Long-term functional outcomes and complications of microsurgical resection of brainstem cavernous malformations: a systematic review and meta-analysis.

Brainstem cavernous malformations (CMs) encompass up to 20% of all intracranial CMs and are considered more aggressive than cerebral CMs because of their high annual bleeding rates. Microsurgical resection remains the primary treatment modality for CMs, but long-term functional outcomes and complications are heterogenous in the literature. The authors performed a systematic review on brainstem CMs in 4 databases: PubMed, EMBASE, Cochrane library, and Google Scholar. We included studies that reported on the long-term functional outcomes and complications of brainstem CMs microsurgical resection. A meta-analysis was performed and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The search yielded 4781 results, of which 19 studies met our inclusion criteria. Microsurgery was performed on 940 patients (mean age 35 years, 46.9% females). Most of the brainstem CMs were located in the pons (n = 475). The pooled proportions of improved, stable, and worsened functional outcomes after microsurgical resection of brainstem CMs were 56.7% (95% CI 48.4-64.6), 28.6% (95% CI 22.4-35.7), and 12.6% (95% CI 9.6-16.2), respectively. CMs located in the medulla were significantly (p = 0.003) associated with a higher proportion of improved outcome compared with those in the pons and midbrain. Complete resection was achieved in 93.3% (95% CI 89.8-95.7). The immediate postoperative complication rate was 37.2% (95% CI 29.3-45.9), with new-onset cranial nerve deficit being the most common complication. The permanent morbidity rate was 17.3% (95% CI 10.5-27.1), with a low mortality rate of 1% from the compiled study population during a mean follow-up of 58 months. Our analysis indicates that microsurgical resection of brainstem CMs can result in favorable long-term functional outcomes with transient complications in the majority of patients. Complete microsurgical resection of the CM is associated with a lower incidence of CM hemorrhage and the morbidity related to it.

Direct, Indirect, and Combined Extracranial-to-Intracranial Bypass for Adult Moyamoya Disease: An Updated Systematic Review and Meta-Analysis.

BACKGROUND: Moyamoya disease is a chronic, progressive cerebrovascular disease involving occlusion or stenosis of the terminal portion of the internal carotid artery. We conducted an updated systematic review and meta-analysis to investigate clinical and angiographic outcomes comparing direct, combined, and indirect bypass for the treatment of moyamoya disease in adults. METHODS: Two independent authors performed Preferred Reporting Items for Systematic reviews and Meta-Analyses guided literature searches in December 2021 to identify articles reporting clinical/angiographic outcomes in adult moyamoya disease patients undergoing bypass. Primary end points used were ischemic and hemorrhagic strokes, clinical outcomes, and angiographic revascularization. Study quality was evaluated with Newcastle-Ottawa and the Oxford Center for Evidence-Based Medicine scales. RESULTS: Four thousand four hundred fifty seven articles were identified in the initial search; 143 articles were analyzed. There were 3827 direct, 3826 indirect, and 3801 combined bypasses. Average length of follow-up was 3.59±2.93 years. Pooled analysis significantly favored direct (odds ratio [OR], 0.62 [0.48-0.79]; P<0.0001; OR, 0.44 [0.32-0.59]; P<0.0001; OR, 0.56 [0.42-0.74]; P<0.0001; OR, 3.1 [2.5-3.8]; P=0.0001) and combined (OR, 0.53 [0.41-0.69]; P<0.0001; OR, 0.28 [0.2-0.41]; P<0.0001; OR, 0.41 [0.3-0.56]; P<0.0001; OR, 3.1 [2.8-4.3]; P=0.0001) over indirect bypass for early stroke, late stroke, late intracerebral hemorrhage, and favorable outcomes, respectively. Indirect bypass was favored over combined (OR, 3.1 [1.7-5.6]; P<0.0001) and direct (OR, 4.12 [2.34-7.25]; P<0.0001) for early intracerebral hemorrhage. The meta-analysis significantly favored direct (OR, 0.37 [0.23-0.60]; P<0.001; OR, 0.49 [0.31-0.77]; P=0.002) and combined (OR, 0.23 [0.12-0.43]; P<0.00001; OR, 0.30 [0.18-0.49]; P<0.00001) bypass over indirect bypass for late stroke and late hemorrhage, respectively. Combined bypass was favored over indirect bypass for favorable outcomes (OR, 2.06 [1.18-3.58]; P=0.01). CONCLUSIONS: Based on combined meta-analysis (43 articles) and pooled analysis (143 articles), the existing literature indicates that combined and direct bypasses have significant benefits for patients suffering from late stroke and hemorrhage versus indirect bypass. Combined bypass was favored over indirect bypass for favorable outcomes. This is a strong recommendation based on low-quality evidence when utilizing the Grades of Recommendation, Assessment, Development, and Evaluation system. These findings have important implications for bypass strategy selection.

