Sex differences in aneurysmal subarachnoid haemorrhage (aSAH): aneurysm characteristics, neurological complications, and outcome.

BACKGROUND: Women are over-represented in aSAH cohorts, but whether their outcomes differ to men remains unclear. We examined if sex differences in neurological complications and aneurysm characteristics contributed to aSAH outcomes. METHODS: In a retrospective cohort (2010-2016) of all aSAH cases across two hospital networks in Australia, information on severity, aneurysm characteristics and neurological complications (rebleed before/after treatment, postoperative stroke < 48 h, neurological infections, hydrocephalus, seizures, delayed cerebral ischemia [DCI], cerebral infarction) were extracted. We estimated sex differences in (1) complications and aneurysm characteristics using chi square/t-tests and (2) outcome at discharge (home, rehabilitation or death) using multinomial regression with and without propensity score matching on prestroke confounders. RESULTS: Among 577 cases (69% women, 84% treated) aneurysm size was greater in men than women and DCI more common in women than men. In unadjusted log multinomial regression, women had marginally greater discharge to rehabilitation (RRR 1.15 95% CI 0.90-1.48) and similar likelihood of in-hospital death (RRR 1.02 95% CI 0.76-1.36) versus discharge home. Prestroke confounders (age, hypertension, smoking status) explained greater risk of death in women (rehabilitation RRR 1.13 95% CI 0.87-1.48; death RRR 0.75 95% CI 0.51-1.10). Neurological complications (DCI and hydrocephalus) were covariates explaining some of the greater risk for poor outcomes in women (rehabilitation RRR 0.87 95% CI 0.69-1.11; death RRR 0.80 95% CI 0.52-1.23). Results were consistent in propensity score matched models. CONCLUSION: The marginally poorer outcome in women at discharge was partially attributable to prestroke confounders and complications. Improvements in managing complications could improve outcomes.

Assessing in vivo flexion-extension quality of motion after cervical disc arthroplasty: a pilot study.

Background: The quality of flexion-extension motion after cervical disc arthroplasty has been a subject of interest due to the number of available devices with different designs and kinematics. Previous studies of motion quality have been limited to measuring the range of motion using two radiographs taken at the extremes of flexion and extension. This is the first study evaluating the in vivo quality of index segment motion using fluoroscopic images collected over the arc of flexion-extension after M6-C cervical disc arthroplasty surgery. Methods: Eligible participants had previously undergone a single-level cervical disc arthroplasty surgery for degenerative cervical spine disease performed by the senior author. Study participants underwent dynamic lateral fluoroscopic imaging to capture the C2-C7 motion between maximal flexion and extension. The amount of motion contribution by individual segments to the C2-C7 motion (termed segmental motion fraction) and its variation throughout the arc of flexion-extension were compared between the index and adjacent segments. The shift of centre of rotation during the arc of motion was also assessed. Results: Ten subjects with a mean age of 43.8 years old were recruited, with an average follow-up of 16.2 months at the time of fluoroscopy. The C2-C7 cervical spine had an average flexion-extension range of 66.7 degrees. The contribution of the index segment averaged over the flexion-extension arc of motion was 18.9% (peak contribution 24.4%) for the C5-C6 group; and 15.5% (peak contribution 25.5%) for the C6-C7 group. The mean cranial-caudal location of the centre of rotation progressively shifted in the cranial direction from C2-C3 to C6-C7 motion segment. Conclusions: Our results demonstrated physiologic quality of motion at the index segment and harmony among its neighbouring segments following cervical disc arthroplasty, without gearshift-like intermittent locking of the prosthesis during the arc of flexion-extension motion. This pilot study provides a basis for the design of future long-term studies with larger sample size to compare the quality of motion between different cervical disc prostheses using the concept of segmental motion fraction as a motion-quality metric.

Association of Onset-to-Treatment Time With Discharge Destination, Mortality, and Complications Among Patients With Aneurysmal Subarachnoid Hemorrhage.

