N-Butyl Cyanoacrylate Transvenous Arteriovenous Malformation Embolization with Arterial Balloon Assistance: Defining Parameters for a Transvenous Approach as a Potential Upfront Treatment Option in Managing Cerebral Arteriovenous Malformations.

Complete obliteration of arteriovenous malformations (AVMs) using a transvenous approach as the primary and stand-alone treatment modality has been increasingly considered as a useful endovascular approach in the treatment of AVMs. AVMs are typically treated with microsurgery, stereotactic radiosurgery, endovascular embolization, or some combination of the three methods. Preservation of the draining vein is a key requisite common to all treatment modalities. Transvenous embolization (TVE) is conventionally not recommended as a stand-alone treatment for the vast majority of AVMs and has been thought to be best indicated when traditional approaches are considered less safe and when specific evaluation criteria are met. We report a case of a 35-year-old asymptomatic male diagnosed with a small intracranial AVM adjacent to the right motor strip which was managed utilizing this approach. We employed endovascular embolization via a transvenous approach with arterial balloon assistance due to the small size of the nidus, eloquent location, en passage arterial supply proximal to the venous varix, and a single draining vein from the fistula. This case illustrates the selective indications and technical nuances of TVE approach in managing AVMs as a potential upfront treatment option. When patients harbor AVMs with specific angio-architectural findings as outlined, TVE utilizing Onyx or N-butyl cyanoacrylate can be safely performed as a primary treatment modality.

Excision of a Retrochiasmatic Craniopharyngioma by Transcallosal, Interforniceal Approach With Exoscope Assistance: 2-Dimensional Operative Video.

Retrochiasmatic craniopharyngiomas are difficult to treat due to their close proximity to critical neurovascular structures. Several surgical approaches with distinct advantages and limitations have been described to access these tumors, including extended transnasal endoscopic approach (ETEA), subtemporal, translamina terminalis, and transpetrosal approach.1-3 We present a 51-yr-old male with a large retrochiasmatic craniopharyngioma extending into the third ventricle, causing obstructive hydrocephalus. Preoperative magnetic resonance imaging (MRI) showed a tumor cyst abutting the fornices expanding the space between two internal cerebral veins (ICV). After surgical consent, we decided to take advantage of this corridor to approach the tumor in its long axis. Surgical goal was to achieve cyst decompression with "safe maximal" resection of the solid component at last to preserve the pituitary function. Though the long axis of the tumor could be approached using ETEA, we preferred this approach in view of cyst decompression early in the surgery while completely avoiding risks such as cerebrospinal fluid (CSF) rhinorrhea, internal carotid artery (ICA) injury, and sinonasal complications. We utilized a 3-dimensional 4 K exoscope, which provides an excellent ergonomic position, and a high-resolution immersive view compared to a microscope or endoscope. Cyst decompression and near-total resection of the solid component was achieved. Postoperatively, his headaches improved and he was neurologically intact with intact neuroendocrine function. Approach-related risks may include but not limited to hemorrhage due to the rupture of venous sinuses or ICV, stalk or hypothalamus injury, and memory disturbances due to forniceal injury. To conclude, the transcallosal, interforniceal approach to retrochiasmatic craniopharyngiomas may provide a safe surgical corridor in select cases. Patient consented to the proposed procedure. All radiological images have been anonymized. IRB/ethics committee approval was not required.

Hemifacial Spasm Due to Bony Stenosis of the Internal Auditory Meatus: Look Beyond the Loop.

