Occipital Nerve Stimulation for Recurrent Trigeminal Neuralgia Without Occipital Pain.

OBJECTIVES: Trigeminal neuralgia (TN) is a severe, debilitating pain condition causing physical and emotional distress. Although the management of TN is well codified with medical and then surgical treatments, 15% to 30% of patients will experience intractable pain. Neuromodulation techniques have been scarcely used for refractory TN, with only small case series and short-term follow-up. MATERIALS AND METHODS: We conducted a retrospective study of patients treated with occipital nerve stimulation (ONS) for medically and surgically resistant TN without painful trigeminal neuropathy. The effectiveness of the ONS was evaluated using the Barrow Neurological Institute (BNI) pain score and the pain relief (0%-100%) at best and at last follow-up. RESULTS: Seven patients who have refractory TN were included. The mean age at ONS was 49 years. The mean pain duration was 8.6 years. The mean number of medical and surgical treatments before ONS was six and five, respectively. A percutaneous trial was performed in five of seven patients; all responded (pain relief > 40%), and four of five patients experienced pain recurrence after explantation. Eventually, six patients had a permanent ONS implantation. The average BNI pain score before implantation was V. The mean follow-up after implantation was 59 months. All patients reported an improvement after implantation. The average BNI score and mean pain relief at best were IIIa and 86.7%, respectively. At last follow-up, the average BNI score and mean pain relief were IIIa and 58.0%, respectively, with three patients experiencing pain recurrence. Adverse events were reported for four patients who required surgical revision for lead breakage (1), erosion (1), migration (1), or hardware-related discomfort (1). One patient finally underwent explantation because of infection. CONCLUSIONS: Although ONS is not validated in this indication, these results suggest that it can induce an improvement in TN recurring after several surgical treatments, and the benefit of the stimulation can be sustained in the long term. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT01842763.

Is Spinal Cord Stimulation Still Effective After One or More Surgical Revisions?

OBJECTIVES: Spinal cord stimulation (SCS) is burdened with surgical complications that may require one or several surgical revision(s), challenging its risk/benefit ratio and cost-effectiveness. Our objective was to evaluate its outcome and efficacy after one or more SCS surgical revisions. MATERIALS AND METHODS: We identified and retrospectively analyzed 116 patients treated by tonic paresthesia-based SCS who experienced one or more complication(s) requiring at least one surgical revision. Data collected included initial indication, revision indication, number of revisions, and lead design (paddle or percutaneous). Outcome after SCS revision was evaluated by pain intensity decrease (comparing baseline and postrevision Numerical Rating Scale [NRS] scores) and percentage of patients reporting pain relief ≥50%. Outcome was analyzed according to the number of surgical revisions and the revision indications. RESULTS: Most of the patients (61%) underwent only one revision (mean delay after implantation 44 months). The most frequent causes of revisions were hardware dysfunction (32%), lead migration (23%), and infection (18%). Revision(s) repaired the SCS issue in 87% of the cases. One year after the first revision, 82% of the patients reported pain relief ≥50%, and the mean NRS decrease was 4.0 compared with baseline (p < 0.001). Benefit of SCS revision tended to decrease with the number of revisions but did not differ across revision indications. No serious surgical complications related to the revision occurred, except for three hematomas occurring after repeated revisions. CONCLUSIONS: Our data suggest that surgical revision of SCS system is safe and led to significant pain relief in most of the cases, provided that the initial indication was good and that the previous stimulation was effective. However, success of SCS revision decreases with the number of revisions.

Occipital Nerve Stimulation for Refractory Chronic Cluster Headache: A Cost-Effectiveness Study.

INTRODUCTION: Occipital nerve stimulation (ONS) is proposed to treat refractory chronic cluster headache (rCCH), but its cost-effectiveness has not been evaluated, limiting its diffusion and reimbursement. MATERIALS AND METHODS: We performed a before-and-after economic study, from data collected prospectively in a nation-wide registry. We compared the cost-effectiveness of ONS associated with conventional treatment (intervention and postintervention period) to conventional treatment alone (preintervention period) in the same patients. The analysis was conducted on 76 rCCH patients from the French healthcare perspective at three months, then one year by extrapolation. Because of the impact of the disease on patient activity, indirect cost, such as sick leave and disability leave, was assessed second. RESULTS: The average total cost for three months was €7602 higher for the ONS strategy compared to conventional strategy with a gain of 0.07 quality-adjusted life-years (QALY), the incremental cost-effectiveness ratio (ICER) was then €109,676/QALY gained. The average extrapolated total cost for one year was €1344 lower for the ONS strategy (p = 0.5444) with a gain of 0.28 QALY (p < 0.0001), the ICER was then €-4846/QALY gained. The scatter plot of the probabilistic bootstrapping had 80% of the replications in the bottom right-hand quadrant, indicating that the ONS strategy is dominant. The average indirect cost for three months was €377 lower for the ONS strategy (p = 0.1261). DISCUSSION: This ONS cost-effectiveness study highlighted the limitations of a short-time horizon in an economic study that may lead the healthcare authorities to reject an innovative strategy, which is actually cost-effective. One-year extrapolation was the proposed solution to obtain results on which healthcare authorities can base their decisions. CONCLUSION: Considering the burden of rCCH and the efficacy and safety of ONS, the demonstration that ONS is dominant should help its diffusion, validation, and reimbursement by health authorities in this severely disabled population.

