Robotic-Assisted Navigation for Stereotactic Neurosurgery: A Cadaveric Investigation of Accuracy, Time, and Radiation.

BACKGROUND AND OBJECTIVES: Despite frequent use, stereotactic head frames require manual coordinate calculations and manual frame settings that are associated with human error. This study examines freestanding robot-assisted navigation (RAN) as a means to reduce the drawbacks of traditional cranial stereotaxy and improve targeting accuracy. METHODS: Seven cadaveric human torsos with heads were tested with 8 anatomic coordinates selected for lead placement mirrored in each hemisphere. Right and left hemispheres of the brain were randomly assigned to either the traditional stereotactic arc-based (ARC) group or the RAN group. Both target accuracy and trajectory accuracy were measured. Procedural time and the radiation required for registration were also measured. RESULTS: The accuracy of the RAN group was significantly greater than that of the ARC group in both target (1.2 ± 0.5 mm vs 1.7 ± 1.2 mm, P = .005) and trajectory (0.9 ± 0.6 mm vs 1.3 ± 0.9 mm, P = .004) measurements. Total procedural time was also significantly faster for the RAN group than for the ARC group (44.6 ± 7.7 minutes vs 86.0 ± 12.5 minutes, P < .001). The RAN group had significantly reduced time per electrode placement (2.9 ± 0.9 minutes vs 5.8 ± 2.0 minutes, P < .001) and significantly reduced radiation during registration (1.9 ± 1.1 mGy vs 76.2 ± 5.0 mGy, P < .001) compared with the ARC group. CONCLUSION: In this cadaveric study, cranial leads were placed faster and with greater accuracy using RAN than those placed with conventional stereotactic arc-based technique. RAN also required significantly less radiation to register the specimen's coordinate system to the planned trajectories. Clinical testing should be performed to further investigate RAN for stereotactic cranial surgery.

Metal contents and size distributions of brake and tire wear particles dispersed in the near-road environment.

Traffic related non-tailpipe particulate matter emissions can rival the continuously decreasing tailpipe emissions in modern fleets. Non-tailpipe emissions have become the dominating source of traffic emissions in California already. This study measured ambient PM2.5 and PM10 concentrations at near road environments for two major highways in California, I-5 in Anaheim and I-710 in Long Beach. A total of 51 elements were measured from filter samples collected over four-hour intervals for a two-week period in the winter of 2020 before the statewide lockdown by the COVID-19 pandemic. Iron was the most abundant element in ΔPM10 (differences between downwind and upwind sites), contributing to 30 % and 24 % of total measured elements in ΔPM10 at the I-5 and I-710 locations, respectively. Iron correlated highly with other brake wear markers (e.g., titanium, copper, barium, manganese, and zirconium) with coefficient of determination (r2) ranging from 0.67 to 0.90 in both PM2.5 and PM10. Silicon was the second most abundant element, contributing to 21 % of total measured elements in ΔPM2.5 and ΔPM10. Silicon showed strong correlations with crustal elements such as calcium (r2 = 0.90), aluminum (r2 = 0.96), and potassium (r2 = 0.72) in ΔPM2.5, and the correlations were even higher in ΔPM10. Barium had a weak correlation with zinc, a commonly used maker for tire wear, with r2 = 0.63 and r2 = 0.11 for ΔPM10 at the I-5 and I-710 locations respectively. Barium showed a positive correlation with crosswind speed and could serve as a good brake wear PM marker. Hourly PM2.5 concentrations of iron and zinc showed cyclic peaks from 0800 to 1000 h at I-5 during weekdays. Particle mass distributions showed peaks near ~7 µm, while particle number distributions showed peaks near 2.1 µm and 6.5 µm, respectively. This is consistent with brake wear and road dust size ranges previously reported.

Ablation of apparent diffusion coefficient hyperintensity clusters in mesial temporal lobe epilepsy improves seizure outcomes after laser interstitial thermal therapy.

