Cameron M. McDougall

Delayed Spontaneous Rupture of a Posterior Inferior Cerebellar Artery Aneurysm Following Treatment with Flow Diversion: A Clinicopathologic Study

SUMMARY: In this report, we present the fatal spontaneous delayed rupture of a previously unruptured large PICA aneurysm following treatment with the PED. Pathology at postmortem examination has supported the theory that intra-aneurysmal thrombus may acutely destabilize the aneurysm wall. Aneurysms with an anatomic arrangement that promote continued flow into the neck may not be optimal candidates for the flow-diversion treatment strategy.

Intracranial-to-intracranial bypass for posterior inferior cerebellar artery aneurysms: options, technical challenges, and results in 35 patients

OBJECT Intracranial-to-intracranial (IC-IC) bypasses are alternatives to traditional extracranial-to-intracranial (EC-IC) bypasses to reanastomose parent arteries, reimplant efferent branches, revascularize branches with in situ donor arteries, and reconstruct bifurcations with interposition grafts that are entirely intracranial. These bypasses represent an evolution in bypass surgery from using scalp arteries and remote donor sites toward a more local and reconstructive approach. IC-IC bypass can be utilized preferentially when revascularization is needed in the management of complex aneurysms. Experiences using IC-IC bypass, as applied to posterior inferior cerebellar artery (PICA) aneurysms in 35 patients, were reviewed. METHODS Patients with PICA aneurysms and vertebral artery (VA) aneurysms involving the PICAs origin were identified from a prospectively maintained database of the Vascular Neurosurgery Service, and patients who underwent bypass procedures for PICA revascularization were included. RESULTS During a 17-year period in which 129 PICA aneurysms in 125 patients were treated microsurgically, 35 IC-IC bypasses were performed as part of PICA aneurysm management, including in situ p3-p3 PICA-PICA bypass in 11 patients (31%), PICA reimplantation in 9 patients (26%), reanastomosis in 14 patients (40%), and 1 V3 VA-to-PICA bypass with an interposition graft (3%). All aneurysms were completely or nearly completely obliterated, 94% of bypasses were patent, 77% of patients were improved or unchanged after treatment, and good outcomes (modified Rankin Scale ≤ 2) were observed in 76% of patients. Two patients died expectantly. Ischemic complications were limited to 2 patients in whom the bypasses occluded, and permanent lower cranial nerve morbidity was limited to 3 patients and did not compromise independent function in any of the patients. CONCLUSIONS PICA aneurysms receive the application of IC-IC bypass better than any other aneurysm, with nearly one-quarter of all PICA aneurysms treated microsurgically at our center requiring bypass without a single EC-IC bypass. The selection of PICA bypass is almost algorithmic: trapped aneurysms at the PICA origin or p1 segment are revascularized with a PICA-PICA bypass, with PICA reimplantation as an alternative; trapped p2 segment aneurysms are reanastomosed, bypassed in situ, or reimplanted; distal p3 segment aneurysms are reanastomosed or revascularized with a PICA-PICA bypass; and aneurysms of the p4 segment that are too distal for PICA-PICA bypass are reanastomosed. Interposition grafts are reserved for when these 3 primary options are unsuitable. A constructive approach that preserves the PICA with direct clipping or replaces flow with a bypass when sacrificed should remain an alternative to deconstructive PICA occlusion and endovascular coiling when complete aneurysm occlusion is unlikely.

Predicting recurrence after chronic subdural haematoma drainage.

BACKGROUND Recurrence of chronic subdural haematomas (CSDHs) after surgical drainage is a significant problem with rates up to 20%. This study focuses on determining factors predictive of haematoma recurrence and presents a scoring system stratifying recurrence risk for individual patients. METHODS Between the years 2005 and 2009, 331 consecutive patients with CSDHs treated with surgery were included in this study. Univariate and multivariate analyses were performed searching for risk factors of increased post-operative haematoma volume and haematoma recurrence requiring repeat drainage. RESULTS We found a 12% reoperation rate. CSDH septation (seen on computed tomogram scan) was found to be an independent risk factor for recurrence requiring reoperation (p=0.04). Larger post-operative subdural haematoma volume was also significantly associated with requiring a second drainage procedure (p<0.001). Independent risk factors of larger post-operative haematoma volume included septations within a CSDH (p<0.01), increased pre-operative haematoma volume (p<0.01), and a greater amount of parenchymal atrophy (p=0.04). A simple scoring system for quantifying recurrence risk was created and validated based on patient age (< or ≥ 80 years), haematoma volume (< or ≥ 160 cc), and presence of septations within the subdural collection (yes or no). CONCLUSION Septations within CSDHs are associated with larger post-operative residual haematoma collections requiring repeat drainage. When septations are clearly visible within a CSDH, craniotomy might be more suitable as a primary procedure as it allows greater access to a septated subdural collection. Our proposed scoring system combining haematoma volume, age, and presence of septations might be useful in identifying patients at higher risk for recurrence.

