Management of Intracranial Aneurysms that Do Not Occlude on Initial Follow-up After Treatment With the Pipeline Embolization Device

Neurosurgery 94:271–277, 2024

The pipeline embolization device (PED) has become widely accepted as a safe and efficacious treatment for intracranial aneurysms with high rates of complete occlusion at initial follow-up. For aneurysms that are not completely occluded at initial follow-up, further treatment decision-making is varied. Furthermore, the risk of aneurysmal rupture in these incompletely occluded aneurysms after PED is not known. The objective of this study was to determine treatment decision-making that results in increased occlusion status at final follow-up and to evaluate risk of rupture in those aneurysms that do not go onto occlusion.

METHODS: This study is a retrospective review of prospective data for intracranial aneurysms treated with PED at two institutions from 2013 to 2019. Aneurysms with near-complete or incomplete occlusion at initial follow-up were included in the statistical analysis.

RESULTS: There were 606 total aneurysms treated at two academic institutions with PED with incomplete occlusion at initial follow-up in 134 aneurysms (22.1%). Of the 134 aneurysms that were nonoccluded at initial follow-up, 76 aneurysms (56.7%) went on to complete or near complete occlusion with final complete or near complete occlusion in 90.4% of all aneurysms treated. The time to final imaging follow-up was 28.2 months (13.8-44.3) Retreatment with a second flow diverter was used in 28 aneurysms (20.9%). No aneurysms that were incompletely occluded at initial follow-up had delayed rupture. Furthermore, older patient age was statistically significant for incomplete occlusion at initial follow-up (P = .05).

CONCLUSION: Intracranial aneurysms treated with the PED that do not occlude at initial follow-up may go on to complete occlusion with continuous observation, alteration in antiplatelet regimens, or repeat treatment. Delayed aneurysmal rupture was not seen in patients with incomplete occlusion.

Clinical and Imaging Outcomes After Trigeminal Schwannoma Radiosurgery: Results From a Multicenter, International Cohort Study

Neurosurgery 94:165–173, 2024

An international, multicenter, retrospective study was conducted to evaluate the long-term clinical outcomes and tumor control rates after stereotactic radiosurgery (SRS) for trigeminal schwannoma.

METHODS: Patient data (N = 309) were collected from 14 international radiosurgery centers. The median patient age was 50 years (range 11-87 years). Sixty patients (19%) had prior resections. Abnormal facial sensation was the commonest complaint (49%). The anatomic locations were root (N = 40), ganglion (N = 141), or dumbbell type (N = 128). The median tumor volume was 4 cc (range, 0.2-30.1 cc), and median margin dose was 13 Gy (range, 10-20 Gy). Factors associated with tumor control, symptom improvement, and adverse radiation events were assessed.

RESULTS: The median and mean time to last follow-up was 49 and 65 months (range 6–242 months). Greater than 5-year follow-up was available for 139 patients (45%), and 50 patients (16%) had longer than 10-year follow-up. The overall tumor control rate was 94.5%. Tumors regressed in 146 patients (47.2%), remained unchanged in 128 patients (41.4%), and stabilized after initial expansion in 20 patients (6.5%). Progression-free survival rates at 3 years, 5 years, and 10 years were 91%, 86%, and 80 %. Smaller tumor volume (less than 8 cc) was associated with significantly better progression-free survival (P = .02). Seventeen patients with sustained growth underwent further intervention at a median of 27 months (3-144 months). Symptom improvement was noted in 140 patients (45%) at a median of 7 months. In multivariate analysis primary, SRS (P = .003) and smaller tumor volume (P = .01) were associated with better symptom improvement. Adverse radiation events were documented in 29 patients (9%).

CONCLUSION: SRS was associated with long-term freedom (10 year) from additional management in 80% of patients. SRS proved to be a valuable salvage option after resection. When used as a primary management for smaller volume tumors, both clinical improvement and prevention of new deficits were optimized.

In‑out‑in technique for petrosal sinus dural arteriovenous fistula obliteration

Acta Neurochirurgica (2023) 165:3793–3798

Dural arteriovenous fistulas (dAVFs) at the superior petrosal sinus are a rare but important subtype that pose a high risk of mortality and morbidity. Treatment for these lesions can be challenging with stand-alone endovascular methods.

