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Biomedical subjects

W L Hirsch

Publications and source records attributed to W L Hirsch.

32 records · Page 2Linked to original sources
PubMed1988

Normal perivascular spaces mimicking lacunar infarction: MR imaging.

Perivascular (Virchow-Robin) spaces normally surround perforating arteries that enter the medial temporal lobes, corpus striatum, and thalamus. The high soft-tissue sensitivity of magnetic resonance (MR) imaging allows for the frequent detection of such cerebrospinal fluid (CSF)-filled spaces. Especially on axial images, these CSF-filled perivascular spaces may be confused with pathologic lesions, such a lacunar infarcts. Postmortem brain specimens demonstrate the anatomy of perivascular spaces around perforating arteries. Orthogonal images in the living patient help confirm this anatomic relationship. The characteristic CSF signal patterns from these foci are further evidence of their anatomic identification and true benign nature.

Brain↗
PubMed1988

Comparison of MR imaging, CT, and angiography in the evaluation of the enlarged cavernous sinus.

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.

Adult↗
PubMedDate not supplied

Eighth nerve signs in a case of multiple sclerosis.

We evaluated a 25-year-old woman with multiple sclerosis who presented with the acute onset of a profound unilateral high-frequency, sensorineural hearing loss that resolved clinically within 10 days. Click-elicited brain stem-evoked responses were abnormal at the time of presentation and demonstrated only limited recovery over a follow-up period of 11 months. Magnetic resonance imaging disclosed a lesion in the eighth nerve root-entry zone and the cochlear nucleus. Our findings in this case support the hypothesis of eighth nerve root-entry zone involvement in sudden hearing loss in multiple sclerosis and reinforce the notion that click-elicited brain stem-evoked responses are useful primarily to evaluate the high-frequency regions of the auditory system.

Adult↗
PubMedDate not supplied

Cavernous sinus tumors: neuroradiologic and neurosurgical considerations on 150 operated cases.

We reviewed the neuroimaging studies of 150 patients with cavernous sinus tumors operated on during an 8-year period. Meningiomas (66 cases), chordomas (18 cases), trigeminal neurolemmomas (12 cases), and chondrosarcomas (11 cases) were the most common diagnosed neoplasms. Neuroradiological findings are briefly described for each different kind of tumor encountered. The surgical impact of these findings is discussed.

Carotid Artery, Internal↗
PubMedDate not supplied

Chordomas of the skull base: MR features.

PURPOSE: To characterize the MR features of skull base chordomas with regard to signal intensity, size, position, extension, and Gd-DTPA enhancement. PATIENTS AND METHODS: The MR imaging studies of 28 patients with surgically proven chordomas of the skull base were retrospectively reviewed. Twenty-two of these patients received intravenous administration of Gd-DTPA. RESULTS: On short TR/short TE images, chordomas generally had low to intermediate signal. On long TR/long TE images, chordomas generally had very high signal that was heterogeneous in 79%. After Gd-DTPA administration, all chordomas demonstrated some degree of contrast enhancement. In most cases, enhancement was demonstrated throughout most of each tumor in a heterogeneous pattern. Chordomas were associated with MR findings of displacement and encasement of vessels, and frequent extension into adjacent structures such as the cavernous sinus, sella, nasopharynx, and hypoglossal canal. CONCLUSION: The MR characterization of the position and extent of these neoplasms played an important role in determining the optimal surgical approaches for gross total tumor resection.

Adolescent↗
PubMedDate not supplied

High signal from the otic labyrinth on unenhanced magnetic resonance imaging.

High signal from the otic labyrinth was observed on precontrast MR scan of two patients who presented with sudden hearing loss and vertigo. The authors suggest the possibility that the high signal was caused by hemorrhage but that clinical significance and therapeutic implications of this finding need further study.

Adult↗
PubMedDate not supplied

Anatomy of the brainstem: correlation of in vitro MR images with histologic sections.

MR imaging was performed on three formaldehyde-fixed brainstem specimens that were sectioned in the axial plane and myelin stained. The histologic sections were used to identify and label the structures demonstrated on short TR/TE axial MR images. Fiber tracts and nuclei that cannot be resolved on in vivo scans were well delineated by in vitro MR. Improved gray-white differentiation may be due to much greater T1 shortening of gray matter relative to white matter after fixation. The excellent anatomic detail provided by these scans should facilitate comparison of clinical scans with histologic sections.

Brain Stem↗
PubMedDate not supplied

Neuroradiologic aspects of pediatric orthotopic liver transplantation.

To investigate the occurrence of neurologic symptomatology in pediatric orthotopic liver transplantation patients and to evaluate the utility of CT in uncovering the origin of their symptoms, we reviewed the medical records and head scans (when performed) of 71 patients. Neurologic problems occurred in 48%; the majority involved seizures, mental status changes, or coma. Patients who only had seizures generally had negative CT scans, except for two patients with minimal subarachnoid hemorrhages. Three-quarters of the comatose patients, however, had significant intracerebral hemorrhages defined by CT. Prominent sulci and ventricles were found in approximately one-third of the patients scanned, but did not correlate with symptomatology or steroid dose.

Cerebral Hemorrhage↗
PubMedDate not supplied

Iohexol vs. metrizamide: study of efficacy and morbidity in cervical myelography.

A double-blind study was conducted in 60 patients undergoing either cervical or more complete myelography via C1-C2 puncture. Patients received either iohexol or metrizamide at a 300 mg l/ml concentration. The contrast media were equally efficacious in the production of high-quality radiographs and CT scans. However, the incidence of adverse reactions differed markedly. Of patients receiving metrizamide, 68% had some type of adverse reaction, whereas only 26% receiving iohexol had symptoms. The incidence of headache (metrizamide, 34%; iohexol, 26%) was not statistically different, but the quality of the headache differed: half of the metrizamide headaches were moderate or severe, whereas all iohexol headaches were mild. Nausea (31%) and vomiting (28%) were common with metrizamide but unusual (3% nausea) with iohexol. Of the metrizamide patients, 21% had overt psychologic changes that did not occur in the iohexol group.

Adult↗
PubMedDate not supplied

Intrasellar and suprasellar paraganglioma: CT and MR findings.

We present the CT and MR findings of an intrasellar and suprasellar paraganglioma in a 17-year-old girl. Paragangliomas in this location are rare. The lesion had several imaging features characteristic of paragangliomas including marked enhancement after contrast and multiple vascular flow voids.

Adolescent↗
PubMedDate not supplied

Imaging of the saphenous vein graft bypass of the cavernous carotid artery.

PURPOSE: To describe the radiographic appearance of the interpositional carotid saphenous vein graft and to compare the efficacy of MR angiography with conventional angiography in determining graft patency and identifying graft irregularities. METHODS: The authors examined saphenous vein graft bypasses of the cavernous carotid artery in 14 patients using CT, MR, and conventional and MR angiography. RESULTS: The course of the graft was typically more inferior, lateral, and anterior than the course of the native vessel. Mild irregularities were found in four of the grafts, but all four "filled out" in a period of months. Time-of-flight angiography was comparable to conventional angiography in four of five patients. Phase-contrast angiography was comparable to conventional angiography in nine of nine cases. CONCLUSIONS: MR angiography is a useful screening modality in the postoperative evaluation of vascular grafts.

Adult↗