Ethanol endovascular management of brain arteriovenous malformations: initial results.

OBJECTIVE: The goal was to determine the safety and efficacy of absolute ethyl alcohol treatment in the management of intra-axial brain arteriovenous malformations (AVMs). METHODS: Seventeen patients (eight female and nine male patients; mean age, 41 yr) underwent ethanol endovascular therapy for treatment of their brain AVMs. Superselective amytal testing preceded all procedures. Neuroleptic intravenous anesthesia was used for 16 patients, and general anesthesia was used for 1 patient. Follow-up monitoring consisted of clinical evaluations, magnetic resonance imaging, and arteriography. RESULTS: In follow-up evaluations (mean follow-up period, 13 mo) after embolization of brain AVMs, neither vascular recanalization nor the neovascular recruitment phenomenon was observed in any patient. Progressive AVM thrombosis at arteriographic follow-up evaluation was a constant feature. Seven patients were cured of their AVMs with ethanol endovascular therapy alone. Three patients were cured of their lesions with ethanol embolization plus surgical resection. One patient was cured of his lesion with ethanol embolization and radiation therapy of the residual nidus. Three patients underwent only partial therapy, with significant improvement in symptoms. Three patients are currently undergoing ethanol endovascular therapy. Complications occurred with 8 of 17 patients, most of which were transient. Two patients died because of late subarachnoid hemorrhages, one patient 4 months and one patient 14 months after partial therapy. CONCLUSION: Progressive and permanent AVM occlusion is a common finding in arteriographic follow-up evaluations. In no patients did arterial recanalization or the neovascular recruitment phenomenon occur. Our initial results indicate that ethanol has a permanence that is seldom encountered with other embolic agents. With aggressive decadron therapy, the complications related to swelling in the brain are largely reversible.

CT imaging of radiopaque shunt catheter after endolymphatic duct surgery.

Until now, shunt catheters used in endolymphatic sac (ELS) and duct surgery have not been visible at computed tomography (CT) imaging. This report summarizes findings at postoperative CT in 50 patients who underwent endolymphatic system decompressive surgery with a new opaque shunt catheter placed at or into the endolymphatic duct (ELD). The catheter was visible in all 50 cases, and the best projection for visualization was the semicoronal view. The postoperative visualization of the opaque shunt catheter allows determination of the exact placement of the catheter (a) in the bony vestibular aqueduct (within the membranous ELD); (b) at the external aperture of the bony vestibular aqueduct (within or at the membranous ELD at its junction with the ELS); or (c) outside the bony vestibular aqueduct system or aperture but presumably within the membranous ELS. These objective findings may be used as a marker to help predict outcomes from this type of nondestructive inner ear surgery, as well as to determine exactly where the surgeon placed the shunt-tube catheter tip.

Isolated abducens nerve palsy: MR imaging findings.

The abducens nerve, the sixth cranial nerve, innervates the lateral rectus muscle of the eye and is responsible for lateral horizontal ocular movement. A wide variety of abnormalities, both primary to the nerve itself and secondarily involving the nerve, can paralyze the abducens nerve. MR imaging offers the best opportunity to detect the underlying abnormality causing abducens nerve palsy. In this pictorial essay, we illustrate the MR imaging features of numerous conditions that cause isolated abducens nerve palsy.

Use of the magnetic resonance contrast agent gadodiamide in the central nervous system. Results of a multicenter trial.

To investigate the safety and efficacy of the low-osmolar, nonionic contrast agent, gadodiamide injection (Omniscan, Sanofi Winthrop Pharmaceuticals, New York, NY), for magnetic resonance imaging (MRI) of the head and spine, a multicenter study involving 439 patients was done at 15 centers as part of a Phase II/III clinical trial. Unenhanced MRI scans were obtained after which the patients were injected with 0.1 mmol/kg gadodiamide, and the MRI was repeated. The patients' vital signs were monitored, and laboratory studies were conducted. Neurologic status was examined before and after the study. The images were evaluated for contrast enhancement. No patient had any significant adverse event or serious change in clinical status. Abnormalities were found in 80% (351) of all patients studied, and it was found that, in 75% (266) of these, the postgadodiamide injection images were improved or facilitated visualization of lesions compared with preinjection images. The investigators believe that, based on the results of this study, gadodiamide injection is safe and effective for imaging the head and spine. They suggest that future studies further assess and compare the safety parameters of gadodiamide injection with those of other nonionic and ionic gadolinium ligands.

MR imaging of symptomatic peripheral vascular malformations.