Methods We describe our “in-out-in” technique for disconnecting dAVFs at the superior petrosal sinus, which includes definitive sacrifice of the superior petrosal sinus and the transverse sigmoid sinus, if involved. This method achieves complete fistula obliteration and minimizes recurrence risk with new arterial feeders.

Conclusions The in-out-in technique is a safe and effective approach for the treatment of dAVFs involving the superior petrosal sinus.

Neuroendoscopic transventricular transchoroidal approach for access to the posterior zone of the third ventricle or pineal region

Neurosurgical Review (2023) 46:323

The endoscopic transventricular transchoroidal approach facilitates entry into the posterior part of the third ventricle, allowing a visualization field from the foramen of Monro to the pineal region through this anatomical corridor. Combined surgery to treat the target lesion and possible endoscopic third ventriculostomy (ETV) can be performed through a single burr hole.

A detailed description of this surgical technique is given, and a series of cases from our center is presented. This retrospective study included patients with lesions in the pineal region or posterior zone of the third ventricle who underwent surgery between 2004 and 2022 in our center for tumor biopsy or endoscopic cyst fenestration. In nine cases, the transchoroidal approach was performed. Demographic and clinical variables were collected: sex, age at diagnosis, clinical presentation, characteristics of the lesion, pathological diagnosis, characteristics of the procedure, complications, subsequent treatments, evolution, follow-up time, and degree of success of the endoscopic procedure. The mean and range of the quantitative variables and frequency of the qualitative variables were analyzed, together with the statistical significance (p < 0.05). Surgical planning was carried out by performing a preoperative MRI, calculating the ideal entry point and trajectory for each case. The preoperative planning of the surgical technique is described in detail.

Of our sample, 55.6% were women, with a mean age of 35 years (7–78). The most common clinical presentation was intracranial hypertension (55.6%), with or without a focus. Eight patients presented hydrocephalus at diagnosis. The most frequent procedure was endoscopic biopsy with ETV (66.7%). The pathological diagnosis varied widely. Procedure-related complications included one case of self-limited bleeding of the choroidal fissure at its opening and one intraventricular hemorrhage due to tumor bleeding in the postoperative period. Non-procedure-related complications comprised two ETV failures and one case of systemic infection, while late complications included one case of disease progression and one case of radionecrosis. Four patients died, one due to poor neurological evolution after post-surgical tumor bleeding and three due to causes unrelated to the procedure. The rest of the patients had a favorable evolution and were asymptomatic or stable.

The transchoroidal approach through a single burr hole is a feasible and safe option for access to the posterior part of the third ventricle. Proper planning of each case is necessary to avoid complications.

Reducing morbidity associated with subdural drain placement after burr‑hole drainage of unilateral chronic subdural hematomas

Acta Neurochirurgica (2023) 165:3207–3215

Placement of a subdural drain after burr-hole drainage of chronic subdural hematoma (cSDH) significantly reduces risk of its recurrence and lowers mortality at 6 months. Nonetheless, measures to reduce morbidity related to drain placement are rarely addressed in the literature. Toward reducing drain-related morbidity, we compare outcomes achieved by conventional insertion and our proposed modification.

Methods In this retrospective series from two institutions, 362 patients underwent burr-hole drainage of unilateral cSDH with subsequent subdural drain insertion by conventional technique or modified Nelaton catheter (NC) technique. Primary endpoints were iatrogenic brain contusion or new neurological deficit. Secondary endpoints were drain misplacement, indication for computed tomography (CT) scan, re-operation for hematoma recurrence, and favorable Glasgow Outcome Scale (GOS) score (≥ 4) at final follow-up.

Results The 362 patients (63.8% male) in our final analysis included drains inserted in 56 patients by NC and 306 patients by conventional technique. Brain contusions or new neurological deficits occurred significantly less often in the NC (1.8%) than conventional group (10.5%) (P = .041). Compared with the conventional group, the NC group had no drain misplacement (3.6% versus 0%; P = .23) and significantly fewer non-routine CT imaging related to symptoms (36.5% versus 5.4%; P < .001). Re-operation rates and favorable GOS scores were comparable between groups.

Conclusion We propose the NC technique as an easy-to-use measure for accurate drain positioning within the subdural space that may yield meaningful benefits for patients undergoing treatment for cSDH and vulnerable to complication risks.