OBJECTIVE: Laser interstitial thermal therapy (LiTT) is a minimally invasive surgical procedure for intractable mesial temporal epilepsy (mTLE). LiTT is safe and effective, but seizure outcomes are highly variable due to patient variability, suboptimal targeting, and incomplete ablation of the epileptogenic zone. Apparent diffusion coefficient (ADC) is a magnetic resonance imaging (MRI) sequence that can identify potential epileptogenic foci in the mesial temporal lobe to improve ablation and seizure outcomes. The objective of this study was to investigate whether ablation of tissue clusters with high ADC values in the mesial temporal structures is associated with seizure outcome in mTLE after LiTT. METHODS: Twenty-seven patients with mTLE who underwent LiTT at our institution were analyzed. One-year seizure outcome was categorized as complete seizure freedom (International League Against Epilepsy [ILAE] Class I) and residual seizures (ILAE Class II-VI). Volumes of hippocampus and amygdala were segmented from the preoperative T1 MRI sequence. Spatially distinct hyperintensity clusters were identified in the preoperative ADC map. Proportion of cluster volume and number ablated were associated with seizure outcomes. RESULTS: The mean age at surgery was 37.5 years and the mean follow-up duration was 1.9 years. Proportions of hippocampal cluster volume (p = .013) and number (p = .03) ablated were significantly higher in patients with seizure freedom. For amygdala clusters, the proportion of cluster number ablated was significantly associated with seizure outcome (p = .026). In the combined amygdalohippocampal complex, ablation of amygdalohippocampal clusters reliably predicted seizure outcome by their volume ablated (area under the curve [AUC] = 0.7670, p = .02). SIGNIFICANCE: Seizure outcome after LiTT in patients with mTLE was associated significantly with the extent of cluster ablation in the amygdalohippocampal complex. The results suggest that preoperative ADC analysis may help identify high-yield pathological tissue clusters that represent epileptogenic foci. ADC-based cluster analysis can potentially assist ablation targeting and improve seizure outcome after LiTT in mTLE.

Spinal cord untethering and midline myelotomy for delayed, symptomatic post-traumatic syringomyelia due to retained ballistic fragments: case report.

INTRODUCTION: Post-traumatic syringomyelia is an uncommon complication after traumatic spinal cord injury. This case study details our decision-making and surgical approach for a patient with symptomatic post-traumatic syringomyelia after sustaining a gunshot wound. CASE PRESENTATION: A 24-year-old man with past medical history of distant American Spinal Injury Association Impairment Grade B spinal cord injury due to ballistic injury developed delayed post-traumatic syringomyelia, resulting in unilateral sensory loss and left upper extremity weakness. CT and MR imaging revealed a syrinx spanning his cervical and thoracic spine causing significant spinal cord compression. To relieve achieve decompression and restore CSF flow dynamics, we performed a bony extradural decompression, bullet fragment extraction, spinal cord untethering, and midline myelotomy. Postoperatively, the patient demonstrated clinical and radiographical improvement. DISCUSSION: Post-traumatic syringomyelia is potentially morbid sequalae of spinal cord injuries. Suspicion for post-traumatic syringomyelia should be maintained in patients with delayed, progressive neurologic deficits. In this setting, surgical intervention may require extradural and intradural procedures to mitigate neural compression along the dilated central canal by the syrinx.

Robot-assisted atlantoaxial fixation: illustrative cases.

BACKGROUND: Placing screws in the high cervical spine can be challenging because of the vital anatomical structures located in that region. Precision and accuracy with screw placement is needed. The use of robotics in the cervical spine has been described before; however, here the authors describe the use of a new robotic setup. OBSERVATIONS: The authors describe 2 cases of robot-assisted placement of C2 pars screws and C1-2 transarticular screws. The operative plans for each patient were as follows: placement of C2 pars screws with C2-4 fusion for hangman's fracture and placement of C1-2 transarticular screws for degenerative disease. Intraoperative computed tomography (CT) was used to plan and navigate the screws. Postoperative CT showed excellent placement of hardware. Both patients presented for initial postoperative clinic visits with no recurrence of prior symptoms. LESSONS: Intraoperative robotic assistance with instrumentation of the high cervical spine, particularly C2 pars and C1-2 transarticular screws, may ensure proper screw placement and help avoid injury.

