Visual Morbidity in Patients With Ophthalmic Segment Aneurysms Treated With Flow Diverters

Neurosurgery 94:538–544, 2024

Flow diverter (FD) treatment for aneurysms of the ophthalmic segment of the internal carotid artery (ICA) may raise concerns about visual morbidity related to coverage of the ophthalmic artery by the device. Our objective was to evaluate clinical and angiographic outcomes associated with FD treatment of these aneurysms, with particular emphasis on visual morbidity.

METHODS: We performed a retrospective analysis of the endovascular databases at 2 US centers to identify consecutive patients with aneurysms along the ophthalmic segment of the ICA that were treated with FDs between January 2010 and December 2022. Baseline demographics, aneurysm characteristics, and periprocedural and postprocedural data, including the occurrence of visual complications, were collected.

RESULTS: One hundred and thirteen patients with 113 aneurysms were identified for inclusion in this study. The mean age of the patients was 59.5 ± 12.4 years, and 103 (91.2%) were women. The ophthalmic artery origin was involved in 40 (35.4%) aneurysms, consisting of a neck origin in 33 (29.2%) and a dome origin in 7 (6.2%). New transient visual morbidity during the hospital stay included impaired visual acuity or blurriness in 1 (0.9%) patient, diplopia in 1 (0.9%), and floaters in 1 (0.9%). New transient visual morbidity during follow-up included impaired visual acuity or blurriness in 5 patients (4.4%), diplopia in 3 (2.7%), ipsilateral visual field defect in 1 (0.9%), and floaters in 6 (5.3%). Permanent visual morbidity occurred in 1 patient (0.9%). Among the 101 patients who had angiographic follow-up, the Raymond-Roy occlusion classifications were I (complete aneurysm occlusion) in 85 (84.2%), II (residual neck) in 11 (10.9%), and III (residual aneurysm) in 5 (4.9%).

CONCLUSION: In our experience, flow diversion for ICA ophthalmic segment aneurysms resulted in low rates of visual morbidity, which was mostly transient in occurrence.

Sacral Tarlov perineurial cysts: a systematic review of treatment options

J Neurosurg Spine 40:375–388, 2024

Tarlov perineurial spinal cysts (TCs) are an underrecognized cause of spinal neuropathic symptoms. TCs form within the sensory nerve root sleeves, where CSF extends distally and can accumulate pathologically. Typically, they develop at the sacral dermatomes where the nerve roots are under the highest hydrostatic pressure and lack enclosing vertebral foramina. In total, 90% of patients are women, and genetic disorders that weaken connective tissues, e.g., Ehlers-Danlos syndrome, convey considerable risk. Most small TCs are asymptomatic and do not require treatment, but even incidental visualizations should be documented in case symptoms develop later. Symptomatic TCs most commonly cause sacropelvic dermatomal neuropathic pain, as well as bladder, bowel, and sexual dysfunction. Large cysts routinely cause muscle atrophy and weakness by compressing the ventral motor roots, and multiple cysts or multiroot compression by one large cyst can cause even greater cauda equina syndromes. Rarely, giant cysts erode the sacrum or extend as intrapelvic masses. Disabling TCs require consideration for surgical intervention.

The authors’ systematic review of treatment analyzed 31 case series of interventional percutaneous procedures and open surgical procedures. The surgical series were smaller and reported somewhat better outcomes with longer term follow-up but slightly higher risks. When data were lacking, authorial expertise and case reports informed details of the specific interventional and surgical techniques, as well as medical, physical, and psychological management.

Cyst-wrapping surgery appeared to offer the best longterm outcomes by permanently reducing cyst size and reconstructing the nerve root sleeves. This curtails ongoing injury to the axons and neuronal death, and may also promote axonal regeneration to improve somatic and autonomic sacral nerve function.

C2 versus C3 or C4 as the upper instrumented vertebra for long-segment cervical fusions: a systematic review and meta-analysis

J Neurosurg Spine 40:265–273, 2024

Selecting C2 versus C3 or C4 (i.e., C3/C4) as the rostral anchoring level in long-segment cervical fusions is a common clinical conundrum. The data regarding proximal failure in long constructs of the cervical spine is scarce. The objective of this study was to systematically review the published literature and perform a meta-analysis of the incidence for proximal adjacent-segment disease (ASD) in the context of long cervical fusions and cervicothoracic fusions ending in C2 versus those ending in the subaxial spine (C3 or C4).

