Preoperative embolization of anastomoses of the jugular bulb: an adjuvant in jugular foramen surgery.

We describe the technique of preoperative embolization of the inferior petrosal sinus/anterior condylar vein complex and the posterior condylar vein in three patients undergoing skull base surgery that required opening of the jugular bulb. Contrary to the usual situation, essentially no blood was lost during the operation, resulting in decreased surgical time and reduced risk to the lower cranial nerves.

Cost-effective evaluation of asymmetric sensorineural hearing loss with focused magnetic resonance imaging.

The poor sensitivity of audiometric brain stem response for small vestibular schwannomas (acoustic neuromas) creates a dilemma for the physician evaluating a patient with signs and symptoms of retrocochlear disease. Magnetic resonance imaging is recognized as the gold standard for the evaluation of these problems, but if a complete examination of the internal auditory canals and head is done on every patient, the cost is high. Although less expensive, screening with audiometric brain stem response risks missing up to 33% of small tumors. Therefore we developed a focused magnetic resonance imaging sequence for evaluation of patients with asymmetric sensorineural hearing loss and/or nonpulsatile tinnitus. The protocol includes a T1-weighted sagittal localizer, pregadolinium and postgadolinium T1-weighted 3-mm contiguous axial slices through the internal auditory canal and the region of the cerebellopontine angle, and T2-weighted axial images through the entire brain. Total scanning time is about 12 minutes, and the estimated cost is $300 to $500. We retrospectively reviewed the imaging records of 485 screening examinations done during an 18-month period. Twenty-four patients had diagnoses definitely or probably producing the hearing loss for an overall positive rate of 5%. By eliminating the need for follow-up audiometric or electrophysiologic studies, we believe a focused magnetic resonance imaging-based diagnostic scheme is actually more cost-effective on a cost-perpatient basis.

Adenoviral-mediated thymidine kinase gene transfer into the primate brain followed by systemic ganciclovir: pathologic, radiologic, and molecular studies.

Transduction of experimental gliomas with the herpes simplex virus thymidine kinase gene (HSV-tk) using a replication-defective adenoviral vector (ADV/RSV-tk) confers sensitivity to ganciclovir (GCV) leading to tumor destruction and prolonged host survival in rodents. To determine treatment tolerance prior to clinical trials, we conducted toxicity studies in 6 adult baboons (Papio sp.). The animals received intracerebral injections of either a high dose of ADV/RSV-tk [1.5 x 10(9) plaque-forming units (pfu)] with or without GCV, or a low dose of ADV/RSV-tk (7.5 x 10(7) pfu) with GCV. The low dose corresponded to the anticipated therapeutic dose; the high dose was expected to be toxic. Magnetic resonance imaging (MRI) of the brain was obtained before treatment and at 3 and 6 weeks after treatment. Animals receiving the high-dose vector and GCV either died or became moribund and required euthanasia during the first 8 days of treatment. Necropsies revealed cavities of coagulative necrosis at the injection sites. Animals receiving only the high-dose vector were clinically normal; however, lesions were detected with MRI at the injection sites corresponding to cystic cavities at necropsy. Animals receiving the low-dose vector and GCV were clinically normal, exhibited small MRI abnormalities, and, although no gross lesions were present at necropsy, microscopic foci of necrosis were present. The vector sequence was detected by polymerase chain reaction (PCR) at the injection sites and in non-adjacent central nervous system tissue in all animals. Recombinant DNA sequence was detected outside of the nervous system in some animals, and persisted up to 6 weeks. The viral vector injections stimulated the production of neutralizing antibodies in the animals. No shedding of the vector was found in urine, feces, or serum 7 days after intracerebral injection. This study suggests that further investigations including clinical toxicity trials of this form of brain tumor therapy are warranted.

Intracranial vascular malformations.

