Michael T. Madison

Functional Magnetic Resonance Imaging as a Management Tool for Cerebral Arteriovenous Malformations

The location of eloquent cortex, such as the motor strip, the visual cortex, or Brocas area, may be difficult to predict even with multiprojectional magnetic resonance imaging (MRI). Distortion and displacement of this cortex may occur with a congenital lesion, such as an arteriovenous malformation, or by an acquired disease, such as a neoplasm. A desire to avoid damaging these eloquent areas by conventional surgery, radiosurgery, or endovascular surgery makes their accurate identification an important part of the pretherapeutic planning process. Blood oxygen level dependent functional MRI is a technique that uses the local increase of oxyhemoglobin concentration in the patient that occurs as a result of the increase in flow rate and blood volume in eloquent cortex undergoing stimulation from, for example, flashing lights, hand movements, or speech. We have used the blood oxygen level dependent technique to localize eloquent cortex relative to arteriovenous malformations and tumors. Using a 4.0-T magnetic resonance (MR) system, there is a sufficiently high degree of spatial resolution of the MR signal intensity changes during stimulation to allow the identification of eloquent cortex. Alternative, non-MR, invasive techniques for functional localization include electrocorticography and stimulation from subdural grids and strips. Noninvasive, non-MR technologies, such as positron emission tomography and magnetoencephalography, can also provide functional localization of eloquent cortex. However, the perfection of functional MRI at the 1.5-T field strength and the large number of such MR systems in operation mean that a highly accurate cerebral cortical localization technique can be available to most neuroscientists without the need to purchase alternative expensive technology.

Outcomes after aneurysm rupture during endovascular coil embolization

OBJECTIVEIntracranial aneurysm rupture during placement of Guglielmi detachable coils has been reported, but the management and consequences of this event have not been extensively described. We present our experience with this feared complication and report possible neuroradiological and neurosurgical interventions to improve outcomes. METHODSWe retrospectively reviewed the records for 701 patients with 734 intracranial aneurysms that were treated with endovascular coiling, during a 6-year period, in the metropolitan Minneapolis-St. Paul (Minnesota) area. This analysis revealed 10 cases of perforation during coiling. The management and outcomes were recorded, and the pertinent literature was reviewed. RESULTSAll 10 cases involved previously ruptured aneurysms. This complication occurred sporadically and was not observed in the first 100 cases. Perforation occurred during microcatheterization of the aneurysm in two cases and during coil deposition in eight cases. Seven of the perforated aneurysms were located in the anterior circulation and three in the posterior circulation. Six of the 10 patients made good or fair recoveries; all three patients with posterior circulation lesions died immediately after rehemorrhage. Elevated intracranial pressure (ICP) was noted for all five patients with intraventricular catheters in place. Bilateral pupil dilation and profound hemodynamic changes were noted for eight patients. Coiling was rapidly completed, and total or nearly total occlusion was achieved in all cases. Emergency ventriculostomy was performed to rapidly reduce increased ICP for two patients, both of whom made good recoveries. Hemodynamic and angiographic factors after perforation, such as prolonged systemic hypertension, persistent dye extravasation after deployment of the first Guglielmi detachable coil, and persistent prolongation of contrast dye transit time (suggesting ongoing ICP elevation), were correlated with poor outcomes. CONCLUSIONPreviously ruptured aneurysms seem to be more susceptible to endovascular treatment-related perforation than are unruptured lesions. Worse prognoses are associated with iatrogenic rupture during coiling of posterior circulation lesions, compared with those in the anterior circulation. When perforation is recognized, the definitive treatment seems to be reversal of anticoagulation therapy and completion of Guglielmi detachable coil embolization. Immediate neurosurgical intervention is limited in these cases and focuses on decreasing ICP via emergency ventriculostomy. However, these measures may be life-saving, and neurosurgical assistance must be readily available during treatment of these cases.

The pathogenesis of arteriovenous malformations: insights provided by a case of multiple arteriovenous malformations developing in relation to a developmental venous anomaly.

OBJECTIVE AND IMPORTANCE Developmental venous anomalies (DVAs) are common anomalies of intracranial venous drainage that may occur in conjunction with other cerebral vascular malformations. The present case raises important questions regarding the association between anomalous venous drainage patterns and the development of arteriovenous malformations (AVMs). CLINICAL PRESENTATION We present the case of a 24-year-old man with small AVMs fed by the superior cerebellar artery that drained directly into a large DVA of the cerebellum. INTERVENTION The patient was managed conservatively and returned 10 years later with recurrent symptoms. A repeat angiogram demonstrated spontaneous thrombosis of the previously documented AVMs; however, new AVMs at a different site that was also fed by the superior cerebellar artery and drained into the same DVA had appeared. The AVMs were completely embolized, and the DVA was left intact. CONCLUSION Recently, increasing attention has focused on the possible importance of venous outflow disturbance and venous hypertension in the pathogenesis and pathophysiology of AVMs. The potential mechanisms for this association and the implications of the present case are discussed, and the pertinent literature is reviewed.

