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The "weekend effect" is the negative effect on disease course and treatment resulting from being admitted to the hospital during a weekend. Whether the weekend effect is associated with worse outcomes for patients treated for aneurysmal subarachnoid hemorrhage (aSAH) is unknown. We assessed neurologic outcomes of patients with aSAH admitted during the weekend versus during the week.A retrospective database was reviewed to identify all patients with aSAH who received open or endovascular treatment from August 1, 2007, to July 31, 2019, at a quaternary center. The primary outcome was a poor neurologic outcome (modified Rankin Scale score2). Propensity adjustment included age, sex, treatment type, Hunt and Hess grade, and Charlson Comorbidity Index.A total of 1014 patients (women, 703 [69.3%]; men, 311 [30.7%]; mean age, 56 [standard deviation, 14]) met inclusion criteria; 726 (71.6%) had weekday admissions, and 288 (28.4%) had weekend admissions. There was no significant difference between patients with a weekday versus a weekend admission in mean (standard deviation) time to treatment (0.85 [1.29] vs. 0.93 [1.30] days, P = 0.10) or length of stay (19 [9] vs. 19 [9] days, P = 0.04). Total cost and rates of delayed cerebral ischemia and vasospasm were similar between the admission groups, both overall and within the open and endovascular treatment cohorts. After propensity adjustment, weekend admission was not a significant predictor of a modified Rankin Scale score greater than 2 (odds ratio [95% confidence interval]; 1.12 [0.85-1.49]; P = 0.4).No difference in neurologic outcomes was associated with weekend admission among this cohort of patients with aSAH.

Intramedullary spinal cord cavernous malformations (SCCMs) account for only 5% of overall cavernous malformations (CMs). The occurrence of recurrent or residual SCCMs has not been well discussed, nor have the technical nuances of resection.To assess the characteristics of residual SCCMs and surgical outcomes and describe the techniques to avoid leaving lesion remnants during primary resection.Demographic, radiologic, intraoperative findings and surgical outcomes data for a cohort of surgically managed intramedullary SCCMs were obtained from an institutional database and retrospectively analyzed. A systematic literature review was performed using PRISMA guidelines.Of 146 SCCM resections identified, 17 were for residual lesions (12%). Patients with residuals included 13 men and 4 women, with a mean age of 43 years (range 16-70). All patients with residual SCCMs had symptomatic presentations: sensory deficits, paraparesis, spasticity, and pain. Residuals occurred between 3 and 264 months after initial resection. Approaches for 136 cases included posterior midline myelotomy (28.7%, n = 39), pial surface entry (37.5%, n = 51), dorsal root entry zone (27.9%, n = 38), and lateral entry (5.9%, n = 8). Follow-up outcomes were similar for patients with primary and residual lesions, with the majority having no change in modified Rankin Scale score (63% [59/93] vs 75% [9/12], respectively, P = .98).SCCMs may cause significant symptoms. During primary resection, care should be taken to avoid leaving residual lesion remnants, which can lead to future hemorrhagic events and neurological morbidity. However, satisfactory results are achievable even with secondary or tertiary resections.

The additional hospital costs associated with delayed cerebral ischemia (DCI) have not been well investigated in prior literature. In this study, the total hospital cost of DCI in aneurysmal subarachnoid hemmorhage (aSAH) patients treated at a single quaternary center was analyzed.All patients in the Post-Barrow Ruptured Aneurysm Trial treated for an aSAH between January 1, 2014, and July 31, 2019, were retrospectively analyzed. DCI was defined as cerebral infarction identified on computed tomography, magnetic resonance imaging, or autopsy after exclusion of procedure-related infarctions. The primary outcome was the difference in total cost (including hospital, discharge facility, and all follow-up) using a propensity-adjusted analysis. Propensity score covariate-adjusted linear regression analysis included age, sex, open versus endovascular treatment, Hunt and Hess score, and Charlson Comorbidity Index score.Of the 391 patients included, 144 (37%) had DCI. Patients with DCI had a significantly greater cost compared to patients without DCI (mean standard deviation $112,081 [$54,022] vs. $86,159 [$38,817]; P 0.001) and a significantly greater length of stay (21 days [11] vs. 18 days [8], P = 0.003, respectively). In propensity-adjusted linear regression analysis, both DCI (odds ratio, $13,871; 95% confidence interval, $7558-$20,185; P 0.001) and length of stay (odds ratio, $3815 per day; 95% confidence interval, $3480-$4149 per day; P 0.001) were found to significantly increase the cost.The significantly higher costs associated with DCI further support the evidence that adverse effects associated with DCI in aSAH pose a significant burden to the health care system.

