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Biomedical subjects

J C Hoffman

Publications and source records attributed to J C Hoffman.

At least 91 records · Page 5Linked to original sources
PubMed1968

Pineal gland: influence on gonads of male rats treated with androgen 3 days after birth.

Either blinding or the injection of 1 milligram of testosterone propionate into male Sprague-Dawley rats, 3 days old, results in testes and accessory organs (seminal vesicles and coagulating glands) that are smaller than normal when the rats are 72 days old. The response to blinding is prevented by removal of the pineal gland, whereas the response to treatment with testosterone is unaffected by pinealectomy. Combination of the two treatments in 3-day- old rats causes testes to be less than one-third their normal size at 72 days of age; pinealectomy in these rats permits the reproductive organs to grow to the same size as those in the androgen-treated animals.

Animals↗
PubMedDate not supplied

Computed tomography of benign masseteric hypertrophy.

Benign masseteric hypertrophy (BMH), although an uncommon condition, is important in the differential diagnosis of parotid region masses. We believe CT is the ideal imaging modality for investigating patients with parotid region masses and that it has proved to be most useful in the diagnosis of masseteric hypertrophy. We present three cases of BMH and describe and discuss the CT findings and differential diagnosis of parotid region masses.

Adult↗
PubMedDate not supplied

Lockjaw secondary to skull base osteochondroma: CT findings.

Osteochondromas arising from the long bones, pelvis, or scapulae are common. However, osteochondromas originating from the base of the skull are extremely unusual. Although these tumors are histologically benign, intracranial extension and their close proximity to the cranial nerves may require complex surgery. We present a case in which CT clearly delineated an osteochondroma arising from the base of the skull. The tumor had created a fusion with the ipsilateral coronoid process of the mandible, thus causing lockjaw.

Adult↗
PubMedDate not supplied

Meningioma of the chiasm and optic nerves: CT and MR findings.

A case of meningioma involving the optic nerves, optic chiasm, and optic tracts at presentation is reviewed. Computed tomography showed the chiasm to be engulfed by tumor, and this finding was helpful in differentiating this lesion from an optic chiasm glioma. Magnetic resonance further characterized the lesion by demonstrating the presence of a cystic component along the lateral aspect of the mass.

Cranial Nerve Neoplasms↗
PubMedDate not supplied

Radiation-induced optic neuropathy: characteristic appearances on gadolinium-enhanced MR.

PURPOSE: To assess the value of contrast-enhanced MR in the evaluation of radiation-induced optic neuropathy. MATERIALS AND METHODS: Three patients with rapid visual loss 1 1/2 to 3 years after radiation therapy to the optic nerves were studied with gadopentetate dimeglumine-enhanced MR images. All patients received over 5000 cGy, experienced rapid, permanent visual loss over several days to weeks, and underwent MR within weeks of presentation. RESULTS: Enhanced MR images on each patient revealed focal discrete enhancement of the intracranial optic nerve. One patient underwent biopsy of the enhancing segment; this revealed pathologic changes of radiation optic neuropathy. Optic nerve enhancement in a patient with visual loss and a prior history of radiation therapy to the orbits or optic nerves suggests radiation optic neuropathy. CONCLUSION: Contrast-enhanced MR of the orbits, optic nerves, and chiasm is the imaging test of choice in patients with vision loss after radiation therapy for sellar or skull base disease; MR findings may obviate the need for biopsy.

Aged↗
PubMedDate not supplied

Endoscopic paranasal sinus surgery: radiographic evaluation of severe complications.