We performed a retrospective study of symptomatic peripheral vascular malformations to determine if MR imaging can be used to distinguish slow-flow venous malformations from high-flow arteriovenous malformations and arteriovenous fistulas. Twenty-seven MR examinations in 25 patients with malformations outside the CNS were reviewed. Sixteen venous malformations, nine arteriovenous malformations, and two arteriovenous fistulas were included. In all cases, the MR findings were correlated with the results of angiography. The distinction between slow-flow venous malformations and high-flow arteriovenous malformations and arteriovenous fistulas was made primarily on T2-weighted MR images, which showed high signal intensity in venous malformations and flow voids in high-flow lesions. In addition to the previously described MR features of venous malformations (serpentine pattern with septations, associated muscle atrophy, and typical T1 and T2 signal intensities), several new MR features were apparent. Venous malformations had a propensity for multifocal involvement (37%), orientation along the long axis of extremities or affected muscles (78%), and adherence to neurovascular distributions (64%). Prominent subcutaneous fat was commonly seen adjacent to the malformation. MR images of arteriovenous malformations and arteriovenous fistulas also commonly showed muscle atrophy and subcutaneous fatty prominence. Our results show that slow-flow venous malformations can be distinguished from high-flow arteriovenous malformations and fistulas on the basis of spin-echo MR signal characteristics. The associated imaging characteristics help in the differential diagnosis in problematic cases.

Multicenter study of gadodiamide injection as a contrast agent in MR imaging of the brain and spine.

To evaluate the safety and efficacy of gadodiamide injection, a nonionic gadolinium chelate complex, in magnetic resonance (MR) imaging of the head and spine, a phase II-III trial was conducted in 439 patients with known or suspected lesions in the central nervous system. All patients received gadodiamide injection in a dosage of 0.1 mmol/kg and were monitored; MR images were evaluated for contrast material enhancement. No serious adverse events or clinically important trends in vital signs, laboratory values, or neurologic status were observed. Gadodiamide injection enhanced or facilitated the visualization of lesions in 266 or 353 patients (75.4%) in whom lesions were shown on unenhanced images, enhanced images, or both; in these 266 patients, the diagnosis was changed in 76 patients (28.6%) and facilitated in 190 patients (71.4%). It is concluded that gadodiamide injection is safe and effective for MR imaging of the head and spine in patients with suspected abnormalities of the central nervous system.

Large cystic optic glioma.

A 5 1/2-year-old boy developed a huge cyst in his chiasmal glioma 4 years after radiation therapy. The cyst produced obtundation but was successfully treated.

Ethanol embolization of vascular malformations.

Absolute ethanol was used to treat 20 patients with symptomatic vascular malformations (SVMs) (ie, venous malformations, arteriovenous malformations, and congenital and posttraumatic arteriovenous fistulas) in whom previous surgery or standard embolotherapy had failed or who were not candidates for surgery. All large complex lesions required multiple embolizations as staged procedures. Immediate thrombosis was achieved in all patients; complications (13% of cases) were generally minor and were treated conservatively. Follow-up studies, performed in 19 of 20 patients, showed persistent occlusion of the SVM in all cases. Ethanol embolization of SVMs, performed according to strict techniques, has proved efficacious in SVM management and is emerging as a definitive form of therapy.

Neuroradiology of vestibular pathways.

Comprehensive efficacious neuroimaging of the vestibular pathways requires cooperation and coordinated efforts between the otologist and the neuroradiologist to avoid duplication of expensive and sometimes invasive study. For peripheral lesions, for example, those of the labyrinthine organ, thin-section CT is optimum as a first examination. For retrolabyrinthine lesions along nerve tracts or in the central pathway, MRI is preferred. When bone erosion occurs, CT can also be helpful in evaluation of the base of the skull to detect and define the extent of these lesions, for example, cholesterol granuloma and glomus tumor.

Magnetic resonance imaging of nonmetallic orbital foreign bodies.

We studied a cadaver head model in which we inserted three orbital foreign bodies. We chose these foreign bodies because of their similarity to substances found in orbital trauma. Teflon and Lucite were used to represent synthetic materials, and dry pine was chosen as a type of organic material. Lucite is similar in radiographic density to plastics used in interior trim for automobiles and spectacle frames. While both orbital ultrasound and plain skull films failed to detect the foreign bodies consistently, both computed tomography and magnetic resonance imaging detected and localized the foreign bodies relatively well. Computed tomography was better in delineating shape and characterizing composition.

Toluene abuse causes diffuse central nervous system white matter changes.

