Shervin R. Dashti

Cranial dural arteriovenous fistula: transarterial Onyx embolization experience and technical nuances

Introduction Traditional endovascular treatment of cranial dural arteriovenous fistulas (DAVFs) consists of a transarterial approach with n-butylcyanoacrylate (nBCA) or a transvenous approach with coil embolization. The advent of Onyx in the endovascular arsenal potentially offers a high probability of obliteration of these vascular lesions through a purely transarterial route. Methods A retrospective review of the Barrow Neurological Institute endovascular database between October 2005 and November 2009 highlighted 50 patients with 63 cranial DAVFs that were treated with transarterial Onyx, with and without adjuvant embolysates, for a total of 76 embolization procedures. Hospital records, cerebral angiography and other diagnostic imaging and clinical visits were reviewed. Results At a median follow-up of 5 months (range 0–25 months), complete angiographic cure was obtained in 41 patients with 50 (79%) DAVFs after transarterial embolization using Onyx combined with other embolysates. When Onyx was used as the sole embolic agent, 32 of 37 DAVFs (87%) in 29 (of 33) patients achieved angiographic cure. Subgroup analysis showed that by using the middle meningeal artery (MMA) as a conduit for primary Onyx embolization, angiographic cures were achieved in 27 of the 37 DAVFs (73%). Periprocedural complications occurred in six (7.9%) sessions in one patients (8%). Only one patient had a permanent complication (2%) with unimproved cranial nerve palsies. Conclusion Transarterial Onyx embolization of cranial DAVFs, particularly using the MMA as a conduit, is a safe and effective curative therapy.

Current patterns of inflicted head injury in children

The purpose of this study was to examine the current patterns of head trauma associated with child abuse. We reviewed the records of all patients admitted to our medical center between 1995 and 1997 with a primary diagnosis of head trauma, and analyzed the clinical presentation, mechanism of injury, socioeconomic status and outcome for these patients. Head trauma was deliberately inflicted in 38/405 children (9%). There were 25 boys and 13 girls, with a median age of 5.5 months. Two thirds of the families lived in the inner city. Of the 99 children under the age of 2 years admitted for head trauma, the injury was inflicted in 32 (32%). Acute subdural hematoma was present in 22/32 (69%) of children with inflicted trauma, but in only 5/68 (7%) with accidental trauma. Retinal hemorrhages were present in 17/32 (53%) abused children, but in no cases of accidental trauma (0/68). Deliberately inflicted injury is a frequent cause of serious head trauma in young children. Head injury is a major cause of morbidity and mortality in the abused child. Child abuse cases correlated strongly with low socioeconomic status. Nonaccidental trauma must be considered strongly in children under 2 years of age who present with acute subdural hematoma in the absence of a history of a motor vehicle accident.

A Novel Tumor Suppressor Protein Promotes Keratinocyte Terminal Differentiation via Activation of Type I Transglutaminase

Tazarotene-induced protein 3 (TIG3) is a recently discovered regulatory protein that is expressed in the suprabasal epidermis. In the present study, we show that TIG3 regulates keratinocyte viability and proliferation. TIG3-dependent reduction in keratinocyte viability is accompanied by a substantial increase in the number of sub-G1 cells, nuclear shrinkage, and increased formation of cornified envelope-like structures. TIG3 localizes to the membrane fraction, and TIG3-dependent differentiation is associated with increased type I transglutaminase activity. Microscopic localization and isopeptide cross-linking studies suggest that TIG3 and type I transglutaminase co-localize in membranes. Markers of apoptosis, including caspases and poly(ADP-ribose) polymerase, are not activated by TIG3, and caspase inhibitors do not stop the TIG3-dependent reduction in cell viability. Truncation of the carboxyl-terminal membrane-anchoring domain results in a complete loss of TIG3 activity. The morphology of the TIG3-positive cells and the effects on cornified envelope formation suggest that TIG3 is an activator of terminal keratinocyte differentiation. Our studies suggest that TIG3 facilitates the terminal stages in keratinocyte differentiation via activation of type I transglutaminase.

