Cordotomy under general anesthesia for a pediatric palliative patient: illustrative case.

BACKGROUND: Computed tomography (CT)-guided cordotomy has been shown to be a safe and effective method for treating cancer pain in adults in a palliative care setting. Its effectiveness has been rarely reported in children. During cordotomy, patient feedback is considered essential. Unfortunately, in this report, the featured patient's age and demeanor precluded an awake cordotomy. The authors report the first case, to their knowledge, of percutaneous cordotomy with the patient under general anesthesia. OBSERVATIONS: An 11-year-old boy with osteosarcoma of the right pelvis presented with medically refractory unilateral nociceptive pain. The pain prevented ambulation, interfered with sleep, was the focus of his concern, and could not be relieved without sedation. A left percutaneous CT-guided cervical cordotomy while he was under general anesthesia was performed without complication and provided sufficient pain relief to allow ambulation and restorative sleep. Pain was no longer an issue for the patient and his family. LESSONS: CT-guided percutaneous cervical cordotomy can be accomplished in a pediatric patient under general anesthesia. The risks of cordotomy under general anesthesia without patient feedback must be weighed against the opportunity to improve palliative care. https://thejns.org/doi/abs/10.3171/CASE2427.

Bilateral Anterior Capsulotomy for Treatment-Resistant Obsessive-Compulsive Disorder.

INTRODUCTION: Ablative surgery is an intervention of last resort for treatment-resistant obsessive-compulsive disorder (TROCD). Our center has been using bilateral anterior capsulotomy (BAC) for the past 20 years for patients eligible for limbic surgery. This report details our experience with BAC for TROCD. METHOD: Five patients with OCD met eligibility criteria for BAC. Entry protocols were complex and took around 6 months to complete. Stereotactic radiofrequency was used to produce the capsulotomies. Lesion length varied between 5.7 and 16.9 mm in the coronal plane. Patients were followed between 4 and 20 years. RESULTS: All 5 patients (100%) were responders as defined by the widely accepted criteria of a reduction of ≥35% in Yale-Brown Obsessive Compulsive Scale (YBOCS) score at 18-month follow-up. Four patients remained responders at the 48 months. One patient was lost to follow-up. Responder status when viewed from the perspective of the YBOCS was sustained over the 4- to 20-year follow-up with one relapse 19 years postsurgery when medications were discontinued. Real-world psychiatric outcomes were different as other vulnerabilities surfaced illustrating the multifactorial determinants of mental health. No patient had any significant long-term neurocognitive or physical side effects. CONCLUSION: BAC should remain an option of last resort for patients with severe OCD who remain unresponsive to all other interventions.

Ventral targeted anterior capsulotomy for treatment-resistant depression and obsessive-compulsive disorder: A treatment method with cases.

BACKGROUND: Ablative surgery using bilateral anterior capsulotomy (BAC) is an option for treatment resistant depression (TRD) and obsessive-compulsive disorder (TROCD). The location and extent of the lesion within anterior limb of the internal capsule (ALIC) remains uncertain. Accumulating evidence has suggested that the lesion should be located ventrally while limiting the dorsal extent. Our center is now targeting specific fiber tracts within the lower half of the ALIC. METHOD: Presurgical diffusion tensor Magnetic Resonance Imaging (MRI) was used to identify individual fibre tracts within the ventral aspect of the ALIC in the last two patients who underwent BAC at our center. One patient had TRD and the other had both TROCD and TRD. Radiofrequency-induced thermal lesions were created in the identified targets with lesion volumes between 20 and 229 mm3 (average 95 mm3). FINDINGS: Both patients were responders with neither experiencing significant side effects including compromised executive functions. LIMITATIONS: The generalizability of our findings is limited because the outcome is based on two subjects. CONCLUSION: This work suggests that BAC can be individually tailored and more limited to the ventral aspect of the ALIC and is effective and safe for TRD and TROCD. Accumulating data also suggests that to be clinically effective the length of the capsulotomy should be about 10mm. BAC's use may increase with the growing utilization and mastery of magnetic resonance guided focused ultrasound.