Intra-aortic Balloon Counterpulsation Augments Cerebral Blood Flow in the Patient with Cerebral Vasospasm: A Xenon-enhanced Computed Tomography Study

OBJECTIVE We previously established the ability of intra-aortic balloon counterpulsation (IABC) to improve cerebral blood flow (CBF) significantly in a canine model of cerebral vasospasm. This study was performed to assess the efficacy of IABC in a patient with cardiac dysfunction and severe cerebral vasospasm that was refractory to traditional treatment measures. METHODS We report our experience with the clinical use of IABC to treat cerebral vasospasm in a patient who suffered subarachnoid hemorrhage and concomitant myocardial infarction. Hypertensive, hypervolemic, hemodilution therapy was ineffective, and IABC was instituted. Xenon-enhanced computed tomography (Xe-CT) was utilized to obtain serial measurements of CBF with and without IABC over a 4-day period. RESULTS IABC dramatically improved cardiac function in this patient, and Xe-CT demonstrated significant improvement in CBF with IABC. The average global CBF was 20.5 +/- 4.4 ml/100g/min before versus 34.7 +/- 3.8 ml/100g/min after IABC (p < 0.0001, paired students t-test). The lower the CBF before IABC, the greater the improvement with IABC (correlation coefficient r = 0.83, p = 0.0007). CBF improvement ranged from 33% to 161% above baseline, average 69.3%. No complications of IABC were observed. CONCLUSIONS This is the first report demonstrating the ability of IABC to improve CBF in a patient with vasospasm. We suggest that IABC is a rational treatment option in select patients with refractory cerebral vasospasm who do not respond to traditional treatment measures.

Dissecting aneurysms of the posterior inferior cerebellar artery: retrospective evaluation of management and extended follow-up review in 6 patients.

OBJECT The authors report the management protocol and successful outcomes in 6 patients with dissecting aneurysms of the posterior inferior cerebellar artery (PICA). METHODS Medical records and neuroimaging studies of 6 patients who underwent surgical treatment of dissecting PICA aneurysms were reviewed. The mean follow-up duration was 1.8 years. No patient was lost to follow-up review. RESULTS Four patients presented with acute subarachnoid hemorrhage and 2 with PICA ischemia. All patients underwent surgery, which entailed proximal occlusion with distal revascularization in 3 cases and circumferential wrap/clip reconstruction in 3 cases. The revascularization techniques used were occipital artery-PICA bypass and PICA-PICA anastomosis. Delayed follow-up angiography was performed in all cases. In patients treated with proximal occlusion, delayed angiography showed minimal retrograde opacification of the dissected segments. The 3 patients treated with wrap/clip reconstruction showed unexpectedly significant normalization of their lesions on angiographic studies. Outcome was good in all cases. CONCLUSIONS Dissecting PICA aneurysms are rare lesions with an apparent propensity for bleeding. Individualized management including distal revascularization with PICA sacrifice or circumferential wrap/clip reconstruction to reinforce the dissected segment produced good outcomes. Patients treated with aneurysm wrapping may show dramatic angiographic improvement of the dissected segment.

Preoperative permanent balloon occlusion of internal carotid artery in patients with advanced head and neck squamous cell carcinoma

Objective/Hypothesis: To determine the value of preoperative balloon occlusion in predicting the safety of carotid artery resection in advanced recurrent head and neck squamous cell carcinoma. Study Design: Retrospective chart review of all cases undergoing planned carotid artery resection for recurrent disease at a major university hospital. Methods: If the carotid artery was encased, a nonemergent carotid artery balloon test occlusion was performed for 30 minutes. If the patient tolerated this, he or she underwent permanent carotid artery occlusion. Results: Twenty‐three patients were prospectively evaluated for resection. Three underwent emergent carotid artery ligation. Twenty others underwent nonemergent carotid artery test occlusion. Of these, 5 patients failed preoperative carotid artery balloon occlusion and 15 patients successfully underwent permanent carotid balloon occlusion. Although eight of these patients died of recurrent disease in less than 1 year, seven patients survived more than 1 year with two patients surviving more than 2 years. Conclusions: Preoperative carotid balloon occlusion predicted patients who could tolerate permanent occlusion. All patients eventually developed recurrent disease, but in 14 of the 15 patients, no hemorrhages occurred.

Carotid stenting and "extarterectomy" in the management of head and neck cancer involving the internal carotid artery: technical case report.

