Hemodynamic instability during treatment of intracranial dural arteriovenous fistula and carotid cavernous fistula with Onyx: preliminary results and anesthesia considerations.

BACKGROUND AND AIM: 9 patients with 10 arteriovenous fistulas were treated with Onyx at our institution over a period of 19 months: 4 direct and indirect carotid-cavernous fistulas (CCFs) and 6 dural arteriovenous fistula (DAVFs). Complete occlusion was achieved with no recurrences or permanent complications in our small series. We report hemodynamic instability, including severe bradycardia and asystole, during embolization of DAVF and CCF with Onyx in several patients. These changes were reversible with interruption of Onyx injection and administration of atropine. No recurrence of symptoms after atropine administration was noted as Onyx embolization continued during the same session or during postprocedural 24 h monitoring. No adverse clinical consequences were noted. RESULTS: Bradycardia was observed in 4 cases, with a brief asystole in 2 of these patients during transarterial and transvenous Onyx delivery at cavernous sinus and orbital levels. Based on our observation, hemodynamic instability was demonstrated during Onyx injection into the vessels that were in close proximity to the trigeminal nerve or its branches, especially in low-flow/low-volume compartment and may represent a direct effect of dimethyl sulfoxide/Onyx on the trigeminal nerve, resulting in vagal response from trigeminocardiac reflex. CONCLUSION: Proposed measures to prevent this complication include pretreatment with atropine or prophylactic placement of transvenous pacemakers in patients with underlying heart block and patients with contraindications to atropine use.

Embolization of a Cavernous Sinus Dural Arteriovenous Fistula with Onyx via Direct Puncture of the Cavernous Sinus through the Superior Orbital Fissure: Asystole Resulting from the Trigeminocardiac Reflex. A Case Report.

SUMMARY: Treatment of cavernous sinus dural arteriovenous fistula (CSDAVF) may be challenging.We describe a patient who had presented with progressive ocular symptoms due to CSDAVF requiring urgent interventional therapy. Initial attempts to embolize the fistula utilizing a transvenous approach through the inferior petrosal sinus failed because of difficult anatomy. Successful occlusion of the fistula was subsequently achieved with injection of ethylene vinyl alcohol copolymer, Onyx (EV3 Neurovascular, Irvine, CA, USA), via direct percutaneous puncture of the cavernous sinus through the superior orbital fissure.A brief period of asystole during the initial injection of Onyx may be the result of the trigeminocardiac reflex.

Treatment of arteriovenous malformations with hydrocoils in a Swine model.

SUMMARY: Arteriovenous malformations (AVM) of the brain are the most common symptomatic congenital vascular malformation of the central nervous system, with significant associated morbidity and mortality. This study compared the feasibility and efficacy of treating AVMs by embolization with hydrocoils with similar treatment with bare platinum coils, using the swine rete mirabile as a model. A right carotid-jugular fistula was created in ten swine.A microcatheter was positioned into the rete mirabile, which was unilaterally (contralateral to the fistula) embolized with hydrocoils in six and bare platinum coils in four swine. Angiograms were evaluated during and immediately after embolization. Embolization with complete cessation of bloodf low in the unilateral rete mirabile was achieved in all animals treated with hydrocoils. The number of coils needed varied from four to seven (diameter 2-4 mm; mean coil length 22.3 cm). Embolization with platinum coils of similar number (seven) and slightly longer length (mean 37.75 cm) had a minimal effect on blood flow, resulting in occlusion of only small compartments. No immediate complications were noted with either coil. Hydrocoils are more effective in achieving embolization than bare platinum coils. Expansion of the hydrocoil over only a few minutes allows precise placement and stabilization of the coil before detachment. Hydrocoilscan be safely placed into small vessels. This approach may be particularly useful to decrease the flow rate, as a first stage of AVM embolizationin high flow AVMs that contain arteriovenous fistulae.

Evidence that kynurenine pathway metabolites mediate hyperbaric oxygen-induced convulsions.

Metabolism of tryptophan (TRP) through the kynurenine (KYN) pathway in brain, liver, and kidney produces intermediates including the neuroactive agonist quinolinic acid (QA) and the antagonists kynurenic acid (KA) and anthranilic acid (AA) for N-methyl D-aspartate (NMDA) receptors in the central nervous system. We hypothesized that elevated concentrations of QA, KA, or AA can moderate the convulsions that are observed during exposure of rats to hyperbaric oxygen (HBO). We found that i.p. administration of TRP or KYN (both of which cross the blood-brain barrier) had no effect on HBO-induced seizures. However, AA (administered i.p.) or gavage administration of the KYN pathway blocking drug Ro 61-8048, both of which enter the brain from the circulatory system, affect the time to first convulsion and/or coma during HBO in a manner consistent with a modulatory role for seizure activity.

Decompressive craniotomy in medically uncontrollable malignant infarction.