Somatotopy of the sensory thalamus: inputs from directional deep brain stimulation in pain patients.

OBJECTIVE: The sensory ventroposterior (VP) thalamic nuclei display a mediolateral somatotopic organization (respectively head, arm, and leg). We studied this somatotopy using directional VP deep brain stimulation (DBS) in patients treated for chronic neuropathic pain. METHODS: Six patients with central (four) or peripheral (two) neuropathic pain were treated by VP DBS using directional leads in a prospective study (clinicaltrials.gov NCT03399942). Lead-DBS toolbox was used for leads localization, visualization, and modeling of the volume of tissue activated (VTA). Stimulation was delivered in each direction, 1 month after surgery and correlated to the location of stimulation-induced paresthesias. The somatotopy was modeled by correlating the respective locations of paresthesias and VTAs. We recorded 48 distinct paresthesia maps corresponding to 48 VTAs (including 36 related to directional stimulation). RESULTS: We observed that, in each patient, respective body representations of the trunk, upper limb, lower limb, and head were closely located around the lead. These representations differed across patients, did not follow a common organization and were not concordant with the previously described somatotopic organization of the sensory thalamus. INTERPRETATION: Thalamic reorganization has been reported in chronic pain patients compared to non-pain patients operated for movement disorders in previous studies using intraoperative recordings and micro-stimulation. Using a different methodology, namely 3D representation of the VTA by the directional postoperative stimulation through a stationary electrode, our study brings additional arguments in favor of a reorganization of the VP thalamic somatotopy in patients suffering from chronic neuropathic pain of central or peripheral origin.

A New Noninvasive Frameless Registration System for Stereotactic Cranial Biopsy: A Technical Note.

BACKGROUND: Although frame-based stereotactic biopsy is still considered the gold standard for brain biopsies, frameless robot-assisted stereotactic systems are now able to provide an equal level of safety and accuracy. However, both systems suffer from a lack of efficiency of the operative workflow. OBJECTIVE: To describe the technique of a new frameless and noninvasive registration tool Neurolocate (Renishaw). This tool, combined with an intraoperative cone-beam computed tomography imaging system like O-ARM (Medtronic), might facilitate the achievement and workflow of robot-assisted stereotactic intracranial biopsies. METHODS: Neurolocate is a 3-dimensional fiducial tool fixed directly on the Neuromate (Renishaw) robot arm. It consists of 5 radio-opaque spherical fiducials, whose geometry is constant. This tool made it possible to carry out the coregistration then the biopsy in the same operating time, following a five-step procedure described here. We retrospectively extracted selected preliminary results from our initial experience. RESULTS: Over 1 year, 23 consecutive adult patients were biopsied with Neurolocate in our center. The mean overall operative time, from patient's installation to skin closure, was 97 minutes ± 27 (SD). The entire procedure took place in a single location unit (operating room), which facilitated workflow and surgical planning. No invasive gesture was performed outside of the operating time. CONCLUSION: Neurolocate is a new frameless and noninvasive registration tool that could improve workflow and flexibility for operating room management and surgical planning. It may also increase the comfort of patients undergoing robot-assisted intracranial stereotactic biopsies. The accuracy and safety profile should be addressed in specific studies.

Application accuracy of Neuromate robot-guided deep brain stimulation procedures using the non-invasive frameless Neurolocate registration system.