Prehospital Traumatic Brain Injury Management Clinical Pearls and Pathophysiology.

Traumatic brain injury (TBI) management is complex. The brain is a sensitive, high-maintenance organ that loses its ability to take care of itself upon injury, and our primary mission is to achieve and maintain optimal levels of cerebral blood flow (CBF) from the moment of injury until recovery. The authors provide a case and discuss prehospital patient management, including adequate oxygen saturation and blood pressure, early recognition of TBI, frequent exams, detailed charting and hand-off, and fast transport to the next echelon of care.

Apparent diffusion coefficient of piriform cortex and seizure outcome in mesial temporal lobe epilepsy after MR-guided laser interstitial thermal therapy: a single-institution experience.

OBJECTIVE: Piriform cortex (PC) is one of the critical structures in the epileptogenesis of mesial temporal lobe epilepsy (mTLE), but its role is poorly understood. The authors examined the utility of apparent diffusion coefficient (ADC; an MR-based marker of tissue pathology) of the PC as a predictor of seizure outcome in patients with mTLE undergoing MR-guided laser interstitial thermal therapy (MRgLITT). METHODS: A total of 33 patients diagnosed with mTLE who underwent MRgLITT at the authors' institution were included in the study. The 6-month postoperative seizure outcomes were classified using the International League Against Epilepsy (ILAE) system as good (complete seizure freedom, ILAE class I) and poor (seizure present, ILAE classes II-VI). The PC and ablation volumes were manually segmented from both the preoperative and intraoperative MRI sequences, respectively. The mean ADC intensities of 1) preablation PC; 2) total ablation volume; 3) ablated portion of PC; and 4) postablation residual PC were calculated and compared between good and poor outcome groups. Additionally, the preoperative PC volumes and proportion of PC volume ablated were examined and compared between the subjects in the two outcome groups. RESULTS: The mean age at surgery was 36.5 ± 3.0 years, and the mean follow-up duration was 1.9 ± 0.2 years. Thirteen patients (39.4%) had a good outcome. The proportion of PC ablated was significantly associated with seizure outcome (10.16 vs 3.30, p < 0.05). After accounting for the variability in diffusion tensor imaging acquisition parameters, patients with good outcome had a significantly higher mean ADC of the preablation PC (0.3770 vs -0.0108, p < 0.05) and the postoperative residual PC (0.4197 vs 0.0309, p < 0.05) regions compared to those with poor outcomes. No significant differences in ADC of the ablated portion of PC were observed (0.2758 vs -0.4628, p = 0.12) after performing multivariate analysis. CONCLUSIONS: A higher proportion of PC ablated was associated with complete seizure freedom. Preoperative and postoperative residual ADC measures of PC were significantly higher in the good seizure outcome group in patients with mTLE who underwent MRgLITT, suggesting that ADC analysis can assist with postablation outcome prediction and patient stratification.

Piriform Cortex Ablation Volume Is Associated With Seizure Outcome in Mesial Temporal Lobe Epilepsy.