PURPOSE: To report our experience with the radiographic evaluation of severe complications resulting from the functional endoscopic sinus surgery (FESS) procedure. PATIENTS: Ten major complications were reviewed retrospectively. FINDINGS: Ten major complications occurred. Eight of 10 had injury to the floor of the anterior cranial fossa, fovea ethmoidalis (roof of the ethmoid sinus), or roof of the sphenoid sinus. Six patients presented with meningitis or rhinorrhea, two presented with headache and massive pneumocephalus; one patient who presented with meningitis had a large nasal frontal encephalocele. Noncontrast brain CT that included the paranasal sinuses adequately evaluated the source of pneumocephalus. Thin-section coronal CT accurately predicted the site of leak in five patients. Both coronal sinus CT and MR imaging were useful to confirm the nasal encephalocele. Two of 10 had vascular injury secondary to FESS. One patient presented with subarachnoid hemorrhage seen on noncontrast CT and cerebral angiography demonstrated an aneurysm of the anterior cerebral artery. The second patient suffered severe intraoperative hemorrhage. Emergency angiography revealed a pseudoaneurysm of the cavernous carotid artery, and balloon occlusion of the artery was performed. No deaths occurred in this series. CONCLUSION: Radiologists should be familiar with the rare, but potential complications of this commonly performed procedure in order to help direct the work-up in an efficacious manner.

Adult↗
PubMedDate not supplied

Improved detection of cerebral hypoperfusion with internal carotid balloon test occlusion and 99mTc-HMPAO cerebral perfusion SPECT imaging.

A new method that employs a cerebral perfusion imaging agent, 99mTc-HMPAO, is described for identifying those patients who clinically pass an internal carotid artery balloon test occlusion but who then may develop a cerebral infarction after permanent occlusion. Test balloon occlusion of the internal carotid artery was performed in 17 patients, and 99mTc-HMPAO was injected intravenously while the balloon was inflated. The balloon was deflated and removed approximately 15-20 min later, and single-photon emission CT (SPECT) imaging of the brain was performed. In patients with an area of focal hypoperfusion, the 99mTc-HMPAO study was repeated the next day to determine if the hypoperfusion was due to the temporary balloon occlusion or to a preexisting abnormality. All 17 patients had normal neurologic examinations at the time of the balloon test occlusion. Fifteen had symmetric perfusion on the 99mTc-HMPAO SPECT scans. Five of these had permanent internal carotid artery occlusion, and four did not develop a neurologic deficit. One patient developed an ipsilateral watershed infarction after internal carotid artery occlusion during significant intraoperative hypotension. Two patients had ipsilateral regions of hypoperfusion with the test occlusion. Both these patients had repeat nonocclusion 99mTc-HMPAO SPECT studies that were normal. One patient is being followed. The second patient had ipsilateral EEG changes associated with temporary intraoperative occlusion of the internal carotid artery during aneurysm surgery. Although the numbers are relatively small, this study suggests that this protocol may be able to predict a good outcome after permanent carotid artery occlusion as well as to identify patients who are at greater risk for developing cerebral infarction after permanent occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Artery Diseases↗
PubMedDate not supplied

Flow-sensitive MR imaging of ventriculoperitoneal shunts: in vitro findings, clinical applications, and pitfalls.

To determine ventriculoperitoneal shunt patency during routine MR imaging of the head, 23 patients were studied with T1-weighted fast-field-echo scans. Without knowledge of the results of previous MR/CT studies or of the patients' clinical history, we reviewed the fast-field-echo studies and divided them according to those judged to have shunt flow (18) and those judged not to have flow (five). Fast-field-echo sequences showed high signal intensity, consistent with CSF flow and shunt patency in 17 medium-pressure systems and one high-pressure system. No signal was seen in five patients with high-pressure valve shunts. Combined clinical evaluation and MR/CT studies showed that three patients had probable shunt malfunction. One patient had true shunt malfunction; and although malfunction was thought to be present in two symptomatic patients, surgical revision showed the shunts to be patent. The possibility of temporary shunt obstruction is postulated to explain the clinical and MR findings in those two cases. The remaining two cases (9% of the patients) had no clinical evidence of shunt malfunction, and the MR findings probably reflected periodic CSF flow. One patient had an intracranial segment that was not connected and showed no flow on MR. No false-positive results (apparent flow in a nonfunctioning shunt) occurred. Using a standard medium-pressure shunt system, we constructed and imaged a phantom, which confirmed our clinical observations. T1-weighted fast-field-echo sequences may be useful in assessing patency of medium-pressure CSF shunt systems.

Cerebrospinal Fluid Shunts↗