Symptomatic vestibular schwannomas can be treated with resection (translabyrinthine, retrosigmoid [suboccipital], or middle cranial fossa approaches) or stereotactic radiosurgery. When appropriate, auditory brainstem stimulators can also be implanted in patients with current or impending hearing loss due to bilateral vestibular schwannomas. Imaging plays a prominent role in determining management following these procedures. In this article, the expected postoperative imaging appearances are depicted. The radiological features of complications are also reviewed, including recurrent tumor, fat graft necrosis, CSF leakage, infection, hydrocephalus, cerebral infarction, venous sinus thrombosis, hemorrhage, and temporal lobe and cerebellar contusions.
Postoperative imaging of vestibular schwannomas
Daniel T. Ginat and Robert L. Martuza
Three-dimensional computerized tomography angiography in the diagnosis of cerebrovascular disease
Robert E. Harbaugh, Daniel S. Schlusselberg, Robert Jeffery, Shawn Hayden, Laurence D. Cromwell, and Daniel Pluta
✓ Computer-generated three-dimensional reconstruction of the intracranial vascular system obtained by contrast-enhanced computerized tomography (CT) has been used in the diagnosis of 20 patients with known or suspected intracranial cerebrovascular disease. This technique allows visualization of the intracranial vasculature without exposing patients to the risks associated with intra-arterial angiography. The color prints and videotape images generated have been used to diagnose the presence of intracranial aneurysms, arteriovenous malformations, and venous angiomas. They have also been used to rule out structural abnormalities in patients with suspected intracranial vascular pathology and to screen patients with a strong family history of intracranial aneurysm. In 11 patients who underwent both three-dimensional CT angiography and intra-arterial angiography, the diagnostic correlation was 100%. No complications from the procedures or from incorrect diagnosis have been encountered. Although this technique requires further development and clinical evaluation, the authors' early experience with three-dimensional CT angiography suggests that this may become a valuable tool in the diagnosis of patients with cerebrovascular disease.
Acute renal failure following cerebral angiography and infusion computerized tomography
Joe S. Robinson, Daniel D. Arzola, and Robert A. Moody
✓ The authors report a case in which acute renal failure developed following angiography and computerized tomography with infusion of contrast material performed within the same day.
Prophylactic antiepileptic drug therapy in patients undergoing supratentorial meningioma resection: a systematic analysis of efficacy
Ricardo J. Komotar, Daniel M. S. Raper, Robert M. Starke, J. Bryan Iorgulescu, and Philip H. Gutin
Meningiomas are one of the more common intracranial neoplasms. The risk of seizures and secondary aspiration, brain edema, and brain injury often leads practitioners to administer prophylactic antiepileptic drugs (AEDs) perioperatively. The efficacy of this practice remains controversial, however, with prior investigations reaching conflicting results and recent studies focusing on AED side effects. The authors performed a systematic analysis of outcomes following supratentorial meningioma resection with and without prophylactic AED administration in the hope of clarifying the role of AEDs in the perioperative care of patients with these lesions.
A MEDLINE search of the literature (1979–2010) was performed. Comparisons were made for patient and tumor characteristics as well as success of repair, morbidity, and seizure outcome. Statistical analyses of categorical variables were undertaken using chi-square and Fisher exact tests.
Nineteen studies, involving 698 patients, were included. There were no significant differences in the extent of resection, perioperative mortality, or recurrence between the AED and no-AED cohorts. Likewise, there were no significant differences in the incidence of early or late seizures between the cohorts.
The results of this systematic analysis supports the conclusion that the prophylactic administration of anticonvulsants during resection of supratentorial meningiomas provides no benefit in the prevention of either early or late postoperative seizures. Despite their traditional role in this patient population, the routine use of AEDs should be carefully reconsidered.
Anterior cervical discectomy and fusion with structural allograft and plates for the treatment of unstable posterior cervical spine injuries
Richard S. Woodworth, William J. Molinari III, Daniel Brandenstein, William Gruhn, and Robert W. Molinari
The purpose of this study was to evaluate complications and radiographic and functional outcomes of isolated anterior stabilization surgery in which structural allograft and plates were used for posterior unstable subaxial cervical spine lateral mass, facet, and ligamentous injuries.
Between August 2003 and January 2008, 19 consecutive patients with unstable lateral mass, facet, and/or posterior ligamentous injuries of the subaxial cervical spine were treated by a single surgeon via an anterior approach. This was performed using structural allograft and plate fixation. Patients with any associated anterior vertebral fractures were excluded from the study. Autogenous bone grafts or bone graft substitutes were not used in any patient. The average age of the patients was 43 years (range 17–87 years) and the mean follow-up period was 20.4 months (range 6–48 months). Seventeen of the 19 patients participated in the study; the other 2 were lost to follow-up. Operative times, estimated blood loss, length of hospital stay (LOS), and perioperative complications were recorded for each patient. Radiographic outcomes included fusion scores and sagittal alignment measurements. Outcome scores with respect to neck pain, satisfaction with surgery, and function were recorded for each patient according to analog pain and satisfaction scales and the Neck Disability Index (NDI). Additionally, NDI and pain scores at final follow-up were compared with a group of healthy, age-matched controls.