Mapping the Landscape of Equitable Access to Advanced Neurotechnologies in Canada.

Geographic, social, political, and economic factors shape access to advanced neurotechnologies, yet little previous research has explored the barriers, enablers, and areas of opportunity for equitable and meaningful access for diverse patient communities across Canada. We applied a mixed-mode approach involving semi-structured interviews and rating scale questions to consult with 24 medical experts who are involved in the care of patients who undergo functional neurosurgery targeting the brain. Seven major themes emerged from the qualitative analysis: Health care system, Neurotechnology features, Patient demographics, Target condition features, Ethics, Upstream barriers and enablers, and Areas of opportunity. Descriptive statistics of the Likert-scale responses suggest that interviewees perceive a disparity between the imperative of access to advanced neurotechnologies for people living in rural and remote areas and the likelihood of achieving such access. The results depict a complex picture of access to functional neurosurgery in Canada with pockets of excellence and a motivation to improve the availability of care for vulnerable populations through the expansion of distributed care models, improved health care system efficiencies, increasing funding and support for patient travel, and increasing awareness about and advocacy for advanced neurotechnologies.

The Location of the Parasympathetic Fibres within the Vagus Nerve Rootlets: A Case Report and a Review of the Literature.

The vagus nerve has motor, sensory, and parasympathetic components. Understanding the nerve's internal anatomy, its variations, and relationship to the glossopharyngeal nerve are crucial for neurosurgeons decompressing the lower cranial nerves. We present a case report demonstrating the location of the parasympathetic fibres within the vagus nerve rootlets. A 47-year-old woman presented with a 1-year history of medically refractory left-sided glossopharyngeal neuralgia and a more recent history of left-sided hemi-laryngopharyngeal spasm. magnetic resonance imaging showed her left posterior inferior cerebellar artery distorting the lower cranial nerves on the affected left side. The patient consented to microvascular decompression of the lower cranial nerves with possible sectioning of the glossopharyngeal and upper sensory rootlets of the vagus nerve. During surgery, electrical stimulation of the most caudal rootlet of the vagus nerve triggered profound bradycardia. None of the more rostral rootlets had a similar parasympathetic response. This case is the first demonstration, to our knowledge, of the location of the cardiac parasympathetic fibres within the human vagus nerve rootlets. This new understanding of the vagus nerve rootlets' distribution of pure sensory (most rostral), motor/sensory (more caudal), and parasympathetic (most caudal) fibres may lead to a better understanding and diagnosis of the vagal rhizopathies. Approximately 20% of patients with glossopharyngeal neuralgia also have paroxysmal cough. This could be due to the anatomical juxtaposition of the IXth cranial nerve with the rostral vagal rootlets with pure sensory fibres (which mediate a tickling sensation in the lungs). A subgroup of patients with glossopharyngeal neuralgia have neuralgia-induced syncope. The cause of this rare condition, "vago-glossopharyngeal neuralgia," has been debated since it was first described by Riley in 1942. Our case supports the theory that this neuralgia-induced bradycardia is reflexively mediated through the brainstem with afferent impulses in the IXth and efferent impulses in the Xth cranial nerve. The rarer co-occurrence of glossopharyngeal neuralgia with hemi-laryngopharyngeal spasm (as seen in this case) may be explained by the proximity of the IXth nerve with the more caudal vagus rootlets which have motor (and probably sensory) supply to the throat. Finally, if there is a vagal rhizopathy related to compression of its parasympathetic fibres, one would expect it to be at the most caudal rootlet of the vagus nerve.

Ablation Surgeries for Treatment-Resistant Depression: A Meta-Analysis and Systematic Review of Reported Case Series.