BACKGROUND: Hemifacial spasm (HFS) is a neuromuscular disorder resulting from cranial nerve VII compression at the root entry zone, characterized by brief, involuntary, progressive spasms of muscles on one side of face. The cisternal part of cranial nerve VII myelinated by Schwann cells is considered relatively resistant to compression. Rarely, direct compression over this segment without coexistent root entry zone compression may also result in HFS. An aberrant vessel posterior inferior cerebellar artery/anterior inferior cerebellar artery loop remains the leading cause of compression at this location. Cerebellopontine angle tumors or cysts may affect cranial nerve VII distally. However, bony meatal stenosis with pure distal facial nerve compression leading to HFS in the absence of other clinical symptoms has not been reported. CASE DESCRIPTION: A 53-year-old woman presented with worsening left HFS for 9 years despite multiple trials of medical therapy, which severely impeded her social life and occupation. Temporal bone computed tomography revealed severe stenosis of the left internal auditory meatus (2.36 mm) compared with the right side (4.67 mm). Under three-dimensional exoscope guidance, a left retrosigmoid suboccipital craniotomy was performed, the posterior bony wall of the internal auditory canal was drilled to decompress the canal, and durotomy was performed to release the contents. Her symptoms resolved without developing facial weakness or hearing deficits. CONCLUSIONS: An aberrant anterior inferior cerebellar artery vascular loop is usually the most frequent lesion causing compression of the distal cisternal part of the facial nerve. However, other purely distal or coexistent lesions must be actively sought for both in preoperative radiologic images and during surgery.

Monitoring Treatment Effectiveness in Intracranial Arteriovenous Shunt Lesions: Emerging Role of Quantitative Magnetic Resonance Venography for Intracranial Arteriovenous Shunts.

BACKGROUND: Quantitative magnetic resonance angiography (qMRA) using noninvasive optimal vessel analysis (NOVA) is a novel noninvasive imaging technique that is being increasingly used to measure blood flow in extracranial and intracranial arteries. By providing important quantitative flow data, NOVA qMRA can facilitate the management of cerebrovascular disease. While the same technology can also be applied to measure flow in intracranial and extracranial veins, NOVA quantitative MRV (qMRV) is only rarely used in neurovascular practice. CASE DESCRIPTION: We report interesting qMRV data in 2 patients with symptomatic intracranial arteriovenous shunts: a 61-year-old man with a left transverse-sigmoid dural arteriovenous fistula and a 40-year-old woman with a left parietal arteriovenous malformation. In each patient, NOVA qMRV demonstrated significant reduction of intracranial venous outflow after therapeutic obliteration of the shunt lesion, heralding marked clinical improvement. CONCLUSIONS: To the best of our knowledge, this is the first report of successful clinical application of NOVA qMRV in adult patients with intracranial arteriovenous malformations or dural arteriovenous fistulas. We propose that NOVA qMRV is a promising technique for noninvasive measurement of intracranial and extracranial venous blood flow and for monitoring treatment effectiveness in patients with intracranial arteriovenous shunt lesions.

Internal Maxillary to Middle Cerebral Artery Bypass Using an Anterior Tibial Artery Graft, Performed Using a 3-Dimensional Exoscope: 2-Dimensional Operative Video.

Fusiform aneurysms remain challenging entities to treat, as maintenance of flow and prevention of branch occlusion are concerns. Use of endovascular stents may risk nearby branch occlusion. We present a 31-yr-old male with a prior subarachnoid hemorrhage from a left middle cerebral artery (MCA) M1 aneurysm. Informed consent for use of the operative video and information was obtained from the patient. Initially, open clipping was performed with noted residual because of risk of nearby branches. On angiography, a growing fusiform segment distal to the initial aneurysm was noted. The patient was referred to our institution for this finding, and a multidisciplinary team reviewed the case. Endovascular treatment was felt to be risky, as stenting could jail nearby MCA branches. Clipping would also risk occlusion because of scaring from previous hemorrhage. Sufficient flow would be needed, and because the ipsilateral superficial temporal artery was sacrificed in the initial craniotomy, the internal maxillary artery (IMAX) was chosen as the bypass source. A cerebrovascular neurosurgeon, skull base otolaryngologist, and vascular surgeon worked together to perform a left-side IMAX to MCA bypass using an anterior tibial artery graft under 3-dimensional exoscopic visualization. Specifically, a 9-0 nylon suture on a BV-130 needle along with straight and tying forceps were used along with heparinized saline. The bypass was noted to be of robust flow, and the patient did very well on postoperative follow-up. The utilization of an anterior tibial artery graft, IMAX exposure, and corresponding bypass provides educational value, as there are only a limited number of videos on this topic.

