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Minimally invasive modification of the Goel-Harms atlantoaxial fusion technique

Neurosurg Focus 54(3):E14, 2023

The Goel-Harms atlantoaxial screw fixation technique for the treatment of atlantoaxial instability and unstable odontoid fractures is reliable and reproducible for a variety of anatomies. The drawbacks of the technique are the potential for significant bleeding from the C2 nerve root venous plexus and the risks associated with posterior midline exposure and retraction, such as pain and wound complications. The authors developed a minimally invasive surgical (MIS) modification of the Goel-Harms technique using intra-articular grafting to facilitate placement of percutaneous lateral mass and pars screws with extended tabs for minimally invasive subfascial rod placement. The objective of this study was to present the authors’ first series of 5 patients undergoing minimally invasive modification in comparison with 51 patients undergoing open atlantoaxial fusion.

METHODS A retrospective analysis of patient comorbid conditions, blood loss, length of surgery, and length of stay was performed on patients undergoing Goel-Harms instrumented fusion (GHIF) for unstable odontoid fractures performed between 2016 and 2021.

RESULTS Patients undergoing the minimally invasive procedure showed significantly less blood loss than those undergoing the open atlantoaxial fusion procedure, with a median blood loss of 30 ml compared with 150 ml using the open technique (p < 0.01). The patients showed no significant differences in length of stay (2 days for MIS vs 4 days for open atlantoaxial fusion, p = 0.25). There were no significant differences in length of surgery for MIS, but a possible trend toward increased operative duration (234 vs 151 minutes, p = 0.112).

CONCLUSIONS In this small pilot study, it was shown that MIS-GHIF can be performed with decreased blood loss in atlantoaxial instability and odontoid fractures. This technique may allow for greater and safer application of the procedure in the elderly and infirm.

 

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The value of intraoperative indocyanine green angiography in microvascular decompression for hemifacial spasm to avoid brainstem ischemia

Acta Neurochirurgica (2023) 165:747–755

Despite being rarely reported, ischemic insults resulting from compromising small brainstem perforators following microvascular decompression (MVD) remain a potential devastating complication. To avoid this complication, we have been using indocyanine green (ICG) angiography intraoperatively to check the flow within the small brainstem perforators. We aim to evaluate the safety and usefulness of ICG videoangiography in MVD.

Methods We extracted retrospective data of patients who received ICG videoangiography from our prospectively maintained database for microvascular decompression. We noted relevant data including demographics, offending vessels, operative technique, outcome, and complications.

Results Out of the 438 patients, 15 patients with a mean age (SD) of 53 ± 10.5 years underwent intraoperative ICG angiography. Male:female was 1:1.14. The mean disease duration prior to surgery was 7.7 ± 5.3 years. The mean follow-up (SD) was 50.7 ± 42.0 months. In 14 patients, the offending vessel was an artery, and in one patient, a vein. Intraoperative readjustment of the Teflon pledget or sling was required in 20% (3/15) of the cases. No patient had any sort of brainstem ischemia. Eighty percent of the patients (12/15) experienced complete resolution of the spasms. 86.7% (13/15) of the patients reported a satisfactory outcome with marked improvement of the spasms. Three patients experienced slight hearing affection after surgery, which improved in two patients later. There was no facial or lower cranial nerve affection.

Conclusion Intraoperative ICG is a safe tool for evaluating the flow within the brain stem perforators and avoiding brainstem ischemia in MVD for hemifacial spasm.

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A Sensorised Surgical Glove to Analyze Forces During Neurosurgery

Neurosurgery 92:639–646, 2023

Measuring intraoperative forces in real time can provide feedback mechanisms to improve patient safety and surgical training. Previous force monitoring has been achieved through the development of specialized and adapted instruments or use designs that are incompatible with neurosurgical workflow.

OBJECTIVE: To design a universal sensorised surgical glove to detect intraoperative forces, applicable to any surgical procedure, and any surgical instrument in either hand.

METHODS: We created a sensorised surgical glove that was calibrated across 0 to 10 N. A laboratory experiment demonstrated that the sensorised glove was able to determine instrument-tissue forces. Six expert and 6 novice neurosurgeons completed a validated grape dissection task 20 times consecutively wearing the sensorised glove. The primary outcome was median and maximum force (N).