OBJECTIVE: to measure the in vivo application accuracy of Neuromate robot-assisted deep brain stimulation procedures (DBS) using the new, non-invasive, frameless Neurolocate registration method. METHODS: Neurolocate accuracy was measured in 17 patients undergoing DBS (32 leads). The registration was obtained by automatic recognition of the spatial location of the Neurolocate fiducials, fixed on the robot arm, on 3D intraoperative computerized tomography (CT) images relative to the patient's skull contours. Application accuracy was measured as the Euclidian distance between the points theoretically targeted on preoperative magnetic resonance imagingand the tip of the guiding tube visible on intraoperative CT images after merging images. RESULTS: Mean robot inaccuracy was 0.72 mm (SD 0.40; range 0.2-1.7 mm). Inaccuracies ≥1.5 mm were observed in 2/32 cases. CONCLUSION: Our study confirms in vivo that the accuracy of the Neurolocate registration is compatible with the accuracy required for DBS procedures.

Combined thalamic and pallidal deep brain stimulation for dystonic tremor.

BACKGROUND: Deep brain stimulation (DBS) has been proposed to treat disabling dystonic tremor (DT), but there is debate about the optimal target. DBS of the globus pallidus interna (GPi) may be insufficient to control tremor, and DBS of the ventral intermediate thalamic nucleus (VIM) may inadequately control dystonic features, raising the question of combining both targets. OBJECTIVES: To report the respective effects on DT symptoms of high-frequency stimulation of the VIM, the GPi and both targets simultaneously stimulated. METHODS: Three patients with DT treated by bilateral high frequency DBS of 2 targets (VIM and GPi) were assessed 12 months after surgery in 4 conditions (VIM and GPi-DBS; GPi-DBS only; VIM-DBS only; DBS switched Off for both targets) by 3 independent movement disorders specialists blinded to the condition. RESULTS: The Fahn-Tolosa-Marin-tremor-rating-scale (FTM-TRS) and Burke-Fahn-Marsden-dystonia-rating-scale (BFM-DRS) scores were more improved by combined DBS than VIM alone or GPi alone. Compared to Off/Off condition, mean total FTM-TRS score decrease was 34%, 42% and 63% respectively with VIM only, GPi only and combined VIM and GPi stimulation. Mean total BFM-DRS score decrease was 34%, 37% and 60% respectively with VIM only, GPi only and combined VIM and GPi stimulation, compared to Off/Off condition. Improvement concerned both motor, functional and activities of daily living sub-scores. No complications or adverse events were observed. CONCLUSION: Combined VIM- and GPi-DBS, by modulating the cerebello-thalamo-cortical network and the basal ganglia-thalamo-cortical network, both involved in DT pathophysiology, may be more efficient than single DBS targeting only one of them.

Treatment of Chronic Refractory Pain by Combined Deep Brain Stimulation of the Anterior Cingulum and Sensory Thalamus (EMOPAIN Study): Rationale and Protocol of a Feasibility and Safety Study.

BACKGROUND: Deep Brain Stimulation (DBS) of the sensory thalamus has been proposed for 40 years to treat medically refractory neuropathic pain, but its efficacy remains partial and unpredictable. Recent pilot studies of DBS targeting the ACC, a brain region involved in the integration of the affective, emotional, and cognitive aspects of pain, may improve patients suffering from refractory chronic pain. ACC-DBS could be complementary to thalamic DBS to treat both the sensory-discriminative and the affective components of chronic pain, but the safety of combined DBS, especially on cognition and affects, has not been studied. METHODS: We propose a prospective, randomized, double-blind, and bicentric study to evaluate the feasibility and safety of bilateral ACC-DBS combined with unilateral thalamic DBS in adult patients suffering from chronic unilateral neuropathic pain, refractory to medical treatment. After a study period of six months, there is a cross-over randomized phase to compare the efficacy (evaluated by pain intensity and quality of life) and safety (evaluated by repeated neurological examination, psychiatric assessment, cognitive assessment, and assessment of affective functions) of combined ACC-thalamic DBS and thalamic DBS only, respectively. DISCUSSION: The EMOPAIN study will show if ACC-DBS is a safe and effective therapy for patients suffering from chronic unilateral neuropathic pain, refractory to medical treatment. The design of the study will, for the first time, assess the efficacy of ACC-DBS combined with thalamic DBS in a blinded way.

Rate of Rebleed and Retreatment of Previously Treated Intracranial Aneurysms.