We describe the findings of magnetic resonance imaging (MRI) of the brain in 6 chronic toluene vapor abusers and the neuropathological findings in 1 abuser not studied by MRI. MRI in 6 chronic toluene abusers revealed the following abnormalities: (1) diffuse cerebral, cerebellar, and brainstem atrophy; (2) loss of differentiation between the gray and white matter throughout the central nervous system; and (3) increased periventricular white matter signal intensity on T2-weighted images. Another chronic toluene abuser (MRI not performed) died as a result of acute toluene overdose. The brain displayed diffuse, ill-defined myelin pallor, maximal in cerebellar, periventricular, and deep cerebral white matter. Neurons were preserved throughout, axonal swelling or beading was not seen, gliosis was minimal, and occasional, scant perivascular macrophage collections were seen. Taken in concert, these findings suggest that the pathological and MRI abnormalities are due to either increased water content of the white matter or subtle toluene-induced metabolic changes in myelin.

Glottic and tracheal stenosis in spinal cord injured patients.

Between 1965 and 1985, 47 cases of glottic and/or tracheal stenosis were diagnosed at the Rocky Mountain Regional Spinal Cord Injury System. A retrospective review of medical records identified associated injuries, pulmonary and other medical complications in this patient population. Radiographic and endoscopic reviews utilised a grading system to classify the severity of stenosis. The clinical symptoms of stenosis were multiple, including dysphonia, aspiration, dysphagia, odynophagia, dyspnea and excessive secretions. The wide spectrum of treatment modalities included endoscopy with excision and/or dilation, general medical management, steroids, radiation therapy, intubation, stent insertion and surgical repair of the stenotic area. Outcome status was reviewed and suggestions provided for the early diagnosis and treatment of this potentially life-threatening condition.

Radiographic imaging of the cochlear implant candidate: preliminary results.

Preoperative radiographic imaging of the temporal bone is well accepted in otology for both the diagnosis of disease and the delineation of anatomic structure for surgical planning. Until recently radiographic techniques have unfortunately failed to demonstrate fibrous or bony obstruction of the basal turn of the cochlea, which may cause difficulties during cochlear implantation. Intraoperative findings have been correlated with preoperative imaging in a consecutive group of six cochlear implant recipients and a series of consistent radiographic signs that may indicate the presence of obstruction of the scala tympani have been identified. A classification system has been developed. Based on thin-section high-resolution computerized tomography (HRCT), the system has been used preoperatively on six cochlear implant recipients. In addition, a systematic evaluation of the temporal bone has been developed for precochlear implant evaluation. This includes the thickness of the parietal bone for seating of the receiving device, the degree of pneumatization of the mastoid, the measurement of the size of the facial recess, the description of the size and orientation of the round window niche, and the patency of the basal turn of the cochlea.

Duplex sonography in the evaluation of carotid artery disease.

High-resolution duplex sonography was compared with biplane magnified carotid angiography in a prospective evaluation of 161 carotid arteries in 86 patients. The duplex scanner combined real-time B-mode imaging (7.5 MHz) with simultaneous range-gated pulsed Doppler frequency analysis (3 MHz). The degree of stenosis was usually determined by the true and residual lumen of the carotid artery at the atherosclerotic plaque on the transverse image. The Doppler frequency signals were automatically converted to velocity data by a minicomputer. The accuracy of the duplex system in detecting and assessing stenoses graded in 20% increments is demonstrated according to specificity, sensitivity, and positive and negative predictive value by both cumulative and subgroup analyses. A 93.7% sensitivity was shown for minimal (0-20%) stenosis and 100% sensitivity for severe (greater than 60%) stenosis. An apparent limitation of duplex sonography is the differentiation of a high-grade stenosis from occlusion (sensitivity, 82.6%; positive predictive value, 90.4%).

Progressive posttraumatic cystic myelopathy: neuroradiologic evaluation.

The neuroradiologic evaluation and findings in 25 symptomatic patients with surgically proven progressive posttraumatic cystic myelopathy are reviewed. To follow patients with spinal cord injury, neuroradiologic algorithms were developed to confirm and define cystic myelopathy. The algorithm used in the early and mid 1970s relied on the myelographic demonstration of a large cord for suspicion of a cyst. Review of this material found that in progressively symptomatic patients 14 of 25 proven cysts were in large cords. A more recent algorithm used computed tomographic metrizamide myelography. In nine of 11 patients studied in this fashion, the cyst filled with contrast material 2--4 hr after injection, yet it did not communicate with the subarachnoid space at subsequent surgery. The origin of the cyst fluid and mechanism of cyst demonstration with metrizamide may be associated with transneural migration of fluid. This condition must be clinically suspected and radiologically confirmed for surgical treatment (cyst-shunt procedure) if neurologic preservation of function is to be maintained.