotomy for Chronic Therapy-Resistant Parkinson's Disease in 51 Consecutive Patients: Single Center Experience.

Background: There is a long history, beginning in the 1940s, of ablative neurosurgery on the pallidal efferent fibers to treat patients suffering from Parkinson's disease (PD). Since the early 1990s, we undertook a re-actualization of the approach to the subthalamic region, and proposed, on a histological basis, to target specifically the pallidothalamic tract at the level of Forel's field H1. This intervention, the pallidothalamic tractotomy (PTT), has been performed since 2011 using the MR-guided focused ultrasound (MRgFUS) technique. A reappraisal of the histology of the pallidothalamic tract was combined recently with an optimization of our lesioning strategy using thermal dose control. Objective: This study was aimed at demonstrating the efficacy and risk profile of MRgFUS PTT against chronic therapy-resistant PD. Methods: This consecutive case series reflects our current treatment routine and was collected between 2017 and 2018. Fifty-two interventions in 47 patients were included. Fifteen patients received bilateral PTT. The median follow-up was 12 months. Results: The Unified Parkinson's Disease Rating Scale (UPDRS) off-medication postoperative score was compared to the baseline on-medication score and revealed percentage reductions of the mean of 84% for tremor, 70% for rigidity, and 73% for distal hypobradykinesia, all values given for the treated side. Axial items (for voice, trunk and gait) were not significantly improved. PTT achieved 100% suppression of on-medication dyskinesias as well as reduction in pain (p < 0.001), dystonia (p < 0.001) and REM sleep disorders (p < 0.01). Reduction of the mean L-Dopa intake was 55%. Patients reported an 88% mean tremor relief and 82% mean global symptom relief on the operated side and 69% mean global symptom improvement for the whole body. There was no significant change of cognitive functions. The small group of bilateral PTTs at 1 year follow-up shows similar results as compared to unilateral PTTs but does not allow to draw firm conclusions at this point. Conclusion: MRgFUS PTT was shown to be a safe and effective intervention for PD patients, addressing all symptoms, with varying effectiveness. We discuss the need to integrate the preoperative state of the thalamocortical network as well as the psycho-emotional dimension.

Incisionless transcranial MR-guided focused ultrasound in essential tremor: cerebellothalamic tractotomy.

BACKGROUND: Already in the late 1960s and early 1970s, targeting of the "posterior subthalamic area (PSA)" was explored by different functional neurosurgical groups applying the radiofrequency (RF) technique to treat patients suffering from essential tremor (ET). Recent advances in magnetic resonance (MR)-guided focused ultrasound (MRgFUS) technology offer the possibility to perform thermocoagulation of the cerebellothalamic fiber tract in the PSA without brain penetration, allowing a strong reduction of the procedure-related risks and increased accuracy. We describe here the first results of the MRgFUS cerebellothalamic tractotomy (CTT). METHODS: Twenty-one consecutive patients suffering from chronic (mean disease duration 29.9 years), therapy-resistant ET were treated with MRgFUS CTT. Three patients received bilateral treatment with a 1-year interval. Primary relief assessment indicators were the Essential Tremor Rating Scale (Fahn, Tolosa, and Marin) (ETRS) taken at follow-up (3 months to 2 years) with accent on the hand function subscores (HF16 for treated hand and HF32 for both hands) and handwriting. The evolution of seven patients with HF32 above 28 points over 32 (group 1) differentiated itself from the others' (group 2) and was analyzed separately. Global tremor relief estimations were provided by the patients. Lesion reconstruction and measurement of targeting accuracy were done on 2-day post-treatment MR pictures for each CTT lesion. RESULTS: The mean ETRS score for all patients was 57.6 ± 13.2 at baseline and 25.8 ± 17.6 at 1 year (n = 10). The HF16 score reduction was 92 % in group 2 at 3 months and stayed stable at 1 year (90 %). Group 1 showed only an improvement of 41 % at 3 months and 40 % at 1 year. Nevertheless, two patients of group 1 treated bilaterally had an HF16 score reduction of 75 and 88 % for the dominant hand at 1 year after the second side. The mean patient estimation of global tremor relief after CTT was 92 % at 2 days and 77 % at 1-year follow-up. CONCLUSIONS: CTT with MRgFUS was shown to be an effective and safe approach for patients with therapy-refractory essential tremor, combining neurological function sparing with precise targeting and the possibility to treat patients bilaterally.