BACKGROUND: Growing evidence suggests that piriform cortex resection during anterior temporal lobectomy is important for achieving good seizure outcome in mesial temporal lobe epilepsy (mTLE). However, the relationship between seizure outcome and piriform cortex ablation during MR-guided laser interstitial thermal therapy (MRgLITT) remains unclear. OBJECTIVE: To determine whether ablation of piriform cortex was associated with seizure outcome in patients with mTLE undergoing MRgLITT. METHODS: We performed preablation and postablation volumetric analyses of hippocampus, amygdala, piriform cortex, and ablation volumes in patients with mTLE who underwent MRgLITT at our institution from 2014 to 2019. RESULTS: Thirty nine patients with mTLE were analyzed. In univariate logistic regression, percent piriform cortex ablation was associated with International League Against Epilepsy (ILAE) class 1 at 6 months (odds ratio [OR] 1.051, 95% CI [1.001-1.117], P = .045), whereas ablation volume, percent amygdala ablation, and percent hippocampus ablation were not ( P > .05). At 1 year, ablation volume was associated with ILAE class 1 (OR 1.608, 95% CI [1.071-2.571], P = .021) while percent piriform cortex ablation became a trend (OR 1.050, 95% CI [0.994-1.109], P = .054), and both percent hippocampus ablation and percent amygdala ablation were not significantly associated with ILAE class 1 ( P > .05). In multivariable logistic regression, only percent piriform cortex ablation was a significant predictor of seizure freedom at 6 months (OR 1.085, 95% CI [1.012-1.193], P = .019) and at 1 year (OR 1.074, 95% CI [1.003-1.178], P = .041). CONCLUSION: Piriform cortex ablation volume is associated with seizure outcome in patients with mTLE undergoing MRgLITT. The piriform cortex should be considered a high yield ablation target to achieve good seizure outcome.

Advances in monitoring for acute spinal cord injury: a narrative review of current literature.

Spinal cord injury (SCI) is a devastating condition that affects about 17,000 individuals every year in the United States, with approximately 294,000 people living with the ramifications of the initial injury. After the initial primary injury, SCI has a secondary phase during which the spinal cord sustains further injury due to ischemia, excitotoxicity, immune-mediated damage, mitochondrial dysfunction, apoptosis, and oxidative stress. The multifaceted injury progression process requires a sophisticated injury-monitoring technique for an accurate assessment of SCI patients. In this narrative review, we discuss SCI monitoring modalities, including pressure probes and catheters, micro dialysis, electrophysiologic measures, biomarkers, and imaging studies. The optimal next-generation injury monitoring setup should include multiple modalities and should integrate the data to produce a final simplified assessment of the injury and determine markers of intervention to improve patient outcomes.

Phase- targeted stimulation modulates phase-amplitude coupling in the motor cortex of the human brain.

BACKGROUND: Phase-amplitude coupling (PAC) in which the amplitude of a faster field potential oscillation is coupled to the phase of a slower rhythm, is one of the most well-studied interactions between oscillations at different frequency bands. In a healthy brain, PAC accompanies cognitive functions such as learning and memory, and changes in PAC have been associated with neurological diseases including Parkinson's disease (PD), schizophrenia, obsessive-compulsive disorder, Alzheimer's disease, and epilepsy. OBJECTIVE: /Hypothesis: In PD, normalization of PAC in the motor cortex has been reported in the context of effective treatments such as dopamine replacement therapy and deep brain stimulation (DBS), but the possibility of normalizing PAC through intervention at the cortex has not been shown in humans. Phase-targeted stimulation (PDS) has a strong potential to modulate PAC levels and potentially normalize it. METHODS: We applied stimulation pulses triggered by specific phases of the beta oscillations, the low frequency oscillations that define phase of gamma amplitude in beta-gamma PAC, to the motor cortex of seven PD patients at rest during DBS lead placement surgery We measured the effect on PAC modulation in the motor cortex relative to stimulation-free periods. RESULTS: We describe a system for phase-targeted stimulation locked to specific phases of a continuously updated slow local field potential oscillation (in this case, beta band oscillations) prediction. Stimulation locked to the phase of the peak of beta oscillations increased beta-gamma coupling both during and after stimulation in the motor cortex, and the opposite phase (trough) stimulation reduced the magnitude of coupling after stimulation. CONCLUSION: These results demonstrate the capacity of cortical phase-targeted stimulation to modulate PAC without evoking motor activation, which could allow applications in the treatment of neurological disorders associated with abnormal PAC, such as PD.