RESULTS: The sensorised glove was able to determine instrument-tissue forces reliably. The average force applied by experts (2.14 N) was significantly lower than the average force exerted by novices (7.15 N) (P = .002). The maximum force applied by experts (6.32 N) was also significantly lower than the maximum force exerted by novices (9.80 N) (P = .004). The sensorised surgical glove’s introduction to operative workflow was feasible and did not impede on task performance.

CONCLUSION: We demonstrate a novel and scalable technique to detect forces during neurosurgery. Force analysis can provide real-time data to optimize intraoperative tissue forces, reduce the risk of tissue injury, and provide objective metrics for training and assessment.

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Spontaneous empyema and brain abscess in an intensive care population: clinical presentation, microbiology, and factors associated with outcome

Acta Neurochirurgica (2023) 165:651–658

Data on critically ill patients with spontaneous empyema or brain abscess are limited. The aim was to evaluate clinical presentations, factors, and microbiological findings associated with the outcome in patients treated in a Neurocritical Care Unit.

Methods In this retrospective study, we analyzed 45 out of 101 screened patients with spontaneous epidural or subdural empyema and/or brain abscess treated at a tertiary care center between January 2012 and December 2019. Patients with postoperative infections or spinal abscess were excluded. Medical records were reviewed for baseline characteristics, origin of infection, laboratory and microbiology findings, and treatment characteristics. The outcome was determined using the Glasgow outcome scale extended (GOSE).

Results Favorable outcome (GOSE 5–8) was achieved in 38 of 45 patients (84%). Four patients died (9%), three remained severely disabled (7%). Unfavorable outcome was associated with a decreased level of consciousness at admission (Glasgow coma scale < 9) (43% versus 3%; p = 0.009), need of vasopressors (71% versus 11%; p = 0.002), sepsis (43% versus 8%; p = 0.013), higher age (65.1 ± 15.7 versus 46.9 ± 17.5 years; p = 0.014), shorter time between symptoms onset and ICU admission (5 ± 2.4 days versus 11.6 ± 16.8 days; p = 0.013), and higher median C-reactive protein (CRP) serum levels (206 mg/l, range 15–259 mg/l versus 17.5 mg/l, range 3.3–72.7 mg/l; p = 0.036). With antibiotics adapted according to culture sensitivities in the first 2 weeks, neuroimaging revealed a progression of empyema or abscess in 45% of the cases.

Conclusion Favorable outcome can be achieved in a considerable proportion of an intensive care population with spontaneous empyema or brain abscess. Sepsis and more frequent need for vasopressors, associated with unfavorable outcome, indicate a fulminant course of a not only cerebral but systemic infection. Change of antibiotic therapy according to microbiological findings in the first 2 weeks should be exercised with great caution.

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Minimally Invasive Preganglionic C2 Root Section for Occipital Neuralgia

Operative Neurosurgery 24:E148–E152, 2023

Occipital neuralgia is a painful condition that is believed to occur from processes that affect the greater, lesser, or third occipital nerves. Diagnosis is often made with a combination of classical symptoms, tenderness over the occipital region, and response to occipital nerve blocks. Cervical computed tomography or MRI may be obtained in multiple positions to detect any impingement. Diagnosis can be made with MRI tractography. Nonsurgical treatments include local anesthetic and steroid injections, anticonvulsant medications, botulinum toxin injections, physical therapy, acupuncture, transcutaneous electrical stimulation, cryoneurolysis, and radiofrequency ablation. Surgical treatments include greater occipital nerve decompression, C2 root section, intradural dorsal root rhizotomy, C1-2 fusion, and occipital nerve stimulation. Although stimulation has been favored in the past decade, complications and maintenance of the devices have led us to return to C2 ganglionectomy.

OBJECTIVE: To report on the use of a minimally invasive technique for C2 ganglionectomy to treat occipital neuralgia.

METHODS: Review demographic, surgery, and outcome data of a minimally invasive C2 root ganglionectomy used to treat to 2 patients with occipital neuralgia.