METHODS Using the PRISMA guidelines, the authors performed a search of the PubMed/MEDLINE, Embase/Ovid, and Cochrane Central databases to identify all full-text articles in the English-language literature with the following inclusion criteria: 1) studies including patients with the upper instrumented vertebra (UIV) at C2 versus C3/C4; 2) patients undergoing ≥ 3-level posterior cervical fusion; and 3) indication for surgery of degenerative disc disease, cervical spondylotic myelopathy, or cervical deformity. Studies that were not published in the English language, case reports, review articles, letters to the editor, and meeting abstracts were excluded. A meta-analysis was conducted using a fixed-effects model when I 2 values were below 70%. Conversely, when I 2 values were equal to or greater than 70%, a random-effects model was used. A funnel plot was used to assess the presence of publication bias.

RESULTS Seven studies consisting of 1215 patients were included in the meta-analysis. There were 403 (32.8%) patients in the C2 UIV group and 812 (67.2%) patients in the C3/C4 UIV group. When the 7 studies were analyzed, the overall rate of reoperation was comparable between the C2 (9.2%) and C3/C4 (9.4%) UIV groups (p = 0.93) but the rate of surgical ASD due to proximal pathology was 1.2% and 3%, respectively (OR 0.36, 95% CI 0.15–0.86; p = 0.02). When comparing between groups, no statistical difference was found regarding the rate of reoperation due to distal pathology or surgical infection.

CONCLUSIONS Long-segment cervical or cervicothoracic constructs that anchor into C2 may have similar complication rates but lower revision rates for proximal ASD than constructs that anchor into the subaxial spine.


The auricula as a new surgical landmark for the transverse-sigmoid-sinus-transition

Brain and Spine 4 (2024) 102757

The transverse-sigmoid-sinus-transition constitutes an important landmark during a retrosigmoid craniotomy. Due to anatomical variations, the location is highly variable. Landmarks for identification of the anterior border of the sigmoid sinus have been described extensively, such as the mastoid notch, digastric point, external auditory meatus and crux of the helix curvature. There is a paucity of landmarks for the identification of the posterior border, however.

Research question: We examined the relationship between the transverse-sigmoid-sinus-transition and the mostposterior-part-of-the-auricula.

Material and methods: We performed a retrospective analysis of one-hundred patients (38 males and 62 females) who underwent cerebral MRI examinations at Antwerp University Hospital (Belgium). Using Brainlab®, the transverse-sigmoid-sinus-transition and most-posterior-part-of-the-auricula coordinates were calculated and compared. Left and right sides were compared in both the anteroposterior and craniocaudal axis.

Results: Mean age was 56.4 ± 16.1 years. Mean MPPA-TSST-distance in the anteroposterior direction was − 1.93 mm (right) and − 1.96 mm (left). Mean MPPA-TSST-distance in the craniocaudal direction was − 5.16 mm (right) and − 5.04 mm (left).

Discussion and conclusion: The transverse-sigmoid-sinus-transition seems to be located more anterior and caudal with respect to the most-posterior-part-of-the-auricula, meaning that it can be considered a save landmark. A correction of five mm needs to be applied in order to identify the inferior border of the transverse sinus. Left/ right and gender had no significant influence. The most-posterior-part-of-the-auricula can be considered a fast and practical anatomical landmark for identification of the transverse-sigmoid-sinus-transition, without affecting operative fluency, especially during an emergency craniotomy.

Microvascular Decompression for Trigeminal Neuralgia Caused by Vascular Compression on the Trigeminal Sensory Nucleus and Descending Trigeminal Tract

World Neurosurg. (2024) 183:106-112

Trigeminal neuralgia (TN) is characterized by paroxysmal episodes of severe shocklike orofacial pain typically resulting from arterial compression on the trigeminal root entry zone. However, neurovascular conflict in more proximal parts of the trigeminal pathway within the pons is extremely rare.

METHODS: The authors present a case of microvascular decompression for TN caused by dual arterial compression on the dorsolateral pons, along with a brief literature review.

