CNS demyelination associated with immune dysregulation and a novel CTLA-4 variant.

BACKGROUND: The cytotoxic T-lymphocyte antigen-4 (CTLA-4) pathway acts as a negative immune regulator of T-cell activation and promotes self-tolerance. CASE: We report the first case of biopsy-proven central nervous system inflammatory demyelination in the context of primary immunodeficiency and a novel CTLA-4 variant. CONCLUSION: This case has significant implications for the development of novel treatments for autoimmune conditions including multiple sclerosis and further emphasises the need for caution with clinical use of CTLA-4 immune checkpoint inhibitors in those with a history of inflammatory demyelination.

Multicentre, clinical trial of burst spinal cord stimulation for neck and upper limb pain NU-BURST: a trial protocol.

BACKGROUND: Spinal cord stimulation (SCS) is an established therapy for chronic neuropathic pain and most frequently utilised for Failed Back Surgery Syndrome (FBSS). BurstDR™ also known as DeRidder Burst-SCS, a novel waveform, has demonstrated superiority to conventional tonic stimulation of the thoracic spine in FBSS. There are case reports of an improvement in multidimensional pain outcomes using DeRidder Burst-SCS in the cervical spine for chronic neck and cervical radicular pain. The safety and efficacy of cervical DeRidder Burst-SCS stimulation still however remain undetermined. METHODS/DESIGN: This is a prospective, multicentre feasibility trial evaluating the safety and therapeutic efficacy of DeRidder Burst-SCS stimulation for the treatment of chronic intractable neck pain with or without radiation to the arm, shoulder, and upper back. After baseline evaluation, subjects will undergo an SCS trial using the Abbott Invisible Trial system according to standard clinical procedures. During the trial phase, SCS leads will be implanted in the cervical epidural space. At the end of the SCS trial, subjects experiencing at least 50% pain relief will be considered for permanent implant. Pain intensity, medication usage, and other multidimensional pain outcomes will be collected. The timing of these will be at baseline, end of the SCS trial and at 3-, 6-, and 12-month visits. Incidence of adverse events will be collected throughout the study duration. DISCUSSION: The results of this feasibility study will validate the efficacy and safety of DeRidder Burst-SCS stimulation in the cervical spine. The results obtained in this study will potentially be used to generate a level 1 evidence-based study with formal statistical hypotheses testing. TRIAL REGISTRATION: www.clinicaltrials.gov Identifier: NCT03159169.

The Neuromodulation Appropriateness Consensus Committee on Best Practices for Dorsal Root Ganglion Stimulation.

INTRODUCTION: The Neuromodulation Appropriateness Consensus Committee (NACC) is dedicated to improving the safety and efficacy of neuromodulation and thus improving the lives of patients undergoing neuromodulation therapies. With continued innovations in neuromodulation comes the need for evolving reviews of best practices. Dorsal root ganglion (DRG) stimulation has significantly improved the treatment of complex regional pain syndrome (CRPS), among other conditions. Through funding and organizational leadership by the International Neuromodulation Society (INS), the NACC reconvened to develop the best practices consensus document for the selection, implantation and use of DRG stimulation for the treatment of chronic pain syndromes. METHODS: The NACC performed a comprehensive literature search of articles about DRG published from 1995 through June, 2017. A total of 2538 article abstracts were then reviewed, and selected articles graded for strength of evidence based on scoring criteria established by the US Preventive Services Task Force. Graded evidence was considered along with clinical experience to create the best practices consensus and recommendations. RESULTS: The NACC achieved consensus based on peer-reviewed literature and experience to create consensus points to improve patient selection, guide surgical methods, improve post-operative care, and make recommendations for management of patients treated with DRG stimulation. CONCLUSION: The NACC recommendations are intended to improve patient care in the use of this evolving therapy for chronic pain. Clinicians who choose to follow these recommendations may improve outcomes.

Effects of Rate on Analgesia in Kilohertz Frequency Spinal Cord Stimulation: Results of the PROCO Randomized Controlled Trial.