Association of intraoperative end-tidal carbon dioxide level with ablation volume during magnetic resonance-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy.

OBJECTIVE: Maximal safe ablation of target structures during magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) is critical to achieving good seizure outcome in patients with mesial temporal lobe epilepsy (mTLE). The authors sought to determine whether intraoperative physiological variables are associated with ablation volume during MRgLiTT. METHODS: Patients with mTLE who underwent MRgLiTT at our institution from 2014 to 2019 were retrospectively analyzed. Ablation volume was determined with volumetric analysis of intraoperative postablation MR images. Physiological parameters (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP], end-tidal carbon dioxide [ETCO2]) measured 40 minutes prior to ablation were analyzed. Univariate and multivariate regression analyses were performed to determine independent predictors of ablation volume. RESULTS: Forty-four patients met the inclusion criteria. The median (interquartile range) ablation volume was 4.27 (2.92-5.89) cm3, and median ablation energy was 7216 (6402-8784) J. The median MAP, SBP, DBP, and ETCO2 values measured during the 40-minute period leading up to ablation were 72.8 (66.2-81.5) mm Hg, 104.4 (96.4-114.4) mm Hg, 62.4 (54.1-69.8) mm Hg, and 34.1 (32.0-36.2) mm Hg, respectively. In univariate analysis, only total laser energy (r = 0.464, p = 0.003) and 40-minute average ETCO2 (r = -0.388, p = 0.012) were significantly associated with ablation volume. In multivariate analysis, only ETCO2 ≤ 33 mm Hg (p = 0.001) was significantly associated with ablation volume. CONCLUSIONS: Total ablation energy and ETCO2, but not blood pressure, may significantly affect ablation volume in mTLE patients undergoing MRgLiTT. Mild hypocapnia was associated with increased extent of ablation. Intraoperative monitoring and modulation of ETCO2 may help improve extent of ablation, prediction of ablation volume, and potentially seizure outcome.

Apparent diffusion coefficient is associated with seizure outcome after magnetic resonance-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy.

BACKGROUND: Magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) is becoming a first-line surgical therapy for mesial temporal lobe epilepsy (mTLE) due to good seizure control and low complication risk. However, seizure outcomes after MRgLiTT remain highly variable and there is a need to improve patient selection and post-operative prognostication. In this retrospective study, we investigated whether the pre-operative MRI-derived apparent diffusion coefficient (ADC), used as a marker of tissue pathology in the mesial temporal structures could help predict seizure outcome. METHODS: Thirty-five patients who underwent MRgLiTT at our institution between 2014 and 2019 were included in the study. Demographic and clinical data were retrospectively collected. Seizure outcome was defined as good (ILAE Class I-II) and poor (ILAE Class III-VI). Volumetrics were performed on pre-ablation hippocampus and amygdala. Ablation volumes, and the proportion of ablated hippocampus and amygdala calculated via their respective mean voxel-wise ADC intensities were quantified from pre-operative and intra-operative post-ablation MRIs and statistically compared between the two outcome cohorts. Univarate and multivariate regression analysis was performed to identify demographic, clinical, and radiographic predictors of seizure outcome. RESULTS: Mean age at LiTT was 36 years and 14 (40 %) were female. Mean follow-up duration was 1.90 ± 0.17 years. Twenty-seven (77 %) patients had mesial temporal sclerosis. There was no significant difference in the ablation volumes and proportion of ablated volume of hippocampus and amygdala between the two outcome groups. Patients with good seizure outcome had significantly higher normalized ADC intensities in the ablated mesial temporal structures compared to those with poor outcome (0.01 ± 0.08 vs.-0.29 ± 0.06; p = 0.015). CONCLUSIONS: mTLE patients with higher ADC intensities in the ablated regions of the hippocampus and the amygdala are more likely to have good seizure outcome following MRgLiTT. Our results suggest that pre-operative ADC analysis may improve both patient selection and epileptogenic zone targeting during MRgLiTT. Further investigation with large, prospective cohorts is needed to validate the clinical utility of ADC in improving seizure outcome following MRgLiTT.