RESULTS: Our patient was a 74-year-old man with episodic left-sided facial stabbing pain. Brain magnetic resonance imaging revealed a dual arterial compression on dorsolateral pons, the known site of the trigeminal sensory nucleus and descending trigeminal tract. Microvascular decompression was performed via a retrosigmoid approach. Complete pain relief and partial improvement of the facial hypesthesia were achieved immediately after surgery and the Barrow Neurological Institute (BNI) pain intensity score improved from V to I, and the BNI hypesthesia score decreased from III to II within a month following surgery. The literature review identified 1 case of TN secondary to an arteriovenous malformation in root entry zone with lateral pontine extension. One month following partial coagulation of the draining vein, the patient was reportedly able to reduce medication dosage by half to achieve an improvement of BNI pain intensity score from V to IIIa.

CONCLUSIONS: Neurovascular compression in the trigeminal tract and nucleus is a rare but potential cause of TN. A thorough investigation of the trigeminal pathway should be considered during preoperative evaluation and intraoperative inspection, particularly if no clear offending vessel is identified.

Radionuclide shuntography for cerebrospinal fluid shunt flow evaluation in adults

J Neurosurg 140:621–626, 2024

Radionuclide shuntography (RS) performed using 99m Tc-DTPA injected into the reservoir of CSF shunts enables evaluation of CSF flow for suspected shunt malfunctions. The goal of this study was to report the authors’ institutional experience with RS and evaluate its utility and associated complications.

METHODS The authors retrospectively reviewed all RS studies performed between November 2003 and June 2022. Patients with shunted hydrocephalus who were ≥ 18 years of age were included. Patients undergoing RS for evaluation of Ommaya reservoirs were excluded. Demographics, hydrocephalus etiology, presenting symptoms, study results, subsequent management, complications, and intraoperative diagnoses were recorded. Chi-square tests were reported for categorical variables and standard 2 × 2 contingency methods were used for sensitivity/specificity analysis.

RESULTS The authors identified 211 RS procedures performed in 142 patients. The mean age at procedure was 55.6 ± 20.9 years (mean ± SD). Normal pressure hydrocephalus was the most common hydrocephalus etiology (37.0%), followed by congenital malformations (26.1%) and idiopathic intracranial hypertension (15.6%). Successful radionuclide injection was achieved in 207 studies (98.1%). Shunt patency was confirmed in 63.8% of successful injections, whereas malfunction was demonstrated in 27.1% and abnormally slow flow was seen in 9.2%. RS studies demonstrating shunt malfunction were more likely to result in subsequent revisions than were studies showing patency (86.6% vs 2.9%; p < 0.0001). The overall sensitivity and specificity of RS for detecting shunt malfunction was 92.3% and 96.2%, respectively. The median follow-up time was 29 months, with 151 cases having ≥ 6 months of follow-up. There were no complications or infections attributable to RS in this cohort.

CONCLUSIONS RS is a useful and safe tool in the workup of shunt malfunction.


Early Voice and Swallowing Disturbance Incidence and Risk Factors After Revision Anterior Cervical Discectomy and Fusion Using a Multidisciplinary Surgical Approach

Neurosurgery 94:444–453, 2024

Dysphagia and vocal cord palsy (VCP) are common otolaryngological complications after revision anterior cervical discectomy and fusion (rACDF) procedures. Our objective was to determine the early incidence and risk factors of VCP and dysphagia after rACDF using a 2-team approach.

METHODS: Single-institution, retrospective analysis of a prospectively collected database of patients undergoing rACDF was enrolled from September 2010 to July 2021. Of 222 patients enrolled, 109 patients were included in the final analysis. All patients had prior ACDF surgery with planned revision using a single otolaryngologist and single neurosurgeon. MD Anderson Dysphagia Inventory and fiberoptic endoscopic evaluation of swallowing (FEES) were used to assess dysphagia. VCP was assessed using videolaryngostroboscopy.

RESULTS: Seven patients (6.7%) developed new postoperative VCP after rACDF. Most cases of VCP resolved by 3 months postoperatively (mean time-to-resolution 79 ± 17.6 days). One patient maintained a permanent deficit. Forty-one patients (37.6%) reached minimum clinically important difference (MCID) in their MD Anderson Dysphagia Inventory composite scores at the 2-week follow-up (MCID decline of ≥6), indicating new clinically relevant swallowing disturbance. Forty-nine patients (45.0%) had functional FEES Performance Score decline. On univariate analysis, there was an association between new VCPs and the number of cervical levels treated at revision (P = .020) with long-segment rACDF (≥4 levels) being an independent risk factor (P = .010). On linear regression, there was an association between the number of levels treated previously and at revision for FEES Performance Score decline (P = .045 and P = .002, respectively). However, on univariate analysis, sex, age, body mass index, operative time, alcohol use, smoking, and individual levels revised were not risk factors for reaching FEES Performance Score decline nor MCID at 2 weeks postoperatively.

