Byron G. Thompson

Recovery of Cognitive Function After Surgery for Aneurysmal Subarachnoid Hemorrhage

Background and Purpose— Abnormalities in neurocognitive function are common after surgery for aneurysmal subarachnoid hemorrhage, even among patients with good functional outcomes. The time course of neurocognitive recovery, along with the long-term effects of mild intraoperative hypothermia (33°C) and aneurysm location, is unknown. We determined these in a subset of subarachnoid hemorrhage patients enrolled in the Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST). Methods— We performed a longitudinal, multicenter, prospective, blinded study of adult IHAST patients with a Glasgow Outcome Score=1 or 2 (independent function), 3 months postsurgery and a matched control group (n=45). Subjects were tested with a 5-test cognitive function battery and standard neurological evaluations at 3, 9 and 15 months postsurgery. The primary outcome measure was a composite score on cognitive test performance. Results— There were 303 IHAST patients available for inclusion: 218 eligible, 185 enrolled (89 hypothermic, 96 normothermic). Significant cognitive improvement was noted from 3 to 9 (P<0.001) and 3 to 15 (P<0.001) months in both hypothermic and normothermic groups, even after adjusting for practice effects observed in the control group. No significant change was identified between 9 and 15 months. Neither mild hypothermia nor aneurysm location (anterior communicating artery versus others) had a significant effect on recovery over time or frequency of cognitive impairment. Compared with control group, the frequency of cognitive impairment (Z score <−1.96) in all patients at 3, 9 and 15 months was 36%, 26% and 23%, respectively. Conclusions— In this population, cognitive improvement continued beyond 3 months, with a plateau between 9 and 15 months. This was not affected by the use of intraoperative hypothermia or anatomical location of aneurysm.

Prasugrel is effective and safe for neurointerventional procedures

Background Clopidogrel bisulfate and aspirin are routinely administered as dual antiplatelet agents for many neurointerventional procedures, especially for intravascular stent placement. Many patients are non-responsive to clopidogrel, either secondary to drug interactions or from variations of cytochrome P450 enzymes. Prasugrel (brand name Effient, Eli Lilly and Company, Indianapolis, IN, USA) is a new antiplatelet agent that has been utilized extensively in patients undergoing cardiovascular procedures but its safety and efficacy during neurointerventional procedures have not been evaluated. Objective To examine whether prasugrel is a safe and effective alternative to clopidogrel for neurointerventional procedures, especially in those patients who are either non-responders or allergic to clopidogrel. Methods The medical records of all patients undergoing neurointerventional procedures at our institution who received prasugrel between January 2009 and July 2011 were retrospectively reviewed. A systematic chart review was performed and the following data were recorded: demographics, aneurysm location, endovascular techniques, peri- and post-procedural complications, hemorrhagic complications, clinical outcome and angiographic outcome. Results 16 patients undergoing neurointerventional procedures received prasugrel over a 2 year interval. All patients who had follow-up studies of P2Y12 inhibition had immediate therapeutic response to prasugrel. There were no complications related to ischemic or intracranial hemorrhage. Conclusion Prasugrel is a viable alternative to clopidogrel for patients undergoing neurointerventional procedures who are non-responders to clopidogrel. Further study is needed to evaluate the safety, efficacy and cost-effectiveness of prasugrel compared with clopidogrel for patients undergoing neurointerventional procedures.

Radial forearm free tissue transfer reduces complications in salvage skull base surgery

OBJECTIVE: Patients who undergo skull base resection after prior surgery or radiation may be at high risk for complications when local flaps alone are used for reconstruction. To determine whether the complication rate could be reduced, fasciocutaneous free tissue transfer was used to reinforce the dural closure in patients who had prior skull base surgery or radiation. METHODS: This study is a case series of 20 patients (14 males, 6 females, aged 8–79 years of age with a mean of 47.7 years) from 1997 to 2001 who had prior skull base surgery or radiation, and underwent salvage skull base resection without large volume defects. All patients had a radial forearm free tissue transfer to reinforce the dural closure. Six patients had an osseous component to the forearm flap to provide vascularized bone to the orbital rim. RESULTS: The overall local complication rate was 35%. Three patients (15%) had major complications including 1 case of meningitis, 1 case of cerebrospinal fluid leak, and 1 case of a flap requiring venous salvage. There were no flap failures, 1 idiopathic median nerve palsy, and no pathologic radius bone fractures. CONCLUSION: Reconstruction with fasciocutaneous free tissue transfer for high-risk patients with low-volume dural defects following skull base resection can minimize the risk of major postoperative complications. EBM rating: C.