OBJECTIVE Ophthalmic artery (OA) aneurysms are surgically challenging lesions that are now mostly treated using endovascular procedures. However, in specialized tertiary care centers with experienced neurosurgeons, controversy remains regarding the optimal treatment of these lesions. This study used propensity adjustment to compare microsurgical and endovascular treatment of unruptured OA aneurysms in experienced tertiary and quaternary settings. METHODS The authors retrospectively reviewed the medical records of all patients who underwent microsurgical treatment of an unruptured OA aneurysm at the University of California, San Francisco, from 1997 to 2017 and either microsurgical or endovascular treatment at Barrow Neurological Institute from 2011 to 2019. Patients were categorized into two cohorts for comparison: those who underwent open microsurgical clipping, and those who underwent endovascular flow diversion or coil embolization. Outcomes included neurological or visual outcomes, residual or recurrent aneurysms, retreatment, and severe complications. RESULTS A total of 345 procedures were analyzed: 247 open microsurgical clipping procedures (72%) and 98 endovascular procedures (28%). Of the 98 endovascular procedures, 16 (16%) were treated with primary coil embolization and 82 (84%) with flow diversion. After propensity adjustment, microsurgical treatment was associated with higher odds of a visual deficit (OR 8.5, 95% CI 1.1–64.9, p = 0.04) but lower odds of residual aneurysm (OR 0.06, 95% CI 0.01–0.28, p < 0.001) or retreatment (OR 0.12, 95% CI 0.02–0.58, p = 0.008) than endovascular therapy. No difference was found between the two cohorts with regard to worse modified Rankin Scale score, modified Rankin Scale score greater than 2, or severe complications. CONCLUSIONS Compared with endovascular therapy, microsurgical clipping of unruptured OA aneurysms is associated with a higher rate of visual deficits but a lower rate of residual and recurrent aneurysms. In centers experienced with both open microsurgical and endovascular treatment of these lesions, the treatment choice should be based on patient preference and aneurysm morphology.

Intraorbital foreign body is a rare condition, especially when extending into the intracranial compartment. When facing this scenario in the ER, the neurosurgeon must carefully choose the optimal point of surgical access in order to reduce morbidity. The authors hereby report the case of a 66 year-old male with a penetrating trauma to the orbit reaching the anterior cranial base through the orbital roof and associated with an intracerebral hematoma. The removal of the foreign body was performed by a dual approach: an 'eyebrow' supraorbital keyhole craniotomy and an intra-orbital extra-ocular exploration, with later microsurgical drainage of the hematoma and evisceration of the eye 48 hours later. The patient developed a pseudomeningocele, which was treated with lumbar puncture and compressive dressing. After proper intravenous antibiotic prophylaxis, the patient was discharged 21 days after hospital admission.

BackgroundMiddle meningeal artery (MMA) embolization results in fewer treatment failures than surgical evacuation for chronic subdural hematomas (cSDHs). We compared the total 1-year hospital cost for MMA embolization versus surgical evacuation for patients with cSDH.MethodsData for patients who presented with cSDHs from January 1, 2018, through May 31, 2020, were retrospectively reviewed. Patients were grouped by initial treatment (surgery vs MMA embolization), and total hospital cost was obtained. A propensity-adjusted analysis was performed. The primary outcome was difference in mean hospital cost between treatments.ResultsOf 170 patients, 48 (28%) underwent embolization and 122 (72%) underwent surgery. cSDHs were larger in the surgical (20.5 (6.7) mm) than in the embolization group (16.9 (4.6) mm; PConclusionsMMA embolization is associated with decreased total hospital cost compared with surgery for cSDHs. This lower cost is directly related to the decreased need for additional treatment interventions.