RGS4 Maintains Chronic Pain Symptoms in Rodent Models.

Regulator of G-protein signaling 4 (RGS4) is a potent modulator of G-protein-coupled receptor signal transduction that is expressed throughout the pain matrix. Here, we use genetic mouse models to demonstrate a role of RGS4 in the maintenance of chronic pain states in male and female mice. Using paradigms of peripheral inflammation and nerve injury, we show that the prevention of RGS4 action leads to recovery from mechanical and cold allodynia and increases the motivation for wheel running. Similarly, RGS4KO eliminates the duration of nocifensive behavior in the second phase of the formalin assay. Using the Complete Freud's Adjuvant (CFA) model of hindpaw inflammation we also demonstrate that downregulation of RGS4 in the adult ventral posterolateral thalamic nuclei promotes recovery from mechanical and cold allodynia. RNA sequencing analysis of thalamus (THL) from RGS4WT and RGS4KO mice points to many signal transduction modulators and transcription factors that are uniquely regulated in CFA-treated RGS4WT cohorts. Ingenuity pathway analysis suggests that several components of glutamatergic signaling are differentially affected by CFA treatment between RGS4WT and RGS4KO groups. Notably, Western blot analysis shows increased expression of metabotropic glutamate receptor 2 in THL synaptosomes of RGS4KO mice at time points at which they recover from mechanical allodynia. Overall, our study provides information on a novel intracellular pathway that contributes to the maintenance of chronic pain states and points to RGS4 as a potential therapeutic target.SIGNIFICANCE STATEMENT There is an imminent need for safe and efficient chronic pain medications. Regulator of G-protein signaling 4 (RGS4) is a multifunctional signal transduction protein, widely expressed in the pain matrix. Here, we demonstrate that RGS4 plays a prominent role in the maintenance of chronic pain symptoms in male and female mice. Using genetically modified mice, we show a dynamic role of RGS4 in recovery from symptoms of sensory hypersensitivity deriving from hindpaw inflammation or hindlimb nerve injury. We also demonstrate an important role of RGS4 actions in gene expression patterns induced by chronic pain states in the mouse thalamus. Our findings provide novel insight into mechanisms associated with the maintenance of chronic pain states and demonstrate that interventions in RGS4 activity promote recovery from sensory hypersensitivity symptoms.

Moyamoya-Related Stroke Risk During Pregnancy: An Evidence-Based Reappraisal.

BACKGROUND: Moyamoya is a rare, yet classic etiology of stroke in young adults, affecting predominately women of childbearing age. The impact of pregnancy on the natural history of symptomatic moyamoya remains a matter of extensive debate, however. METHODS: In October 2017, a MEDLINE search was performed using 14 keywords. A total of 12 original articles reporting on cohorts of at least 5 patients were retrieved and reviewed. Individual study data were extracted, pooled, and analyzed. RESULTS: A total of 736 pregnancies in 483 patients were included in our analysis. The mean age at delivery was 31 years, and the mean age at diagnosis (before pregnancy) was 22.6 years. Clinical presentation was ischemic stroke in 50.8%, hemorrhagic stroke in 45.9%, headaches in 2.1%, and ischemic-hemorrhagic stroke in 1.2%. After excluding patients first diagnosed during or after pregnancy (n = 283) and those who had been revascularized before pregnancy (n = 183), a total of 270 pregnancies in 188 patients were analyzed. During 224.6 patient-years of follow-up, 22 moyamoya-related neurologic events occurred (annual event rate 9.8%), more than two-thirds of which were transient (12 transient ischemic attacks and 3 seizures). Seven strokes occurred (6 hemorrhagic and 1 ischemic), yielding an annual stroke risk of 3.1%. As a result, 1 patient died and 2 were permanently disabled (annual death/disability rate 1.3%). All remaining patients experienced favorable functional outcomes. CONCLUSIONS: The risk of moyamoya-related stroke during pregnancy, delivery, and the postpartum period appears to be similar to or lower than that suggested by published natural history studies in symptomatic patients. A neuroprotective effect of pregnancy in moyamoya patients cannot be excluded.