Predictors of Progression-Free Survival in Patients With Spinal Intramedullary Ependymoma: A Multicenter Retrospective Study by the Neurospinal Society of Japan

Neurosurgery 93:1046–1056, 2023

Ependymoma is the most common spinal intramedullary tumor. Although clinical outcomes have been described in the literature, most of the reports were based on limited numbers of cases or been confined to institutional experience. The objective of this study was to analyze more detailed characteristics of spinal intramedullary ependymoma (SIE) and provide clinical factors associated with progression-free survival (PFS).

METHODS: This retrospective observational multicenter study included consecutive patients with SIE in the cervical or thoracic spine treated surgically at a total of 58 institutions between 2009 and 2020. The results of pathological diagnosis at each institute were confirmed, and patients with myxopapillary ependymoma, subependymoma, or unverified histopathology were strictly excluded from this study. Outcome measures included surgical data, surgery-related complications, postoperative systemic adverse events, postoperative adjuvant treatment, postoperative functional condition, and presence of recurrence.

RESULTS: This study included 324 cases of World Health Organization grade II (96.4%) and 12 cases of World Health Organization grade III (3.6%). Gross total resection (GTR) was achieved in 76.5% of cases. Radiation therapy (RT) was applied after surgery in 16 cases (4.8%), all of which received local RT and 5 of which underwent chemotherapy in combination. Functional outcomes were significantly affected by preoperative neurological symptoms, tumor location, extent of tumor resection, and recurrence. Multivariate regression analysis suggested that limited extent of tumor resection or recurrence resulted in poor functional outcomes. Multiple comparisons among the groups undergoing GTR, subtotal resection and biopsy, or partial resection of the tumor showed that the probability of PFS differed significantly between GTR and other extents of resection.

CONCLUSION: When GTR can be safely obtained in the surgery for SIE, functional maintenance and longer PFScan be expected.

 

Pseudoprogression versus true progression in glioblastoma: what neurosurgeons need to know

J Neurosurg 139:748–759, 2023

Management of patients with glioblastoma (GBM) is complex and involves implementing standard therapies including resection, radiation therapy, and chemotherapy, as well as novel immunotherapies and targeted small-molecule inhibitors through clinical trials and precision medicine approaches. As treatments have advanced, the radiological and clinical assessment of patients with GBM has become even more challenging and nuanced.

Advances in spatial resolution and both anatomical and physiological information that can be derived from MRI have greatly improved the noninvasive assessment of GBM before, during, and after therapy.

Identification of pseudoprogression (PsP), defined as changes concerning for tumor progression that are, in fact, transient and related to treatment response, is critical for successful patient management. These temporary changes can produce new clinical symptoms due to mass effect and edema. Differentiating this entity from true tumor progression is a major decision point in the patient’s management and prognosis.

Providers may choose to start an alternative therapy, transition to a clinical trial, consider repeat resection, or continue with the current therapy in hopes of resolution. In this review, the authors describe the invasive and noninvasive techniques neurosurgeons need to be aware of to identify PsP and facilitate surgical decision-making.

Robot‑assisted endoscopic third ventriculostomy under intraoperative CT imaging guidance

Acta Neurochirurgica (2023) 165:2525–2531

The robot-assisted neurosurgical procedures have recently benefited of the evolution of intraoperative imaging, including mobile CT unit available in the operating room. This facilitated use paved the way to perform more neurosurgical procedures under robotic assistance. Endoscopic third ventriculocisternostomy requires both a safe transcortical trajectory and a smooth manipulation.

Method We describe our technique of robot-assisted endoscopic third ventriculocisternostomy combining robotic assistance and intraoperative CT imaging.

Conclusion Robot-assisted endoscopic third ventriculocisternostomy using modern intraoperative neuroimaging can be easily implemented and prevented erroneous trajectory and abrupt endoscopic movements, reducing surgically induced brain damages.

Brain metastasis resection: the impact of fluorescence guidance (MetResect study)

Neurosurg Focus 55(2):E10, 2023

Maximal resection of brain metastases (BMs) improves both progression-free survival and overall survival (OS). Fluorescein sodium (FL) in combination with the YELLOW 560-nm filter is a safe and feasible method for visualizing residual tumor tissue during BM resection. The authors of this study aimed to show that use of FL would positively influence the volumetric extent of resection (EOR) and thus the survival outcome in patients undergoing BM resection.

