Deep Brain Stimulation of Bilateral Centromedian Thalamic Nuclei in Pediatric Patients with Lennox-Gastaut Syndrome: An Institutional Experience.

BACKGROUND: Surgical management of pediatric patients with nonlesional, drug-resistant epilepsy, including patients with Lennox-Gastaut syndrome (LGS), remains a challenge given the lack of resective targets in most patients and shows seizure freedom rates <50% at 5 years. The efficacy of deep brain stimulation (DBS) is less certain in children than in adults. This study examined clinical and seizure outcomes for pediatric patients with LGS undergoing DBS targeting of the centromedian thalamic nuclei (CMTN). METHODS: An institutional review board-approved retrospective analysis was performed of patients aged ≤19 years with clinical diagnosis of LGS undergoing bilateral DBS placement to the CMTN from 2020 to 2021 by a single surgeon. RESULTS: Four females and 2 males aged 6-19 years were identified. Before surgery, each child experienced at least 6 years of refractory seizures; 4 children had experienced seizures since infancy. All took antiseizure medications at the time of surgery. Five children had previous placement of a vagus nerve stimulator and 2 had a previous corpus callosotomy. The mean length of stay after DBS was 2 days. No children experienced adverse neurologic effects from implantation; the mean follow-up time was 16.3 months. Four patients had >60% reduction in seizure frequency after surgery, 1 patient experienced 10% reduction, and 1 patient showed no change. No children reported worsening seizure symptoms after surgery. CONCLUSIONS: Our study contributes to the sparse literature describing CMTN DBS for children with drug-resistant epilepsy from LGS. Our results suggest that CMTN DBS is a safe and effective therapeutic modality that should be considered as an alternative or adjuvant therapy for this challenging patient population. Further studies with larger patient populations are warranted.

Deep Brain Stimulation for Refractory Tourette Syndrome: Electrode Position and Clinical Outcome.

The efficacy of deep brain stimulation (DBS) for refractory Tourette syndrome (TS) is accepted, but whether the efficacy of DBS treatment in the Japanese population is equivalent to those reported internationally and whether adverse effects are comparable are not yet known. This study evaluated the clinical practice and outcome of DBS for TS in a Japanese institution. This study included 25 consecutive patients with refractory TS treated with thalamic centromedian-parafascicular nucleus DBS. The severity of tics was evaluated with the Yale Global Tic Severity Scale (YGTSS) before surgery, at 1 year after surgery, and at the last follow-up of 3 years or more after surgery. The occurrence of adverse events, active contact locations, and stimulation conditions were also evaluated. YGTSS tic severity score decreased by average 45.2% at 1 year, and by 56.6% at the last follow-up. The reduction was significant for all aspects of the scores including motor tics, phonic tics, and impairment. The mean coordinates of active contacts were 7.62 mm lateral to the midline, 3.28 mm posterior to the midcommissural point, and 3.41 mm above anterior commissure-posterior commissure plane. Efficacy and stimulation conditions were equivalent to international reports. The stimulation-induced side effects included dysarthria (32.0%) and paresthesia (12.0%). Device infection occurred in three patients (12.0%) as a surgical complication. The DBS device was removed because of infection in two patients. DBS is an effective treatment for refractory TS, although careful indication is necessary because of the surgical risks and unknown long-term outcome.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience.

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.

Lead Repositioning Guided by Both Physiology and Atlas Based Targeting in Tourette Deep Brain Stimulation.

Background: The centromedian (CM) region of the thalamus is a common target for deep brain stimulation (DBS) treatment for Tourette Syndrome (TS). However, there are currently no standard microelectrode recording or macrostimulation methods to differentiate CM thalamus from other nearby structures and nuclei. Case Report: Here we present a case of failed conventional stereotactic targeting in TS DBS. Postoperative local field potential recordings (LFPs) showed features including beta power desynchronization during voluntary movement and thalamo-cortical phase amplitude coupling at rest. These findings suggested that the DBS lead was suboptimally placed in the ventral intermediate (VIM) nucleus of the thalamus rather than the intended CM region. Due to a lack of clinical improvement in tic severity scales three months following the initial surgery, the patient underwent lead revision surgery. Slight repositioning of the DBS leads resulted in a remarkably different clinical outcome. Afterwards, LFPs revealed less beta desynchronization and disappearance of the thalamo-cortical phase amplitude coupling. Follow-up clinical visits documented improvement of the patient's global tic scores. Discussion: This case provides preliminary evidence that combining physiology with atlas based targeting may possibly enhance outcomes in some cases of Tourette DBS. A larger prospective study will be required to confirm these findings. Highlight: This report demonstrates a case of failed centromedian nucleus region deep brain stimulation (DBS). We observed suboptimal tic improvement several months following DBS surgery and subsequent lead revision improved the outcome. The neurophysiology provided an important clue suggesting the possibility of suboptimally placed DBS leads. Repeat LFPs during lead revision revealed less beta desynchronization and disappearance of the thalamo-cortical phase amplitude coupling. There was improvement in tic outcome following slight repositioning during bilateral DBS lead revision. This case provides preliminary evidence supporting the use of physiology to augment the atlas based targeting of Tourette DBS cases.