OBJECTIVE: The PROCO RCT is a multicenter, double-blind, crossover, randomized controlled trial (RCT) that investigated the effects of rate on analgesia in kilohertz frequency (1-10 kHz) spinal cord stimulation (SCS). MATERIALS AND METHODS: Patients were implanted with SCS systems and underwent an eight-week search to identify the best location ("sweet spot") of stimulation at 10 kHz within the searched region (T8-T11). An electronic diary (e-diary) prompted patients for pain scores three times per day. Patients who responded to 10 kHz per e-diary numeric rating scale (ED-NRS) pain scores proceeded to double-blind rate randomization. Patients received 1, 4, 7, and 10 kHz SCS at the same sweet spot found for 10 kHz in randomized order (four weeks at each frequency). For each frequency, pulse width and amplitude were titrated to optimize therapy. RESULTS: All frequencies provided equivalent pain relief as measured by ED-NRS (p ≤ 0.002). However, mean charge per second differed across frequencies, with 1 kHz SCS requiring 60-70% less charge than higher frequencies (p ≤ 0.0002). CONCLUSIONS: The PROCO RCT provides Level I evidence for equivalent pain relief from 1 to 10 kHz with appropriate titration of pulse width and amplitude. 1 kHz required significantly less charge than higher frequencies.

Retrospective Case Series on the Treatment of Painful Diabetic Peripheral Neuropathy With Dorsal Root Ganglion Stimulation.

BACKGROUND: The dorsal root ganglion (DRG) has been identified as an important neural structure in the development and maintenance of chronic pain. We present a retrospective case series of patients with refractory painful diabetic peripheral neuropathy (PDPN) that underwent electrical stimulation of the DRG and report on changes in their overall perceived pain and complication rates. METHODS: Ten diabetic males (mean age 65.2 [SD 8.8] years) with painful symptoms of the lower limbs were enrolled and trialed with up to four quadripolar percutaneous DRG stimulation leads between L2 and L5 spinal levels. Patients received a fully implantable neurostimulation system (Abbott Laboratories, Sunnyvale, CA, USA) immediately or after a successful trial period (>50% reduction in pain). Overall perceived pain was measured by visual analogue scale (VAS) at baseline, one-week postimplantation and one-, three-, six-, and twelve-month follow-up (n = 5). RESULTS: Ten patients were included in this retrospective study. Seven of these subjects received permanent stimulator implants after successful externalized or intraoperative trials. Two of those patients subsequently required explantation, due to failure to capture primary pain area (n = 1) and personal reasons (n = 1). For the five subjects that proceeded to clinical follow-ups, baseline VAS was reduced by an average of 63.90% (SD 21.39; p < 0.001) postimplantation. For four patients with available 12-month follow-up data, mean relative reduction in overall perceived pain averaged 64.16% (SD 35.8; p< 0.001). CONCLUSION: Early findings from this small retrospective case series, suggest DRG is a safe and effective neuromodulation modality to improve painful symptoms in PDPN patients. Future prospective trials are required to further investigate the use of DRG stimulation for this clinical indication.

Deep brain stimulation of the periaqueductal gray releases endogenous opioids in humans.

Deep brain stimulation (DBS) of the periaqueductal gray (PAG) is used in the treatment of severe refractory neuropathic pain. We tested the hypothesis that DBS releases endogenous opioids to exert its analgesic effect using [11C]diprenorphine (DPN) positron emission tomography (PET). Patients with de-afferentation pain (phantom limb pain or Anaesthesia Dolorosa (n=5)) who obtained long-lasting analgesic benefit from DBS were recruited. [11C]DPN and [15O]water PET scanning was performed in consecutive sessions; first without, and then with PAG stimulation. The regional cerebral tracer distribution and kinetics were quantified for the whole brain and brainstem. Analysis was performed on a voxel-wise basis using statistical parametric mapping (SPM) and also within brainstem regions of interest and correlated to the DBS-induced improvement in pain score and mood. Brain-wide analysis identified a single cluster of reduced [11C]DPN binding (15.5% reduction) in the caudal, dorsal PAG following DBS from effective electrodes located in rostral dorsal/lateral PAG. There was no evidence for an accompanying focal change in blood flow within the PAG. No correlation was found between the change in PAG [11C]DPN binding and the analgesic effect or the effect on mood (POMSSV) of DBS. The analgesic effect of DBS in these subjects was not altered by systemic administration of the opioid antagonist naloxone (400ug). These findings indicate that DBS of the PAG does indeed release endogenous opioid peptides focally within the midbrain of these neuropathic pain patients but we are unable to further resolve the question of whether this release is responsible for the observed analgesic benefit.

Characterising the Analgesic Effect of Different Targets for Deep Brain Stimulation in Trigeminal Anaesthesia Dolorosa.