Importance: Rapid access to specialized care is recommended to improve outcomes after aneurysmal subarachnoid hemorrhage (SAH), but understanding of the optimal onset-to-treatment time for aneurysmal SAH is limited. Objective: To assess the optimal onset-to-treatment time for aneurysmal SAH that maximized patient outcomes after surgery. Design, Setting, and Participants: This cohort study assessed 575 retrospectively identified cases of first-ever aneurysmal SAH occurring within the referral networks of 2 major tertiary Australian hospitals from January 1, 2010, to December 31, 2016. Individual factors, prehospital factors, and hospital factors were extracted from the digital medical records of eligible cases. Data analysis was performed from March 1, 2020, to August 31, 2021. Exposures: Main exposure was onset-to-treatment time (time between symptom onset and aneurysm surgical treatment in hours) derived from medical records. Main Outcomes and Measures: Clinical characteristics, complications, and discharge destination were extracted from medical records and 12-month survival obtained from data linkage. The associations of onset-to-treatment time (in hours) with (1) discharge destination of survivors (home vs rehabilitation), (2) 12-month survival, and (3) neurologic complications (rebleed, delayed cerebral ischemia, meningitis, seizure, hydrocephalus, and delayed cerebral injury) were investigated using natural cubic splines in multivariable Cox proportional hazards and logistic regression models. Results: Of the 575 patients with aneurysmal SAH, 482 patients (mean [SD] age, 55.0 [14.5] years; 337 [69.9%] female) who received endovascular coiling or neurosurgical clipping were studied. A nonlinear association of treatment delay was found with the odds of being discharged home vs rehabilitation (effective df = 3.83 in the generalized additive model, χ2 test P = .002 for the 4-df cubic spline), with a similar nonlinear association remaining significant after adjustment for sex, treatment modality, severity, Charlson Comorbidity Index, history of hypertension, and hospital transfer (likelihood ratio test: df = 3, deviance = 9.57, χ2 test P = .02). Both unadjusted and adjusted cox regression models showed a nonlinear association between time to treatment and 12-month mortality with the lowest hazard of death with receipt of treatment at 12.5 hours after symptom onset, although the nonlinear term became nonsignificant upon adjustment. The odds of being discharged home were higher with treatment before 20 hours after onset, with the probability of being discharged home compared with rehabilitation or other hospital increased by approximately 10% when treatment was received within the first 12.5 hours after symptom onset and increased by an additional 5% from 12.5 to 20 hours. Time to treatment was not associated with any complications. Conclusions and Relevance: This cohort study found evidence that more favorable outcomes (discharge home and survival at 12 months) were achieved when surgical treatment occurred at approximately 12.5 hours. These findings provide more clarity around optimal timelines of treatment with people with aneurysmal SAH; however, additional studies are needed to confirm the findings.

The Magnetic Resonance Imaging (MRI)-Directed Implantable Guide Tube Technique: Accuracy and Applications in Deep Brain Stimulation.

OBJECTIVE: The magnetic resonance imaging (MRI)-directed implantable guide tube technique allows for direct targeting of deep brain structures without microelectrode recording or intraoperative clinical assessment. This study describes a 10-year institutional experience of this technique including nuances that enable performance of surgery using readily available equipment. METHODS: Eighty-seven patients underwent deep brain stimulation surgery using the guide tube technique for Parkinson disease (n = 59), essential tremor (n = 16), and dystonia (n = 12). Preoperative and intraoperative MRI was analyzed to measure lead accuracy, volume of pneumocephalus, and the ability to safely plan a trajectory for multiple electrode contacts. RESULTS: Mean target error was measured to be 0.7 mm (95% confidence interval [CI] 0.6-0.8 mm) in the anteroposterior plane, 0.6 mm (95% CI 0.5-0.7 mm) in the mediolateral plane, and 0.8 mm (95% CI 0.7-0.9 mm) in the superoinferior plane. Net deviation (Euclidean error) from the planned target was 1.3 mm (95% CI 1.2-1.4 mm). Mean intracranial air volume per lead was 0.2 mL (95% CI 0.1-0.4 mL). In total, 52 patients had no intracranial air on postoperative imaging. In all patients, a safe trajectory could be planned to target for multiple electrode contacts without violating critical neural structures, the lateral ventricle, sulci, or cerebral blood vessels. CONCLUSIONS: The MRI-directed implantable guide tube technique is a highly accurate, low-cost, reliable method for introducing deep brain electrodes. This technique reduces brain shift secondary to pneumocephalus and allows for whole trajectory planning of multiple electrode contacts.

Adherence to evidence-based processes of care reduces one-year mortality after aneurysmal subarachnoid hemorrhage (aSAH).