Stereotactic radiosurgery is an effective treatment option for trigeminal neuralgia (TN), with frameless stereotactic radiosurgery (fSRS) allowing for a less invasive experience. A single-institutional series and systematic review of the literature were performed for cases of TN treated with fSRS.Patients at our institution with TN that were treated with fSRS from the years 2012-2021 were included. Similarly, multiple databases were searched for studies regarding TN treated with fSRS where patient-level data was included from 2004-2020. Pain levels, via the Barrow Neurological Institute (BNI) scale, before and after treatment were analyzed. Pooled analysis was performed to compare treatment outcomes between studies using CyberKnife and LINAC modalities.Twenty-three patients at our institution were treated with LINAC fSRS (median treatment dose: 85 Gy). Most patients had TN refractory to previous procedural treatments. Eight (35%) patients had an excellent posttreatment response (BNI I-II), while 11 (48%) patients had a good result (BNI IIIa/b). Eight patients had recurrence of pain. A total of 30 articles were included in the systematic review, encompassing 1705 patients. At last follow-up, 63.1% (774/1227) of patients endorsed an excellent response, while 16.1% (197/1227) had a good response, and 22.5% (215/957) of patients had recurrence. Pain response, facial numbness rates, and pain recurrence rates were not significantly different between CyberKnife and LINAC modalities.Frameless SRS for TN appears to be an efficacious noninvasive option for patients with substantial comorbidities, who have failed other treatment methods, although it can be limited by higher recurrence rates.

BACKGROUND: The COVID-19 pandemic has significantly affected patient care across specialties. Ramifications for neurosurgery include substantial disruptions to surgical training and changes in nonurgent patient presentations to the emergency department. This study quantifies the effects of the COVID-19 pandemic on the number of emergency department patients who were referred to the neurosurgery department for further consultation and treatment and identifies and describes trends in the characteristics of these visits. METHODS: A retrospective review was performed of neurosurgical consultations at a single high-volume institution for 28 call-day periods before and after the official announcement of the pandemic. Primary outcomes included consultations per call-day, patient presentation category, and patient admission. RESULTS: The neurosurgical service was consulted regarding 629 patients (367 male patients) during the study period, with 471 (75%) and 158 (25%) patients presenting before and after the announcement of the COVID-19 pandemic, respectively. The mean number of neurosurgical consultations per call-day was significantly lower in the COVID-19 period (5.6 consultations) compared with the pre-COVID-19 period (16.8 consultations) (P < 0.001). After adjusting for patient demographics, the rate of presentation for general nonurgent concerns, such as back pain, headaches, and other general weaknesses, significantly decreased (odds ratio [95% confidence interval], 0.60 [0.47-0.77], P < 0.001). CONCLUSIONS: Neurosurgical consultations significantly decreased after the onset of the COVID-19 pandemic, with a substantially lower overall number of consultations necessitating operative interventions. Furthermore, the relative number of patients with nonemergent neurological conditions significantly decreased during the pandemic.

Background and importance Posterior inferior cerebellar artery (PICA) aneurysms are uncommon, and aneurysms associated with anatomical PICA variants are even rarer. Although often treated endovascularly, aneurysms associated with anatomical PICA variants may not be suitable for endovascular intervention because of the risk of compromise of brainstem perforators and may be more amenable to open techniques. This case report describes the successful treatment of an aneurysm associated with a double-origin PICA (DOPICA) by distally reimplanting one of the PICA limbs. Clinical presentation A 78-yr-old man with a Hunt-Hess grade III, Fisher grade IV subarachnoid hemorrhage secondary to a ruptured distal right PICA aneurysm associated with a DOPICA was treated with PICA-PICA bypass and trapping of the aneurysm. This is the first reported case in the literature of successful bypass of a DOPICA-associated aneurysm. Radiographically, the bypass remained patent with successful obliteration of the aneurysm, and at discharge from the hospital, the patient had a Glasgow Coma Scale score of 15 and modified Rankin Scale score of 3. Conclusion This case demonstrates a novel reimplantation bypass for a ruptured aneurysm that exploits this rare variant anatomy of a DOPICA.

BackgroundAn association between poor dentition and the risk of ischemic stroke has previously been reported in the literature. In this study we assessed oral hygiene (OH), including tooth loss and the presence of dental disease, to determine if an association exists with functional outcomes following mechanical thrombectomy (MT) for large-vessel ischemic stroke.MethodsA retrospective review was conducted of consecutive adult patients at a single comprehensive stroke center who underwent MT from 2012 to 2018. Inclusion criteria included availability of CT imaging to radiographically assess OH. A multivariate analysis was performed, with the primary outcome being 90-day post-thrombectomy modified Rankin Scale (mRS) score >2.ResultsA total of 276 patients met the inclusion criteria. The average number of missing teeth was significantly higher in patients with a poor functional outcome (mean (SD) 10 (11) vs 4 (6), pConclusionMissing teeth and the presence of dental disease are inversely correlated with functional independence following MT, independent of thrombectomy success or tPA status.