CONCLUSION: VCP is more likely to occur in long-segment rACDF but is often temporary. Clinically relevant and functional rates of dysphagia approach 37% and 45%, respectively, at 2 weeks postoperatively after rACDF.

Midpoint of C7 Lateral Mass Serves as an Accurate Reference Point for the Placement of T1 Pedicle Screws: An Anatomic Study

Operative Neurosurgery 26:323–329, 2024

Free-hand placement of T1 pedicle screws can often be challenging. A reliable freehand technique for placement of T1 pedicle screws can overcome some of the difficulties associated with poor fluoroscopy in this region. The purpose of this study was to propose a novel anatomic landmark for accurate identification of the T1 entry point using the midpoint of the C7 lateral mass as a reference point. Our hypothesis is that the midpoint of the C7 lateral mass is within 1–2 mm of the center of the T1 pedicle.

METHODS: Using 3-dimensional reconstruction software, the pedicle of T1 and the lateral mass of C7 were isolated to assess the location of the T1 pedicle relative to the C7 lateral mass. Specifically, the distance between the center of the T1 pedicle and the center of the C7 lateral mass was measured on 40 computed tomography scans. Furthermore, a clinical validation of this technique was performed by assessing the postoperative computed tomography scans of 53 patients undergoing cervicothoracic instrumentation. The Gertzbein and Robbins classification system was used to grade the accuracy of T1 pedicle screw placements in all patients using this technique.

RESULTS: The average horizontal deviation + SD from centers of the T1 pedicle and the C7 lateral mass was 0.398 mm ± 0.953 mm. The T1 pedicle on average was slightly medial to the center of the C7 lateral mass. A total of 98.1% of T1 pedicle screws placed in vivo using the free-hand technique were of Grade A.

CONCLUSION: In this article, we demonstrate that the center of the C7 lateral mass overlays the T1 pedicle and the optimal entry point is immediately below the midpoint of the C7 lateral mass. This approach provides a practical and accurate landmark in posterior cervicothoracic spine procedures that reduce the need for additional radiation exposure or increased operative time with image-guided techniques.

Anterior retropharyngeal approach (ARPA) for high cervical spine

Acta Neurochirurgica (2024) 166:122

One of the major challenges in operating on the spine lies in taking an anterior approach for the high cervical spine. In patients with a short neck, Klippel-Fiel syndrome or when the C3 vertebra is high in relation to the hyoid bone, it will be difficult to access the C3 body. The transoral route is a highly contaminated zone, and therefore, no instrumentation or grafts can be placed through it.

Method The anterior retropharyngeal approach (ARPA) for the high cervical spine.

Conclusion The anterior retropharyngeal approach is an excellent approach for the high cervical spine where instrumentation is needed. This route provides wide exposure of the C1–C3 region, avoiding the contaminated of the oral cavity.

Gravity Line–Hip Axis Offset as a Guide for Global Alignment to Prevent Recurrent Proximal Junctional Kyphosis/Failure

Operative Neurosurgery 26:268–278, 2024

Proximal junctional kyphosis/failure (PJK/F) is a potentially serious complication after adult spinal deformity (ASD) corrective surgery. Recurrent PJK/F is especially troublesome, necessitating fusion extension and occasionally resulting in irreversible neurological deficits. The gravity line (GL) offers valuable insights into global sagittal balance. This study aims to examine the postoperative GL–hip axis (GL-HA) offset as a critical risk factor for recurrent PJK/F.

METHODS: We retrospectively reviewed patients with ASD who had undergone revision surgery for initial PJK/F at a single academic center. Patients were categorized into 2 groups: nonrecurrent PJK/F group and recurrent PJK/F group. Demographics, surgical characteristics, preoperative and postoperative parameters of spinopelvic and global alignment, and the Scoliosis Research Society-22 scores were assessed. We examined these measures for differences and correlations with recurrent PJK/F.