BACKGROUND AND OBJECTIVES: Ablative lesion procedures remain as the last option in treatment of refractory depression. Contemporary ablative psychosurgeries involve producing lesions in the anterior limb of the internal capsule (bilateral anterior capsulotomy - BAC), the supragenual anterior cingulate gyrus and cingulum (bilateral anterior cingulotomy - BACING), and subgenual anterior cingulate gyrus and subcortical orbitofrontal white matter (bilateral subcaudate tractotomy - BST). A combination of BACING and BST is known as limbic leukotomy (bilateral limbic leukotomy - BLL). All procedures claim some success, but cohorts are small, depression assessment instruments differ, and inclusion and outcome criteria and follow-up duration vary. In some cohorts, more than one type of surgery was performed in several patients, further confounding interpreting the available data. Current evidence is equivocal on which surgical target works best. Method and Aim: This systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standard on published cohorts was conducted to review and identify which is the best standalone ablative procedure for treatment-resistant depression (TRD) based on response rate (event rate) and adverse-effect profile using the Comprehensive Meta-Analysis software. RESULTS AND CONCLUSION: As a standalone neurosurgical procedure, we found that BAC appears to be the most effective and safest of all the ablative targets for TRD. A major limitation of this conclusion is the paucity of published case series where sample sizes are small and all are open label.

Sweet spots of standard and directional leads in patients with refractory essential tremor: white matter pathways associated with maximal tremor improvement.

OBJECTIVE: In patients with essential tremor (ET) treated with standard deep brain stimulation (sDBS) whose ET had progressed and who no longer received optimal benefit from sDBS, directional deep brain stimulation (dDBS) may provide better tremor control. Current steering may provide better coverage of subcortical structures related to tremor control in patients with ET and significant progression without optimal response to sDBS. METHODS: This study included 6 patients with ET initially treated with sDBS whose tremor later progressed and who then underwent reimplantation with dDBS to optimize their tremor control. To investigate the differences in the local effects of sDBS and dDBS, the authors generated the volume of tissue activation (VTA) to calculate the sweet spots associated with the best possible tremor control with no side effects. Then, to investigate the anatomical structures associated with maximal tremor control, the white matter pathways of the posterior subthalamic areas (PSAs) were generated and their involvement with the sDBS and dDBS sweet spots was calculated. RESULTS: Tremor improvement was significantly better with dDBS (68.4%) than with sDBS (48.7%) (p = 0.017). The sDBS sweet spot was located within the ventral intermediate nucleus, whereas the sweet spot of the dDBS was mainly located within the PSA. The sweet spots of both sDBS and dDBS involved a similar portion of the cerebellothalamic pathway. However, the dDBS had greater involvement of the pallidofugal pathways than the sDBS. CONCLUSIONS: In patients with ET treated with sDBS who later had ET progression, dDBS provided better tremor control, which was related to directionality and a more ventral position. The involvement of both the cerebellothalamic and pallidofugal pathways obtained with dDBS is associated with additional improvement over the sDBS.

Tractography-Guided Anterior Capsulotomy for Major Depression and Obsessive-Compulsive Disorder: Targeting the Emotion Network.

BACKGROUND: Bilateral anterior capsulotomy (BAC) is an effective surgical option for patients with treatment-resistant major depression (TRMD) and treatment-resistant obsessive-compulsive disorder (TROCD). The size of the lesion and its precise dorsal-ventral location within the anterior limb of the internal capsule (ALIC) remain undefined. OBJECTIVE: To present a method to identify the trajectories of the associative and limbic white matter pathways within the ALIC for targeting in BAC surgery. METHODS: Using high-definition tractography, we prospectively tested the feasibility of this method in 2 patients with TRMD and TROCD to tailor the capsulotomy lesion to their limbic pathway. RESULTS: The trajectories of the associative and limbic pathways were identified in the ALIC of both patients and we targeted the limbic pathways by defining the dorsal limit of the lesion in a way to minimize the damage to the associative pathways. The final lesions were smaller than those that have been previously published. This individualized procedure was associated with long-term benefit in both patients. CONCLUSION: Tractography-guided capsulotomy is feasible and was associated with long-term benefit in patients with TRMD and TROCD.