Uncertainty and Agreement Regarding the Role of Flow Diversion in the Management of Difficult Aneurysms

BACKGROUND AND PURPOSE: The role of flow diversion in the management of aneurysms remains unknown. We sought to evaluate the community agreement regarding indications for flow diversion. MATERIALS AND METHODS: A portfolio of 35 difficult aneurysm cases was sent to 40 clinicians with varying backgrounds and experience. Responders were asked whether they considered flow diversion a treatment option, whether other options were possible, whether recruitment in a randomized trial would be considered, and to select their final choice. Agreement was studied by using κ statistics. RESULTS: Decisions for flow diversion were more frequent (n = 300, 39%) than decisions to coil (n = 163, 21.2%), to observe (n = 121, 15.7%), to occlude the parent vessel (n = 102, 13.2%), or to clip (n = 66, 8.6%). Sidewall aneurysm morphology was associated with flow diversion as the final choice (P = .001). Interjudge agreement was fair at best (κ <0.3) for all cases and all judges, despite high certainty levels (range, 7.2–8.9 ± 2.0 on a 0–10 scale). Agreement was no better within specialties or with more experience. All patients were judged to have other treatment options. Judges were willing to offer trial participation in 417 of 741 (56.3%) scenarios, more frequently when the aneurysm was sidewall (P = .001) or in the anterior circulation (P = .028). CONCLUSIONS: Individuals did not agree regarding the indications for flow diversion. There is sufficient uncertainty to justify trials designed to protect patients from the potential risks of premature adoption of an innovation.

Covered carotid stents as an adjunct in the surgical treatment of carotid body tumors: a report of 2 cases and a review of the literature.

BACKGROUND AND IMPORTANCE: Carotid body tumors are a technically challenging surgical problem. One of the primary goals of surgery and often one of the most difficult aspects of management involves preservation of the ipsilateral internal carotid artery (ICA). We report a small case series with challenging aspects to ICA preservation that were successfully treated with covered stenting and review the literature to date on this topic. CLINICAL PRESENTATION: Two patients with carotid body tumors were selected for covered ICA stenting, the first because of bilateral disease and the second because of failure of test occlusion. The patients were initially loaded with antiplatelet agents, and the stents were deployed transfemorally. The patients were kept on dual therapy (acetylsalicylic acid and Plavix) for 6 weeks, followed by acetylsalicylic acid alone, which was discontinued 1 week before surgery. The patients were admitted 3 days before surgery, and intravenous heparin was started and then stopped 6 hours preoperatively. Both tumors were completely resected with minimal blood loss, and the ipsilateral ICA was successfully preserved in both cases. CONCLUSION: The covered ICA stent offers a significant adjunct for preserving the ICA in carotid body tumor resection. ABBREVIATIONS: CBT, carotid body tumor ICA, internal carotid artery

Pediatric Traumatic Retroclival Epidural Hematoma

A previously healthy ten-year-old girl was involved in a high speed motor vehicle accident (MVA) in which she was the belted front-seat passenger. The patients teeth marks on the dashboard were evidence of a high-velocity impact. Her Glasgow Coma Score on scene was 13, and she was amnestic for the event. She was subsequently transported to the emergency room in full spinal precautions; on arrival she was hemodynamically stable with a Glasgow Coma Score of 14, complaining of neck and jaw pain. Neurological examination revealed impaired abduction of the right eye, with no other focal deficits. She had oral lacerations and bruising over the mandibles bilaterally. Computed tomogram (CT) scan of the head was initially interpreted as normal, but on closer inspection demonstrated a 4mm retroclival hematoma (Figure 1). Sagittal CT through the upper cervical spine revealed the hematoma was epidural, bounded by the spheno-occipital synchondrosis superiorly and by the mid-body of the axis inferiorly (Figure 2). The odontoid was retroflexed (Figure 2). Bilateral mandibular fractures were also uncovered on facial imaging.