BACKGROUND: There is limited research on the provision of evidence-based care and its association with outcomes after aneurysmal subarachnoid hemorrhage (aSAH). AIMS: We examined adherence to evidence-based care after aSAH and associations with survival and discharge destination. Also, factors associated with evidence-based care including age, sex, Charlson comorbidity index, severity scores, and delayed cerebral ischemia and infarction were examined for association with survival and discharge destination. METHODS: In a retrospective cohort (2010-2016) of all aSAH cases across two comprehensive cerebrovascular centres, we extracted 3 indicators of evidence-based aSAH care from medical records: (1) antihypertensives prior to aneurysm treatment, (2) nimodipine, and (3) aneurysm treatment (coiling/clipping). We defined 'optimal care' as receiving all eligible processes of care. Survival at 1 year was obtained by data linkage. We estimated (1) proportion of patients and characteristics associated with receiving processes of care, (2) associations between processes of care with 1-year mortality using cox-proportional hazard model and discharge destination with log binomial regression adjusting for age, sex, severity of aSAH, delayed cerebral ischemia and/or cerebral infarction and comorbidities. Sensitivity analyses explored effect modification of the association between processes of care and outcome by management type (active versus comfort measures). RESULTS: Among 549 patients (69% women), 59% were managed according to the guidelines. Individual indicators were associated with lower 1-year mortality but not discharge destination. Optimal care reduced mortality at 1 year in univariable (HR 0.24 95% CI 0.17-0.35) and multivariable analyses (HR 0.51 95% CI 0.34-0.77) independent of age, sex, severity, comorbidities, and hospital network. CONCLUSION: Adherence to processes of care reduced 1-year mortality after aSAH. Many patients with aSAH do not receive evidence-based care and this must be addressed to improve outcomes.

Endodermal Cyst Arising from the Oculomotor Nerve: A Case Report Outlining the Novel Insertion of Cysto-subarachnoid Shunt for Refractory Disease.

BACKGROUND: Endodermal cysts of the oculomotor nerve are rare presentations. Only case reports are available to help guide clinicians with managing this rare entity. CASE DESCRIPTION: A 3-year-old boy presented with an acute on chronic left oculomotor nerve palsy due to a left interpeduncular cistern cyst found on magnetic resonance imaging. He underwent a left pterional craniotomy and fenestration of the histologically proven endodermal cyst and had initial improvement at the 2-month review. He subsequently developed clinical and radiologic evidence of recurrence and was treated surgically with a refenestration and insertion of a cysto-subarachnoid shunt through a trans-sylvian approach. At 6-month follow-up, there was complete resolution of the oculomotor nerve palsy with interval development of oculomotor synkinesis. CONCLUSIONS: Magnetic resonance imaging is an essential modality in the follow-up of these patients postoperatively in the setting of unchanged or deteriorated neurology. Fenestration of the cyst is appropriate first-line surgical management; however, a cysto-subarachnoid shunt is a safe consideration in recurrent, symptomatic cysts and provides sustained symptom resolution.

Transfer times and patient outcomes - A review of head injuries requiring surgery in Tasmania 2006-2017.

The Royal Hobart Hospital (RHH) provides the only neurosurgical service in the state of Tasmania, Australia, with many patients requiring surgical treatment of intracranial injuries needing to be transferred from peripheral hospitals around the state to Hobart. This retrospective review analysed the medical records of all patients who underwent a neurosurgical intervention at RHH for an intracranial injury over a 10½ year period to ascertain if prolonged transfer times correlated with poorer patient outcomes. A total of 360 patients were included in the study, with 159 patients presenting initially to a peripheral hospital and subsequently transferred to RHH for surgery. A correlation analysis found no statistically significant relationship between transfer times from peripheral hospitals and patient Glasgow Outcome Scale (GOS) scores at 6 months post-surgery (r = 0.065, P = 0.434). There was also no correlation between transfer times and discharge destination (r = 0.088, P = 0.275). We concluded that patient transfers for head injury management in Tasmania are timely and meeting patient needs.

Infantile Optic Pathway Glioblastoma.

BACKGROUND: Optic pathway gliomas and glioblastomas remain a rare entity within the infant population. CASE DESCRIPTION: We outline the case of a 6-month-old female who presented with failure to thrive, nystagmus and features of raised intracranial pressure. Subsequent magnetic resonance imaging demonstrated an infiltrating tumor radiating from the optic nerves bilaterally. She underwent emergent ventriculoperitoneal shunting and biopsy. Histology confirmed a World Health Organization grade IV glioblastoma. CONCLUSIONS: The patient remained clinically and radiologically stable at 1 year. Optic pathway glioblastoma in this population is a previously undescribed entity that requires multidisciplinary input to guide ongoing therapy.

