BACKGROUND AND OBJECTIVE Middle meningeal artery embolization (MMAe) is an effective treatment for chronic subdural hematoma (cSDH), but the optimal embolic agent remains debated. Landmark randomized trials predominantly used liquid embolics, although calibrated microspheres remain widely used. We compared clinicoradiologic outcomes after MMAe with 75 μm Embozene microspheres versus liquid embolics (n-butyl cyanoacrylate or Onyx 18). METHODS We retrospectively reviewed single-agent MMAe for cSDH at a tertiary center (January 2019-January 2025). The embolized MMA was the unit of analysis; agent choice was discretionary. The efficacy cohort required 2-8 week imaging (n = 66); the safety cohort included all single-agent procedures (n = 67; 35 particle, 32 liquid). Primary outcomes were embolization failure and unplanned surgical evacuation. Secondary outcomes included early SDH thickness, midline shift, and latest modified Rankin scale (mRS). RESULTS Fifty patients underwent 66 embolizations (16 bilateral): 34 particle and 32 liquid. Embolization failure occurred in 5/34 versus 4/32, and unplanned evacuation in 3/34 versus 1/32; events were few and the comparison underpowered. Female patients were more frequent in the particle group (47% vs 19%, P = 0.020). Early SDH thickness was 8 (6) versus 6 (6) mm (P = 0.340). The safety cohort had one fatal posterior-circulation infarct after Embozene (1/35 vs 0/32) and no other periprocedural complications. CONCLUSION Embolization failure was similar between 75 μm Embozene and liquid embolics, while unplanned evacuation was numerically higher with particles. Given infrequent events, limited sample size, and baseline imbalances, agent selection may be individualized by anatomy, visualization, and operator experience.
Background Cerebral aneurysm clipping generally provides durable occlusion, but residual aneurysm regrowth or recurrence after apparently complete treatment may rarely require reoperation. Reoperative microsurgery is challenging because previous clips, dense scarring, altered vascular anatomy, and complex aneurysm-wall pathology may restrict exposure and vascular control. We reviewed technical challenges and operative strategies in microsurgical retreatment after clipping, supplemented by 2 illustrative cases. Methods We present 2 illustrative cases comprising 3 previously clipped aneurysms requiring microsurgical retreatment and performed a structured search of PubMed, Scopus, and Cochrane. Studies reporting technical aspects of microsurgical retreatment after clipping were reviewed, and operative challenges and strategies were descriptively synthesized. Results Twenty-two studies reported relevant technical aspects. Recurring challenges included adhesive scarring, management of previous clips, limited vascular control, prolonged ischemia, thrombosed or atherosclerotic aneurysm components, branch or perforator incorporation, complex clip reconstruction, and need for revascularization. Reported strategies included sharp spring-to-blade dissection, selective clip removal, temporary vascular control, thrombectomy or dome reduction, multiclip reconstruction, neurophysiological monitoring, and bypass procedures. Conclusions Microsurgical retreatment after previous clipping requires individualized sequencing and combination of established cerebrovascular techniques according to the reoperative anatomy. Understanding scar-related loss of tissue planes, previous clip management, vascular control, aneurysm reconstruction, and potential revascularization may facilitate operative planning in complex cases. Endovascular retreatment should be considered when anatomically appropriate.
Objective The rhomboid lip (RL) is a variable sheet-like neural structure extending from the lateral recess of the fourth ventricle into the cerebellopontine angle (CPA). This technical note describes the radiological, microsurgical, and histopathological features of a markedly developed RL encountered during CPA meningioma surgery, with emphasis on its intraoperative identification and selective surgical management. Methods A 60-year-old woman underwent retrosigmoid resection of a 12-mm left CPA meningioma. Preoperative magnetic resonance imaging suggested a well-developed RL extending from the foramen of Luschka toward the internal auditory canal. Intraoperatively, the RL was assessed according to its morphological features and anatomical relationships and was preserved or selectively divided according to the exposure required during tumor removal. RL tissue that required division for surgical exposure was subsequently examined histopathologically. Results The RL appeared thicker and less transparent than the arachnoid, with veins coursing along its surface. Its relationship with cranial nerve IX and the choroid plexus provided useful anatomical landmarks for identification. The portion overlying the vestibulocochlear nerve was preserved during most of the tumor dissection and divided only when additional exposure was required for complete tumor removal. Histopathological examination demonstrated ependymal and glial layers, confirming the structure as RL. Simpson grade II resection was achieved without new cranial nerve deficits. Conclusions A well-developed RL can be recognized as a distinct anatomical structure using morphological and anatomical landmarks. During CPA surgery, selective preservation or division according to the evolving operative corridor may facilitate anatomically informed surgical dissection.
Background Moyamoya disease (MMD) presents distinctive perioperative challenges owing to impaired cerebrovascular autoregulation and exhausted vascular reserve. Perioperative predictors of neurological deficit remain undercharacterized. Methods This single-center retrospective cohort study analyzed 24 consecutive MMD patients undergoing revascularization (2017–2022). A multidomain dataset encompassing Suzuki stage, surgical technique, intraoperative hemodynamics, perioperative laboratories, and anesthetic variables was analyzed using ROC analysis and exploratory penalized logistic regression with leave-one-out cross-validation. Results Thirty-nine procedures were performed (23 Stage I, 16 Stage II; all primary MMD). Stage I comprised direct STA-MCA bypass (74%), combined (17%), and indirect techniques (8.6%); Suzuki stage III predominated (46%). Neurological deficits occurred in 14 of 23 patients (61%) after Stage I: 8 (57%) resolved before discharge, 4 (29%) persisted, and 2 (14%) were fatal; rates fell to 31% at Stage II. Neither surgical technique nor Suzuki stage predicted deficits (P = 1.000; P = 0.368). Anesthesia duration was the strongest discriminator (AUC 0.73; threshold >480 minutes), followed by preoperative hemoglobin (AUC 0.68; <14.3 g dl−1), though neither reached univariate significance. The two-variable model achieved leave-one-out AUC 0.64 (95% CI 0.39–0.86); adding disease-severity covariates reduced discrimination. EtCO2 variability correlated with functional outcome (P=0.031) and deficits with ICU stay >2 days (P=0.040). Conclusions Longer anesthesia duration and lower preoperative hemoglobin were the most consistent associates of neurological deficit; surgical technique and disease severity were not. Both are potentially modifiable perioperative targets, but associations are hypothesis-generating and require prospective multicenter validation.