RESULTS: Our study included 32 patients without recurrent PJK/F and 28 patients with recurrent PJK/F. No significant differences were observed in baseline demographics, operative characteristics, or Scoliosis Research Society-22 scores before and after surgery. Importantly, using a cutoff of À52.6 mm from logistic regression, there were considerable differences and correlations with recurrent PJK/F in the postoperative GL-HA offset, leading to an odds ratio of 7.0 (95% CI: 1.94-25.25, P = .003).

CONCLUSION: Postoperative GL-HA offset serves as a considerable risk factor for recurrent PJK/F in patients with ASD who have undergone revision surgery. Overcorrection, with GL-HA offset less than À5 cm, is associated with recurrent PJK/F. The instrumented spine tends to align the GL near the HA, even at the cost of proximal junction.

Anterior Petrosectomy With Intertentorial Approach

Operative Neurosurgery 26:301–308, 2024

The extradural anterior petrosal approach (EAPA) can present a challenge because it deals with critical structures in a narrow, confined corridor. It is associated with several potential approach-related risks including temporal lobe and venous injuries. Tentorial peeling has the potential to largely eliminate these risks during the approach and may offer more options for tailoring the dural opening to the anatomic region that one wants to expose.

METHODS: Anatomic dissections of five adult injected non–formalin-fixed cadaveric heads were performed. Anterior petrosectomy with intertentorial approach (APIA) through a tentorial peeling was completed. Step-by-step documentation of the cadaveric dissections and diagrammatic representations are presented along with an illustrative case.

RESULTS: Tentorial peeling separates the tentorium into a temporal tentorial leaf and posterior fossa tentorial leaf, adding a fourth dural layer to the three classic ones described during a standard EAPA. This opens out the intertentorial space and offers more options for tailoring the dural incisions specific to the pathology being treated. This represents a unique possibility to address brainstem or skull base pathology along the mid- and upper clivus with the ability to keep the entire temporal lobe and basal temporal veins covered by the temporal tentorial leaf. The APIA was successfully used for the resection of a large clival chordoma in the illustrative case.

CONCLUSION: APIA is an interesting modification to the classic EAPA to reduce the approach-related morbidity. The risk reduction achieved is by eliminating the exposure of the temporal lobe while maintaining the excellent access to the petroclival region. It also provides several options to tailor the durotomies based on the localization of the lesion.

Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies

Operative Neurosurgery 26:279–285, 2024

Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy.

METHODS: A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella–sphenoid angle (a representation of the coronal slope of FO). Mann–Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation.

RESULTS: Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella–sphenoid angles (median = 52.00°vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically.

CONCLUSION: We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

Comparison of Lumbar Interbody Fusion with 3D-Printed Porous Titanium Cage Versus Polyetheretherketone Cage in Treating Lumbar Degenerative Disease: A Systematic Review and Meta-Analysis

World Neurosurg. (2024) 183:144-156

OBJECTIVE: To compare the safety and radiological effectiveness of lumbar interbody fusion with a 3D-printed porous titanium (3D-PPT) cage versus a polyetheretherketone (PEEK) cage for the treatment of lumbar degenerative disease.

METHODS: This study was registered at PROSPERO (CRD42023461511). We systematically searched the PubMed, Embase, and Web of Science databases for related studies from inception to September 3, 2023. Review Manager 5.3 was used to conduct this meta-analysis. The reoperation rate, complication rate, fusion rate, and subsidence rate were assessed using relative risk and 95% confidence intervals.

RESULTS: Ten articles reporting 9 studies comparing lumbar interbody fusion with 3D-PPT cages versus PEEK cages for the treatment of lumbar degenerative disease were included. The subsidence rate at the 1-year follow-up in the 3DPPT cage was significantly lower than that in the PEEK cage. The fusion rate in the 3D-PPT cage was significantly higher than that in the PEEK cage at the 6month follow-up. No significant difference was identified between the 2 groups at the 12-month follow-up. No significant difference was identified between the 2 groups in terms of the complication rate and reoperation rate. There was a trend toward a lower complication rate and reoperation rate with the 3DPPT cage.

CONCLUSIONS: Compared with the PEEK cage, the 3D-PPT cage may be a safer implant. The 3D-PPT cage was associated with a higher fusion rate and lower subsidence rate. The 3D-PPT cage may accelerate the intervertebral fusion process, improve the quality of fusion and prevent the occurrence of subsidence.