Diffuse idiopathic skeletal hyperostosis masquerading as asthma: case report.

A 52-year-old man with a 10-year history of treatment-resistant asthma presented with repeated exacerbations over the course of 10 months. His symptoms were not responsive to salbutamol or inhaled corticosteroid agents, and he developed avascular necrosis of his left hip as a result of prolonged steroid therapy. Physical examination and radiography revealed signs consistent with diffuse idiopathic skeletal hyperostosis (DISH), including a C7-T1 osteophyte causing severe tracheal compression. The patient underwent C6-T1 anterior discectomy and fusion, and the compressive osteophyte was removed, which completely resolved his "asthma." Postoperative pulmonary function tests showed normalization of his FEV1/FVC ratio, and there was no airway reactivity on methacholine challenge. DISH is a systemic, noninflammatory condition characterized by ossification of spinal entheses, and it can present with respiratory disturbances due to airway compression by anterior cervical osteophytes. The authors present, to the best of their knowledge, the first documented case of asthma as a presentation of DISH.

Modulation of saccades in humans by electrical stimulation of the posterior subthalamic area.

OBJECTIVE: Posterior subthalamic area (PSA) deep brain stimulation (DBS) targeting the zona incerta (ZI) is an emerging treatment for tremor syndromes, including Parkinson's disease (PD) and essential tremor (ET). Evidence from animal studies has indicated that the ZI may play a role in saccadic eye movements via pathways between the ZI and superior colliculus (incerto-collicular pathways). PSA DBS permitted testing this hypothesis in humans. METHODS: Sixteen patients (12 with PD and 4 with ET) underwent DBS using the MRI-directed implantable guide tube technique. Active electrode positions were confirmed at the caudal ZI. Eye movements were tested using direct current electrooculography (EOG) in the medicated state pre- and postoperatively on a horizontal predictive task subtending 30°. Postoperative assessments consisted of stimulation-off, constituting a microlesion (ML) condition, and high-frequency stimulation (HFS; frequency = 130 Hz) up to 3 V. RESULTS: With PSA HFS, the first saccade amplitude was significantly reduced by 10.4% (95% CI 8.68%-12.2%) and 12.6% (95% CI 10.0%-15.9%) in the PD and ET groups, respectively. With HFS, peak velocity was reduced by 14.7% (95% CI 11.7%-17.6%) in the PD group and 27.7% (95% CI 23.7%-31.7%) in the ET group. HFS led to PD patients performing 21% (95% CI 16%-26%) and ET patients 31% (95% CI 19%-38%) more saccadic steps to reach the target. CONCLUSIONS: PSA DBS in patients with PD and ET leads to hypometric, slowed saccades with an increase in the number of steps taken to reach the target. These effects contrast with the saccadometric findings observed with subthalamic nucleus DBS. Given the location of the active contacts, incerto-collicular pathways are likely responsible. Whether the acute finding of saccadic impairment persists with chronic PSA stimulation is unknown.

Surgical Management of Spontaneous Spinal Cerebrospinal Fluid Epidural Fistula.

BACKGROUND: Intracranial hypotension secondary to spontaneous spinal cerebrospinal fluid (CSF) fistula is a rare condition that can have serious sequelae. Early diagnosis and treatment can be challenging. CASE DESCRIPTION: We present the case of a 17-year-old male who presented with a history of sudden-onset, postural headaches associated with upper thoracic back pain. Magnetic resonance imaging (MRI) demonstrated a thoracic extradural fluid collection and slumping of the brain within the posterior fossa. The patient was initially managed with a period of bed rest, followed by a thoracic epidural blood patch. Symptoms recurred and subsequent operative exploration found a large arachnoid cyst with CSF egress through a linear split in the axilla of the right T7 nerve root. The arachnoid cyst was resected, and the defect was closed primarily. All symptoms completely resolved. MRI at 3 months postoperatively demonstrated normal spinal configuration and resolution of brain sagging. CONCLUSIONS: Spontaneous CSF leaks are a rare cause of postural headache. Although epidural blood patching is an easy and safe intervention, early serial imaging to ascertain the evolution of the pathology may identify cases that are amenable to early surgical management.