RESULTS: We report on 2 patients with clinically stereotypical unilateral occipital neuralgia confirmed by greater occipital nerve block, but with no imaging correlate. Both were successfully managed by C2 ganglionectomy through an 18-mm tubular retractor and outpatient surgery. Accompanying text, still photographs, and video describe the technique in detail.

CONCLUSION: Minimally invasive C2 ganglionectomy can be used to successfully treat occipital neuralgia.

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Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training

J Neurosurg 138:732–739, 2023

Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity.

METHODS Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)–middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)–PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery–anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey.

RESULTS A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models.

CONCLUSIONS The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

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Idiopathic Ventral Spinal Cord Hernia—A Single-Center Case Series of 11 Patients

Operative Neurosurgery 24:268–275, 2023

Idiopathic spinal cord herniations (ISCH) are rare defects of the ventromedial or mediolateral dura mater with herniation of the spinal cord through the defect with approximately 350 described cases worldwide. Patients usually become symptomatic with motor or sensory neurological deficits and gait disturbances.

OBJECTIVE: To describe characteristic symptoms and clinical findings and to evaluate the postoperative course and outcomes of ISCH. METHODS: We present a single-center data analysis of a case series of 11 consecutive patients who were diagnosed with ISCH and underwent surgery in our department between 2009 and 2021.

RESULTS: All herniations were located in the thoracic spine between T2 and T9. In most cases, gait ataxia and dysesthesia led to further workup and subsequently to the diagnosis of ISCH. A “far-enough” posterior-lateral surgical approach, hemilaminectomy or laminectomy with a transdural approach, was performed under intraoperative neurophysiological monitoring which was followed by adhesiolysis, repositioning of the spinal cord and sealing using a dura patch. After surgery, clinical symptoms improved in 9 of 11 patients (81.8%), while only 1 patient experienced deterioration of symptoms (9.1%) and 1 patient remained equal (9.1%). The median preoperative McCormick grade was 3 (±0.70), while the median postoperative grade was 2 (±0.98) (P = .0047).

CONCLUSION: In our case series of ISCH, we found that in most patients, neurological deficits improved postoperatively. This indicates that surgery in ISCH should not be delayed in symptomatic patients.

 

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Novel Merging of CT and MRI to Allow for Safe Navigation into Kambin’s Triangle for Percutaneous Lumbar Interbody Fusion

Operative Neurosurgery 24:331–340, 2023

For percutaneous lumbar fusion (percLIF), magnetic resonance imaging and computed tomography are critical to defining surgical corridors. Currently, these scans are performed separately, and surgeons then use fluoroscopy or neuromonitoring to guide instruments through Kambin’s triangle. However, anatomic variations and intraoperative positional changes are possible, meaning that safely accessing Kambin’s triangle remains a challenge because nerveroot visualization without endoscopes has not been thoroughly described.

OBJECTIVE: To overcome the known challenges of percLIF and reduce the likelihood of iatrogenic injuries by showing real-time locations of neural and bony anatomy.

METHODS: The authors demonstrate an intraoperative navigational platform that applies nerve root segmentation and image fusion to assist with percLIF. Five patients from a single institution were included.

RESULTS: Of the 5 patients, the mean age was 71 ± 8 years and 3 patients (60%) were female. One patient had general anesthesia while the remaining 4 patients underwent awake surgery with spinal anesthesia. The mean area for the L4-L5 Kambin’s triangle was 76.1 ± 14.5 mm2. A case example is shown where the side of approach was based on the fact that Kambin’s triangle was larger on one side compared with the other. The mean operative time was 170 ± 17 minutes, the mean blood loss was 32 ± 16 mL, and the mean hospital length of stay was 19.6 ± 8.3 hours. No patients developed postoperative complications.

CONCLUSION: This case series demonstrates the successful and safe application of nerve segmentation using magnetic resonance imaging/computed tomography fusion to perform percLIF and provide positive patient outcomes.

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Factors Predicting Cerebrospinal Fluid Leaks in Microvascular Decompressions: A Case Series of 1011 Patients

Operative Neurosurgery 24(3):p 262-267, March 2023.

Microvascular decompression (MVD) using a retrosigmoid approach is a highly effective, open-surgical procedure for neurovascular conflict in the posterior fossa, although there is a risk of postoperative cerebrospinal fluid (CSF) leak.