Soluble FLT1 Gene Therapy Alleviates Brain Arteriovenous Malformation Severity

Background and Purpose— Brain arteriovenous malformation (bAVM) is an important risk factor for intracranial hemorrhage. Current therapies are associated with high morbidities. Excessive vascular endothelial growth factor has been implicated in bAVM pathophysiology. Because soluble FLT1 binds to vascular endothelial growth factor with high affinity, we tested intravenous delivery of an adeno-associated viral vector serotype-9 expressing soluble FLT1 (AAV9-sFLT1) to alleviate the bAVM phenotype. Methods— Two mouse models were used. In model 1, bAVM was induced in R26CreER;Eng2f/2f mice through global Eng gene deletion and brain focal angiogenic stimulation; AAV2-sFLT02 (an AAV expressing a shorter form of sFLT1) was injected into the brain at the time of model induction, and AAV9-sFLT1, intravenously injected 8 weeks after. In model 2, SM22&agr;Cre;Eng2f/2f mice had a 90% occurrence of spontaneous bAVM at 5 weeks of age and 50% mortality at 6 weeks; AAV9-sFLT1 was intravenously delivered into 4- to 5-week-old mice. Tissue samples were collected 4 weeks after AAV9-sFLT1 delivery. Results— AAV2-sFLT02 inhibited bAVM formation, and AAV9-sFLT1 reduced abnormal vessels in model 1 (GFP versus sFLT1: 3.66±1.58/200 vessels versus 1.98±1.29, P<0.05). AAV9-sFLT1 reduced the occurrence of bAVM (GFP versus sFLT1: 100% versus 36%) and mortality (GFP versus sFLT1: 57% [12/22 mice] versus 24% [4/19 mice], P<0.05) in model 2. Kidney and liver function did not change significantly. Minor liver inflammation was found in 56% of AAV9-sFLT1–treated model 1 mice. Conclusions— By applying a regulated mechanism to restrict sFLT1 expression to bAVM, AAV9-sFLT1 can potentially be developed into a safer therapy to reduce the bAVM severity.

Primary lymphoma isolated to the trigeminal nerve.

included computed tomography (CT), magnetic resonance imaging (MRI) (Figure 1A and B), and cerebrospinal fluid analysis. Medical treatment for trigeminal neuralgia was started, however this proved to be unsuccessful. His pain worsened, and repeat MRI showed an enlarged, non-enhancing lesion at the root entry zone of the trigeminal nerve (Figure 1C). A neoplastic etiology was suspected, and the patient was investigated for metastatic disease. Normal studies included a CT of the neck, chest, abdomen, and pelvis, multiple lumbar punctures, two positron emission tomography (PET) studies, a bone marrow biopsy, and lab and hematological work-up for inflammatory and paraneoplastic causes. Neurosurgical referral was then made for tumor biopsy. Via a retrosigmoid approach the nerve was found to be grossly

Angiographic demonstration of upward transtentorial herniation.

A 47-year-old female experienced a sudden onset headache with associated nausea and vomiting, and was found on computed tomogram (CT) scan to have suffered a Grade 3 subarachnoid hemorrhage (SAH) with associated vermian hemorrhage. Subsequent CTA demonstrated a posterior fossa arteriovenous malformation (AVM) with two flow-associated aneurysms, a posterior inferior cerebellar artery (PICA) aneurysm, and a superior cerebellar artery (SCA) aneurysm, which was felt responsible for the hemorrhage (Figure A). During hospital transfer, her level of consciousness became compromised, decreasing to a Glasgow Coma Score (GCS) of 10. An external ventricular drain (EVD) was placed, releasing cerebrospinal fluid (CSF) under moderate pressure. An hour following placement of the EVD, her GCS further decreased to 6, with a loss of her left corneal and gag reflexes, in spite of a supratentorial intracranial pressure (ICP) of 14 mm H20. While the surgical team was mobilized for posterior fossa decompression, the patient was treated with 500 mL of 20%

Ultrasound for the evaluation of stenosis after flow diversion

Background and purpose Flow diversion is a relatively new strategy used to treat complex cerebral aneurysms. The optimal method for radiographic follow-up of patients treated with flow diverters has not been established. The rate and clinical implications of in-stent stenosis for these devices is unclear. We evaluate the use of transcranial Doppler ultrasound (TCD) for follow-up of in-stent stenosis. Materials and methods We analyzed 28 patients treated with the Pipeline embolization device (PED) over the course of 42 months from January 2009 to June 2012. Standard conventional cerebral angiograms were performed in all patients. TCD studies were available in 23 patients. Results Angiographic and TCD results were compared and found to correlate well. Conclusions TCD is a potentially useful adjunct for evaluating in-stent stenosis after flow diversion.