METHODS Analyzing their institution’s prospective brain tumor registry, the authors identified 539 consecutive patients with BMs (247 women, mean age 62.8 years) by using preoperative high-quality MR images for volumetric analysis. BMs were resected under white light (WL) in 293 patients (54.4%; WL group) and under FL guidance in 246 patients (45.6%; FL group). Sex, age, presurgical Karnofsky Performance Status (KPS), recursive partitioning analysis class, and adjuvant treatment modalities were well balanced between the two groups. Volumetric analysis was performed in a blinded fashion by quantifying pre- and postoperative tumor volume based on gadolinium-enhanced T1-weighted sequences.

RESULTS In the FL group, the postoperative tumor volume was significantly smaller (p = 0.01), and hence the quantitative EOR was significantly larger (p = 0.024) and OS was significantly longer (p = 0.0001) (log-rank testing). Multivariate Cox regression modeling showed that age, presurgical KPS, metastasis status, and FL-guided resection are independent prognostic factors for survival.

CONCLUSIONS Compared with WL resection, FL-guided BM resection increased resection quality, significantly improved EOR, and prolonged OS.

Microsurgical anatomy and pathoanatomy of the outer arachnoid membranes in the cerebellopontine angle

Acta Neurochirurgica (2023) 165:1791–1805

The cerebellopontine angle (CPA) is a frequent region of skull base pathologies and therefore a target for neurosurgical operations. The outer arachnoid is the key structure to approach the here located lesions. The goal of our study was to describe the microsurgical anatomy of the outer arachnoid of the CPA and its pathoanatomy in case of space-occupying lesions.

Methods Our examinations were performed on 35 fresh human cadaveric specimens. Macroscopic dissections and microsurgical and endoscopic examinations were performed. Retrospective analysis of the video documentations of 35 CPA operations was performed to describe the pathoanatomical behavior of the outer arachnoid.

Results The outer arachnoid cover is loosely attached to the inner surface of the dura of the CPA. At the petrosal surface of the cerebellum the pia mater is strongly adhered to the outer arachnoid. At the level of the dural penetration of the cranial nerves, the outer arachnoid forms sheath-like structures around the nerves. In the midline, the outer arachnoid became detached from the pial surface and forms the base of the posterior fossa cisterns. In pathological cases, the outer arachnoid became displaced. The way of displacement depends on the origin of the lesion. The most characteristic patterns of changes of the outer arachnoid were described in case of meningiomas, vestibular schwannomas, and epidermoid cysts of the CPA.

Conclusion The knowledge of the anatomy of the outer arachnoid of the cerebellopontine region is essential to safely perform microsurgical approaches as well as of dissections during resection of pathological lesions.

Safety of brainstem safe entry zones: comparison of microsurgical outcomes associated with superficial, exophytic, and deep brainstem cavernous malformations

J Neurosurg 139:113–123, 2023

Safe entry zones (SEZs) enable safe tissue transgression to lesions beneath the brainstem surface. However, evidence for the safety of SEZs is scarce and is based on anatomical studies, case reports, and small series.

METHODS A cohort of 154 patients who underwent microsurgical brainstem cavernous malformation (BSCM) treatment during a 23-year period and who had preoperative MR images and intraoperative photographs or videos was retrospectively examined. This study assessed the safety of SEZs for access to deep BSCMs, preoperative MRI to predict BSCM surface proximity, and the relationships between BSCM subtype, surgical approach, and SEZs. Lesions were characterized as exophytic, superficial, or deep on the basis of preoperative MRI and intraoperative inspection. Outcomes were scored as good (modified Rankin Scale [mRS] score ≤ 2) or poor (mRS score > 2) and relative outcomes as stable/ improved or worse relative to baseline (± 1 point).

RESULTS Resections included 34 (22%) in the midbrain, 102 (66%) in the pons, and 18 (12%) in the medulla. Of those, 23 (15%) were exophytic, 57 (37%) were superficial, and 74 (48%) were deep. Established SEZs were used for 97% (n = 72) of deep lesions; the preferred SEZ associated with its subtype was used for 91% (n = 67). MR images accurately depicted exophytic BSCMs that did not require SEZ approaches (sensitivity, 96%) but overestimated the proximity of lesions superficial to brainstem surfaces (specificity, 67%), resulting in unanticipated SEZ use. Final neurological outcomes were good in 80% of patients with follow-up data (119/149), and relative outcomes were stable/improved in 93% (139/149). Outcomes for patients with brainstem transgression through an SEZ did not differ from outcomes for patients with superficial or exophytic lesions that did not require SEZ use (final mRS score ≤ 2 in 72% of all patients with deep lesions vs 82% of all patients with superficial or exophytic lesions [p = 0.10]). Among patients with follow-up, the rates of permanent new cranial nerve deficits in patients with deep BSCMs and superficial or exophytic BSCMs were 21% and 20%, respectively (p = 0.81), with no significant change in overall cranial nerve deficit (0 and −1, p = 0.65).