Cavernous Malformation of the Optic Nerve and Chiasm: Prompt Suspicion and Surgery Matter.

BACKGROUND: Cavernous malformations (CMs) of the optic nerve and chiasm are extremely rare, accounting for less than 1% of all intracranial CMs. Acute, subacute, or progressive visual loss from CM may occur with or without hemorrhage. Prompt surgical excision of the CM offers the best hope to improve or stabilize vision. Given its rarity, optic nerve and chiasm CMs may not be readily suspected. We provide 3 cases of optic nerve and chiasm CM, highlighting key neuroimaging features and the importance of expedited intervention. METHODS: Case records of the neuro-ophthalmology clinics of the Bascom Palmer Eye Institute and the University of Colorado, and literature review of reported cases of optic CM. RESULTS: A 49-year-old woman reported acute progressive painless vision loss in the right eye. MRI showed a suprasellar mass with heterogeneity in signal involving the right prechiasmatic optic nerve. Surgical excision of the CM 5 days after onset of visual loss improved vision from 20/300 to 20/30. A 29-year-old woman with acute painless blurred vision in the right eye had anterior chiasmal junctional visual field defects corresponding to a heterogeneously minimally enhancing mass with blood products enlarging the optic chiasm and proximal right optic nerve. Surgical excision of the CM 8 weeks after onset of visual loss improved vision from 20/40 to 20/15 with improved visual fields. A 33-year-old woman with a history of familial multiple CMs, diagnosed at age 18, reported new-onset severe headache followed by blurred vision. MRI showed a hemorrhagic lesion of the optic chiasm and right optic tract. She was 20/20 in each eye with a reported left superior homonymous hemianopia. No intervention was recommended. Vision of the right eye worsened to 20/400 2 months later. The patient was followed over 13 years, and the MRI and visual function remained unchanged. Literature review yielded 87 optic CM cases occurring across gender and nearly all ages with visual loss and headache as the most common presenting symptoms. Optic chiasm is the most common site of involvement (79%). Nearly 95% of reported CM cases were treated with surgery with 81% with improved vision and 1% with worsened vision. CONCLUSION: MRI features are critical to the diagnosis of optic nerve and chiasm CM and may mimic other lesions. A high index of suspicion by the neuro-ophthalmologist and neuroradiologist leads to early recognition and intervention. Given optic CM displaces and does not infiltrate neural tissue, expedited surgical resection by a neurosurgeon after consideration of other diagnostic possibilities improves visual function in most cases.

Extradural clinoidectomy for resection of clinoidal meningioma.

Extradural anterior clinoidectomy is a versatile technique to increase exposure of the sellar and parasellar region. It is of particular use in the resection of clinoidal meningiomas, as sphenoidal and clinoidal hyperostosis can cause compression of the optic nerve. Extradural clinoidectomy follows a series of steps, consisting of (1) unroofing of the superior orbital fissure, (2) unroofing of the optic canal, (3) removal of the optic strut, and (4) removal of the anterior clinoid process. The authors show these steps in detail, as well as their application to the resection of a large clinoidal meningioma. The video can be found here: https://youtu.be/O1Fcef29ETg .

Lateral parietal arteriovenous malformation with feeding artery aneurysm.

Superficial arteriovenous malformations (AVMs) with favorable Spetzler-Martin grading are amenable to primary surgical resection. Careful preoperative workup including preoperative angiograms is essential to identify feeding artery aneurysms and deep venous drainage. The authors present a 37-year-old female who presented with a Spetzler-Martin Grade II right parietal superficial AVM with a 5-mm feeding artery aneurysm from the posterior cerebral artery. Given the risk of hemorrhage, the AVM was resected completely without any complications. On subsequent postoperative angiograms, the feeding artery aneurysm diminished in caliber. Feeding artery aneurysms may regress spontaneously after resection of an AVM due to flow-related changes. The video can be found here: https://youtu.be/PpwODc9iI3g .

Atypical radiographic features of skull base cholesterol granuloma.