Size and Location of Ruptured Intracranial Aneurysms: A 5-Year Clinical Survey.

BACKGROUND: Prospective international cohort trials have suggested that incidental cerebral aneurysms with diameters less than 10 mm are unlikely to rupture. Consequently, small ruptured cerebral aneurysms should rarely be seen in clinical practice. To verify this theory, dimensions and locations of ruptured cerebral aneurysms were analyzed across the state of Tasmania, Australia. METHODS: We retrospectively reviewed medical records and diagnostic tests of all patients admitted with ruptured cerebral aneurysms during a 5-year interval. Aneurysm location, maximum size, dome-to-neck ratio, volume, and presence of daughter sacs were determined by preoperative digital subtraction angiography or computed tomography angiography. RESULTS: A total of 131 ruptured cerebral aneurysms were encountered and treated by microsurgical clipping (n = 59) or endovascular techniques (n = 72). The mean maximum aneurysm diameter was 6.4 ± 3.7 mm, dome-to-neck ratio 2 ± 0.8, aneurysm volume 156 ± 372 mm(3), and daughter sacs were present in 70 aneurysms (53.4%). The anterior communicating artery was the most common location (37.4%). Cumulative maximum diameters of ruptured aneurysms were ≤5 mm in 49%, ≤7 mm in 73%, and ≤10 mm in 90%. CONCLUSIONS: Despite findings from prospective international cohort trials, small ruptured intracranial aneurysms are common in clinical practice. In consequence, it seems important to identify those patients with small but vulnerable unruptured aneurysms before conservative management is considered.

Thoracic discectomy by posterior pedicle-sparing, transfacet approach with real-time intraoperative ultrasonography: Clinical article.

OBJECT: Symptomatic thoracic disc herniations (TDHs) are relatively uncommon, and the technical challenges of resecting the offending disc are formidable due to the location of spinal cord that has relatively poor perfusion characteristics within a narrow canal. The majority of disc herniations are long-standing calcified discs that can be adherent to the ventral dura. Real-time intraoperative ultrasound (RIOUS) visualization of the spinal cord during the retraction and resection of the disc greatly enhances the safety and efficacy of disc resection. The authors have adopted the posterior laminectomy with pedicle-sparing transfacet approach with real-time ultrasound guidance in their practice, and they present the clinical outcome in their patients to illustrate the safety profile of this technique. METHODS: Sixteen consecutive patients undergoing operative management of TDHs were identified from the authors' database. All patients underwent microdiscectomy through a posterior transfacet pedicle-sparing approach under RIOUS. Outcomes and complications were retrospectively assessed in this patient series. Clinical records and pre- and postoperative imaging studies were scrutinized to assess levels and types of disc herniation, blood loss, surgical time, pre- and postoperative Nurick grades, Japanese Orthopaedic Association (JOA) scores, and complications. RESULTS: All patients had single-level symptomatic TDHs. The patients presented with symptoms including thoracic myelopathy, axial back pain, urinary symptoms, and thoracic radiculopathy. Thoracic disc herniations involved levels T2-3 to T12-L1. Discs were classified as central or paracentral, and as calcified or noncalcified. All discs were successfully removed with no incidence of neural injury or CSF leak. The mean estimated blood loss was 523 ml, and the mean surgical time was 159 minutes. Nurick grades improved on average from 3.3 to 1.6. The mean JOA scores improved from 5.7 to 8.3 out of 11. The mean Hirabayashi recovery rate of the JOA score was 57%. All patients reported improvement in symptoms compared with preoperative status except for 1 patient with an American Spinal Injury Association Grade A spinal cord injury prior to surgery. The average duration of follow-up was 10.5 months. One patient developed postoperative wound infection that required additional operative debridement and revision of hardware. CONCLUSIONS: Thoracic discectomy via a posterior pedicle-sparing transfacet approach is an adequate method of managing herniations at any thoracic level. The safety of the operation is significantly enhanced by the use of realtime intraoperative ultrasonography.

Spinal subarachnoid hemorrhage secondary to rupture of an isolated radicular artery aneurysm.

Aneurysmal subarachnoid hemorrhage (aSAH) of spinal origin is an uncommon entity and comprises less than 1% of all aSAH. The paucity of clinical cases creates challenges to its diagnosis and management. We present the case of a 58-year-old male, who presented with a spinal subarachnoid hemorrhage secondary to a de novo spinal radicular artery aneurysm. Spinal subarachnoid hemorrhages typically occur secondary to arteriovenous malformations or arterial wall weakness seen in collagen vascular disease. Fewer than 20 cases of isolated spinal arterial aneurysms have been published. SAHs of spinal origin are exceedingly rare and thus a high index of suspicion is required for an accurate and timely diagnosis.