CONCLUSIONS Neurological outcomes for patients with deep BSCMs were equivalent to those for superficial or exophytic BSCMs, validating the safety of SEZs for deep BSCMs. Preoperative T1-weighted MR images overestimated the lesion’s surface proximity, necessitating detailed knowledge of SEZs and readiness to use them in cases of radiologicalmicrosurgical discordance. Most patients achieved favorable outcomes despite the transgression of eloquent brainstem tissue in and around SEZs.

The transfrontal isthmus approach for insular glioma surgery

J Neurosurg 139:20–28, 2023

The classic transopercular or transsylvian approach to insular gliomas removes the tumor laterally through the insular cortex. This study describes a new anteroposterior approach through the frontal isthmus for insular glioma surgery.

METHODS The authors detailed the surgical techniques for resection of insular gliomas through the transfrontal isthmus approach. Fifty-nine insular gliomas with at least Berger-Sanai zone I involvement were removed with the new approach, and extent of resection and postoperative neurological outcomes were assessed.

RESULTS Fifty-nine patients were enrolled in the study, including 35 men and 24 women, with a mean (range) age 44.3 (19–75) years. According to the Berger-Sanai classification system, the most common tumor was a giant glioma (67.8%), followed by involvement of zones I and IV (18.6%). Twenty-two cases were Yaşargil type 3A/B, and 37 cases were Yaşargil type 5A/B. The average angle between the lateral plane of the putamen and sagittal line was 33.53°, and the average width of the isthmus near the anterior insular point was 33.33 mm. The average angle between the lateral plane of the putamen and the sagittal line was positively correlated with the width of the isthmus near the anterior insular point (r = 0.935, p < 0.0001). The median (interquartile range [IQR]) preoperative tumor volume was 67.82 (57.64–92.19) cm 3 . Of 39 low-grade gliomas, 26 (66.67%) were totally resected; of 20 high-grade gliomas, 19 (95%) were totally resected. The median (IQR) extent of resection of the whole group was 100% (73.7%–100%). Intraoperative diffusion-weighted imaging showed no cases of middle cerebral artery– or lenticulostriate artery–related stroke. Extent of insular tumor resection was positively correlated with the angle of the lateral plane of the putamen and sagittal line (r = −0.329, p = 0.011) and the width of the isthmus near the anterior insular point (r = −0.267, p = 0.041). At 3 months postoperatively, muscle strength grade exceeded 4 in all cases, and all patients exhibited essentially normal speech. The median (IQR) Karnofsky performance score at 3 months after surgery was 90 (80–90).

CONCLUSIONS The transfrontal isthmus approach changes the working angle from lateral-medial to anterior-posterior, allowing for maximal safe removal of insular gliomas.

Risk of Tract Seeding Following Laser Interstitial Thermal Therapy for Brain Tumors

Neurosurgery 93:198–205, 2023

The management of intracranial oncological disease remains a significant challenge despite advances in systemic cancer therapy. Laser interstitial thermal therapy (LITT) represents a novel treatment for local control of brain tumors through photocoagulation with a stereotactically implanted laser fiber. Because the use of laser interstitial thermal therapy continues to increase within neurosurgery, characterization of LITT is necessary to improve outcomes.

OBJECTIVE: To quantify the risk of tumor seeding along the laser fiber tract in patients receiving LITT for primary or metastatic brain tumors at a high-volume treatment center.

METHODS: We retrospectively reviewed all patients receiving LITT from 2015 to 2021 at our medical center. Patients with biopsy-confirmed tumors were included in this study. Tract seeding was identified as discontinuous, newly enhancing tumor along the LITT tract.

RESULTS: Fifty-six patients received LITT for biopsy-confirmed tumors from 2015 to 2021, with tract seeding identified in 3 (5.4%). Twenty-nine (51.8%) patients had gliomas, while the remainder had metastases, of which lung was the most common histology (20 patients, 74%). Tract seeding was associated with ablation proceeding inward from superficial tumor margin closest to the cranial entry point (P = .03). Patients with tract seeding had a shorter median time to progression of 1.1 (0.1-1.3) months vs 4.2 (2.2-8.6) months (P = .03).