Tremor and Quality of Life in Patients With Advanced Essential Tremor Before and After Replacing Their Standard Deep Brain Stimulation With a Directional System.

OBJECTIVES: Patients with essential tremor treated with thalamic deep brain stimulation may experience increased tremor with the progression of their disease. Initially, this can be counteracted with increased stimulation. Eventually, this may cause unwanted side-effects as the circumferential stimulation from a standard ring contact spreads into adjacent regions. Directional leads may offer a solution to this clinical problem. We aimed to compare the ability of a standard and a directional system to reduce tremor without side-effects and to improve the quality of life for patients with advanced essential tremor. MATERIALS AND METHODS: Six advanced essential tremor patients with bilateral thalamic deep brain stimulation had their standard system replaced with a directional system. Tremor rating scale scores were prospectively evaluated before and after the replacement surgery. Secondary analyses of quality of life related to tremor, voice, and general health were assessed. RESULTS: There was a significantly greater reduction in tremor without side-effects (p = 0.017) when using the directional system. There were improvements in tremor (p = 0.031) and voice (p = 0.037) related quality of life but not in general health for patients using optimized stimulation settings with the directional system compared to the standard system. CONCLUSIONS: In this cohort of advanced essential tremor patients who no longer had ideal tremor reduction with a standard system, replacing their deep brain stimulation with a directional system significantly improved their tremor and quality of life. Up-front implantation of directional deep brain stimulation leads may provide better tremor control in those patients who progress at a later time point.

Hemi-laryngopharyngeal Spasm (HeLPS): Defining a New Clinical Entity.

OBJECTIVE: Hemi-laryngopharyngeal spasm (HeLPS) has recently been described in the neurosurgical literature as a cause of intermittent laryngopharyngeal spasm and cough due to vascular compression of the vagus nerve at the cerebellopontine angle. We present the diagnostic criteria for this syndrome. METHODS: A retrospective chart review of six patients with HeLPS and three patients misdiagnosed with this condition are presented. All patients were diagnosed and treated at a tertiary care academic centre from July 2013 to July 2017. RESULTS: Patients with HeLPS had five defining characteristics: 1) All patients had symptoms of episodic laryngopharyngeal spasm and coughing. Patients were asymptomatic between episodes and were refractory to speech therapy and reflux management. 2) Laryngoscopy showed hyperactive twitching of the ipsilateral vocal fold in two of the six patients. No other inter-episodic abnormalities were seen. 3) Botulinum toxin A injections into the thyroarytenoid muscle on the affected ipsilateral side reduced laryngopharyngeal spasms. Botulinum toxin injection in the contralateral thyroarytenoid muscle did not improve laryngopharyngeal spasm. 4) Magnetic resonance imaging revealed ipsilateral neurovascular compression of the vagus nerve rootlets by the posterior inferior cerebellar artery. 5) Microvascular decompression (MVD) surgery of the ipsilateral vagus nerve resolved all symptoms (follow-up 2-4 years). CONCLUSION: The diagnostic criteria for hemi-laryngopharyngeal spasm (HeLPS) are proposed. Otolaryngology recognition of this new clinical entity may lead to a surgical cure and avoid the unnecessary therapies associated with misdiagnosis. LEVEL OF EVIDENCE: 4.

Concurrent Glossopharyngeal Neuralgia and Hemi-Laryngopharyngeal Spasm (HeLPS): A Case Report and a Review of the Literature.