Lateral‑PLIF for spinal arthrodesis

Acta Neurochirurgica (2024) 166:123

Posterior lumbar interbody fusion (PLIF) surgery represents an effective option to treat degenerative conditions in the lumbar spine. To reduce the drawbacks of the classical technique, we developed a variant, so-called Lateral-PLIF, which we then evaluated through a prospective consecutive series of patients.

Methods All adult patients treated at our institute with single or double level Lateral-PLIF for lumbar degenerative disease from January to December 2017 were prospectively collected. Exclusion criteria were patients < 18 years of age, traumatic patients, active infection, or malignancy, as well as unavailability of clinical and/or radiological follow-up data. The technique consists of insert the cages bilaterally through the transition zone between the central canal and the intervertebral foramen, just above the lateral recess. Pre- and postoperative (2 years) questionnaires and phone interviews (4 years) assessed pain and functional outcomes. Data related to the surgical procedure, postoperative complications, and radiological findings (1 year) were collected.

Results One hundred four patients were selected for the final analysis. The median age was 58 years and primary symptoms were mechanical back pain (100, 96.1%) and/or radicular pain (73, 70.2%). We found a high fusion rate (95%). A statistically significant improvement in functional outcome was also noted (ODI p < 0.001, Roland-Morris score p < 0.001). Walking distance increased from 812 m ± 543 m to 3443 m ± 712 m (p < 0.001). Complications included dural tear (6.7%), infection/ wound dehiscence (4.8%), and instrument failure (1.9%) but no neurological deterioration.

Conclusions Lateral-PLIF is a safe and effective technique for lumbar interbody fusion and may be considered for further comparative study validation with other techniques before extensive use to treat lumbar degenerative disease.

Zabramski classification in predicting the occurrence of symptomatic intracerebral hemorrhage in sporadic cerebral cavernous malformations

J Neurosurg 140:792–799, 2024

The authors aimed to investigate the evolutionary characteristics of the Zabramski classification of cerebral cavernous malformations (CCMs) and the value of the Zabramski classification in predicting clinical outcome in patients with sporadic CCM.

METHODS This retrospective study consecutively included cases of sporadic CCM that had been untreated from January 2001 through December 2021. Baseline and follow-up patient information was recorded. The evolution of the Zabramski classification of a sporadic CCM was defined as the initial lesion type changing into another type for the first time on MRI follow-up. The primary outcome was the occurrence of a hemorrhage event, which was defined as a symptomatic event with radiological evidence of overt intracerebral hemorrhage.

RESULTS Among the 255 included cases, 55 (21.6%) were classified as type I CCM, 129 (50.6%) as type II CCM, and 71 (27.8%) as type III CCM, based on initial MRI. During a mean follow-up of 58.8 ± 33.6 months, 51 (20.0%) patients had lesion classification transformation, whereas 204 (80.0%) patients maintained their initial type. Among the 51 transformed lesions, 29 (56.9%) were type I, 11 (21.6%) were type II, and 11 (21.6%) were type III. Based on all follow-up imaging, of the initial 55 type I lesions, 26 (47.3%) remained type I and 27 (49.1%) regressed to type III because of hematoma absorption; 91.5% of type II and 84.5% of type III lesions maintained their initial type during MRI follow-up. The classification change rate of type I lesions was statistically significantly higher than those of type II and III lesions. After a total follow-up of 1157.7 patient-years, new clinical hemorrhage events occurred in 40 (15.7%) patients. The annual cumulative incidence rate for symptomatic hemorrhage in all patients was 3.4 (95% CI 2.5–4.7) per 100 person-years. Kaplan-Meier survival analysis showed that the annual cumulative incidence rate for symptomatic hemorrhage of type I CCM (15.3 per 100 patient-years) was significantly higher than those of type II (0.6 per 100 patient-years) and type III (2.3 per 100 patient-years).

CONCLUSIONS This study suggests that the Zabramski classification is helpful in estimating clinical outcome and can assist with surgical decision-making in patients with sporadic CCM.

Cavernous venous malformations in and around the central nervous system. Part 2: Intradural

J Neurosurg 140:746–754, 2024

Cavernous venous malformations (CavVMs) account for a spectrum of lesions with a shared pathogenesis. Their anatomical location dictates their clinical features and surgical treatment. Extradural and dura-based CavVMs were discussed in Part 1 of this review.