Ultrasound in Traumatic Spinal Cord Injury: A Wide-Open Field.

Traumatic spinal cord injury (SCI) is a common and devastating condition. In the absence of effective validated therapies, there is an urgent need for novel methods to achieve injury stabilization, regeneration, and functional restoration in SCI patients. Ultrasound is a versatile platform technology that can provide a foundation for viable diagnostic and therapeutic interventions in SCI. In particular, real-time perfusion and inflammatory biomarker monitoring, focal pharmaceutical delivery, and neuromodulation are capabilities that can be harnessed to advance our knowledge of SCI pathophysiology and to develop novel management and treatment options. Our review suggests that studies that evaluate the benefits and risks of ultrasound in SCI are severely lacking and our understanding of the technology's potential impact remains poorly understood. Although the complex anatomy and physiology of the spine and the spinal cord remain significant challenges, continued technological advances will help the field overcome the current barriers and bring ultrasound to the forefront of SCI research and development.

Total Fasting and Dehydration in the Operating Room: How Can Surgeons Survive and Thrive?

OBJECTIVES: Hydration and nutrition are critical to achieving optimal performance. This study aimed to assess the impact of limited oral intake in the operating room environment on surgical resident health, well-being, and performance. DESIGN: Electronic survey was sent to 94 surgical trainees at our institution in 2020. Chi-square analyses were performed to assess for differences in survey responses by sex. SETTING: A single tertiary-care institution. PARTICIPANTS: Surveys were sent to surgical residents and fellows in general surgery, neurosurgery, and orthopedic surgery. Seventy-nine (80%) of the 94 residents and fellows responded. RESULTS: Of the 79 responses, most trainees (79%) experienced dehydration within 6 hours of operating. Forty-four (56%) reported no fluid intake for greater than 6 hours on average, and 39 (49%) reported that they frequently had difficulty rehydrating in between cases. Most of the respondents (70%) frequently experienced symptoms of dehydration, including orthostasis, headache, and constipation. Fifty-six (71%) believed that dehydration frequently affected their performance. Compared to men, women were more likely to feel dehydrated within 4 hours of operating (58% vs. 25%, p = 0.005). Women were also more likely to have difficulty rehydrating in between cases (75% vs. 38%, p = 0.0026), experience symptoms of dehydration (92% vs. 60%, p = 0.0049), and report that dehydration affects surgical performance (88% vs. 64%, p = 0.0318). CONCLUSIONS: Prolonged fasting and dehydration are common issues that may negatively impact performance and wellbeing of surgical trainees. Also, dehydration may affect men and women differently.

Opioid use and spinal cord stimulation therapy: The long game.

Spinal cord stimulation (SCS) has been considered as an alternative therapy to reduce opioid requirements in certain chronic pain disorders. However, information on long-term opioid consumption patterns and their impact on SCS device explantation is lacking. We conducted a retrospective study of 45 patients to characterize long-term patterns of opioid usage after SCS implantation. Daily morphine equivalent dosage (MED) increased, decreased, and remained the same in 40%, 40%, and 20% of patients at 1-year follow-up, respectively. Twelve (27%) underwent explantation due to treatment failure at a median of 18 months after implantation. Pre-operative opioid status (naïve vs. active use) was not associated with explantation (18% vs. 29%, p = 0.699) and neither was the daily MED change status (i.e. increased, decreased, unchanged) at 1-year (p = 0.499, 1.000, 0.735, respectively). Following explantation, reduction in the daily MED was seen in 92% of patients with dosages falling below pre-operative baseline in nine. Among the opioid naïve patients, 55% were on opioids at last follow-up (average 32.4 ± 14.6 months). Our results indicate that daily opioid consumption does not decrease in most patients 1-year after SCS implantation. Furthermore, post-operative evaluation beyond 1-year is necessary to assess the efficacy and durability of SCS therapy as well as its impact on opioid requirement. Lastly, rigorous patient selection and pre-operative risk assessment for misuse and dependence are paramount to improving outcome after SCS implantation.