MEK7-dependent Activation of p38 MAP Kinase in Keratinocytes

Previous studies suggest that a PKC/Ras/MEKK1 cascade regulates involucrin (hINV) gene expression in human epidermal keratinocytes. MEK7, which is expressed in epidermis, has been identified as a member of this cascade (Efimova, T., LaCelle, P., Welter, J. F., and Eckert, R. L. (1998) J. Biol. Chem. 273, 24387–24395 and Efimova, T., and Eckert, R. L. (2000) J. Biol. Chem. 275, 1601–1607). However, the kinase that functions downstream of MEK7 has not been identified. Our present studies show that MEK7 expression in keratinocytes markedly activates p38α and modestly activates JNK. Activation of p38 MAPK by MEK7 is a novel finding, as previous reports have assigned MEK7 as a JNK regulator. We also demonstrate that this regulation is physiologically important, as the p38α- and JNK-dependent activities regulate hINV promoter activity and expression of the endogenous hINVgene.

Mg2+ Block Unmasks Ca2+/Ba2+ Selectivity of α1G T-Type Calcium Channels

Abstract We have examined permeation by Ca 2+ and Ba 2+ , and block by Mg 2+ , using whole-cell recordings from α 1G T-type calcium channels stably expressed in HEK 293 cells. Without Mg o 2+ , inward currents were comparable with Ca 2+ and Ba 2+ . Surprisingly, three other results indicate that α 1G is actually selective for Ca 2+ over Ba 2+ . 1) Mg 2+ block is ∼7-fold more potent with Ba 2+ than with Ca 2+ . With near-physiological (1mM) Mg o 2+ , inward currents were ∼3-fold larger with 2mM Ca 2+ than with 2mM Ba 2+ . The stronger competition between Ca 2+ and Mg 2+ implies that Ca 2+ binds more tightly than Ba 2+ . 2) Outward currents (carried by Na + ) are blocked more strongly by Ca 2+ than by Ba 2+ . 3) The reversal potential is more positive with Ca 2+ than with Ba 2+ , thus P Ca > P Ba . We conclude that α 1G can distinguish Ca 2+ from Ba 2+ , despite the similar inward currents in the absence of Mg o 2+ . Our results can be explained by a 2-site, 3-barrier model if Ca 2+ enters the pore 2-fold more easily than Ba 2+ but exits the pore at a 2-fold lower rate.

Management of anterior inferior cerebellar artery aneurysms: an illustrative case and review of literature

Aneurysms of the anterior inferior cerebellar artery (AICA) are relatively rare among intracranial aneurysms. They can occur in 1 of 3 regions of the AICA: 1) craniocaudal (high or low riding), 2) mediolateral-premeatal (proximal), and 3) meatal-postmeatal (distal). The management strategies for treatment differ according to the location and configuration of the aneurysm. The existing body of neurosurgical literature contains articles published on aneurysms arising from the AICA near the basilar artery (BA), intracanalicular/meatal aneurysms, and distal AICA. Several therapeutic options exist, encompassing microsurgical and endovascular techniques. The authors describe a case of treatment involving a large BA-AICA aneurysm approached via exposure of the presigmoid dura using a retromastoid suboccipital craniectomy and partial petrosectomy. Treatment of these lesions requires detailed knowledge of the anatomy, and an anatomical overview of the AICA with its arterial loops and significant branches is presented, including a discussion of the internal auditory (labyrinthine) artery, recurrent perforating arteries, subarcuate artery, and cerebellosubarcuate artery. The authors discuss the various surgical approaches (retromastoid, far lateral, subtemporal, and transclival) with appropriate illustrations, citing the advantages and disadvantages in accessing these AICA lesions in relation to these approaches. The complications of these different surgical techniques and possible clinical effects of parent artery occlusion during AICA surgery are highlighted.