Intracranial vascular malformations are nonneoplastic developmental anomalies that present a variety of clinical patterns, ranging from asymptomatic to fatal intracranial hemorrhage. A practicing radiologist can expect to encounter these abnormalities, which include capillary telangiectasias, venous angiomas (also called developmental venous anomalies), cavernous angiomas, and arteriovenous malformations. The imaging findings that characterize these lesions are reviewed in this article, along with their pathological and clinical features.

Metastatic adenocarcinoma to the brain: MR with pathologic correlation.

PURPOSE: To describe the appearance on T2-weighted scans of metastatic adenocarcinoma to the brain and to show that the hypointensity frequently associated with these lesions is not related to the presence of mucin, blood products, iron, or calcium. METHODS: The MR scans of 14 patients with metastatic adenocarcinoma to the brain were reviewed retrospectively. The signal intensity on T2-weighted scans of the solid enhancing portion of the tumors was compared with white matter. Histologic examination of the surgical specimens included special stains to search for calcium, mucin, and iron. RESULTS: Eight of nine surgical and all six nonsurgical lesions were either iso- or hypointense to white matter on T2-weighted scans. There was no correlation with tumor histology or the presence of mucin, blood products, iron, or calcium. CONCLUSIONS: The presence of a hypointense intraaxial mass on T2-weighted scans strongly suggests the possibility of metastatic adenocarcinoma. The MR appearance is not explained by the presence of mucin, blood products, iron, or calcium. This phenomenon most likely reflects the relaxation parameters of the tissue from which the metastasis arose.

Placement of a ferromagnetic intracerebral aneurysm clip in a magnetic field with a fatal outcome.

Magnetic resonance (MR) imaging may be contraindicated in patients with biomedical devices, among the most dangerous of which are intracranial aneurysm clips, owing to the possibility of torque and dislodgement. A case is presented in which a patient with a reportedly nonferromagnetic clip was placed in a magnetic field. The patient developed an acute intracerebral hemorrhage in the MR unit, with a fatal outcome. Imaging studies strongly suggested a torqued clip as the cause. Autopsy revealed a torn middle cerebral artery from clip movement, and the clip was identified as a ferromagnetic type. This is the first reported case, to the authors' knowledge, of a fatal outcome due to an intracranial aneurysm clip placed in a magnetic field.

MR appearance of extravasated gadolinium contrast medium.

This case illustrates that a large zone of signal void can be produced on short relaxation time MR images when gadopentate dimeglumine is injected through an infiltrated intravenous catheter. The authors consider the physics behind this paradoxical decrease in signal intensity where there are high concentrations of gadopentate dimeglumine.

MR appearance of an orbital leiomyoma.

The authors describe the MR appearance of an intraconal orbital vascular leiomyoma that probably arose from smooth muscle in the wall of a vein. Cavernous hemangiomas, schwannomas, neurofibromas, and other well-encapsulated masses can have a similar appearance.

Ankle arthrodesis with vertical Steinmann's pins in rheumatoid arthritis.

Many techniques for ankle arthrodesis have been described but some of them are not applicable in patients with severe rheumatoid arthritis (RA) who have also developed osteopenia and decreased bone density. A technique utilizing two longitudinally placed Steinmann's pins to fixate and align the joint was used in five patients with severe RA and is described here. Results showed a 100% fusion rate and patient satisfaction over an average follow-up time of six years. This ankle arthrodesis technique was found to be applicable in arthritic patients with osteopenia and decreased bone density caused by RA.

Bilateral hip and bilateral knee arthroplasties in a patient with ochronotic arthropathy.

Alkaptonuria is a rare, autosomal-recessive, inborn, metabolic disease that causes ochronotic arthropathy leading to disabling arthritis. Few reports of arthroplasty in patients with this disease have been published, and none documents four total joint replacements in the same patient. This case report describes the history and findings in a 70-year-old man who underwent bilateral hip and knee total joint arthroplasties with significant improvement in pain and exercise tolerance. The metabolic and clinical aspects of alkaptonuria are also discussed.