BACKGROUND AND IMPORTANCE: Hemi-laryngopharyngeal spasm (HeLPS) has been recently described but is not yet widely recognized. Patients describe intermittent coughing and choking and can be cured following microvascular decompression of their Xth cranial nerve. This case report and literature review highlight that HeLPS can co-occur with glossopharyngeal neuralgia (GN) and has been previously described (but not recognized) in the neurosurgical literature. CLINICAL PRESENTATION: A patient with GN and additional symptoms compatible with HeLPS is presented. The patient reported left-sided, intermittent, swallow-induced, severe electrical pain radiating from her ear to her throat (GN). She also reported intermittent severe coughing, throat contractions causing a sense of suffocation, and dysphonia (HeLPS). All her symptoms resolved following a left microvascular decompression of a loop of the posterior inferior cerebellar artery that was pulsating against both the IXth and Xth cranial nerves. A review of the senior author's database revealed another patient with this combination of symptoms. An international literature review found 27 patients have been previously described with symptoms of GN and the additional (but not recognized at the time) symptoms of HeLPS. CONCLUSION: This review highlights that patients with symptoms compatible with HeLPS have been reported since 1926 in at least 4 languages. This additional evidence supports the growing recognition that HeLPS is another neurovascular compression syndrome. Patients with HeLPS continue to be misdiagnosed as conversion disorder. The increased recognition of this new medical condition will require neurosurgical treatment and should alleviate the suffering of these patients.

Vagus Associated Neurogenic Cough Occurring Due to Unilateral Vascular Encroachment of Its Root: A Case Report and Proof of Concept of VANCOUVER Syndrome.

OBJECTIVES: A patient is presented with neurogenic cough due to a unilateral vascular compression of a vagus nerve rootlet at the brainstem with complete resolution of cough following microvascular decompression of that nerve. This etiology of a neurogenic cough has not been previously reported to our knowledge. The proportion of patients with neurogenic cough refractory to all current therapies and suffering with this treatable condition remains to be defined. We introduce the concept of Vagus Associated Neurogenic Cough Occurring due to Unilateral Vascular Encroachment of its Root (VANCOUVER syndrome) and present the salient features of this condition. METHODS: A case review is presented with details of the patient's history, examination, imaging, laryngoscopy, intraoperative findings, and long-term clinical outcome. RESULTS: A 60-year-old man presented with a 15-year history of non-productive cough refractory to antibiotics, and anti-reflux medications. Investigations by an allergist, a cardiologist, a gastroenterologist, two pulmonologists, and an otolaryngologist were negative. MRI demonstrated a vascular compression of his left vagus nerve and microvascular decompression of that nerve resolved his symptoms. There were no surgical complications and the patient remains asymptomatic at 1 year. CONCLUSIONS: Neurogenic cough has been likened to a vagus nerve neuropathy in a similar way that trigeminal neuralgia is a trigeminal nerve neuropathy. Both cause intermittent sensory phenomena in their distribution and can be ameliorated with neuropathic medications. We demonstrate that neurogenic cough, like trigeminal neuralgia, may be caused by a vascular compression of its nerve root. A proposed mechanism of this type of neurogenic cough is presented along with a potential diagnostic paradigm for these patients.

Hypoactivity in the Paraterminal Gyrus Following Bilateral Anterior Capsulotomy.

OBJECTIVE: Bilateral anterior capsulotomy (BAC) is one of the ablative neurosurgical procedures used to treat major depressive disorder or obsessive-compulsive disorder when all other therapies fail. Tristolysis, a reduction in sadness, is the most striking clinical effect of BAC and is seen in the first 1 to 2 weeks after surgery. This retrospective study measured regional cerebral blood flow (rCBF) following surgery to identify which cortical regions were impacted and could account for this clinical effect. METHODS: All patients had their capsulotomies done in Vancouver by the same team. Pre- and postoperative single-photon emission computed tomography perfusion scans were analyzed for 10 patients with major depressive disorder and 3 with obsessive-compulsive disorder. rCBF was measured semiquantitatively by calculating the ratio between an identified region of interest and a whole brain reference area. RESULTS: Decreased rCBF was found in the paraterminal gyri. Increased rCBF was found in the dorsolateral prefrontal cortices and in the left lateral temporal lobe. CONCLUSIONS: BAC causes hypoactivity in the paraterminal gyri and is the most likely explanation for its tristolytic effect, suggesting that the paraterminal gyrus is the limbic cortical locus for the emotion of sadness. Increased activity in the dorsolateral prefrontal cortices may be occurring via connectional diaschisis, and suppression by overactive paraterminal gyri during depression may account for some of the neurocognitive deficits observed during depressive episodes.