Pediatric brainstem lesions are diagnoses that require tissue sampling to advance our understanding of them and their management. Frameless, robot-assisted biopsy of these lesions has emerged as a novel, viable biopsy approach. Correspondingly, the aim of this study was to quantitively and qualitatively summarize the contemporary literature regarding the likelihood of achieving tumor diagnosis and experiencing any postoperative complications.Searches of 7 electronic databases from inception to September 2022 were conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles were screened against prespecified criteria. Outcomes were pooled by random-effects meta-analyses of proportions where possible.A total of 8 cohort studies satisfied all criteria. They described 99 pediatric patients with brainstem lesions in whom frameless, robot-assisted biopsy was involved in their work-up. There were 62 (63%) male and 37 (37%) female patients with a median age of 9 years at time of biopsy. Overall, all patients had sufficient tissue obtained by initial biopsy for evaluation. Pooled estimate of achieving tumor diagnosis was 100% (95% confidence interval [CI] 97%-100%) across all studies with a high degree of certainty. Across all studies, there were no cases of procedure-related mortality. The pooled estimates of transient and permanent complications after biopsy were 10% (95% CI 4%-19%) and 0% (95% CI 0%-2%), respectively, of very low and low degrees of certainty each.The contemporary metadata demonstrates the frameless, robot-assisted biopsy of pediatric brainstem lesions is both effective and safe when performed in an experienced setting. Further research is needed to augment robot and automated technologies into workup algorithms.

BackgroundStudies have shown an association between surgical treatment volume and improved quality metrics. This study evaluated nationwide results in carotid artery stenting (CAS) procedural readmission rates, costs, and length of stay based on hospital treatment volume.MethodsWe used the Nationwide Readmissions Database for carotid stenosis from 2010 to 2015. Patients receiving CAS were matched based on demographics, illness severity, and relevant comorbidities. Patients were matched 1:1 between low- and high-volume centers using a non-parametric preprocessing matching program to adjust for parametric causal inferences. Nearest-neighbor propensity score matching was performed using logit distance.ResultsLow- and high-volume centers admitted a mean (SD) of 4.68 (3.79) and 25.10 (16.86) patients undergoing CAS per hospital, respectively. Comorbidities were significantly different and initially could not be adequately matched. Because of significant differences in baseline patient population characteristics after attempted matching between low- and high-volume centers, we used propensity adjustment with multivariate analysis. Using this alternative approach, no significant differences were observed between low- and high-volume centers for the presence of any complication, postoperative stroke, postoperative myocardial infarction, and readmission at 30 days.ConclusionIn 1:1 nearest-neighbor matching with a high number of patients, our analysis did not result in well-matched cohorts for the effect of case volume on outcomes. Comparing analytical techniques for various outcomes highlights that outcome disparities may not be related to quality differences based on hospital size, but rather variability in patient populations between low- and high-volume institutions.

Sturge-Weber syndrome (SWS) is a capillary-venous malformation affecting the brain, the eye, and the adjacent trigeminal dermatomes of the skin. This illness is usually diagnosed during the first years of life. If left undiagnosed (and consequently untreated), the condition could develop into severe refractory seizures, ischemic strokes, visual loss, and early cognitive impairment. We report a case of a 23-year-old female patient with a port-wine facial stain, presenting her first convulsive episode in adulthood, associated with a moderate dilation of the deep venous system in the angiography, which raised the diagnostic of Sturge-Weber syndrome.

Although fluorescein is widely used for intraoperative angiography, some of its side effects remain obscure. In this report, we present the case of a 41-year-old patient with chronic ischemia caused by moyamoya syndrome who underwent bypass revascularization with intraoperative fluorescein angiography (FA). Immediately after the surgery, the patient presented homogeneous fluorescence of the entire skin. We discuss this curious phenomenon as well as other side effects that may arise due to FA.