BACKGROUND: Several deep brain stimulation (DBS) targets have been explored for the alleviation of trigeminal anaesthesia dolorosa. We aimed to characterise the analgesia produced from the periaqueductal grey (PAG) and centromedian-parafascicular (CmPf) nucleus using a within-subject design. METHOD: We report a case series of 3 subjects implanted with PAG and CmPf DBS systems for the treatment of anaesthesia dolorosa. At follow-up, testing of onset and offset times, magnitude, and thermal and mechanical sensitivity was performed. RESULTS: The mean pain score of the cohort was acutely reduced by 56% (p < 0.05) with PAG and 67% (p < 0.01) with CmPf stimulation at mean time intervals of 38 and 16 min, respectively. The onset time was 12.5 min (p < 0.05) for PAG stimulation and 2.5 min (p < 0.01) for CmPf. The offset time was 2.5 min (p < 0.05) for PAG and 12.5 min (p < 0.01) for CmPf. The two targets were effective at different stimulation frequencies and were not antagonistic in effect. CONCLUSION: The mechanisms by which stimulation at these two targets produces analgesia are likely to be different. Certain pain qualities may respond more favourably to specific targets. Knowledge of onset and offset times for the targets can guide optimisation of stimulation settings. The use of more than one stimulation target may be beneficial and should be considered in anaesthesia dolorosa patients.

Deep brain stimulation for the treatment of resistant hypertension.

Hypertension is a leading risk factor for the development of several cardiovascular diseases. As the global prevalence of hypertension increases, so too has the recognition of resistant hypertension. Whilst figures vary, the proportion of hypertensive patients that are resistant to multiple drug therapies have been reported to be as high as 16.4 %. Resistant hypertension is typically associated with elevated sympathetic activity and abnormal homeostatic reflex control and is termed neurogenic hypertension because of its presumed central autonomic nervous system origin. This resistance to conventional pharmacological treatment has stimulated a plethora of medical devices to be investigated for use in hypertension, with varying degrees of success. In this review, we discuss a new therapy for drug-resistant hypertension, deep brain stimulation. The utility of deep brain stimulation in resistant hypertension was first discovered in patients with concurrent neuropathic pain, where it lowered blood pressure and improved baroreflex sensitivity. The most promising central target for stimulation is the ventrolateral periaqueductal gray, which has been well characterised in animal studies as a control centre for autonomic outflow. In this review, we will discuss the promise and potential mechanisms of deep brain stimulation in the treatment of severe, resistant hypertension.

Microsurgical Resection of Calcified C2 Cavernous Malformation: 2-Dimensional Operative Video.

We present the case of a 58-year-old woman presenting with left upper limb paresthesia and bilateral lower limb spasm who was found to have a likely radiation-induced calcified intramedullary cavernous malformation at the level of C2.1-4 Owing to the symptomatic nature of the lesion with progressive increase in size and associated cord edema on serial imaging, through a lateral approach, the patient underwent a microsurgical left C2-3 hemilaminectomy and medial facetectomy to access the ventral exophytic calcified component.5-7 Debulking and piecemeal resection were performed with the aid of an ultrasonic bone aspirator with "claw" attachment while minimizing any manipulation of neural parenchyma.8-13 Ultimately, near total resection was achieved as a rim of capsule was left densely adherent to the spinal cord. Postoperatively, no new neurologic deficits were noted, and imaging as early as 1 week postoperatively showed significant reduction of cord signal abnormality. The technical considerations for the ultrasonic bone claw and the literature on treatment outcomes for calcified intramedullary spinal cavernous malformations are reviewed. The patient consented to the procedure and to the publication of her images. Institutional review board approval was deemed not necessary because of the retrospective, case report nature of this work.

Novel use of narrow paddle electrodes for occipital nerve stimulation--technical note.