An Analysis of Clinical Outcome and Tractography following Bilateral Anterior Capsulotomy for Depression.

INTRODUCTION: Bilateral anterior capsulotomy (BAC) is an effective surgical procedure for patients with treatment-resistant major depression (TRMD). In this work, we analyze the connectivity of the BAC lesions to identify connectivity "fingerprints" associated with clinical outcomes in patients with TRMD. METHODS: We performed a retrospective study of ten patients following BAC surgery. These patients were divided into "responders" and "non-responders" based on the relative change in the Beck depression inventory (BDI) score after surgery. We generated the dorsolateral prefrontal associative (DLPFC) pathways and the ventromedial prefrontal limbic (vmPFC) pathways going through the anterior limb of the internal capsule and analyzed if the overlap of the BAC lesions with these pathways was associated with either outcome. Finally, we used the BAC lesions of our patients to generate group-averaged connectivity "fingerprints" associated with either outcome. RESULTS: Six patients were responders (≥50% improvement in BDI), four patients were non-responders (<50% improvement). No significant impairments were found in most neuropsychological tests after surgery. The overlap analysis showed that in the responder group, there was less involvement of the DLPFC pathways than the vmPFC pathways (p = 0.001). Conversely, in the non-responder group, there was no significant difference between the involvement of both pathways (p = 0.157). The responder and non-responder connectivity fingerprint showed significant connections with the vmPFC limbic areas. However, the non-responder connectivity fingerprint also showed stronger connectivity to associative areas including the DLPFC and lateral orbitofrontal cortices. CONCLUSIONS: The optimum outcome following BAC surgery in this cohort was associated with interruption of vmPFC pathways and the relative preservation of DLPFC pathways.

Defining the Anatomy of the Vagus Nerve and Its Clinical Relevance for the Neurosurgical Treatment of Glossopharyngeal Neuralgia.

The neurosurgical treatment of glossopharyngeal neuralgia includes microvascular decompression or rhizotomy of the nerve. When considering open section of the glossopharyngeal nerve, numerous authors have recommended additional sectioning of the 'upper rootlets' of the vagus nerve because these fibers can occasionally carry the pain fibers causing the patient's symptoms. Sacrifice of vagus nerve rootlets, however, carries the potential risk of dysphagia and dysphonia. In this study, the anatomy and physiology of the vagus nerve rootlets are characterized to provide guidance for surgical decision-making. Twelve patients who underwent posterior fossa craniotomy with intraoperative electrophysiological monitoring of the vagus nerve rootlets were included in this study. In the 7 patients with glossopharyngeal neuralgia, the clinical outcomes and complications were further analyzed. In half of the patients, electrophysiological data demonstrated pure sensory function in the rostral rootlet(s) of the vagus nerve and motor responses in its caudal rootlets. This orientation of the vagus nerve, with some pure sensory function in its most rostral rootlet(s), was defined as Type A. In the other half of patients, all vagus nerve rootlets (including the most rostral) had motor responses. This was defined as Type B. The surgical strategy was guided by whether the patient had a Type A or Type B vagus nerve. For those with Type B, no vagus nerve rootlets were sacrificed. None of the patients with glossopharyngeal neuralgia developed any permanent neurological deficits. We recommend intraoperative electrophysiological testing of the vagus nerve rootlets. If the testing reveals motor innervation in the rostral vagal rootlet (Type B), that rootlet may be decompressed but should not be sectioned to avoid a motor complication. Patients with pure sensory innervation of the rostral rootlet(s) (Type A) can have decompression or section of those rootlets without complication.