CONCLUSION: Although the risk of tract seeding after LITT is reassuringly low, it is associated with decreased progression-free survival. This risk may be related to surgical technique or experience. Follow-up radiosurgery to the LITT tract has the potential to prevent this complication.

Innovative design of bone quality-targeted intervertebral spacer: accelerated functional fusion guiding oriented collagen and apatite microstructure without autologous bone graft

The Spine Journal 23 (2023) 609−620

Although autologous bone grafting is widely considered as an ideal source for interbody fusion, it still carries a risk of nonunion. The influence of the intervertebral device should not be overlooked. Requirements for artificial spinal devices are to join the vertebrae together and recover the original function of the spine rapidly. Ordered mineralization of apatite crystals on collagen accelerates bone functionalization during the healing process. Particularly, the stable spinal function requires the ingrowth of an ordered collagen and apatite matrix which mimics the intact intervertebral microstructure. This collagen and apatite ordering is imperative for functional bone regeneration, which has not been achieved using classical autologous grafting.

PURPOSE: We developed an intervertebral body device to achieve high stability between the host bone and synthesized bone by controlling the ordered collagen and apatite microstructure.

STUDY DESIGN: This was an in vivo animal study.

METHODS: Intervertebral spacers with a through-pore grooved surface structure, referred to as a honeycomb tree structure, were produced using metal 3D printing. These spacers were implanted into normal sheep at the L2−L3 or L4−L5 disc levels. As a control group, grafting autologous bone was embedded. The mechanical integrity of the spacer/bone interface was evaluated through push-out tests.

RESULTS: The spacer with honeycomb tree structure induced anisotropic trabecular bone growth with textured collagen and apatite orientation in the through-pore and groove directions. The pushout load of the spacer was significantly higher than that of the conventional autologous graft spacer. Moreover, the load was significantly correlated with the anisotropic texture of the newly formed bone matrix.

CONCLUSIONS: The developed intervertebral spacer guided the regenerated bone matrix orientation of collagen and apatite, resulting in greater strength at the spacer/host bone interface than that obtained using a conventional gold-standard autologous bone graft.

CLINICAL SIGNIFICANCE: Our results provide a foundation for designing future spacers for interbody fusion in human.

Association of Preoperative Vascular Wall Imaging Patterns and Surgical Outcomes in Patients With Unruptured Intracranial Saccular Aneurysms

Neurosurgery 92:421–430, 2023

MR vascular wall imaging (VWI) may have prognostic value in patients with unruptured intracranial aneurysms (UIAs).

OBJECTIVE: To evaluate the value of VWI as a predictor of surgical outcome in patients with UIAs.

METHODS: This prospective cohort study evaluated surgical outcomes in consecutive patients with UIAs who underwent surgical clipping at a single center. All participants underwent high-resolution VWI and were followed for at least 6 months. The primary clinical outcome was modified Rankin scale (mRS) score 6 months after surgery.

RESULTS: The number of patients in the no wall enhancement, uniformwall enhancement (UWE), and focal wall enhancement (FWE) groups was 37, 145, and 154, respectively. Incidence of postoperative complications was 15.5% in the FWE group, 12.4% in the UWE group, and 5.4% in the no wall enhancement group. The proportion of patients with mRS score >2 at the 6-month follow-up was significantly higher in the FWE group than in the UWE group (14.3% vs 6.9%; P = .0389). In the multivariate analysis, FWE (odds ratio, 2.573; 95% CI 1.001-6.612) and positive proximal artery remodeling (odds ratio, 10.56; 95% CI 2.237-49.83) were independent predictors of mRS score >2 at the 6-month follow-up.

CONCLUSION: Preoperative VWI can improve the surgeon’s understanding of aneurysm pathological structure. Type of aneurysmal wall enhancement on VWI is associated with clinical outcome and incidence of salvage anastomosis and surgical complications.

