Roger A. Hyman

Far lateral lumbar disc herniations and associated structural abnormalities : an evaluation in 60 patients of the comparative value of CT, MRI, and myelo-CT in diagnosis and management

The management of 60 patients with far lateral lumbar disc herniations operated on over a 5-year period are presented. These lesions were located superiorly within the neural foramens beneath or distal to the facet joints. The type of surgery performed in 43 of 60 (72%) of these patients was significantly altered by the presence of diffuse and lateral recess stenosis. This was better appreciated on the myelogram and myelo-CT (M-CT) studies than with the noncontrast CT and MRI examinations alone. Myelo-CT findings were particularly valuable in assessing patients who had previous surgical procedures.

Metastasis of intracranial germinoma through a ventriculoperitoneal shunt.

A young man developed a tumor in the pineal region that grew along ventricular surfaces and caused obstructive hydrocephalus. Cytologic examination of cerebrospinal fluid demonstrated malignant cells consistent with germinoma. Following a ventriculoperitoneal shunt and radiotherapy, the tumor and the hydrocephalus regressed. Three years later, an intraperitoneal tumor appeared that was diagnosed by transcutaneous biopsy specimen as a germinoma. The abdominal germinoma also regressed after radiotherapy. While extracranial metastases of intracranial germinomas via shunts are probably rare, their occurrence, as exemplified by this case, argues for including protective filters in the shunts.

Case report. Diagnosis of Pick's disease by computed tomography.

Picks disease is a rare cause of dementia. It often shows a characteristic pattern of atrophy affecting primarily the anterior portions of the frontal and temporal lobes. This pattern, as shown by computed tomography, may suggest the diagnosis.

The Effect of Nuclear Magnetic Resonance Imaging on Metallic Middle Ear Prostheses

Nuclear magnetic resonance imaging, a relatively new diagnostic instrument, is a noninvasive imaging method which, among its many advantages, uses no ionizing radiation. There are a few limitations and contraindications to its use. There may be displacement of intracerebral aneurysm clips and metallic implants, and cardiac pacemakers can be disabled because of the high magnetic field created by this device. We studied the effects of a magnetic field on metallic middle ear prosthetics and concluded that nuclear magnetic resonance imaging should offer no risks to hearing or otologic function in patients with nonferromagnetic metallic middle ear prosthetics. Nuclear magnetic resonance imaging is contraindicated in patients with cochlear implants.

Computed tomographic evaluation of therapeutically induced changes in primary and secondary brain tumors.

SummaryA prospective study was initiated to evaluate computed tomography as a method for monitoring therapeutically induced changes in brain tumors. Early postoperative scans may be misleading in the evaluation of residual tumor because of trauma to the blood-brain barrier during operation. The size of the dominant mass (17/25), enhancement (11/25), edema (11/25), and ventricular distorition (14/25) were decreased in many patients after radiation therapy. Occasional tumors increased in size during radiation therapy (3/25). Enlargement of the lateral ventricles developed in 9 of 25 patients. Computed tomography offers definite advantages over nuclide brain scans, angiography and other diagnostic studies for evaluating therapeutically induced changes in brain tumors.

Computed tomography in ossification of the posterior longitudinal spinal ligament

SummaryA patient with cervical myelopathy was found to have extensive ossification within the posterior longitudinal ligament. Computed tomography of the spine was of value for precisely defining the degree of narrowing of the spinal canal. The nature of this disease entity is discussed.

The widened interspinous distance: a useful sign of anterior cervical dislocation in the supine frontal projection.

Anterior dislocation of the cervical spine may be detected reliably in the supine frontal projection by evaluating the cervical spinous processes. A widened interspinous distance (ISD) which measures more than one and one-half times the ISD above and more than one and one-half times the ISD below indicates the presence of an anterior cervical dislocation at the level of abnormal widening. Measurements of the interspinous distances from the C3-C4 interval through the C7-T1 interval in 500 patients with normal cervical spines and in 14 patients with documented anterior cervical dislocations revealed neither false positive nor false negative diagnoses by these criteria.

The Origin of the Left Gastric Artery

Five hundred celiac angiograms were reviewed to evaluate the frequency of clinically significant variations in the origin of the left gastric artery. In 13 of 500 cases, the left gastric artery arose anomalously most often as a direct branch of the aorta; in 14 of 500 cases, the left gastric artery primarily supplied the liver with only minor contributions to the stomach. An aberrant origin of the left gastric artery necessarily influences the angiographic diagnosis and therapy of gastrointestinal hemorrhage.

Fat within the falx: MR demonstration of falcine bony metaplasia with marrow formation.

Falcine bony metaplasia frequently is incorrectly labeled “dense calcification” on brain CT and conventional radiography. Of 3,000 brain magnetic resonance (MR) scans reviewed, 12 demonstrated a central area of increased signal intensity on T1 and T2 weighted images with a smooth peripheral rim of diminished signal intensity within the region of the falx. The central area of increased signal intensity corresponded to fat in the medullary cavity and the peripheral area of low signal intensity corresponded to cortical bone. The CT scans, available in nine of 12 patients, were compared with the MR scans and revealed dense mineralization in the corresponding region of the falx. A postmortem specimen of densely “calcified” falx cerebri was examined that revealed cortical bone and a medullary cavity complete with bony trabeculae and marrow. The MR findings of falx ossification should not be confused with other entities of greater clinical significance.

Hemorrhagic subependymal giant cell astrocytoma.

We describe the CT and MR findings in a patient diagnosed with tuberous sclerosis after presenting with a hemorrhagic subependymal giant cell astrocytoma (SEGCA). While these tumors are not uncommon in tuberous sclerosis, hemorrhage into them is extremely rare.