Transsulcal approach supported by navigation-guided neurophysiological monitoring for resection of paracentral cavernomas.

OBJECTIVES: The aim of the study is to evaluate tools that can improve surgical precision and minimize surgical trauma for removal of cavernomas in the paracentral area. Moreover, the surgical strategies for the treatment of symptomatic epilepsy in cavernoma patients are discussed. PATIENTS AND METHODS: Between June 2000 and July 2007, 17 patients suffering from paracentral cavernoma underwent surgery via a transsulcal approach with the aid of neuronavigation, functional mapping and neurophysiological intraoperative monitoring. To optimize outcome for procedures in the paracentral area, the hemosiderin-stained tissue was removed entirely except for a small proportion on the side of precentral gyrus. RESULTS: All cavernomas and their adjacent sulci could be precisely located with the aid of ultrasonography-assisted neuronavigation. By combining preoperative fMRI and intraoperative neurophysiological monitoring, including SEP, MEP and cortical mapping, the motor cortex could be defined in all cases. Thus damage to the primary motor area could be avoided during resection of cavernomas. All the lesions located in the paracentral area were removed completely via transsulcal microsurgical approach without neurological deficits. No significant seizures were induced during surgery. CONCLUSIONS: The successful excision of these lesions was effected by the following four key factors: (1) the precise location of the lesion supported by intraoperative neuronavigation; (2) the preservation of the eloquent area with the aid of functional mapping; (3) a minimally invasive transsulcal microsurgical approach; and (4) the entire removal of cavernoma and hemosiderin-stained tissue.

A minimally invasive transsulcal approach to the paracentral inner lesion.

OBJECTIVE: Surgical options to remove lesions located deep in the sulcus at the paracentral area are limited. To minimize therapeutic morbidities, such as cortical injuries before the removal, a transsulcal approach was applied by taking the results of neuroimaging and functional mapping into consideration. METHODS: Four patients with paracentral inner lesions including anaplastic astrocytoma, cortical dysplasia, and cavernous angioma were operated on. All lesions were located deep in the paracentral sulci. According to the outcome of MRI and functional mapping of the cortex over the lesion, the central or the postcentral sulcus was opened toward the lesion. Immediately after complete dissection of the sulcus to remove the lesion, neurological findings were evaluated in the awake state. RESULTS: All lesions were situated beneath the hand or foot area. The transsulcal approach was successfully conducted without any neurological deficits in all cases. CONCLUSION: Microsurgical techniques based on anatomic and functional information allow surgeons to reach the lesions deep in the paracentral area safely.

Center median-parafascicular complex and pain control. Review from a neurosurgical perspective.

The center median-parafascicular (CM-Pf) complex, which constitutes the major portion of the intralaminar thalamus in man, has long been known to be involved in the processing of pain under normal and pathological conditions. Yet, these 'forgotten' nuclei with their rich connectivity to other thalamic nuclei, the basal ganglia and cortical areas have received only relatively little attention over the past two decades. With regard to the recent reinterest in functional stereotactic neurosurgery as a treatment option for chronic refractory pain, the CM-Pf complex has been reconsidered as a target. This review provides a systematic overview on the current knowledge about the anatomy and connectivity of the CM-Pf complex, neurophysiological studies, and on concepts of its role in pain processing under various conditions. We also review the previous experience with ablative surgery and deep brain stimulation of the CM-Pf complex. Studies in men and experimental animals indicate that the CM-Pf complex is part of a medial pain system, which appears to be involved primarily in affective and motivational dimensions of pain. Single-unit recordings from the CM-Pf complex have shown that the activity of CM-Pf cells is modified by painful stimuli. Under pathological conditions, bursting firing patterns and altered discharge rates were found. Thalamotomies targeting at the CM-Pf complex yielded beneficial results for chronic pain, but interpretation of the results is limited. With bifocal deep brain stimulation, short-term effects of CM-Pf stimulation were superior to those of somatosensory thalamic stimulation in neuropathic pain. There is evidence, that the CM-Pf complex might also be involved in the mediation of the beneficial effects of somatosensory thalamic stimulation and periventricular grey stimulation.