In this part, intradural CavVMs are discussed, encompassing malformations growing within the intradural space without direct dural involvement. In addition to classic intra-axial CavVMs, cranial nerve CavVMs, intraventricular CavVMs, and intradural extramedullary spinal CavVMs are discussed in this group, given the similar natural history and specific management challenges.

Herein the authors focus on critical clinical aspects of and surgical management of these malformations based on their location and discuss optimal surgical approaches at each of these anatomical locations with illustrative cases. The commonalities of the natural history and surgical management that are dictated by anatomical considerations lend to a new location-based taxonomy for classification of CavVMs.

Noninvasive assessment of glymphatic dysfunction in idiopathic normal pressure hydrocephalus with diffusion tensor imaging

J Neurosurg 140:612–620, 2024

Diffusion tensor imaging (DTI) along the perivascular space (ALPS) (DTI-ALPS)—by calculating the ALPS index, a ratio accentuating water diffusion in the perivascular space—has been proposed as a noninvasive, indirect MRI method for assessing glymphatic function. The main aim of this study was to investigate whether DTI-ALPS would reveal glymphatic dysfunction in idiopathic normal pressure hydrocephalus (iNPH) and whether the ALPS index was associated with disease severity.

METHODS Thirty iNPH patients (13 men; median age 77 years) and 27 healthy controls (10 men; median age 73 years) underwent MRI and clinical assessment with the Timed Up and Go test (TUG) and Mini-Mental State Examination (MMSE); only the patients were evaluated with the Hellström iNPH scale. MRI data were analyzed with the DTI-ALPS method and Radscale screening tool.

RESULTS: iNPH patients showed significantly lower mean ALPS index scores compared with healthy controls (median [interquartile range] 1.09 [1.00–1.15] vs 1.49 [1.36–1.59], p < 0.001). Female healthy controls showed significantly higher ALPS index scores than males in both hemispheres (e.g., right hemisphere 1.62 [1.47–1.67] vs 1.33 [1.14–1.41], p = 0.001). This sex difference was not seen in iNPH patients. The authors found a moderate exponential correlation between mean ALPS index score and motor function as measured with time required to complete TUG (r = −0.644, p < 0.001), number of steps to complete TUG (r = −0.571, p < 0.001), 10-m walk time (r = −0.637, p < 0.001), and 10-m walk steps (r = −0.588, p < 0.001). The authors also found a positive linear correlation between mean ALPS index score and MMSE score (r = 0.416, p = 0.001). Simple linear regression showed a significant effect of diagnosis (B = −0.39, p < 0.001, R 2 = 0.459), female sex (B = 0.232, p = 0.002, R 2 = 0.157), and Evans index (B = −4.151, p < 0.001, R 2 = 0.559) on ALPS index. Multiple linear regression, including diagnosis, sex, and Evans index score, showed a higher predictive value (R 2 = 0.626) than analysis of each of these factors alone.

CONCLUSIONS The ALPS index, which was significantly decreased in iNPH patients, could serve as a marker of disease severity, both clinically and in terms of neuroimaging. However, it is important to consider the significant influence of biological sex and ventriculomegaly on the ALPS index, which raises the question of whether the ALPS index solely reflects glymphatic function or if it also encompasses other types of injury. Future studies are needed to address potential confounding factors and further validate the ALPS method.


Long-Term Results After Surgery for Degenerative Cervical Myelopathy

Neurosurgery 94:454–460, 2024

Degenerative cervical myelopathy (DCM) is a frequent cause of spinal cord dysfunction, and surgical treatment is considered safe and effective. Long-term results after surgery are limited. This study investigated long-term clinical outcomes through data from the Norwegian registry for spine surgery.

METHODS: Patients operated at the university hospitals serving Central and Northern Norway were approached for long-term follow-up after 3 to 8 years. The primary outcome was change in the Neck Disability Index, and the secondary outcomes were changes in the European Myelopathy Scale score, quality of life (EuroQoL EQ-5D); numeric rating scales (NRS) for headache, neck pain, and arm pain; and perceived benefit of surgery assessed by the Global Perceived Effect scale from 1 year to long-term follow-up.