Development of a Smart Hospital Assistant: Integrating Artificial Intelligence and a Voice-User Interface for Improved Surgical Outcomes.

Patient safety and efficiency are top priorities in any surgical procedure. One effective way to achieve these objectives is to automate the logistical and routine tasks that occur in the operating suite. Inspired by smart assistant technology already widely used in the consumer sector, we engineered the Smart Hospital Assistant (SHA), a smart, voice-controlled virtual assistant that handles natural speech recognition while executing non-surgical functions to aid any surgery. In simulated procedures, the SHA reduced operating time, optimized surgical staff resources, and reduced the number of major touch-points that can lead to surgical site infections. The SHA holds promise not only for use in the operating theater, but also in understaffed healthcare environments where automation can improve healthcare delivery.

Traumatic sacral dermoid cyst rupture with intracranial subarachnoid seeding of lipid particles: illustrative case.

BACKGROUND: Intracranial deposits of fat droplets are an unusual presentation of a spinal dermoid cyst after spontaneous rupture and are even more uncommon after trauma. Here, the authors present a case with this rare clinical presentation, along with a systematic review of the literature to guide decision making in these patients. OBSERVATIONS: A 54-year-old woman with Lynch syndrome presented with severe headache and sacrococcygeal pain after a traumatic fall. Computed tomography of the head revealed multifocal intraventricular and intracisternal fat deposits, which were confirmed by magnetic resonance imaging (MRI) of the neuroaxis; in addition, a ruptured multiloculated cyst was identified within the sacral canal with proteinaceous/hemorrhagic debris, most consistent with a sacral dermoid cyst with rupture into the cerebrospinal fluid (CSF) space. An unruptured sacral cyst was later noted on numerous previous MRI scans. In our systematic review, we identified 20 similar cases, most of which favored surgical treatment. LESSONS: Rupture of an intraspinal dermoid cyst must be considered when intracranial fat deposits are found in the context of cauda equina syndrome, meningism, or hydrocephalus. Complete tumor removal with close postoperative follow-up is recommended to decrease the risk of complications. CSF diversion must be prioritized if life-threatening hydrocephalus is present.

Non-staged bilateral Globus Pallidus Internus deep brain stimulation lead revision using intraoperative MRI: a case report and literature review.

BACKGROUND: Deep brain stimulation (DBS) lead revision due to suboptimal therapy is common but there is no standardised protocol. We describe a novel technique using iMRI to perform concurrent new Globus Pallidus Internus (GPi) DBS lead implantation and old lead removal in a dystonia patient.Case-description: A 60-year-old woman with medication and neurotoxin-refractory isolated cervical dystonia underwent awake bilateral GPi DBS surgery with MER-guided lead implantation. She initially had a favourable response but later reported suboptimal benefit despite reprogramming. MRI demonstrated suboptimal lead placement and MRI-guided revision surgery under general anesthesia was planned. The goal was to place new leads superior and medial to the existing leads. Using a 1.5 T iMRI and the ClearPoint® NeuroNavigation system, new leads were placed through the existing burr holes, into the new targets with radial errors < 0.08mm bilaterally without crossing the old leads. The old leads were then removed and the new leads connected to the existing pulse generator. The patient tolerated the procedure well and had improved side-effect profile at all contacts at 1-month follow-up. CONCLUSIONS: Non-staged iMRI-guided DBS revision surgery under general anesthesia is technically feasible and is an alternative strategy to a staged iMRI-guided revision surgery or an awake MER-guided revision surgery in select patients.