OBJECTIVE:
To identify factors associated with postoperative CSF leakage after MVD.

METHODS:
We retrospectively reviewed all patients who underwent MVDs at our institution from 2007 to 2020. Patient demographics, clinical diagnoses, and procedural characteristics were recorded and compared. Factors leading to CSF leak were analyzed using χ2, univariate, and multivariate regression.

RESULTS:
Of 1011 patients who underwent MVDs, 37 (3.7%) presented with postoperative CSF leaks. In univariate analysis, the use of Cranios/Norian to obliterate the air cells was protective against CSF leak (P = .01). Craniotomies (P = .002), the use of dural substitutes such as Durepair (P = .04), dural onlays such as DuraGen (P = .04), muscle/fascia (P = .03), and titanium mesh cranioplasty >5 cm (P = .03) were associated with CSF leak. On multivariate analysis, only the presence of craniotomies (P = .04) and nonprimary dural closure (P = .03) were significant risk factors for CSF leak. When excluding the 34 (3.4%) patients who underwent a craniotomy, the lack of primary dural closure still remained significantly associated with postoperative CSF leak (P = .04).

CONCLUSION:
Our results represent one of the largest series of posterior fossa surgeries for a uniform indication in North America. Our study demonstrates increased risk for postoperative CSF leak when craniotomies are performed and when primary dural closure is not established. Given the small sample of patients who received a craniotomy, however, future studies corroborating this finding should be performed.

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Risk of intracranial aneurysm recurrence after microsurgical clipping based on 3D digital subtraction angiography

J Neurosurg 138:717–723, 2023

Current knowledge of recurrence rates after intracranial aneurysm (IA) surgery relies on 2D digital subtraction angiography (DSA), which fails to detect more than 75% of small aneurysm remnants. Accordingly, the discrimination between recurrence and growth of a remnant remains challenging, and actual assessment of recurrence risk of clipped IAs could be inaccurate. The authors report, for the first time, 3D-DSA–based long-term durability and risk factor data of IA recurrence and remnant growth after microsurgical clipping.

METHODS Prospectively collected data for 305 patients, with a total of 329 clipped IAs that underwent baseline 3DDSA, were evaluated. The incidence of recurrent IA was described by Kaplan-Meier curves. Risk factors for IA recurrence were analyzed by multivariable Cox proportional hazards and logistic regression models.

RESULTS The overall observed proportion of IA recurrence after clipping was 2.7% (9 of 329 IAs) at a mean followup of 46 months (0.7% per year). While completely obliterated IAs did not recur during follow-up, incompletely clipped aneurysms (76 of 329) demonstrated remnant growth in 11.8% (3.4% per year). Young age and large initial IA size significantly increased the risk of IA recurrence.

CONCLUSIONS The findings support those in previous studies that hypothesized that completely clipped IAs have an extremely low risk of recurrence. Conversely, the results highlight the significant risk posed by incompletely clipped IAs. Young patients with initial large IAs and incomplete obliteration have an especially high risk for IA recurrence and therefore should be monitored more closely.

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Extended endoscopic transsphenoidal approach for suprasellar craniopharyngiomas

Acta Neurochirurgica (2023) 165:677–683

Craniopharyngiomas are benign sellar lesions. Surgical excision of craniopharyngiomas is difficult because of the surrounding important neurovascular structures. The choice of surgery depends on the histological type, location, hormonal status, and size of the craniopharyngioma, surrounding neurovascular structures, and invasion of the brain parenchyma.

Methods We describe the resection of an adamantinomatous craniopharyngioma using an extended endoscopic endonasal approach and discuss the relevant surgical anatomy, indications, limitations, and possible complications.

Conclusions The extended endoscopic endonasal approach allows successful removal of the craniopharyngioma and poses little risk to surrounding neurovascular structures.

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A Retrospective Analysis of Pedicle Screw Placement Accuracy Using the ExcelsiusGPS Robotic Guidance System

Operative Neurosurgery 24:242–247, 2023

Robotic guidance has become widespread in spine surgery. Although the intent is improved screw placement, further system-specific data are required to substantiate this intention for pedicle screws in spinal stabilization constructs.

OBJECTIVE: To determine the accuracy of pedicle screws placed with the aid of a robot in a cohort of patients immediately after the adoption of the robot-assisted surgery technique.