Multimodality treatment of a ruptured grade IV posterior fossa arteriovenous malformation in a patient pregnant with twins: case report

Introduction Brain arteriovenous malformations (AVM) account for a significant percentage of brain hemorrhages in pregnant patients. There is general consensus that ruptured AVMs in pregnant women should be managed based on neurosurgical rather than obstetric considerations. Since the risk of re-hemorrhage is significantly higher in the pregnant patient with a ruptured AVM, aggressive treatment during pregnancy must be considered if this can be accomplished with acceptable risk. Recent advances in endovascular technology have increased the potential for successful treatment of previously inoperable high-grade AVMs. Case report A 17-year-old woman pregnant with twins experienced sudden onset headache and became unresponsive at 20 weeks gestation. A CT scan of the head showed cerebellar hemorrhage and obstructive hydrocephalus. Cerebral angiography showed a 5.5 cm AVM in the cerebellar vermis with deep drainage for a Spetzler Martin grade IV classification. Extensive two-stage Onyx embolization with complete casting of the nidus was performed. The patient delivered healthy twin girls at 36 weeks gestation by a planned cesarean section. This was followed by surgical resection of the AVM 4 months later with minimal blood loss. A follow-up angiogram showed no evidence of AVM recurrence 3 months after surgical resection. Her balance was significantly improved and she walked unassisted. She had mild cerebellar speech. Her twin girls are progressing normally. Conclusion Extensive endovascular Onyx embolization is feasible in the setting of a ruptured high-grade AVM during pregnancy. The rationale for proceeding with treatment is the perceived higher likelihood of re-hemorrhage from such a lesion.

Brain abscess formation at the site of intracerebral hemorrhage secondary to central nervous system vasculitis.

Brain abscess is a rare but very dangerous neurosurgical lesion. Prompt diagnosis and emergency surgical evacuation are the hallmarks of therapy. Brain abscess following ischemic and hemorrhagic stroke is a rare entity. These cases are often preceded by episodes of bacteremia, sepsis, and local infection. The authors report the case of a 30-year-old woman who presented with a cerebral abscess at the site of a recent intraparenchymal hemorrhage.

Acute interdural hematoma mimicking epidural hematoma: a case report.

Intracranial hematoma rarely presents between two dural layers of pachimeninges. Here, we present a case of an interdural hematoma with similar appearance to an epidural hematoma. A 51-year-old man presented with a left temporal contusion following a motor vehicle accident. After craniotomy and contusion removal, the post-operative CT scan showed a parietal intracranial hematoma located posterior and superior to the bone flap. The CT scan appearance of the new hematoma was similar to the CT scan appearance of an epidural hematoma. Upon operation, we determined that the hematoma was located between two layers of dura mater, i.e., an interdural hematoma. We removed the hematoma and sutured the two layers of dura to each other at multiple sites. Interdural hematoma is a rare entity. Its appearance in a CT scan can be mistaken for an extradural hematoma.

Endovascular Treatment for Venous Sinus Stenosis in Idiopathic Intracranial Hypertension: An Observational Study of Clinical Indications, Surgical Technique, and Long-Term Outcomes

BACKGROUND Idiopathic intracranial hypertension (IIH) is characterized by increased intracranial pressure. IIH causes significant morbidity marked by incapacitating headaches and visual disturbances. This study investigated the long-term outcomes of venous sinus stenting in a large group of patients with IIH. METHODS We retrospectively reviewed all patients at our institution who underwent venous sinus stenting for IIH over 6 years (July 1, 2012-June 30, 2018). A particular focus was dedicated to collecting demographic, clinical, radiologic, and outcomes data. All patients had failed medical management. RESULTS Of the 110 patients evaluated for IIH, 42 underwent venous sinus stenting, with a mean follow-up of 25.6 months (range, 8.7-60.7 months). The mean age was 32 years (range, 15-52 years), 38 (90%) were women, and the mean body mass index was 35.6 kg/m2 (range, 18.6-47.5 kg/m2). Prior to the stenting procedure, all patients had headaches, visual disturbances, and papilledema. Of the 39 patients who had an ophthalmologic evaluation poststenting, 29 (74%) had resolution of their papilledema. Eighteen patients (43%) had complete resolution of their headaches after the stenting procedure, whereas 22 patients (52%) remained under a neurologists care for chronic migraine and other types of headaches. Two patients underwent a restenting procedure for disease progression, and 1 patient experienced an in-stent thrombosis. CONCLUSIONS A multidisciplinary approach involving neurosurgeons, ophthalmologists, radiologists, and neurologists is integral in the management of patients with IIH to prevent the complications of papilledema. Venous sinus stenting offers a safe and effective means of treating IIH.