OBJECTIVES: Occipital nerve stimulation (ONS), an established treatment for medically intractable headache syndromes, has lead migration rates quoted up to 24%. In a series of patients with ideal characteristics for this treatment modality, we describe an operative technique for ONS involving the novel use of narrow paddle electrodes: "S8 Lamitrode" (St. Jude Medical [SJM], St. Paul, MN, USA). MATERIALS AND METHODS: Five patients (occipital neuralgia [ON] = 4; chronic migraine [CM] = 1) were treated with ONS between 2010 and 2011. All patients had a successful trial of peripheral neurostimulation (Algotec Ltd, Crawley, UK) therapy. Operative technique involved the use of a park-bench position, allowing simultaneous exposure of the occipital and infraclavicular regions. Through a retromastoid/occipital incision just beneath the external occipital protruberance, exposing the extrafascial plane, the S8 Lamitrode is implanted to intersect both greater occipital nerves for bilateral pain or unilateral greater and lesser occipital nerves for unilateral ON or with significant component of the pain relating to the lesser occipital nerve. RESULTS: Over the median follow-up of 12 months, there were no episodes of lead migration or revision. There also was significant improvement in symptoms in all patients. CONCLUSIONS: This is the first reported use of S8 Lamitrode electrode for ONS. This narrow electrode is suited for this role leading to minimal trauma during surgical placement, facilitates resolution of problems with lead migration, and optimizes effect with stimulation focused more in direction of the occipital nerves without skin involvement. To date, the SJM Genesis neurostimulation system, with percutaneous electrodes only, is CE mark approved in Europe for peripheral nerve stimulation of the occipital nerves for the management of pain and disability for patients diagnosed with intractable CM. Further developments and studies are required for better devices to suit ONS, thereby avoiding frequently encountered problems and which may clarify the role of paddle leads in ONS.

Deep Brain Stimulation of the Anterior Nucleus of the Thalamus in Drug-Resistant Epilepsy in the MORE Multicenter Patient Registry.

BACKGROUND AND OBJECTIVES: The efficacy of deep brain stimulation of the anterior nucleus of the thalamus (ANT DBS) in patients with drug-resistant epilepsy (DRE) was demonstrated in the double-blind Stimulation of the Anterior Nucleus of the Thalamus for Epilepsy randomized controlled trial. The Medtronic Registry for Epilepsy (MORE) aims to understand the safety and longer-term effectiveness of ANT DBS therapy in routine clinical practice. METHODS: MORE is an observational registry collecting prospective and retrospective clinical data. Participants were at least 18 years old, with focal DRE recruited across 25 centers from 13 countries. They were followed for at least 2 years in terms of seizure frequency (SF), responder rate (RR), health-related quality of life (Quality of Life in Epilepsy Inventory 31), depression, and safety outcomes. RESULTS: Of the 191 patients recruited, 170 (mean [SD] age of 35.6 [10.7] years, 43% female) were implanted with DBS therapy and met all eligibility criteria. At baseline, 38% of patients reported cognitive impairment. The median monthly SF decreased by 33.1% from 15.8 at baseline to 8.8 at 2 years (p < 0.0001) with 32.3% RR. In the subgroup of 47 patients who completed 5 years of follow-up, the median monthly SF decreased by 55.1% from 16 at baseline to 7.9 at 5 years (p < 0.0001) with 53.2% RR. High-volume centers (>10 implantations) had 42.8% reduction in median monthly SF by 2 years in comparison with 25.8% in low-volume center. In patients with cognitive impairment, the reduction in median monthly SF was 26.0% by 2 years compared with 36.1% in patients without cognitive impairment. The most frequently reported adverse events were changes (e.g., increased frequency/severity) in seizure (16%), memory impairment (patient-reported complaint, 15%), depressive mood (patient-reported complaint, 13%), and epilepsy (12%). One definite sudden unexpected death in epilepsy case was reported. DISCUSSION: The MORE registry supports the effectiveness and safety of ANT DBS therapy in a real-world setting in the 2 years following implantation. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that ANT DBS reduces the frequency of seizures in patients with drug-resistant focal epilepsy. TRIAL REGISTRATION INFORMATION: MORE ClinicalTrials.gov Identifier: NCT01521754, first posted on January 31, 2012.

Spinal arachnoiditis and cyst formation with subarachnoid haemorrhage.

We present the case of a 58-year-old lady with p-ANCA vasculitis who suffered a WFNS grade 1 subarachnoid haemorrhage (Fisher grade 1) secondary to a ruptured left posterior inferior cerebellar artery aneurysm and then developed a rare complication of radiologically progressive spinal arachnoiditis despite maintained clinical response to definitive treatment measures.

Trochlear myokymia secondary to cerebellopontine angle arachnoid cyst.

Superior oblique myokymia (SOM) is a rare disorder with an unclear pathogenesis. We describe a first reported case of chronic disabling SOM in association with a cerebellopontine angle arachnoid cyst, who had a gradual and eventually complete symptomatic resolution 8 months following cyst marsupialisation. Among other aetiologies, SOM may therefore be due to abnormal CSF flow dynamics resulting in structural compromise of the nerve.

Trends in diversity, equity and inclusion publications in neurological journals: 2015-2020.