OBJECTIVE AND IMPORTANCEHead and neck cancer that invades the internal carotid artery (ICA) represents a significant management challenge. We describe a novel technique that allows for aggressive tumor removal without disrupting blood flow through the affected ICA. CLINICAL PRESENTATIONA 62-year-old man was referred to our institution for management of a neck malignancy involving the ICA. Cerebral angiography suggested that there was good collateral flow from the opposite hemisphere, but the patient reported visual loss in the ipsilateral eye during balloon test occlusion of the ICA. INTERVENTIONA self-expanding stent was deployed in the ICA; it spanned the entire length of the artery involved by tumor. One month later, the patient underwent tumor resection. During surgery, a long ICA arteriotomy was performed directly down to the mesh of the stent. A neoendothelium had formed within the stent, which prevented arterial bleeding. The carotid wall was dissected from the stent without difficulty and removed en bloc with the surrounding tumor. The exposed stent was wrapped circumferentially with a synthetic patch material. The patient tolerated the procedure well, and postoperative angiography demonstrated normal filling of the ICA. CONCLUSIONWe describe a novel approach to a patient with head and neck cancer involving the cervical ICA. Preliminary stenting, which allows time for endothelialization before surgery, may permit aggressive tumor resection without interrupting flow through the ICA. This technique obviates the need for complicated carotid reconstruction procedures and avoids the risk of delayed ischemia from carotid sacrifice.

Pseudomyasthenia resulting from a posterior carotid artery wall aneurysm: a novel presentation: case report.

OBJECTIVE AND IMPORTANCE Painful oculomotor palsy can result from enlargement or rupture of intracranial aneurysms. The IIIrd cranial nerve dysfunction in this setting, whether partial or complete, is usually fixed or progressive and is sometimes reversible with surgery. We report an unusual oculomotor manifestation of a posterior carotid artery wall aneurysm, which mimicked ocular myasthenia gravis. CLINICAL PRESENTATION A 47-year-old woman developed painless, intermittent, partial IIIrd cranial nerve palsy. She presented with isolated episodic left-sided ptosis, which initially suggested a metabolic or neuromuscular disorder. However, digital subtraction angiography revealed a left posterior carotid artery wall aneurysm, just proximal to the origin of the posterior communicating artery. INTERVENTION The aneurysm was successfully clipped via a pterional craniotomy. During surgery, the aneurysm was observed to be compressing the oculomotor nerve. The patient’s symptoms resolved after the operation. CONCLUSION The variability of incomplete IIIrd cranial nerve deficits can present a diagnostic challenge, and the approach for patients with isolated IIIrd cranial nerve palsies remains controversial. Although intracranial aneurysms compressing the oculomotor nerve classically produce fixed or progressive IIIrd cranial nerve palsies with pupillary involvement, anatomic variations may result in atypical presentations. With the exception of patients who present with pupil-sparing but otherwise complete IIIrd cranial nerve palsy, clinicians should always consider an intracranial aneurysm when confronted with even subtle dysfunction of the oculomotor nerve.

RADIOLOGIC DIAGNOSIS AND STAGING OF HEAD AND NECK SQUAMOUS CELL CARCINOMA

The predominant extracranial head and neck cancer in adults is squamous cell carcinoma. The purpose of this article is to discuss the radiographic evaluation of these patients with CT scans or MR imaging before therapeutic intervention. Specific focus is given to the efficacy of CT scans and MR imaging, as an adjunct to clinical staging for evaluation of the primary tumor, and metastatic adenopathy. MR imaging, because of its improved soft tissue contrast and multiplanar capability, is probably superior to CT scans for evaluation of the primary tumor in patients with squamous cell carcinoma. CT scans, however, remain the gold standard for identifying metastatic adenopathy and in most institutions remain the study of choice for evaluating this patient population.

Microsurgical treatment of unruptured middle cerebral artery aneurysms: a large, contemporary experience

OBJECTIVEAdvances in endovascular therapy for the treatment of middle cerebral artery (MCA) aneurysms have led to scrutiny of its benefits compared with microsurgical repair. To provide information regarding complication rates and outcomes, the authors reviewed the results of a large series of unruptured MCA aneurysms treated with open microsurgery.METHODSThe authors included all patients who underwent surgical repair of an unruptured MCA aneurysm between 1997 and 2015. All surgical procedures, including clipping, wrapping, bypass, and parent artery occlusion, were performed by a single neurosurgeon. Aneurysm occlusion was assessed using intraoperative digital subtraction angiography (DSA) or DSA and indocyanine green videoangiography in all cases. Postoperatively, all patients were monitored in a neurointensive care unit overnight. Clinical follow-up was scheduled for 2-4 weeks after surgery, and angiographic follow-up was performed in those patients with subtotally occluded aneurysms at 1, 2, and 5 years postoperation.RESULTSThe authors treated 750 unruptured MCA aneurysms in 716 patients: 649 (86.5%) aneurysms were small, 75 (10.0%) were large, and 26 (3.5%) were giant. Most aneurysms (n = 677, 90%) were treated by primary clip reconstruction. The surgical morbidity rate was 2.8%, and the mortality rate was 0%. Complete angiographic aneurysm occlusion was achieved in 92.0% of aneurysms. At final follow-up, 713 patients had a modified Rankin Scale (mRS) score of 0, 2 patients had an mRS score of 2 or 3, and 1 had an mRS score of 4.CONCLUSIONSIn high-volume centers, microsurgical management of MCA aneurysms can be performed with very low morbidity rates. Currently, microsurgical repair appears to be a highly effective method of treating MCA aneurysms.