METHODS: A retrospective, Institutional Review Board–approved study was performed on the first 100 patients at a single facility, who had undergone spinal surgeries with the use of robotic techniques. Pedicle screw accuracy was graded using the Gertzbein– Robbins Scale based on pedicle wall breach, with grade A representing 0 mm breach and successive grades increasing breach thresholds by 2 mm increments. Preoperative and postoperative computed tomography scans were also used to assess offsets between the objective plan and true screw placements.

RESULTS: A total of 326 screws were analyzed among 72 patients with sufficient imaging data. Ages ranged from 21 to 84 years. The total accuracy rate based on the Gertzbein– Robbins Scale was 97.5%, and the rate for each grade is as follows: A, 82%; B, 15.5%; C, 1.5%; D, 1%; and E, 0. The average tip offset was 1.9 mm, the average tail offset was 2.0 mm, and the average angular offset was 2.6°.

CONCLUSION: Robotic-assisted surgery allowed for accurate implantation of pedicle screws on immediate adoption of this technique. There were no complications attributable to the robotic technique, and no hardware revisions were required.

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Spinal Intradural Arachnoid Cysts in Adults

Neurosurgery 92:450–463, 2023

Adult spinal intradural arachnoid cysts are rare pathologic entities with an unclear etiopathogenesis. These lesions can be dichotomized into primary (idiopathic) or secondary (related to inflammation, intradural surgery, or trauma) etiologies. Limited series have depicted optimal management strategies and clinical outcomes.

OBJECTIVE: To illustrate our experience with spinal intradural arachnoid cysts and to present a literature review of surgically treated cysts to elucidate the clinical and anatomic differences between etiologies.

METHODS: Institutional review revealed 29 patients. Various data were extracted from the medical record. Initial and follow-up symptomatologies of the surgical cohort were compared. The literature review included case series describing cysts managed surgically.

RESULTS: From patients treated surgically at our institution (22), there was a significant reduction in thoracic back pain postoperatively (P = .034). A literature review yielded 271 additional cases. Overall, primary and secondary lesions accounted for 254 and 39 cases, respectively. Cysts of secondary origin were more likely localized ventral to the spinal cord (P = .013). The rate of symptomatic improvement after surgical intervention for primary cysts was more than double than that of secondary cysts (P < .001). Compared with primary etiologies, the rates of radiographic progression (P = .032) and repeat surgery (P = .041) were each more than double for secondary cysts.

CONCLUSION: Surgical intervention for spinal intradural arachnoid cysts improves thoracic back pain. The literature supports surgical intervention for symptomatic primary spinal intradural arachnoid cysts with improved clinical outcomes. Surgery should be cautiously considered for secondary cysts given worse outcomes.

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Dissociation of Broca’s area from Broca’s aphasia in patients undergoing neurosurgical resections

J Neurosurg 138:847–857, 2023

Broca’s aphasia is a syndrome of impaired fluency with retained comprehension. The authors used an unbiased algorithm to examine which neuroanatomical areas are most likely to result in Broca’s aphasia following surgical lesions.

METHODS Patients were prospectively evaluated with standardized language batteries before and after surgery. Broca’s area was defined anatomically as the pars opercularis and triangularis of the inferior frontal gyrus. Broca’s aphasia was defined by the Western Aphasia Battery language assessment. Resections were outlined from MRI scans to construct 3D volumes of interest. These were aligned using a nonlinear transformation to Montreal Neurological Institute brain space. A voxel-based lesion-symptom mapping (VLSM) algorithm was used to test for areas statistically associated with Broca’s aphasia when incorporated into a resection, as well as areas associated with deficits in fluency independent of Western Aphasia Battery classification. Postoperative MRI scans were reviewed in blinded fashion to estimate the percentage resection of Broca’s area compared to areas identified using the VLSM algorithm.

RESULTS A total of 289 patients had early language evaluations, of whom 19 had postoperative Broca’s aphasia. VLSM analysis revealed an area that was highly correlated (p < 0.001) with Broca’s aphasia, spanning ventral sensorimotor cortex and supramarginal gyri, as well as extending into subcortical white matter tracts. Reduced fluency scores were significantly associated with an overlapping region of interest. The fluency score was negatively correlated with fraction of resected precentral, postcentral, and supramarginal components of the VLSM area.