Accuracy of magnetic resonance imaging-directed frame-based stereotaxis.

BACKGROUND: Accurate placement of a probe to the deep regions of the brain is an important part of neurosurgery. In the modern era, magnetic resonance image (MRI)-based target planning with frame-based stereotaxis is the most common technique. OBJECTIVE: To quantify the inaccuracy in MRI-guided frame-based stereotaxis and to assess the relative contributions of frame movements and MRI distortion. METHODS: The MRI-directed implantable guide-tube technique was used to place carbothane stylettes before implantation of the deep brain stimulation electrodes. The coordinates of target, dural entry point, and other brain landmarks were compared between preoperative and intraoperative MRIs to determine the inaccuracy. RESULTS: The mean 3-dimensional inaccuracy of the stylette at the target was 1.8 mm (95% confidence interval [CI], 1.5-2.1. In deep brain stimulation surgery, the accuracy in the x and y (axial) planes is important; the mean axial inaccuracy was 1.4 mm (95% CI, 1.1-1.8). The maximal mean deviation of the head frame compared with brain over 24.1 ± 1.8 hours was 0.9 mm (95% CI, 0.5-1.1). The mean 3-dimensional inaccuracy of the dural entry point of the stylette was 1.8 mm (95% CI, 1.5-2.1), which is identical to that of the target. CONCLUSION: Stylette positions did deviate from the plan, albeit by 1.4 mm in the axial plane and 1.8 mm in 3-dimensional space. There was no difference between the accuracies at the dura and the target approximately 70 mm deep in the brain, suggesting potential feasibility for accurate planning along the whole trajectory.

High-frequency pallidal stimulation for camptocormia in Parkinson disease: case report.

BACKGROUND AND IMPORTANCE: Camptocormia is characterized by abnormal flexion of the thoracolumbar spine that increases during upright posture and abates in the recumbent position and has been reported to occur in patients with Parkinson disease. Camptocormia causes significant spinal and abdominal pain, impairment of balance, and social stigma. CLINICAL PRESENTATION: A 57-year-old woman with Parkinson disease developed severe camptocormia, which did not improve with trials of antiparkinsonian and muscle relaxant medications. The patient was successfully treated with bilateral globus pallidus interna deep brain stimulation surgery under general anesthesia. High-frequency neuromodulation afforded relief of camptocormia and improvement in Parkinson disease symptoms. CONCLUSION: Camptocormia in Parkinson disease may represent a form of dystonia and can be treated effectively with chronic pallidal neuromodulation.

Accuracy of postoperative computed tomography and magnetic resonance image fusion for assessing deep brain stimulation electrodes.

BACKGROUND: Knowledge of the anatomic location of the deep brain stimulation (DBS) electrode in the brain is essential in quality control and judicious selection of stimulation parameters. Postoperative computed tomography (CT) imaging coregistered with preoperative magnetic resonance imaging (MRI) is commonly used to document the electrode location safely. The accuracy of this method, however, depends on many factors, including the quality of the source images, the area of signal artifact created by the DBS lead, and the fusion algorithm. OBJECTIVE: To calculate the accuracy of determining the location of active contacts of the DBS electrode by coregistering postoperative CT image to intraoperative MRI. METHODS: Intraoperative MRI with a surrogate marker (carbothane stylette) was digitally coregistered with postoperative CT with DBS electrodes in 8 consecutive patients. The location of the active contact of the DBS electrode was calculated in the stereotactic frame space, and the discrepancy between the 2 images was assessed. RESULTS: The carbothane stylette significantly reduces the signal void on the MRI to a mean diameter of 1.4 ± 0.1 mm. The discrepancy between the CT and MRI coregistration in assessing the active contact location of the DBS lead is 1.6 ± 0.2 mm, P < .001 with iPlan (BrainLab AG, Erlangen, Germany) and 1.5 ± 0.2 mm, P < .001 with Framelink (Medtronic, Minneapolis, Minnesota) software. CONCLUSION: CT/MRI coregistration is an acceptable method of identifying the anatomic location of DBS electrode and active contacts.