Genitalia-related complications of ventriculoperitoneal shunts, such as scrotal migrations, are rare and most frequently presenting during the first year of the system placement, usually in the pediatric population, due to several factors, including vaginal process patency and increased abdominal pressure. Despite being typically benign, hernias, hydroceles, perforations, and catheter migration to the scrotum can lead to permanent disabilities and lethal complications, such as ventriculoperitoneal shunt dysfunction. We report a case of a late-onset, atraumatic, ventriculoperitoneal shunt fracture and catheter migration to the scrotum in a 22-year-old male, six years after its implantation, presenting in the emergency department due to acute hydrocephalus symptoms.

Background Although rare, cavernous malformations (CMs) of the optic nerve and anterior optic pathway (optic pathway cavernous malformations [OPCMs]) can occur, as described in several single case reports in the literature. Objective To describe the technical aspects of microsurgical management of CMs of the optic pathway on the basis of an extensive single-center experience and review of the literature. Methods A systematic literature review was performed to augment an earlier review, using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. In addition, an institutional database was searched for all patients undergoing surgical resection of OPCMs. Patient information, surgical technique, and clinical and radiographic outcomes were assessed. Results Since the previous report, 14 CMs were resected at this institution or by the senior author at another institution. In addition, 34 cases were identified in the literature since the systematic review in 2015, including some earlier cases that were not discussed in the previous report. Most OPCMs were resected via pterional, orbital-pterional, and orbitozygomatic craniotomies. Visual outcomes were similar to those in earlier reports, with 70% of patients reporting stable to normal vision postoperatively. Conclusion OPCMs can occur throughout the anterior visual pathway and may cause significant symptoms. Surgery is feasible and should be considered for OPCMs presenting to a surface of the nerve. Favorable results can be obtained with resection, although optimal results are obtained with patients who present with milder symptoms without longstanding damage to the optic apparatus.

OBJECTIVE The brainstem cavernous malformation (BSCM) grading system predicts neurological outcomes associated with microsurgical resection and assists neurosurgeons in selecting patients for treatment. The predictive accuracy of the BSCM grading system should be validated in a large cohort from high-volume centers to generalize its use. METHODS An external validation cohort comprised patients with a BSCM resected by the senior author (M.T.L.) since the publication of the BSCM grading system and those resected by another neurosurgeon (R.F.S.) over a 16-year period. Size, crossing the axial midpoint, the presence of a developmental venous anomaly, patient age, and timing of last hemorrhage were used to assign BSCM grades from 0 to VII. Poor neurological outcomes were recorded as modified Rankin Scale scores > 2 at last follow-up examination. RESULTS A total of 277 patients were included in the study. The average BSCM grade was 3.9, and the majority of BSCMs (181 patients, 65%) were intermediate grade (grades III–V). Outcomes were predicted by BSCM grade, with good outcomes observed in 47 of 54 patients (87%) with low-grade BSCMs, in 135 of 181 patients (75%) with intermediate-grade BSCMs, and in 21 of 42 patients (50%) with high-grade BSCMs. Conversely, proportions of patients with neurological deterioration increased with increasing BSCM grade, with worsening observed in 2 of 54 patients (4%) with low-grade BSCMs, in 29 of 181 patients (16%) with intermediate-grade BSCMs, and in 17 of 42 patients (40%) with high-grade BSCMs. In the chi-square analysis, high-grade BSCMs were associated with increased odds of neurological worsening compared to low- and intermediate-grade BSCMs (OR 5.0, 95% CI 2.4–10.4; p < 0.001). The receiver operating characteristic analysis demonstrated acceptable discrimination for predicting unfavorable functional outcomes (modified Rankin Scale score > 2) with an area under the curve of 0.74 (95% CI 0.68–0.80; p < 0.001). CONCLUSIONS This study validates the BSCM grading system in a large cohort of patients from two high-volume surgeons. BSCM grade predicted neurological outcomes with accuracy comparable to that of other grading systems in widespread use. The BSCM grading system establishes categories of low-, intermediate-, and high-grade BSCMs and a boundary or cutoff for surgery at BSCM grade V. BSCM grading guides the analysis of a particular patient’s condition, but treatment recommendations must be individualized, and neurosurgeons must calibrate BSCM grading to their own outcome results, unique abilities, and practices.