CONCLUSIONS Broca’s aphasia does not typically arise from neurosurgical resections in Broca’s area. When Broca’s aphasia does occur after surgery, it is typically in the early postoperative period, improves by 1 month, and is associated with resections of ventral sensorimotor cortex and supramarginal gyri.

 

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Clinical Outcomes of Liposomal Bupivacaine Erector Spinae Block in Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery

Neurosurgery 92:590–598, 2023

Postoperative pain is a barrier to early mobility and discharge after lumbar surgery. Liposomal bupivacaine (LB) has been shown to decrease postoperative pain and narcotic consumption after transforaminal lumbar interbody fusions (TLIFs) when injected into the marginal suprafascial/subfascial plane-liposomal bupivacaine (MSSP-LB). Erector spinae plane (ESP) infiltration is a relatively new analgesic technique that may offer additional benefits when performed in addition to MSSP-LB.

OBJECTIVE: To evaluate postoperative outcomes of combining ESP-LB with MSSP-LB compared with MSSP-LB alone after single-level TLIF.

METHODS: A retrospective analysis was performed for patients undergoing single-level TLIFs under spinal anesthesia, 25 receiving combined ESP-LB and MSSP-LB and 25 receiving MSSP-LB alone. The primary outcome was length of hospitalization. Secondary outcomes included postoperative pain score, time to ambulation, and narcotics usage.

RESULTS: Baseline demographics and length of surgery were similar between groups. Hospitalization was significantly decreased in the ESP-LB + MSSP-LB cohort (2.56 days vs 3.36 days, P = .007), as were days to ambulation (0.96 days vs 1.29 days, P = .026). Postoperative pain area under the curve was significantly decreased for ESP-LB + MSSP-LB at 12 to 24 hours (39.37 ± 21.02 vs 53.38 ± 22.11, P = .03) and total (44.46 ± 19.89 vs 50.51 ± 22.15, P = .025). Postoperative narcotic use was significantly less in the ESP-LB + MSSP-LB group at 12 to 24 hours (13.18 ± 4.65 vs 14.78 ± 4.44, P = .03) and for total hospitalization (137.3 ± 96.3 vs 194.7 ± 110.2, P = .04).

CONCLUSION: Combining ESP-LB with MSSP-LB is superior to MSSP-LB alone for single level TLIFs in decreasing length of hospital stay, time to ambulation, postoperative pain, and narcotic use.

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Placebo-Controlled Effectiveness of Idiopathic Normal Pressure Hydrocephalus Shunting

Neurosurgery 92:481–489, 2023

Multiple prospective nonrandomized studies have shown 60% to 70% of patients with idiopathic normal pressure hydrocephalus (iNPH) improve with shunt surgery, but multicenter placebo-controlled trial data are necessary to determine its effectiveness.

OBJECTIVE: To evaluate the effectiveness of cerebrospinal fluid shunting in iNPH through comparison of open vs placebo shunting groups at 4 months using a pilot study.

METHODS: Patients were randomized to a Codman Certas Plus valve (Integra LifeSciences) set at 4 (open shunt group) or 8 (“virtual off”; placebo group). Patients and assessors were blinded to treatment group. The primary outcome measure was 10-m gait velocity. Secondary outcome measures included functional scales for bladder control, activities of daily living, depression, and quality of life. Immediately after 4-month evaluation, all shunts were adjusted in a blinded fashion to an active setting and followed to 12months after shunting.

RESULTS: A total of 18 patients were randomized. At the 4-month evaluation, gait velocity increased by 0.28 ± 0.28m/s in the open shunt group vs 0.04 ± 0.17m/s in the placebo group. The estimated treatment difference was 0.22 m/s ([P = .071], 95% CI 0.02 to 0.46). Overactive Bladder Short Form symptom bother questionnaire significantly improved in open shunt vs placebo (P = .007). The 4-month treatment delay did not reduce the subsequent response to active shunting, nor did it increase the adverse advents rate at 12 months.