Radiation dose reduction during neurointerventional procedures by modification of default settings on biplane angiography equipment

Background Neurointerventional procedures represent a significant source of ionizing radiation. We sought to assess the effect during neurointerventional procedures of varying default rates of radiation dose in fluoroscopy (F) and image acquisition (IA) modes, and frame rates during cine acquisition (CINE) on total X-ray dose, acquisition exposures, fluoroscopy time, and complications. Methods We retrospectively reviewed procedures performed with two radiation dose and CINE settings: a factory setting dose cohort (30 patients, F 45 nGy/pulse, IA 3.6 μGy/pulse, factory CINE frame rate) and a reduced dose cohort (30 patients, F 32 nGy/pulse, IA 1.2 μGy/pulse, with a decreased CINE frame rate). Total radiation dose, dose area product, number of acquisition exposures, fluoroscopy time, and complications were compared between the groups. Means comparisons (t tests) were employed to evaluate differences in the outcome variables between the two groups. p Value <0.05 was considered significant. Results The reduced dose cohort had a significant reduction in mean radiation dose (factory, 3650 mGy; reduced, 1650 mGy; p=0.005) and dose area product (factory, 34 700 μGy×m2; reduced, 15 000 μGy×m2; p=0.02). There were no significant differences between cohorts in acquisition exposure (p=0.73), fluoroscopy time (p=0.45), or complications. Conclusions Significant reductions in radiation dose delivered by neurointerventional procedures can be achieved through simple modifications of default radiation dose in F and IA and frame rate during CINE without an increase in procedural complexity (fluoroscopy time) or rate of complications.

Endovascular Treatment of Cerebral Vasospasm: Vasodilators and Angioplasty

Cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is a delayed, reversible narrowing of the intracranial vasculature that occurs most commonly 4 to 14 days after aneurysmal SAH and can lead to permanent ischemic injury. Angiographic spasm occurs in up to 70% of patients following SAH, and approximately half become symptomatic. Estimates of patients who are disabled by vasospasm, or die because of it, range from 5% to 9%, with vasospasm accounting for 12% to 17% of all fatalities or cases of disability after SAH. This article discusses the multiple medical and endovascular therapies used to prevent or treat vasospasm.

Intraoperative monitoring for intracranial aneurysms: the Michigan experience.

Summary: Intraoperative neurophysiological monitoring is routinely used during the repair (endovascular or microsurgical) of intracranial aneurysms at major centers. There is a continued need of data sets from institutions with dedicated intraoperative neurophysiological monitoring services to further define the predictive factors of postoperative neurological deficits. We retrospectively reviewed and analyzed our database of all patients who underwent repair of intracranial aneurysms (endovascular or microsurgical). A total of 406 patients underwent 470 procedures. The changes were noted during monitoring in 3.83% of the cases. Most of the changes were first detected in somatosensory evoked potential (88.89%) followed by brainstem auditory evoked potential (16.67%). Changes were completely reversible in 44.44%, only partly reversible in 22.22%, and irreversible in 33.33% of cases. Intraoperative neurophysiological monitoring changes demonstrated high sensitivity, specificity, and negative predictive value for postoperative neurological deficits. The association between intraoperative neurophysiological monitoring changes and Glasgow outcome scale was significant for reversible changes compared against irreversible and partly reversible changes. Presence of any intraoperative neurophysiological monitoring modality change during repair of intracranial aneurysm may suggest a higher risk for postoperative neurological deficits. Reversibility of the changes is a favorable marker, whereas irreversible changes are predictive of postoperative neurological deficits with deterioration of Glasgow outcome scale on a longer follow-up.