Cholesterol granulomas (CGs) are the most common benign lesions of the petrous apex (PA) and have distinct computed tomography (CT) and magnetic resonance imaging (MRI) characteristics. On CT, CGs of the PA (PACG) present as expansile lesions with erosion of bony trabeculae. MRI shows a hyperintense lesion on T1-and T2-weighted images and do not enhance with gadolinium. The objective is to describe the radiographic features of CGs of the skull base that do not arise from the PA. This study is a retrospective review. Three patients were operated on for suspected recurrent endolymphatic sac tumor, intracranial cholesteatoma, and recurrent sphenoid wing meningioma based on CT and MRI findings. Pathology results were consistent with CG in all three cases. All patients had bone erosion on CT. These skull base CGs did not demonstrate similar MRI features. These lesions were hyperintense, iso-to-hyperintense, and hypointense on T1-weighted MRI, respectively. These CGs were hyperintense in two cases and iso-to-hyperintense in one case on T2-weighted MRI. These lesions either demonstrated central or rim enhancement after gadolinium administration. Skull base CGs that do not arise from the PA demonstrate a broad spectrum of radiographic characteristics on MRI that are not typical of PACG.

Primary intrinsic chiasmal germinoma.

Intracranial germinomas are typically present in the suprasellar or pineal location, and their origin within the optic nerve or chiasm is extremely rare. We report a 25-year-old woman with an exophytic primary optic chiasm germinoma who underwent partial resection followed by radiation and had no detectable tumor on magnetic resonance imaging at 1-year follow-up.

Left-sided retrosigmoid craniotomy for the resection of a vestibular schwannoma.

The cerebellopontine angle is the site for a wide-range of neoplastic and vascular pathologies. The retrosigmoid craniotomy remains the primary means by which to gain surgical access to this anatomically complex region. We present our standard technique for the completion of a retrosigmoid craniotomy and the resection of a left-sided vestibular schwannoma. Anatomy pertinent to the approach, including, the transverse and sigmoid sinuses, cranial nerves, and internal auditory canal (IAC) is displayed. Special emphasis is placed on patient positioning, adequate bone removal, and tumor resection. The drilling of the IAC and tumor dissection from the VII-VIII complex is also highlighted. Hearing preservation was achieved. The video can be found here: http://youtu.be/FFZju5vcBi0 .

Approaches to the Middle Cerebellar Peduncle for Resection of Pontine Cavernomas.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: The expanded retrosigmoid approach with splitting of the horizontal cerebellar fissure provides a more direct and shorter route for central and dorsolateral pontine lesions while minimizing retraction of tracts, nuclei, and cerebellum. 1-4. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: The middle cerebellar peduncle is partially covered by the petrosal surface of the cerebellum. The horizontal cerebellar fissure (petrosal fissure) divides the petrosal surface of the cerebellar hemisphere into superior and inferior parts. Splitting the petrosal fissure separates the superior and inferior petrosal surfaces and exposes the posterolateral middle cerebellar peduncle (posterior and lateral to the root entry zone of CN5). 1-4. ESSENTIALS STEPS OF THE PROCEDURE: Expanded retrosigmoid craniotomy is performed, including unroofing of the sigmoid sinus; petrosal fissure is split to expose the posterolateral middle cerebellar peduncle; entry point for resection of the cavernoma is identified; nims stimulator stimulator is used to confirm the absence of tracts and nuclei; myelotomy is performed; and cavernoma and its draining vein (but not the developmental venous anomaly) are removed using a combination of traction and countertraction against gliotic plane. PITFALLS/AVOIDANCE OF COMPLICATIONS: Wide splitting of the horizontal cerebellar fissure minimizes retraction or resection of the cerebellum and offers the best angle of attack. Knowledge of brainstem anatomy and use of intraoperative navigation are critical to avoid complications. VARIANTS AND INDICATIONS FOR THEIR USE: Far lateral through the middle cerebellar peduncle is a variant that can be used to resect pontine cavernomas if a caudocranial trajectory is preferred.The patient consented to the procedure and to the publication of her image.

Treatment of Recurrent, Twice Coiled, Previously Ruptured Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Aneurysm With Excision and End-to-End Anastomosis: 2-Dimensional Operative Video.

Anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) variant is a well-established variant of the vertebrobasilar system. AICA-PICA aneurysms are extremely rare.1-3 There are only 12 cases reported in the literature.1-3 Here, we are presenting a case of a previously ruptured AICA-PICA dissecting aneurysm which had undergone coil embolization twice at an outside institution. The aneurysm continued to grow, and therefore, the patient was transferred to our institution for definitive treatment. Placement of a flow diverter was felt not to be feasible because of the acute bend of the vessel at the neck of the aneurysm. After a retrosigmoid craniotomy, the aneurysm sac was opened to untether the coil mass from the neck of the aneurysm. Clip reconstruction was attempted but intraoperative blood flow measurements demonstrated no flow in the distal outflow artery, indicating that the clip was occluding the parent vessel at the neck because of the challenging geometry and atherosclerosis. We then proceeded with an excision and end-to-end anastomosis of the AICA-PICA. The details of vascular reconstruction while the inflow and outflow arteries are at acute angle are described. Intraoperative indocyanine video angiography demonstrated complete exclusion of the aneurysm from the circulation and patency of the bypass. Postoperative computed tomography angiography demonstrated bypass patency. Postoperatively, the patient required a temporary external ventricular drain for hydrocephalus; however, she was eventually discharged home without any neurological deficits. The patient gave informed consent for the surgery and video recording. Institutional Review Board approval was deemed unnecessary.