CONCLUSION: This multicenter, randomized pilot study demonstrates the effectiveness, safety, and feasibility of a placebo-controlled trial in iNPH, and found a trend suggesting gait velocity improves more in the open shunt group than in the placebo group.

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A system of anatomical triangles defining dissection routes to brainstem cavernous malformations

J Neurosurg 138:768–784, 2023

Anatomical triangles defined by intersecting neurovascular structures delineate surgical routes to pathological targets and guide neurosurgeons during dissection steps. Collections or systems of anatomical triangles have been integrated into skull base surgery to help surgeons navigate complex regions such as the cavernous sinus. The authors present a system of triangles specifically intended for resection of brainstem cavernous malformations (BSCMs). This system of triangles is complementary to the authors’ BSCM taxonomy that defines dissection routes to these lesions.

METHODS The anatomical triangle through which a BSCM was resected microsurgically was determined for the patients treated during a 23-year period who had both brain MRI and intraoperative photographs or videos available for review.

RESULTS Of 183 patients who met the inclusion criteria, 50 had midbrain lesions (27%), 102 had pontine lesions (56%), and 31 had medullary lesions (17%). The craniotomies used to resect these BSCMs included the extended retrosigmoid (66 [36.1%]), midline suboccipital (46 [25.1%]), far lateral (30 [16.4%]), pterional/orbitozygomatic (17 [9.3%]), torcular (8 [4.4%]), and lateral suboccipital (8 [4.4%]) approaches. The anatomical triangles through which the BSCMs were most frequently resected were the interlobular (37 [20.2%]), vallecular (32 [17.5%]), vagoaccessory (30 [16.4%]), supracerebellar-infratrochlear (16 [8.7%]), subtonsillar (14 [7.7%]), oculomotor-tentorial (11 [6.0%]), infragalenic (8 [4.4%]), and supracerebellar-supratrochlear (8 [4.4%]) triangles. New but infrequently used triangles included the vertebrobasilar junctional (1 [0.5%]), supratrigeminal (3 [1.6%]), and infratrigeminal (5 [2.7%]) triangles. Overall, 15 BSCM subtypes were exposed through 6 craniotomies, and the approach was redirected to the BSCM by one of the 14 triangles paired with the BSCM subtype.

CONCLUSIONS A system of BSCM triangles, including 9 newly defined triangles, was introduced to guide dissection to these lesions. The use of an anatomical triangle better defines the pathway taken through the craniotomy to the lesion and refines the conceptualization of surgical approaches. The triangle concept and the BSCM triangle system increase the precision of dissection through subarachnoid corridors, enhance microsurgical execution, and potentially improve patient outcomes.

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“July Effect” in Spinal Fusions: A Coarsened Exact-Matched Analysis

Neurosurgery 92:623–631, 2023

Few neurosurgical studies examine the July Effect within elective spinal procedures, and none uses an exact-matched protocol to rigorously account for confounders.

OBJECTIVE: To evaluate the July Effect in single-level spinal fusions, after coarsened exact matching of the patient cohort on key patient characteristics (including race and comorbid status) known to independently affect neurosurgical outcomes.

METHODS: Two thousand three hundred thirty-eight adult patients who underwent single-level, posterior-only lumbar fusion at a single, multicenter university hospital system were retrospectively enrolled. Primary outcomes included readmissions, emergency department visits, reoperation, surgical complications, and mortality within 30 days of surgery. Logistic regression was used to analyze month as an ordinal variable. Subsequently, outcomes were compared between patients with surgery at the beginning vs end of the academic year (ie, July vs April–June), before and after coarsened exact matching on key characteristics. After exact matching, 99 exactly matched pairs of patients (total n = 198) were included for analysis.

RESULTS: Among all patients, operative month was not associated with adverse postoperative events within 30 days of the index operation. Furthermore, patients with surgeries in July had no significant difference in adverse outcomes. Similarly, between exact-matched cohorts, patients in July were observed to have noninferior adverse postoperative events.

CONCLUSION: There was no evidence suggestive of a July Effect after single-level, posterior approach spinal fusions in our cohort. These findings align with the previous literature to imply that teaching hospitals provide adequate patient care throughout the academic year, regardless of how long individual resident physician assistants have been in their particular role.