RESULTS: We included 144 patients operated between January 2013 and June 2018. In total, 123 participants (85.4%) provided patient-reported outcome measures (PROMs) at long-term follow-up. There was no significant change in PROMs from 1 year to long-term follow-up, including Neck Disability Index (mean 1.0, 95% CI À2.1-4.1, P = .53), European Myelopathy Scale score (mean À0.3, 95% CI À0.7-0.1, P = .09), EQ-5D index score (mean À0.02, 95% CI À0.09-0.05, P = .51), NRS neck pain (mean 0.3 95% CI À0.2-0.9, P = .22), NRS arm pain (mean À0.1, 95% CI À0.8-0.5, P = .70), and NRS headache (mean 0.4, 95% CI À0.1-0.9, P = .11). According to Global Perceived Effect assessments, 106/121 patients (87.6%) reported to be stable or improved (“complete recovery,” “much better,” “slightly better,” or “unchanged”) at long-term follow-up compared with 88.1% at 1 year. Dichotomizing the outcome data based on severity of DCM did not demonstrate significant changes either.

CONCLUSION: Long-term follow-up of patients undergoing surgery for DCM demonstrates persistence of statistically significant and clinically meaningful improvement across a wide range of PROMs.

Radiosurgery With Prior Embolization Versus Radiosurgery Alone for Intracranial Arteriovenous Malformations

Neurosurgery 94:478–496, 2024

The addition of adjuvant embolization to radiosurgery has been proposed as a means of improving treatment outcomes of intracranial arteriovenous malformations (AVMs). However, the relative efficacy and safety of radiosurgery with adjuvant embolization vs radiosurgery alone remain uncertain. Moreover, previous systematic reviews and meta-analyses have included a limited number of studies and did not consider the effects of baseline characteristics, including AVM volume, on the outcomes. This systematic review aimed to evaluate the efficacy of preradiosurgery embolization for intracranial AVMs with consideration to matching status between participants in each treatment group.

METHODS: A systematic review and meta-analysis were conducted by searching electronic databases, including PubMed, Scopus, and Cochrane Library, up to January 2023. All studies evaluating the utilization of preradiosurgery embolization were included.

RESULTS: A total of 70 studies (9 matched and 71 unmatched) with a total of 12 088 patients were included. The mean age of the included patients was 32.41 years, and 48.91% of the patients were female. Preradiosurgery embolization was used for larger AVMs and patients with previous hemorrhage (P < .01, P = .02, respectively). The obliteration rate for preradiosurgery embolization (49.44%) was lower compared with radiosurgery alone (61.42%, odds ratio = 0.56, P < .01), regardless of the matching status of the analyzed studies. Although prior embolization was associated higher rate of cyst formation (P = .04), it lowered the odds of radiation-induced changes (P = .04). The risks of minor and major neurological deficits, postradiosurgery hemorrhage, and mortality were comparable between groups.

CONCLUSION: This study provides evidence that although preradiosurgery embolization is a suitable option to reduce the AVM size for future radiosurgical interventions, it may not be useful for same-sized AVMs eligible for radiosurgery. Utilization of preradiosurgery embolization in suitable lesions for radiosurgery may result in the added cost and burden of an endovascular procedure.

Cavernous venous malformations in and around the central nervous system. Part 1: Dural and extradural

J Neurosurg 140:735–745, 2024

Cavernous-type malformations are venous lesions that occur in multiple locations throughout the body, and when present in the CNS, they have canonically been referred to as cavernomas, cavernous angiomas, and cerebral cavernous malformations. Herein all these lesions are referred to as “cavernous venous malformations” (CavVMs), which is congruent with the current International Society for the Study of Vascular Anomalies classification system.

Even though histologically similar, depending on their location relative to the dura mater, these malformations can have different features. In Part 1 of this review, the authors discuss and review pertinent clinical knowledge with regard to CavVMs as influenced by anatomical location, starting with the dural and extradural malformations. They particularly emphasize dural CavVMs (including those in the cavernous sinus), orbital CavVMs, and spinal CavVMs. The genetic and histopathological features of CavVMs in these locations are reviewed, and commonalities in their presumed mechanisms of pathogenesis support the authors’ conceptualization of a spectrum of a single disease entity. Illustrative cases for each subtype are presented, and the pathophysiological and genetic features linking dural and extradural to intradural CavVMs are examined.

A new classification is proposed to segregate CavVMs based on the location from which they arise, which guides their natural history and treatment.