BACKGROUND: Contemporary information on health equity related efforts by scientific neurological journals, as measured by publications related to diversity, equity and inclusion (DEI) and health disparities related to social determinants of health (SDH) are lacking. OBJECTIVE: To assess the yearly rates of DEI and SDH related publications in the highest cited general neurology and neurological sub-specialty journals and compare them to the highest cited medical journals over a 6-year period. METHODS: We included publications from 15 general neurology and neurological subspecialty journals between January 1st 2015 to December 31st 2020. For comparison we included the 15 most cited medical journals as measured by H-Index. We performed a PubMed search in each of the listed journals using key MeSH terms. Two-proportions Z-test and chi-square trend analyses were used to compare differences between journal types. RESULTS: Total yearly proportion of DEI and SDH related publications in neurological journals was 3.9% compared to 6.2% in the highest cited medical journals for years 2015 to 2020 (p=0.001). There was no change in overall trend in publications related to DEI and SDH topics in neurological (ρ = -0.082, p=0.45) or highest cited medical journals between 2015 and 2020 (ρ = -0.065, p=0.54). CONCLUSION: Neurological journals had a significantly lower yearly proportion of DEI and SDH related publications compared to top-cited medical journals. Despite heightened awareness of racial/ethnic health disparities and inequities driven by SDH there was no change in related publications in neurological journals between 2015-2020.

Direct brain infusion of glial cell line-derived neurotrophic factor in Parkinson disease.

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor with restorative effects in a wide variety of rodent and primate models of Parkinson disease, but penetration into brain tissue from either the blood or the cerebro-spinal fluid is limited. Here we delivered GDNF directly into the putamen of five Parkinson patients in a phase 1 safety trial. One catheter needed to be repositioned and there were changes in the magnetic resonance images that disappeared after lowering the concentration of GDNF. After one year, there were no serious clinical side effects, a 39% improvement in the off-medication motor sub-score of the Unified Parkinson's Disease Rating Scale (UPDRS) and a 61% improvement in the activities of daily living sub-score. Medication-induced dyskinesias were reduced by 64% and were not observed off medication during chronic GDNF delivery. Positron emission tomography (PET) scans of [(18)F]dopamine uptake showed a significant 28% increase in putamen dopamine storage after 18 months, suggesting a direct effect of GDNF on dopamine function. This study warrants careful examination of GDNF as a treatment for Parkinson disease.

The effect of race on composite thrombotic events in patients with COVID-19.

COVID-19 associated coagulopathy and mortality related to thrombotic complications have been suggested as biological mediators in racial disparities related to COVID-19. We studied the adjusted prevalence of acute ischemic stroke, pulmonary embolism, myocardial infarction, and deep venous thrombosis stratified by race in hospitalized patients in one New York City borough during the local COVID-19 surge. The multi-racial cohort included 4299 patients hospitalized with COVID-19, 9% of whom were white, 40% black, 41% Hispanic and 10% Asian or other. We found a 6.1% prevalence of composite thrombotic events. There were no significant race-specific differences in thrombotic events when adjusting for basic demographics, socioeconomic factors, medical comorbidities or biomarkers using a stepwise regression model. We therefore found no evidence that the racial disparities related to COVID-19, and specifically thrombotic complications, are caused by biological differences in race.

Neuralgia of the glossopharyngeal and vagal nerves: long-term outcome following surgical treatment and literature review.

This study describes our experience in the surgical treatment of neuralgia of the glossopharyngeal and vagal nerves. Over the last 19 years, 21 patients underwent surgery. Their case notes were reviewed to obtain demographic information, clinical presentation, surgical findings and early results. All patients were then contacted by telephone for long-term results and complications. Independent analysis of results was carried out by a Neurology team. Ten patients had microvascular decompression (MVD). Four patients had MVD and nerve section. In the remaining seven patients, the glossopharyngeal and first two rootlets of the vagal nerve were sectioned. Nineteen (90%) of 21 patients experienced complete relief of pain immediately after surgery. The remaining patients reported an improvement in their symptoms. There were no mortalities. Four patients experienced short-term complications, which resolved. Two patients were left with a persistent hoarse voice. At follow-up (mean duration of 4 years), there was no recurrence in symptoms. In our experience, surgery is safe and effective for the treatment of vago-glossopharyngeal neuralgia.

Deep Brain Stimulation for Facial Pain.

