Posterior-Transcallosal Approach to a Choroidal Fissure Arteriovenous Malformation: Video of Adapting a "Bridging Vein Free" Corridor to This Complex Region.

Choroidal fissure arteriovenous malformations (ChFis-AVMs) are uncommon and challenging to treat due to their deep location and pattern of supply.1 The choroidal fissure lies between the thalamus and fornix, from the foramen of Monroe to the inferior choroidal point.2 AVMs in this location receive their supply from the anterior, lateral posterior choroidal artery and medial posterior choroidal arteries and drain to the deep venous system.3 The anterior-transcallosal corridor to the ChFis is favored due to the ease in opening the taenia fornicis from the foramen Monroe, and it increases in length for lesions located more posteriorly.4-7 We present a case of a posterior ChFis-AVM. The patient, a previously healthy woman in her 20s, presented with a sudden severe headache. She was diagnosed with intraventricular hemorrhage. This was managed conservatively with subsequent magnetic resonance imaging and digital subtraction angiography revealing a ChFis-AVM at the body of the left lateral ventricle, between the fornix and superior layer of the tela choroidae. It received its supply from the left lateral posterior choroidal artery and medial posterior choroidal artery and drained directly into the internal cerebral vein, classified as Spetzler-Martin grade II.8 A posterior-transcallosal approach to the ChFis was chosen to reduce the working distance and afford a wider corridor by avoiding cortical bridging veins (Video 1). Complete resection of the AVM was achieved with no additional morbidity. Microsurgery in experienced hands offers the best chance of cure for AVMs.9 In this case we demonstrate how to adapt the transcallosal corridor to the choroidal fissures for safe AVM surgery in this complex location.

Importance of Arachnoid Dissection in Arteriovenous Malformation Microsurgery: A Technical Note.

Intracranial arteriovenous malformations (AVMs) are congenital anomalies where arteries and veins connect without a capillary bed. AVMs are the leading cause of nontraumatic intracerebral hemorrhages in people younger than 35 years old.1 The leptomeninges (arachnoid and pia) form from the meninx primitiva.2,3 Endothelial channels produce a vascular plexus in the meninx connected by primitive arachnoid. Remodeling of the plexus in response to changing metabolic demands results in a recognizable pattern of arteries and veins.2,3 Defects at the level of capillaries during arteriovenous specification are most likely responsible for arteriovenous fistula formation.4-6 Interplay between the congenital dysfunction and flow-related maturation in adulthood, when vasculogenesis has stopped, produces the AVM.6,7 The relationship between the primitive arachnoid and aberrant AVM vessels is preserved and forms the basis of microsurgical disconnection discussed in Video 1. Several authors have described dissecting these natural planes to delineate the abnormal AVM vessels, relax the brain, and avoid morbidity during AVM surgery.8-10 We recommend sharp arachnoid dissection with a scalpel or microscissors, occasionally helped by blunt dissection with patties or bipolar forceps. We present a 2-dimensional video of the microsurgical resection of a right parietal AVM. The patient, a healthy 30-year-old female, presented with intermittent headaches and mild impairment of arithmetic and visuospatial ability. Magnetic resonance imaging and digital subtraction angiography showed a compact 3.5-cm supramarginal gyrus AVM supplied by the middle cerebral artery, with superficial drainage. Complete microsurgical resection was performed without morbidity. We demonstrate the principles of arachnoid dissection requisite to disentanglement of the nidus and safe resection of the AVM.

Successful treatment of vancomycin-resistant enterococcal infection of an external ventricular drain with 2 weeks of intravenous linezolid.

Hydrocephalus is a common condition worldwide, and is frequently managed by diversion of cerebrospinal fluid (CSF), either externally with a drain or internally with a shunt. An external ventricular drain (EVD) can be an essential treatment modality, but is associated with a risk of infection, most commonly caused by Staphylococcal species, which can result in meningitis or ventriculitis and a delay in the definitive management of the hydrocephalus. Here, we report the case of a patient who required an EVD to manage post-operative hydrocephalus following a craniotomy and microvascular decompression for trigeminal neuralgia. He subsequently developed EVD-associated infection with a vancomycin-resistant Enterococcus faecium (VRE), which was treated successfully with a 2-week course of intravenous linezolid monotherapy. The authors believe this to be the only described case of successful treatment within this time frame of a CSF VRE infection associated with indwelling foreign material.