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Contralateral subfrontal approach for tuberculum sellae meningioma

J Neurosurg 138:598–609, 2023

Tuberculum sellae meningiomas (TSMs) present a burdensome surgical challenge because of their adjacency to vital neurovascular structures. The contralateral subfrontal approach provides an outstanding corridor for removing a TSM with an excellent visual outcome and limited complications. The authors present their long-term surgical experience in treating TSMs via the contralateral subfrontal approach and discuss patient selection, surgical techniques, and clinical outcomes.

METHODS Between 2005 and 2021, the authors used the contralateral subfrontal approach in 74 consecutive patients presenting with TSMs. The surgical decision-making process and surgical techniques are described, and the clinical outcomes were retrospectively analyzed.

RESULTS The mean patient age was 54.4 years, with a female predominance (n = 61, 82%). Preoperatively, 61 patients (82%) had vision symptoms and 73 (99%) had optic canal invasion by tumor. Gross-total resection was achieved in almost all patients (n = 70, 95%). The visual function improvement and stabilization rate was 91% (67/74). Eight patients (11%) showed a worsening of visual function on the less-compromised (approach-side) optic nerve. There was no occurrence of cerebrospinal fluid leakage. Four patients (5%) experienced recurrences after the initial operation (mean follow-up duration 63 months). There were no deaths in this study.

CONCLUSIONS The contralateral subfrontal approach provides a high chance of complete tumor removal and visual improvement with limited complications and recurrences, especially when the tumor is in a unilateral or midline location causing unilateral visual symptoms or bilateral asymmetrical visual symptoms, regardless of tumor size or encasement of major vessels. With the appropriate patient selection, surgical technique, and familiarity with surrounding neurovascular structures, this approach is reliable for TSM surgery.

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Comparison of clinical outcomes between cervical disc arthroplasty and anterior cervical discectomy and fusion for the treatment of single-level cervical spondylosis: a 10-year follow-up study

The Spine Journal 23 (2023) 361−368

The theoretical advantage of cervical disc arthroplasty includes preserved motion at the cervical level, which may reduce degeneration of the adjacent segments. The long-term follow-up results are still controversial.

PURPOSE: The present study aimed to retrospectively study the long-term efficacy and complications of cervical disc arthroplasty using a single commercially-available device in a single center.

STUDY DESIGN: This was a propensity-score matched cohort study.

PATIENT SAMPLE: This study enrolled 148 single-level cervical degenerative disease patients from January 2009 to March 2012. After 1:1 propensity score matching, 39 patients remained in the ACDF or ACDR groups.

OUTCOME MEASURES: The outcome measures were neurological functions (Neck Disability Index (NDI) and Japan Orthopedic Association (JOA) scores), radiographic evaluations (cervical curvature, operative segment range of motion, degenerative condition of adjacent segments, heterotopic ossification (HO) of the surgical segment), and complications.

METHODS: NDI and JOA scores were used to evaluate patient neurological functions. Cervical curvature (C2-C7 Cobb angle) and operative segment range of motion (ROM) were compared between the two groups. Grading criteria for osteophyte formation were used to evaluate the degenerative condition of adjacent segments. HO after ACDR was graded according to the McAfee grading method.

RESULTS: The average follow-up time was 119.3 §17.2 months. Satisfactory improvements in neurological function were obtained for both the ACDR and ACDF groups. There were no significant differences in VAS or NDI scores between the two groups. In the ACDR group, the ROM of the operative segment increased from 6.7 §4.3˚ before the operation to 8.9 §3.5˚ on the second day after the operation (p<.001). The ROM of the operative segment was 8.1 §4.0˚ at the 1-year follow-up, 7.2 §3.6˚ at the 2-year follow-up, 5.7 §4.5˚ at the 5-year follow-up and 4.3 §3.9˚ at the last follow-up. ASD was more likely to develop in the caudal adjacent segments and progressed with the follow-up time. At the last follow-up, HO was present in 27 patients (69.23%), while high-grade HO (McAfee scores III and IV) was detected in 6 patients (15.38%).

CONCLUSIONS: Through nearly 10 years of follow-up, ACDR was as effective as ACDF for treating single-level degenerative cervical disc disease. However, HO and the role of ACDR in the protection of ASD remains to be further observed and followed up.

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