Somatotopic organization of the human spinothalamic tract: in vivo computed tomography-guided mapping in awake patients undergoing cordotomy.

OBJECTIVEThe location of the human spinothalamic tract (STT) in the anterolateral spinal cord has been known for more than a century. The exact nature of the neuronal fiber lamination within the STT, however, remains controversial. After correlating in vivo macrostimulation-induced pain/temperature sensation during percutaneous cervical cordotomy with simultaneous CT imaging of the electrode tip location, the authors present a modern description of the somatotopy of the human cervical STT.METHODSTwenty patients underwent CT-guided percutaneous cervical cordotomy to alleviate contralateral medication-refractory cancer pain. Patient responses to electrical stimulation (0.01-0.1 V, 50 Hz, 1 msec) were recorded and the electrode location for each response was documented with a contemporaneous CT scan. In a post hoc analysis of the data, the location for each patient's response(s) was measured and drawn on a diagram of their cord. Positive responses were represented only when the lowest possible voltage (≤ 0.02 V) elicited a response. Negative responses were recorded if there was no clinical response at 0.1 V.RESULTSClinically, patients did well with an average reduction in opiates of 75% at 1 week, and 67% were able to leave the palliative care unit. The size of the cervical cord varied between patients, with an average lateral extent (width) of 11 mm and a height of 9 mm. Responses from the lower limb were represented superficially (lateral) and posteriorly within the anterolateral cord. The area with responses from the upper limb was larger and surrounded those with responses from the lower limb primarily anteriorly and medially, but also posteriorly.CONCLUSIONSIn this study, the somatotopic organization of the human STT was elucidated for the first time using in vivo macrostimulation and contemporaneous CT imaging during cordotomy. In this cohort of patients, the STT from the lower-limb region was located superficially and posteriorly in the anterolateral quadrant of the cervical cord, with the STT from the upper-limb region surrounding it primarily anteriorly and medially (deep) but also posteriorly. The authors discuss how the previous methods of cordotomy may have biased the earlier versions of STT lamination. They suggest that an ideal spinal cord entry site for cordotomy of either the upper- or lower-limb pain fibers is halfway between the equator and anterior pole of the cord.

Canadian Assessment of Deep Brain Stimulation Access: The Canada Study.

BACKGROUND: The Canada Health Act requires reasonable access to all medically necessary therapies. No information is available to assess the current access to neuromodulation across Canada. This study quantifies the current rate of deep brain stimulation (DBS) for the entire country of Canada. Analyses were performed to determine whether there were differences in access based on provincial or territorial location, rural or non-rural region, or socioeconomic status. METHODS: All implanted DBS devices in Canada over a 2-year epoch (January 2015 to December 2016) were supplied by either Boston Scientific or Medtronic. Investigators received anonymized data from these companies, including patient age and home residence region. The 2016 Statistics Canada census data were used to determine the rate of DBS surgery and whether access was related to provincial location, rural versus non-rural region or socioeconomic status. RESULTS: A total of 722 patients were studied. The rate of DBS surgery for the entire country was ten per million population per year. Saskatchewan was significantly above (374%) the national average, whereas Quebec (40%) and Newfoundland & Labrador (32%) were significantly below the national average. No patients from the three territories received DBS. There were no significant differences in access from rural versus non-rural areas or in regions within provinces with different socioeconomic status. CONCLUSIONS: This is the first study to quantify all patients receiving DBS within an entire country. The current rate of DBS surgery within Canada is ten cases per million per year. Statistically significant regional differences were discovered and discussed.

Subcallosal cingulate deep brain stimulation for treatment-resistant depression: a multisite, randomised, sham-controlled trial.