BACKGROUND: Intracranial aneurysms (IAs) can be treated through endovascular treatment (EVT) or microsurgery (MS). Treated IAs can recanalize, which can lead to rupture or retreatment. OBJECTIVE: The aim of our study was to evaluate the natural history of previously treated IA, by evaluating the risk of rupture and the risk of retreatment. METHODS: All patients treated for an IA between 2007 and 2017 in 4 hospitals were included. The rate of (recurrent) hemorrhage and the rate of prophylactic retreatment were retrospectively evaluated. Kaplan-Meier survival analysis with log-rank tests was used to compare the rates of rupture or retreatment. Patients with ruptured and unruptured aneurysms were separated, and we compared the risk of retreatment between EVT and the surgical treatment. RESULTS: A total of 4997 IAs were included in the study, corresponding to 20,489 patient-years. Overall, 28 (0.6%) aneurysms that had been previously treated demonstrated hemorrhage. Moreover, 237 (4.7%) aneurysms were retreated for recanalization without hemorrhage. The rate of retreatment was higher in the EVT-treated IAs as compared with the MS-treated IAs (LogRank: P < 0.0001) and higher in the previously ruptured IAs versus unruptured IAs (LogRank: P < 0.0001). However, the rate of posttreatment hemorrhage/IA rupture was similar for both groups. CONCLUSIONS: The rate of IA retreatment is low; however, the rate of hemorrhage/rupture from treated IAs is even lower. A higher rate of retreatment was noted in EVT-treated IAs versus MS-treated IAs and in ruptured IAs versus unruptured IAs; however, the rate of hemorrhage or rerupture was comparable between the groups.

Long-Term Efficacy of Occipital Nerve Stimulation for Medically Intractable Cluster Headache.

BACKGROUND: Occipital nerve stimulation (ONS) has been proposed to treat refractory chronic cluster headache (rCCH) but its efficacy has only been showed in small short-term series. OBJECTIVE: To evaluate ONS long-term efficacy in rCCH. METHODS: We studied 105 patients with rCCH, treated by ONS within a multicenter ONS prospective registry. Efficacy was evaluated by frequency, intensity of pain attacks, quality of life (QoL) EuroQol 5 dimensions (EQ5D), functional (Headache Impact Test-6, Migraine Disability Assessment) and emotional (Hospital Anxiety Depression Scale [HAD]) impacts, and medication consumption. RESULTS: At last follow-up (mean 43.8 mo), attack frequency was reduced >50% in 69% of the patients. Mean weekly attack frequency decreased from 22.5 at baseline to 9.9 (P < .001) after ONS. Preventive and abortive medications were significantly decreased. Functional impact, anxiety, and QoL significantly improved after ONS. In excellent responders (59% of the patients), attack frequency decreased by 80% and QoL (EQ5D visual analog scale) dramatically improved from 37.8/100 to 73.2/100. When comparing baseline and 1-yr and last follow-up outcomes, efficacy was sustained over time. In multivariable analysis, low preoperative HAD-depression score was correlated to a higher risk of ONS failure. During the follow-up, 67 patients experienced at least one complication, 29 requiring an additional surgery: infection (6%), lead migration (12%) or fracture (4.5%), hardware dysfunction (8.2%), and local pain (20%). CONCLUSION: Our results showed that long-term efficacy of ONS in CCH was maintained over time. In responders, ONS induced a major reduction of functional and emotional headache-related impacts and a dramatic improvement of QoL. These results obtained in real-life conditions support its use and dissemination in rCCH patients.

Chronic fornix deep brain stimulation in a transgenic Alzheimer's rat model reduces amyloid burden, inflammation, and neuronal loss.

Recent studies have suggested deep brain stimulation (DBS) as a promising therapy in patients with Alzheimer's disease (AD). Particularly, the stimulation of the forniceal area was found to slow down the cognitive decline of some AD patients, but the biochemical and anatomical modifications underlying these effects remain poorly understood. We evaluated the effects of chronic forniceal stimulation on amyloid burden, inflammation, and neuronal loss in a transgenic Alzheimer rat model TgF344-AD, as well as in age-matched control rats. 18-month-old rats were surgically implanted with electrodes in stereotactic conditions and connected to a portable microstimulator for chronic DBS in freely moving rats. The stimulation was continuous during 5 weeks and animals were immediately sacrificed for immunohistochemical analysis of pathological markers. Implanted, but non-stimulated rats were used as controls. We found that chronic forniceal DBS in the Tg-AD rat significantly reduces amyloid deposition in the hippocampus and cortex, decreases astrogliosis and microglial activation and lowers neuronal loss, as determined by NeuN staining. In control animals, the stimulation neither affects neuroinflammation nor neuronal count. In the Tg-F344-AD rat model, 5 weeks of forniceal DBS decreased amyloidosis, inflammatory responses, and neuronal loss in both cortex and hippocampus. These findings strongly suggest a neuroprotective effect of DBS and support the beneficial effects of targeting the fornix in Alzheimer's disease patients.