Vertebral Artery Pseudoaneurysm After Extreme Lateral Transcondylar Transodontoid Approach for Clival Chordoma: 2-Dimensional Operative Video.

Chordomas can be treated surgically, with radiotherapy, and more recently, chemotherapy.1,2 A 22-year-old female patient presented with recurrence of a clival chordoma, after subtotal resection at an outside institution 3 months prior. MRI showed a predominantly midline lesion at the craniocervical junction with significant lateral extension eccentric to the left. A 3-staged operation was planned. A redo-endoscopic endonasal transclival transodontoid approach3-5 was used to resect the midline component, followed by an extreme lateral transcondylar transodontoid approach with transposition of the ipsilateral vertebral artery followed by drilling of the ipsilateral occipital condyle and C1 lateral mass to resect the lateral component, followed by occiput to C3 fusion given the induced craniocervical instability. Careful subperiosteal dissection with preservation of the periosteal sheath overlying the vertebral artery was performed. There was no overt evidence of vertebral artery injury intraoperatively or on immediate postoperative imaging. However, 3 weeks later, the patient presented with blood from the oral/nasal cavity. Computed tomography angiography showed an unexpected left vertebral artery pseudoaneurysm. Pseudoaneurysms can develop after microtears in the muscularis layer.6-8 Management is based on size, location, and vertebral artery dominance.9,10 This pseudoaneurysm was coiled. Postcoiling, the patient had left hypoglossal palsy. We demonstrate the step-by-step technique of an extreme lateral transcondylar transodontoid approach for a clival chordoma and the unfortunate complication of a vertebral artery pseudoaneurysm with discussion of its etiology and management options for this potentially devastating complication. The patient consented to the procedure/publication. Institutional Review Board approval not obtained as the patient was deidentified, and no additional risk is posed by the publication of this video.

Step-by-Step Dissection of the Extreme Lateral Transodontoid Approach to the Anterior Craniovertebral Junction: Surgical Anatomy and Technical Nuances.

BACKGROUND: Multicompartmental lesions of the anterior craniovertebral junction require aggressive management. However, the lesions can be difficult to reach, and the surgical procedure is difficult to understand. The aim of this study was to create a procedural, stepwise microsurgical educational resource for junior trainees to learn the surgical anatomy of the extreme lateral transodontoid approach (ELTOA). METHODS: Ten formalin-fixed, latex-injected cadaveric heads were dissected under an operative microscope. Dissections were performed under the supervision of a skull base fellowship-trained neurosurgeon who has advanced skull base experience. Key steps of the procedure were documented with a professional camera and a high-definition video system. A relevant clinical case example was reviewed to highlight the principles of the selected approach and its application. The clinical case example also describes a rare complication: a pseudoaneurysm of the vertebral artery. RESULTS: Key steps of the ELTOA include patient positioning, skin incision, superficial and deep muscle dissection, vertebral artery dissection and transposition, craniotomy, clivus drilling, odontoidectomy, and final extradural and intradural exposure. CONCLUSIONS: The ELTOA is a challenging approach, but it allows for significant access to the anterior craniovertebral junction, which increases the likelihood of gross total lesion resection. Given the complexity of the approach, substantial training in the dissection laboratory is required to develop the necessary anatomic knowledge and to minimize approach-related morbidity.

Retrospective comparison of craniotomy and decompressive craniectomy for surgical evacuation of nontraumatic, supratentorial intracerebral hemorrhage.

Surgical evacuation of nontraumatic, supratentorial intracerebral hemorrhage (SICH) is uncommonly performed, and outcomes are generally poor. On the basis of published experimental data and the authors' anecdotal observations, a retrospective chart review study was performed to test the hypothesis that large decompressive craniectomies (DCs), compared with craniotomies, would improve clinical outcomes after surgical evacuation of SICH. For patients with putaminal SICH, DC was associated with a statistically significant improvement in midline shift, compared with craniotomy. Decompressive craniectomies also resulted in a strong trend toward decreased likelihood of poor neurological outcome (modified Rankin Scale score > 3). For patients with lobar SICH, no associations were found between DC or craniotomy and clinical outcomes. For patients selected to undergo surgical evacuation of putaminal SICH, a DC in addition to surgical evacuation of the hematoma might improve outcome.