BACKGROUND: Deep brain stimulation (DBS) of the subcallosal cingulate white matter has shown promise as an intervention for patients with chronic, unremitting depression. To test the safety and efficacy of DBS for treatment-resistant depression, a prospective, randomised, sham-controlled trial was conducted. METHODS: Participants with treatment-resistant depression were implanted with a DBS system targeting bilateral subcallosal cingulate white matter and randomised to 6 months of active or sham DBS, followed by 6 months of open-label subcallosal cingulate DBS. Randomisation was computer generated with a block size of three at each site before the site started the study. The primary outcome was frequency of response (defined as a 40% or greater reduction in depression severity from baseline) averaged over months 4-6 of the double-blind phase. A futility analysis was performed when approximately half of the proposed sample received DBS implantation and completed the double-blind phase. At the conclusion of the 12-month study, a subset of patients were followed up for up to 24 months. The study is registered at ClinicalTrials.gov, number NCT00617162. FINDINGS: Before the futility analysis, 90 participants were randomly assigned to active (n=60) or sham (n=30) stimulation between April 10, 2008, and Nov 21, 2012. Both groups showed improvement, but there was no statistically significant difference in response during the double-blind, sham-controlled phase (12 [20%] patients in the stimulation group vs five [17%] patients in the control group). 28 patients experienced 40 serious adverse events; eight of these (in seven patients) were deemed to be related to the study device or surgery. INTERPRETATION: This study confirmed the safety and feasibility of subcallosal cingulate DBS as a treatment for treatment-resistant depression but did not show statistically significant antidepressant efficacy in a 6-month double-blind, sham-controlled trial. Future studies are needed to investigate factors such as clinical features or electrode placement that might improve efficacy. FUNDING: Abbott (previously St Jude Medical).

Establishing a Standard of Care for Deep Brain Stimulation Centers in Canada.

During the "DBS Canada Day" symposium held in Toronto July 4-5, 2014, the scientific committee invited experts to share their knowledge regarding deep brain stimulation (DBS) management of movement disorders in three domains: (1) the programming algorithms, (2) the necessary team to run a neurosurgery program, and (3) the appropriate scales to better define in a more comprehensive fashion the effect of the brain surgery. Each presentation was followed by an open discussion, and this article reports on the conclusions of this meeting on these three questions. Concerning programming, the role of the pulse width and the switching off of the stimulation at night for thalamic stimulation for the control of tremor have been discussed. The algorithms proposed in the literature for programming in Parkinson's disease (PD) need validation. In dystonia, the use of monopolar vs bipolar parameters, the use of low vs high frequencies and the use of smaller versus larger pulse widths all need to be examined properly. Concerning the necessary team to run a neurosurgical program, recommendations will follow the suggestions for standardized outcome measures. Regarding the outcome measures for DBS in PD, investigations need to focus on the non-motor aspects of PD. Identifying which nonmotor symptoms respond to DBS would allow a better screening before and satisfaction postoperatively. There is an important need for more data to determine the optimal programming protocol and the standard measures that should be performed routinely by all centers.

Deep Brain Stimulation Target Selection for Parkinson's Disease.

During the "DBS Canada Day" symposium held in Toronto July 4-5, 2014, the scientific committee invited experts to discuss three main questions on target selection for deep brain stimulation (DBS) of patients with Parkinson's disease (PD). First, is the subthalamic nucleus (STN) or the globus pallidus internus (GPi) the ideal target? In summary, both targets are equally effective in improving the motor symptoms of PD. STN allows a greater medications reduction, while GPi exerts a direct antidyskinetic effect. Second, are there further potential targets? Ventral intermediate nucleus DBS has significant long-term benefit for tremor control but insufficiently addresses other motor features of PD. DBS in the posterior subthalamic area also reduces tremor. The pedunculopontine nucleus remains an investigational target. Third, should DBS for PD be performed unilaterally, bilaterally or staged? Unilateral STN DBS can be proposed to asymmetric patients. There is no evidence that a staged bilateral approach reduces the incidence of DBS-related adverse events.