OBJECTIVE Good functional outcomes after aneurysmal subarachnoid hemorrhage (aSAH) are often dependent on early detection and treatment of cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI). There is growing evidence that continuous monitoring with cranial electroencephalography (cEEG) can predict CVS and DCI. Therefore, the authors sought to assess the value of continuous cEEG monitoring for the detection of CVS and DCI in aSAH. METHODS The cerebrovascular database of a quaternary center was reviewed for patients with aSAH and cEEG monitoring between January 1, 2017, and July 31, 2019. Demographic data, cardiovascular risk factors, Glasgow Coma Scale score at admission, aneurysm characteristics, and outcomes were abstracted from the medical record. Patient data were retrospectively analyzed for DCI and angiographically assessed CVS. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and odds ratio for cEEG, transcranial Doppler ultrasonography (TCDS), CTA, and DSA in detecting DCI and angiographic CVS were calculated. A systematic literature review was conducted in accordance with PRISMA guidelines querying the PubMed, Cochrane Controlled Trials Register, Web of Science, and Embase databases. RESULTS A total of 77 patients (mean age 60 years [SD 15 years]; female sex, n = 54) were included in the study. Continuous cEEG monitoring detected DCI and angiographically assessed CVS with specificities of 82.9% (95% CI 66.4%–93.4%) and 94.4% (95% CI 72.7%–99.9%), respectively. The sensitivities were 11.1% (95% CI 3.1%–26.1%) for DCI (n = 71) and 18.8% (95% CI 7.2%–36.4%) for angiographically assessed CVS (n = 50). Furthermore, TCDS detected angiographically determined CVS with a sensitivity of 87.5% (95% CI 71.0%–96.5%) and specificity of 25.0% (95% CI 7.3%–52.4%). In patients with DCI, TCDS detected vasospasm with a sensitivity of 85.7% (95% CI 69.7%–95.2%) and a specificity of 18.8% (95% CI 7.2%–36.4%). DSA detected vasospasm with a sensitivity of 73.9% (95% CI 51.6%–89.8%) and a specificity of 47.8% (95% CI 26.8%–69.4%). CONCLUSIONS The study results suggest that continuous cEEG monitoring is highly specific in detecting DCI as well as angiographically assessed CVS. More prospective studies with predetermined thresholds and endpoints are needed to assess the predictive role of cEEG in aSAH.

OBJECTIVE Rare arteriovenous malformations (AVMs) of the optic apparatus account for < 1% of all AVMs. The authors conducted a systematic review of the literature for cases of optic apparatus AVMs and present 4 cases from their institution. The literature is summarized to describe preoperative characteristics, surgical technique, and treatment outcomes for these lesions. METHODS A comprehensive search of the English-language literature was performed in accordance with established Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all published cases of AVM in the optic apparatus in the PubMed, Web of Science, and Cochrane databases. The authors also searched their prospective institutional database of vascular malformations for such cases. Data regarding the clinical and radiological presentation, visual acuity, visual fields, extent of resection, and postoperative outcomes were gathered. RESULTS Nine patients in the literature and 4 patients in the authors’ single-surgeon series who fit the inclusion criteria were identified. The median age at presentation was 29 years (range 8–39 years). Among these patients, 11 presented with visual disturbance, 9 with headache, and 1 with multiple prior subarachnoid hemorrhages; the AVM in 1 case was found incidentally. Four patients described prior symptoms of headache or visual disturbance consistent with sentinel events. Visual acuity was decreased from baseline in 10 patients, and 11 patients had visual field defects on formal visual field testing. The most common visual field defect was temporal hemianopia, found in one or both eyes in 7 patients. The optic chiasm was affected in 10 patients, the hypothalamus in 2 patients, the optic nerve (unilaterally) in 8 patients, and the optic tract in 2 patients. Six patients underwent gross-total resection; 6 patients underwent subtotal resection; and 1 patient underwent craniotomy, but no resection was attempted. Postoperatively, 9 of the patients had improved visual function, 1 had no change, and 3 had worse visual acuity. Eight patients demonstrated improved visual fields, 1 had no change, and 4 had narrowed fields. CONCLUSIONS AVMs of the optic apparatus are rare lesions. Although they reside in a highly eloquent region, surgical outcomes are generally good; the majority of patients will see improvement in their visual function postoperatively. Microsurgical technique is critical to the successful removal of these lesions, and preservation of function sometimes requires subtotal resection of the lesion.