The average surgical time was 60 minutes (range 28–108 minutes), and the estimated blood loss averaged 48.9 ml per surgical procedure (range 20–150 ml). The LOS for the 13 patients who had no other associated injuries averaged 2.2 days (range 2–3 days). Fifteen of 17 patients achieved solid radiographic fusion, and no patient demonstrated instability. Only 1 patient had significant loss of the initial sagittal alignment correction at final follow-up. The average NDI score for the 17 patients was 6.5 (range 0–11), indicating mild disability and comparing favorably to a group of healthy age-matched controls. There was no statistical difference in pain scores for the trauma patients and control group at ultimate follow-up (1.5 vs 0.3, respectively). Satisfaction scores for the 17 trauma patients were high, averaging 94% (range 80–100%). Ten of the 11 patients with preoperative radiculopathy demonstrated complete resolution of this condition. Complications occurred in 1 patient with transient hoarseness and 1 with transient swallowing difficulty. There were no wound complications. Screw breakage occurred in 1 patient, and an additional patient required revision surgery for pseudarthrosis.
Anterior cervical discectomy and fusion performed using interbody structural allograft and plate fixation is highly effective in the treatment of unstable posterior cervical lateral mass, facet, and ligamentous injuries. This treatment option results in low intraoperative blood loss, short operating times, and a brief LOS. Radiographic outcomes with respect to segmental stability are excellent, and fusion rates with the use of structural allograft alone are high. Outcomes with respect to pain, function, and patient satisfaction are high, and complications are acceptably low.
Cerebral cavernous malformations: from genes to proteins to disease
Daniel D. Cavalcanti, M. Yashar S. Kalani, Nikolay L. Martirosyan, Justin Eales, Robert F. Spetzler, and Mark C. Preul
Over the past half century molecular biology has led to great advances in our understanding of angio- and vasculogenesis and in the treatment of malformations resulting from these processes gone awry. Given their sporadic and familial distribution, their developmental and pathological link to capillary telangiectasias, and their observed chromosomal abnormalities, cerebral cavernous malformations (CCMs) are regarded as akin to cancerous growths. Although the exact pathological mechanisms involved in the formation of CCMs are still not well understood, the identification of 3 genetic loci has begun to shed light on key developmental pathways involved in CCM pathogenesis. Cavernous malformations can occur sporadically or in an autosomal dominant fashion. Familial forms of CCMs have been attributed to mutations at 3 different loci implicated in regulating important processes such as proliferation and differentiation of angiogenic precursors and members of the apoptotic machinery. These processes are important for the generation, maintenance, and pruning of every vessel in the body. In this review the authors highlight the latest discoveries pertaining to the molecular genetics of CCMs, highlighting potential new therapeutic targets for the treatment of these lesions.
Crescent sign on magnetic resonance angiography revealing incomplete stent apposition: correlation with diffusion-weighted changes in stent-mediated coil embolization of aneurysms
Robert S. Heller, William R. Miele, Daniel D. Do-Dai, and Adel M. Malek
Few data are available on how closely stents appose the luminal vessel wall in stent-mediated coil embolization of intracranial aneurysms and on the effect of incomplete stent apposition on procedural thromboembolic complications.
Postprocedural 3-T MR diffusion-weighted imaging and time-of-flight angiography were obtained in 58 patients undergoing stent-mediated coil embolization of aneurysms using the Enterprise closed-cell and Neuroform open-cell self-expanding intracranial microstents.
A distinctive semilunar signal pattern, identified using 3-T MR angiography, represented flow outside the confines of the stent struts in patients in whom Enterprise but not Neuroform devices were used. This pattern, designated as the crescent sign, was confirmed to correspond to incomplete stent apposition by use of high-resolution angiographic flat-panel CT scanning revealing flow ingress into and egress out of the isolated luminal wedge. The presence of the crescent sign was seen in 18 of 33 Enterprise-treated but in 0 of 25 Neuroform-treated cases, and was more likely in stents delivered in the tortuous internal carotid artery (p = 0.034). The crescent sign was strongly predictive of ipsilateral postprocedural lesions seen on diffusion-weighted imaging in the entire population (OR 18, 95% CI 4.33–74.8; p < 0.0001). In the Enterprise stent subset, ipsilateral lesions were detected on diffusion-weighted imaging in 15 (45%) of 33 cases; the crescent sign was seen in 12 (80%) of 15 patients with ipsilateral lesions on diffusion-weighted imaging, but in only 6 of 18 patients without lesions (OR 8, 95% CI 1.61–39.6; p = 0.006).