Multi-Detector Row CT Angiography with Direct Intra-Arterial Contrast Injection for the Evaluation of Neurovascular Disease: Technique, Applications, and Initial Experience

SUMMARY: The purpose of this study was to evaluate the usefulness of 64-section multi-detector row CT angiography (CTA) with direct intra-arterial contrast injection (IA-CTA) for the evaluation of neurovascular disease. This technique was used in 11 patients at our institution. All studies were technically successful, and there were no complications. Small vascular malformations were mapped easily on high-resolution IA-CTA images, enabling microsurgical resection or stereotactic radiosurgery. In a similar fashion, additional morphologic features were revealed on IA-CTA images not seen on standard 2D and 3D digital subtraction angiography. Of 11 patients undergoing IA-CTA, 7 patients had further anatomic clarity of the small arteriovenous fistula/malformation and 4 patients had changes in the treatment plan on the basis of the IA-CTA findings.

Intracranial Endovascular Balloon Test Occlusion-Indications, Methods, and Predictive Value

The balloon test occlusion is one method by which surgeons evaluate whether a patient will be able to tolerate permanent occlusion of an extracranial or intracranial vessel. This article discusses the indications, methods, predictive value, and complications of the balloon test occlusion. It also briefly describes the Wada test in the context of preoperative evaluation of patients who are candidates for temporal lobectomy.

Transarterial Embolization of a Cervical Dural Arteriovenous Fistula: Presenting with Subarachnoid Hemorrhage

We describe a case of a 75-year-old man who presented with acute onset of headache and subarachnoid hemorrhage and initial cerebral angiography was deemed “negative”. In retrospect, a faint contrast collection was present adjacent to the right vertebral artery at the C1 level suspicious for a small dural arteriovenous fistula (dAVF). Follow-up angiography with selective micro-catheter injections of the right vertebral artery and C1 radicular artery confirmed a complex dAVF with characteristically specific venous drainage patterns associated with a subarachnoid hemorrhage presentation. Subsequently, the cervical dAVF was treated with superselective glue embolization resulting in complete occlusion. Cervical dAVFs are extremely rare vascular causes of subarachnoid hemorrhage. Both diagnostic angiography and endovascular treatment of these lesions can be challenging, especially in an emergent setting, requiring selective evaluation of bilateral vertebral arteries and careful attention to their cervical segments. Although only a single prior case of a cervical dAVF presenting with subarachnoid hemorrhage has been successfully treated with embolization, modern selective transarterial techniques may allow easier detection and treatment of subtle pathologic arteriovenous connections.

Correlation of thrombus formation on 7 T MRI with histology in a rat carotid artery side wall aneurysm model

Background/purpose Various aneurysm animal models have been utilized to study the histological reaction post coil embolization. Our aim was to evaluate the imaging findings at day 14 of a rat external carotid artery side wall aneurysm treated with coil embolization using a gradient echo sequence on 7 T MRI and to correlate this with the histological findings. Materials and methods Male Sprague Drawley rats were utilized to create a sidewall external carotid artery blind pouch aneurysm. A 5 mm segment of hydrocoil or bare platinum coil was inserted into the created aneurysm. Five sham operated rats were used as controls. The arterial construct was harvested on day 14. The block of tissue was evaluated with histopathology and immunohistochemistry. Prior to sacrifice, the animal underwent 7 T MRI. Statistical analysis was then performed to assess the correlation of signal abnormality with intra-aneurysmal thrombus formation on histology. Results 10 rats were used for the experiment. Five rats had implantation of hydrocoils and five of bare platinum coils. There was a statistically significant linear correlation between the intra-aneurysmal thrombus on histology and gradient echo 7 T MRI sequences. There was no correlation demonstrated in the hydrocoil implanted group. No thrombus or abnormal signal was seen in the sham group. Conclusions In our experiment, thrombus formation in aneurysms treated with bare platinum coils is well correlated with the presence of abnormal signal on 7 T MRI at 14 days. No correlation was appreciated in the hydrocoil implanted group due to the presence of intra-aneurysmal reactive tissue instead of thrombus.