Stereotactic radiosurgery for Koos grade IV vestibular schwannoma in patients ≥ 65 years old

Acta Neurochirurgica (2023) 165:211–220

Surgery is the preferred treatment for large vestibular schwannomas (VS). Good tumor control and cranial nerve outcomes were described in selected Koos IV VS after single-session stereotactic radiosurgery (SRS), but outcomes in elderly patients have never been specifically studied. The aim of this study is to report clinical and radiological outcomes after single-session SRS for Koos IV VS in patients ≥ 65 years old.

Method This multicenter, retrospective study included patients ≥ 65 years old, treated with primary, single-session SRS for a Koos IV VS, and at least 12 months of follow-up. Patients with life-threatening or incapacitating symptoms were excluded. Tumor control rate, hearing, trigeminal, and facial nerve function were studied at last follow-up.

Results One-hundred and fifty patients (median age of 71.0 (IQR 9.0) years old with a median tumor volume of 8.3 cc (IQR 4.4)) were included. The median prescription dose was 12.0 Gy (IQR 1.4). The local tumor control rate was 96.0% and 86.2% at 5 and 10 years, respectively. Early tumor expansion occurred in 6.7% and was symptomatic in 40% of cases. A serviceable hearing was present in 16.1% prior to SRS and in 7.4% at a last follow-up of 46.5 months (IQR 55.8). The actuarial serviceable hearing preservation rate was 69.3% and 50.9% at 5 and 10 years, respectively. Facial nerve function preservation or improvement rates at 5 and 10 years were 98.7% and 91.0%, respectively. At last follow-up, the trigeminal nerve function was improved in 14.0%, stable in 80.7%, and worsened in 5.3% of the patients. ARE were noted in 12.7%. New hydrocephalus was seen in 8.0% of patients.

Conclusion SRS can be a safe alternative to surgery for selected Koos IV VS in patients ≥ 65 years old. Further follow-up is warranted.

Transseptal interforniceal endoscopic removal of superiorly recessed colloid cysts

J Neurosurg 137:813–819, 2022

Transforaminal endoscopic colloid cyst resection is well described. However, some anatomical colloid cyst variants may warrant a modified approach. Rarely, colloid cysts separate the forniceal columns and grow superiorly within the leaflets of the septum pellucidum. Thus, the authors’ goal was to characterize the imaging features, clinical presentation, surgical strategy, and outcomes of patients with this superiorly recessed colloid cyst variant.

METHODS A retrospective evaluation of patients who underwent endoscopic resection of colloid cysts from 1999 to 2020 was performed. The patients were dichotomized depending on whether the cyst was located predominately below the forniceal columns or was superiorly recessed (forniceal column separation with variable intraseptal extension). This comparative cohort study focused on clinical presentation, imaging features, operative technique, and patient outcome.

RESULTS In total, 182 patients were identified. Seventeen patients had colloid cysts that were defined as superiorly recessed and underwent transseptal interforniceal removal, and 165 patients underwent a standard transforaminal approach. Patients had similar demographic characteristics. However, transseptal cysts were on average larger (17.8 mm vs 11.4 mm, p < 0.0001), and these patients had a greater frontal-occipital horn ratio (0.45 vs 0.41, p = 0.012). They were also more likely to have undergone a previous resection (p = 0.02). The two cohorts had similar surgical outcomes, with no differences in extent of resection, recurrence, or complications.

CONCLUSIONS Superiorly recessed intraseptal colloid cysts are larger and tend to splay the bodies of the fornix, thus requiring a parasagittal transseptal interforniceal endoscopic approach. This achieves complete removal with comparatively negligible morbidity or rare recurrence (5.9%).

Dumbbell-shaped pituitary adenomas: prognostic factors for prediction of tumor nondescent of the supradiaphragmal component from a multicenter series

J Neurosurg 137:609–617, 2022

Dumbbell-shaped pituitary adenomas (DSPAs) are a subgroup of macroadenomas with suprasellar extension that are characterized by a smaller diameter at the level of the diaphragma sellae opening compared with the supradiaphragmal tumor component (SDTC). Hence, DSPAs may be particularly prone to a nondescending suprasellar tumor component and risk for residual tumor or postoperative bleeding.

METHODS A multicenter retrospective cohort analysis of 99 patients with DSPA operated on via direct endoscopic endonasal transsphenoidal approach between 2011 and 2020 was conducted. Patient recruitment was performed at two tertiary care centers (Medical University of Vienna and University of Southern California) with expertise in endoscopic skull base surgery. DSPA was defined as having a smaller diameter at the level of the diaphragma sellae compared with the SDTC.