Incomplete stent apposition is detectable on 3-T MR angiography as a crescent sign, and was found to be highly prevalent in Enterprise closed-cell design stents used to assist coil embolization of aneurysms. Incomplete stent apposition was also associated with periprocedural ipsilateral hyperintense lesions on diffusion-weighted imaging. These results identify an association between incomplete stent apposition and thromboembolic complications in stent-mediated coil embolization of intracranial aneurysms.
Sublaminar fixation for traumatic lumbar fracture subluxation with lateral listhesis in a 2-year-old patient
Daniel S. Yanni, Aurora S. Cruz, Alexander Y. Halim, Amandip S. Gill, Michael G. Muhonen, Robert F. Heary, and Ira M. Goldstein
Pediatric spinal trauma can present a surgeon with difficult management decisions given the rarity of these cases, pediatric anatomy, and a growing spine. The need to stabilize a traumatically unstable pediatric spine can be an operative challenge given the lack of instrumentation available. The authors present a surgical technique and an illustrative case that may offer a novel, less disruptive method of stabilization. A 2-year-old girl presented after an assault with an L1–2 fracture subluxation with lateral listhesis and fractured jumped facets exhibited on CT scans. CT also showed intact growth plates at the vertebral body, pedicles, and posterior elements. MRI showed severe ligamentous injury, conus medullaris compression, and an epidural hematoma. Neurologically, the patient moved both lower extremities asymmetrically. Given the severity of the deformity and neurological examination and disruption of the stabilizing structures, the authors made the decision to surgically decompress the L-1 and L-2 segments with bilateral laminotomies, evacuate the epidural hematoma, and reduce the deformity with sublaminar stabilization using braided polyester cables bilaterally, thus preserving the growth plates. They also performed a posterolateral onlay fusion at L-1 and L-2 using autograft and allograft placed due to the facet disruption. At the 42-month follow-up, imaging showed fusion of L-1 and L-2 with good alignment, and the hardware was subsequently explanted. The patient was neurologically symmetric in strength, ambulating, and had preserved alignment. Her bones and spinal canal continued to grow in relation to the other levels.
Blood supply and vascular reactivity of the spinal cord under normal and pathological conditions
Nikolay L. Martirosyan, Jeanne S. Feuerstein, Nicholas Theodore, Daniel D. Cavalcanti, Robert F. Spetzler, and Mark C. Preul
The authors present a review of spinal cord blood supply, discussing the anatomy of the vascular system and physiological aspects of blood flow regulation in normal and injured spinal cords. Unique anatomical functional properties of vessels and blood supply determine the susceptibility of the spinal cord to damage, especially ischemia. Spinal cord injury (SCI), for example, complicating thoracoabdominal aortic aneurysm repair is associated with ischemic trauma. The rate of this devastating complication has been decreased significantly by instituting physiological methods of protection. Traumatic SCI causes complex changes in spinal cord blood flow, which are closely related to the severity of injury. Manipulating physiological parameters such as mean arterial blood pressure and intrathecal pressure may be beneficial for patients with an SCI. Studying the physiopathological processes of the spinal cord under vascular compromise remains challenging because of its central role in almost all of the body's hemodynamic and neurofunctional processes.
Intraarterial administration of norcantharidin attenuates ischemic stroke damage in rodents when given at the time of reperfusion: novel uses of endovascular capabilities
Imad S. Khan, Mitchell Odom, Moneeb Ehtesham, Daniel Colvin, C. Chad Quarles, BethAnn McLaughlin, and Robert J. Singer
Matrix metalloprotease-9 (MMP-9) plays a critical role in infarct progression, blood-brain barrier (BBB) disruption, and vasogenic edema. While systemic administration of MMP-9 inhibitors has shown neuroprotective promise in ischemic stroke, there has been little effort to incorporate these drugs into endovascular modalities. By modifying the rodent middle cerebral artery occlusion (MCAO) model to allow local intraarterial delivery of drugs, one has the ability to mimic endovascular delivery of therapeutics. Using this model, the authors sought to maximize the protective potential of MMP-9 inhibition by intraarterial administration of an MMP-9 inhibitor, norcantharidin (NCTD).
Spontaneously hypertensive rats were subjected to 90-minute MCAO followed immediately by local intraarterial administration of NCTD. The rats’ neurobehavioral performances were scored according to the ladder rung walking test results and the Garcia neurological test for as long as 7 days after stroke. MRI was also conducted 24 hours after the stroke to assess infarct volume and BBB disruption. At the end of the experimental protocol, rat brains were used for active MMP-9 immunohistochemical analysis to assess the degree of MMP-9 inhibition.
NCTD-treated rats showed significantly better neurobehavioral scores for all days tested. MR images also depicted significantly decreased infarct volumes and BBB disruption 24 hours after stroke. Inhibition of MMP-9 expression in the ischemic region was depicted on immunohistochemical analysis, wherein treated rats showed decreased active MMP-9 staining compared with controls.
Intraarterial NCTD significantly improved outcome when administered at the time of reperfusion in a spontaneously hypertensive rat stroke model. This study suggests that supplementing endovascular revascularization with local neuroprotective drug therapy may be a viable therapeutic strategy.