Patients with progressive neurological deficit following large cerebral infarctions are viewed to have a uniformly poor prognosis. We present two patients with large middle cerebral artery infarctions in which a decompressive craniotomy was life saving and resulted in functional outcome. The clinical course of patients with malignant infarction and the treatment issues involved including patient selection and the timing and extent of cranial decompression are discussed.

Hydroxyl radicals detected via brain microdialysis in rats breathing air and during hyperbaric oxygen convulsions.

Microdialysis was done on 300-400 g, awake, male rats with microdialysis probes inserted through guide cannulas into the striatum (Bregma co-ordinates A 0.5, L 2.9, D -4.0 for guide cannulas implanted 5 days previously). Rats were exposed to hyperbaric oxygen (HBO; 6 atm absolute, 5 atm gauge pressure of oxygen with carbon dioxide absorbed by soda lime). Artificial cerebrospinal fluid (CSF) containing 5 mM sodium salicylate was perfused at 1 microl/min and collected over sequential 10 min intervals with rats breathing air, then HBO, and after decompression. Times to convulsions and duration and severity of convulsions were observed and recorded. CSF samples were analyzed for 2,3- and 2,5-dihydroxybenzoic acid (DHBA), reaction products of hydroxyl radicals with salicylate, by HPLC and compared to authentic standards. Recovery of DHBAs was 48% from fluid surrounding microdialysis probes, based on in vitro tests. The average time to the first convulsion was 21 min and rats convulsed an average of 4 times during 40 min in HBO. There were no significant differences in hydroxyl radical production by this protocol during any of the 10 min collection periods in air or HBO (average in pmoles for 10 microl of all samples: 2,3-DHBA = 7.0 +/- 2.5 and 2,5-DHBA = 11.3 +/- 4.1). The failure to detect an increase in hydroxyl radicals in HBO prior to or during convulsions appears valid since each rat served as its own control.

The transcallosal interforniceal approach to the third ventricle: anatomic and microsurgical aspects.

OBJECTIVE: The ability to visualize median-sagittal brain structures by magnetic resonance imaging improves planning for surgery to treat lesions of the third ventricle. The most appropriate path to the third ventricle is the transcallosal approach. The present study was undertaken to describe the surgical anatomy and landmarks encountered during this approach. METHODS: The transcallosal-interforniceal approach was undertaken in 30 formalin-fixed brains using an operating microscope. The surface landmarks for the approach pathway were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. Using these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures that are encountered during the surgical approach. Measurements that were made include the following: 1) the distance between P5 and the cingulate sulcus, 2) the distance between the cingulate sulcus and the corpus callosum, 3) the height of the corpus callosum, 4) the distance between the anterior commissure and the foramen of Monro, and 5) the distance between the lower margin of the corpus callosum and the fornix. RESULTS: Mean values for these key measurements were as follows: 1) 23.96 mm (range, 15.0-32.0 mm); 2) 13.50 mm (range, 8.0-20.0 mm) with reference to P5 and 12.73 mm (range, 16.0-18.0 mm) with reference to P7; 3) 6.12 mm (range, 4.0-8.0 mm) with reference to P5 and 6.60 mm (range, 4.0-9.0 mm) with reference to P7; 4) 4.96 mm (range, 2.5-10.0 mm), independent of P5 and P7; and 5) 8.46 mm (range, 3.0-16.0 mm) with reference to P5 and 11.04 mm (range, 6.0-22.0 mm) with reference to P7. CONCLUSION: The detailed quantitative information obtained in this study about the interforniceal approach permitted definition of surgical approach pathways that preserve important anatomic structures, such as the motor strip, genu of the corpus callosum, fornical commissure (hippocampal commissure), anterior commissure, and fornical columns. The approach through this surgical corridor can easily be planned and performed in individual cases using median-sagittal magnetic resonance imaging scans.

[The clinico-anatomical characteristics and the reasons for diagnostic errors in vascular micromalformations and cavernous defects in the cerebral vessels]. / Kliniko-anatomicheskaia kharakteristika i prichiny diagnosticheskikh oshibok pri sosudistykh mikromal'formatsiiakh i kavernoznykh porokakh sosudov golovnogo mozga.

The presurgical clinical diagnosis of vascular micromalformations and cavernous defects of the brain vessels is one of the most intricate problems. Forty-seven observations of patients with verified histological diagnosis of various vascular micromalformations: arteriovenous, venous, cavernous, and undifferentiated ones were analyzed. There was a direct relationship between the clinical course of defects and difficulties in presurgical diagnosis, on the one hand, and the type of vascular micromalformations, the presence of hematomas, residual recurrent hemorrhages, vascular thromboses, the degree of glial hyperplasia and a tumor, on the other. The analysis of 50 observations of patients with cavernous malformations of different sizes demonstrated the heterogeneity of a histological pattern in this type of vascular pathology and the relationship of the clinical course to the morphological structure of cavernous malformations. This is indicative of the necessity of making a comprehensive examination of patients with cavernous malformations.