RESULTS On preoperative MRI, all DSPAs were macroadenomas (maximum diameter range 17–71 mm, volume range 2–88 cm 3 ). Tumor descent was found in 73 (74%) of 99 patients (group A), and nondescent in 26 (26%) of 99 patients (group B) intraoperatively. DSPAs in group A had a significantly smaller diameter (30 vs 42 mm, p < 0.001) and significantly smaller volume (10 vs 22 cm 3 , p < 0.001) than those in group B. The ratio of the minimum area at the level of the diaphragmal opening in comparison with the maximum area of the suprasellar tumor component (“neck-to-dome area”) was significantly lower in group A than in group B (1.7 vs 2.7, p < 0.001). Receiver operating characteristic curve analysis revealed an area under the curve of 0.75 (95% CI 0.63–0.87). At a cutoff ratio of 1.9, the sensitivity and specificity for a nondescending suprasellar tumor component were 77% and 34%, respectively.

CONCLUSIONS In the present study, the neck-to-dome area ratio was of prognostic value for prediction of intraoperative tumor nondescent in DSPAs operated on via a direct endonasal endoscopic approach. Pituitary adenoma SDTC nondescent carried the inherent risk of hemorrhagic transformation in all cases.

Artificial disc replacement and adjacent-segment pathology: 10-year outcomes of a randomized trial

J Neurosurg Spine 36:945–953, 2022

Artificial disc replacement (ADR) is designed to preserve motion and thus protect against adjacent segment pathology (ASP) and act as an alternative treatment to fusion surgery. The question remains, how well do ADR devices perform after 10 years of follow-up compared with fusion surgery in terms of patient satisfaction, sustainability, and protection against ASP?

METHODS This was the 10-year follow-up study of 153 participants who underwent ADR or fusion surgery after anterior decompression due to cervical degenerative radiculopathy (ISRCTN registration no. 44347115). Scores on the Neck Disability Index (NDI), EQ-5D, and visual analog scale for neck and arm pain were obtained from the Swedish Spine Registry and analyzed using ANCOVA. Information about secondary surgical procedures was collected from medical records and presented as Kaplan-Meier curves. MRI and flexion-extension radiography were performed, and ASP was
graded according to the Miyazaki classification system.

RESULTS Ten participants were lost to follow-up, which left 143 participants (80 underwent ADR and 65 underwent anterior cervical discectomy and fusion). There were no differences between groups in terms of patient-reported outcome measures (10-year difference in NDI scores 1.7 points, 95% CI −5.1 to 8.5, p = 0.61). Nineteen (24%) participants in the ADR group compared with 9 (14%) in the fusion group underwent secondary surgical procedures. The higher reoperation rate of the ADR group was mainly due to 11 female participants with device loosening. The rates of reoperation due
to ASP were similar between groups, which was confirmed with MRI assessment of ASP that also showed no differences between the groups (p = 0.21).
CONCLUSIONS This was the first 10-year follow-up study to compare ADR with fusion surgery and to provide MRI information for the assessment of ASP. The authors found no benefit of ADR over fusion surgery after anterior  decompression for cervical degenerative radiculopathy.

 

The endonasal midline inferior intercavernous approach to the cavernous sinus

Acta Neurochirurgica

https://doi.org/10.1007/s00701-022-05284-w

Traditional endoscopic endonasal approaches to the cavernous sinus (CS) open the anterior CS wall just medial to the internal carotid artery (ICA), posing risk of vascular injury. This work describes a potentially safer midline sellar entry point for accessing the CS utilizing its connection with the inferior intercavernous sinus (IICS) when anatomically present.

Methods The technique for the midline intercavernous dural access is described and depicted with cadaveric dissections and a clinical case.

Results An endoscopic endonasal approach exposed the periosteal dural layer of anterior sella and CS. The IICS was opened sharply in midline through its periosteal layer. The feather knife was inserted and advanced laterally within the IICS toward the anterior CS wall, thereby gradually incising the periosteal layer of the IICS. The knife was turned superiorly then inferiorly in a vertical direction to open the anterior CS wall. This provided excellent access to the CS compartments, maintained the meningeal layer of the IICS and the medial CS wall, and avoided an initial dural incision immediately adjacent to the ICA.

Conclusion The midline intercavernous dural access to the CS assisted by a 90° dissector-blade is an effective modification to previously described techniques, with potentially lower risk to the ICA.