Electro-modulation of subcortical deep brain structures by surgically implanted electrodes is now standard evidence-based treatment for movement disorders such as Parkinson's disease and essential tremor and is approved for dystonia and obsessive-compulsive disorder under a humanitarian exemption. Historically, deep brain stimulation (DBS) for multiple indications has demonstrated acceptable complication rates, rare mortality, and reducing morbidity as the technology and the techniques of its application have advanced. DBS for the amelioration of pain has been performed since the early 1950s, and became widely used in the 1970s, when targeting the somatosensory thalamus was shown to be efficacious for intractable pain syndromes including facial pain. The technique fell out of favour in the late 1990s after 2 multicentre trials failed to meet end-point criteria. Since these trials, DBS for pain has remained for investigational or "off-label" use. Criticisms from previous literature have involved unsuitability of patient selection, as well as inconsistencies in neurosurgical technique. Clinical success with DBS for facial pain has been for the treatment of a variety of chronic neuropathic and nociceptive pain syndromes; including trigeminal neuropathy, post-herpetic neuralgia, deafferentation facial pain, "atypical" facial pain, cluster headaches and other trigeminal autonomic cephalalgias, as well as head and neck pathologies, most often which have been resistant to all other 1st- and 2nd-line medical and surgical treatments, when DBS has become a "last treatment option." An enhanced understanding of the mechanisms of action of DBS for pain will enhance outcome, and appropriately prescribe evolving novel nuclear brain targets.

Intraoperative intravenous ibuprofen use is not associated with increased post-tonsillectomy bleeding.

OBJECTIVES: Intravenous (IV) ibuprofen was approved by the FDA for use in pediatric patients in November 2015. The objective of this study was to compare bleeding rates in pediatric tonsillectomy patients who received intraoperative intravenous ibuprofen versus those who did not. Secondary objectives included analyzing factors that correlated with return to the Emergency Department (ED) for pain or dehydration. METHODS: Charts were reviewed for all patients 0-18 years of age who underwent a tonsillectomy with or without adenoidectomy at a tertiary care children's hospital from 1/1/2017 through 5/21/2018. Demographic information and perioperative medications including the use of intraoperative intravenous ibuprofen were recorded. ED visits and operating room (OR) returns for bleeding were tracked for up to 30 days after surgery. RESULTS: 1085 charts were analyzed. Intraoperative IV ibuprofen was used in 132 cases (12.2%). Primary bleeds, defined as bleeding within 24 h of surgery, occurred in 1 (0.76%) of 132 patients who received IV ibuprofen, and 1 (0.10%) of 953 patients who did not receive IV ibuprofen. Secondary bleeds, defined as bleeds after 24 h from surgery occurred in 2 (1.52%) of 132 patients who received IV ibuprofen and 38 (3.99%) of 953 patients who did not receive IV ibuprofen. No statistical difference was found between the two groups in rates of overall (primary plus secondary) bleeding requiring return to ED (p = 0.759) or return to OR (p = 0.710). CONCLUSION: The observed bleeding rate after pediatric tonsillectomy was not statistically different in patients who received intraoperative IV ibuprofen versus those who did not receive this medication. LEVEL OF EVIDENCE: III.

Comparison of atlas- and magnetic-resonance-imaging-based stereotactic targeting of the subthalamic nucleus in the surgical treatment of Parkinson's disease.

AIMS: To assess the variability of the subthalamic nucleus (STN) size, orientation and target coordinates from direct visualization on high-resolution magnetic resonance (MR) images in patients undergoing surgical intervention for Parkinson's disease. METHODS: Sixty-six patients with Parkinson's disease were included in this study. The STN was visualized directly on high-resolution MR images, the size and orientation in both coronal and axial planes were recorded, as were the coordinates of the dorsolateral STN target in relation to the anterior-posterior commissural (AC-PC) line. The same STN target was defined in the Schaltenbrand atlas and atlas-based coordinates in proportion to the patient's AC-PC dimension were calculated. MR-imaging-based STN target coordinates were compared with the corresponding atlas-based coordinates. RESULTS: Marked variation of STN size and orientation was observed. A significant difference was demonstrated on comparing left- and right-sided x and y coordinates. The comparison between MR-imaging-based and atlas-derived target coordinates demonstrated a significant difference in all directions except the left y coordinate. CONCLUSIONS: This study demonstrates the substantial individual variability of STN size, orientation and target coordinates and a significant difference between target coordinates obtained by direct visual targeting on MR images and those obtained by indirect targeting based on atlases.