Management of a dural arteriovenous fistula versus arteriovenous malformation of the internal auditory canal with radiosurgery.

We present a case of a 61-year-old male who presented with an 8-month history of left hypacusis, tinnitus, and gait imbalance. MRI showed a vascular lesion in the left internal auditory canal (IAC). Angiogram showed a vascular lesion filling from the ascending pharyngeal and anterior inferior cerebellar artery (AICA) with drainage into the sigmoid sinus suggestive of either a dural arteriovenous malformation (dAVF) vs arteriovenous malformation (AVM) of the IAC. The decision was made to operate to prevent risk of future hemorrhage [1-5]. Endovascular options were not as ideal given access transarterially through the AICA would be risky, access transvenously would be difficult and it was unclear whether this lesion was a dAVF or AVM. The patient underwent a retrosigmoid approach. A tuft of arterialized vessels surrounding CN7/8 was identified and no true nidus was found so it was thought that this lesion was a dAVF. The plan was to clip the arterialized vein as is normally done for dAVF. However, there was engorgement of the vascular lesion upon clipping of the arterialized vein indicating risk of rupture if the clip was left insitu. It was too risky to drill the posterior wall of the IAC to expose the fistulous point more proximally. As a result, 2 clips were placed on the AICA branches. Postoperative angiogram showed some slowing of the vascular lesion but it was still present. Given the AICA feeder, it was decided that this lesion was a dAVF with mixed features of an AVM and the decision was made to gamma knife the lesion 3 months postoperatively. Patient underwent gamma knife targeting the dura superior to the IAC with 18 Gy at the 50 % isodose line. At 2 years follow up, the patient's symptoms improved and he remained neurologically intact. Imaging revealed complete obliteration of the dAVF. This case illustrates the step by step management of a dAVF that mimicked a true pial AVM. The patient consented to the procedure and participating in this surgical video.

Intraoperative venous congestion and brainstem venous hemorrhagic infarction during retrosigmoid for acoustic neuroma.

Venous hemorrhagic infarction is rare but can occur during acoustic neuroma resection [1-5]. We present the case of a 27-year-old male with 1.5 years of progressive headaches, tinnitus, imbalance and hearing loss. Imaging revealed a left Koos 4 acoustic neuroma. The patient underwent a retrosigmoid approach for resection. During surgery, a vein of significant size within the capsule of the tumor was encountered and was necessary to take to proceed with resection. After coagulation of the vein, intraoperative venous congestion with cerebellar edema and hemorrhagic infarction ensued, requiring resection of a portion of the cerebellum. Given the hemorrhagic nature of the tumor, continuing tumor resection was necessary to prevent postoperative hemorrhage. This was carried out until hemostasis was achieved. 85 % resection was achieved, leaving a residual against the brainstem and cisternal course of the facial nerve. Postoperatively, the patient required 5 weeks hospitalization followed by 1 month of rehabilitation. At discharge to rehabilitation, patient had trach, PEG, left House-Brackmann 5 facial weakness, left sided deafness, and right upper extremity hemiparesis (1/5). At 7 months follow up, he continued to have left House-Brackmann 5 facial weakness and left sided deafness but trach and PEG had been removed and strength had improved to 5/5. We demonstrate in this video the unfortunate and rare occurrence of intraoperative venous hemorrhagic infarction during acoustic neuroma resection - particularly for large tumors in young patients - and discuss its etiology and surgical steps that are necessary to partially remedy its devastating impact on the patient. The patient consented to the procedure and participating in this surgical video.

Macrovascular Decompression for Hemifacial Spasm Using Sling Technique.

Hemifacial spasm (HFS) is a painless, involuntary twitching of the facial muscles that usually involves the orbicularis oculi muscle.1,2 It is commonly caused by the anterior inferior cerebellar artery or posterior inferior cerebellar artery.1,2 However, a dolichoectatic vertebrobasilar artery (VBA) can impinge the facial nerve.1 Macrovascular decompression with sling transposition is a common management paradigm.1-9 We present a case of a 56-year-old male who presented with left-sided HFS, pulsatile tinnitus, and hearing loss for the past 2 years. The patient underwent a retrosigmoid craniotomy and Gore-Tex sling transposition of a dolichoectatic VBA (Video 1). Complete improvement of symptoms was noted postoperatively with no associated complications. We review the preoperative workup, operative technique, relevant anatomy, and literature and provide technical pearls for this procedure.