Currarino syndrome: repair of the dysraphic anomalies and resection of the presacral mass in a combined neurosurgical and general surgical approach.

OBJECTIVEIt is well established that Currarino syndrome (CS) may be associated with spinal dysraphism. Here, the authors report on 10 CS patients with dysraphic anomalies who had undergone a combined neurosurgical and general surgical approach to repair the dysraphic anomalies and resect the presacral mass in a single operation. They discuss the spectrum of spinal dysraphism that may coexist in CS in the context of its developmental etiology.METHODSChildren with a confirmed CS diagnosis who had undergone the combined operative approach were identified from a departmental database. Presenting features were recorded and preoperative imaging was analyzed to record features of the presacral mass and the dysraphic anomalies. The histopathological nature of the resected presacral mass and the outcomes postoperatively and at the last follow-up were reviewed.RESULTSBetween 2008 and 2015, 10 patients presented with CS, 9 with constipation. Median age at the time of surgery was 1.3 years. Six of the 10 patients had anorectal malformation consisting of anal stenosis, rectal stenosis, or imperforate anus. Spinal anomalies included anterior meningocele (5 cases), low-lying conus (8), terminal syrinx (4), fatty filum (5), caudal lipoma (3), and intraspinal cyst (1). In all cases, the lumbosacral spinal canal was accessed via a midline approach with laminoplasty, allowing spinal cord untethering and repair of the dysraphic anomalies. Following dural closure, the incision was extended inferiorly to incorporate a posterior sagittal approach to resect the presacral mass. The histopathological nature of the mass was mature teratoma (8 cases), complex hamartomatous malformation (1), or neurenteric cyst (1). There were no new instances of neurological deterioration, with most instances of persisting morbidity related to constipation (6 cases) or neurogenic bladder dysfunction (8). There were no infective complications, no instances of cerebrospinal fluid fistula, no recurrences of the presacral mass, and no cases of retethering of the spinal cord.CONCLUSIONSAlthough not part of the original triad, spinal dysraphic anomalies are common in CS and in keeping with a disorder of secondary neurulation. Lumbosacral MRI is an essential investigation when CS is suspected. Children are at risk of sphincter impairment due to the anorectal malformation; however, both spinal cord tethering and compression from the presacral mass may further compromise long-term continence. A combined operative approach to repair the dysraphic anomalies and resect the presacral mass is described with good postoperative and long-term outcomes.

Microtubules, polarity and vertebrate neural tube morphogenesis.

Microtubules (MTs) are key cellular components, long known to participate in morphogenetic events that shape the developing embryo. However, the links between the cellular functions of MTs, their effects on cell shape and polarity, and their role in large-scale morphogenesis remain poorly understood. Here, these relationships were examined with respect to two strategies for generating the vertebrate neural tube: bending and closure of the mammalian neural plate; and cavitation of the teleost neural rod. The latter process has been compared with 'secondary' neurulation that generates the caudal spinal cord in mammals. MTs align along the apico-basal axis of the mammalian neuroepithelium early in neural tube closure, participating functionally in interkinetic nuclear migration, which indirectly impacts on cell shape. Whether MTs play other functional roles in mammalian neurulation remains unclear. In the zebrafish, MTs are important for defining the neural rod midline prior to its cavitation, both by localizing apical proteins at the tissue midline and by orienting cell division through a mirror-symmetric MT apparatus that helps to further define the medial localization of apical polarity proteins. Par proteins have been implicated in centrosome positioning in neuroepithelia as well as in the control of polarized morphogenetic movements in the neural rod. Understanding of MT functions during early nervous system development has so far been limited, partly by techniques that fail to distinguish 'cause' from 'effect'. Future developments will likely rely on novel ways to selectively impair MT function in order to investigate the roles they play.