E R Heinz

Adipose Tissue in the Filum Terminale: A Computed Tomographic Finding That May Indicate Tethering of the Spinal Cord

&NA; Adipose tissue in the filum terminale is frequently associated with tethering of the spinal cord in patients with spina bifida occulta (3, 8). We recently saw a patient with low back pain and no spina bifida occulta, in whom adipose tissue was noted in the area of the filum on an unenhanced computed tomographic (CT) scan. The patient had a tethered cord. This case suggested that, when CT scanning is done as the first imaging study in the evaluation of low back pain, fatty tissue in the area of the filum may be an indicator for tethering of the spinal cord. The present study was undertaken to determine the validity of using CT scan‐detectable filal fat in the identification of possible tethered spinal cords among a group of patients experiencing low back pain. The presence of fat in the fila of 12 patients with the radiologically and histologically tethered cord syndrome was evaluated and the fila of 47 autopsied patients whose clinical history showed no back pain were examined histologically. There were accumulations of adipose tissue in the fila of 11 of the 12 (91%) patients with the tethered cord syndrome and in the fila of 9 of the 47 patients (17%) in the autopsy series. Of the 9 autopsy patients with fat in their fila, however only 3 patients (6%) exhibited collections of adipose tissue in the CT detection range (2 mm). These results demonstrate that, although CT scan‐detectable adipose tissue can be found in the filum of an occasional patient without tethered cord, CT detectable fat in the filum of a patient with low back pain should prompt an evaluation for a tethered spinal cord. CT scanning has potential as a noninvasive tool in such a work‐up.

Dynamic Computed-Tomography Study of the Brain

The dynamic computed tomography (CT) study of the brain consists of the rapid intravenous injection of 49 ml of radiographic contrast material in 7 sec followed by serial 5 sec CT scans with interscan times of only I see. The data from these scans can be reprocessed to create 12 segmented images in 35 see. When small samples of four to six pixels of cortex are examined by the cursor, sharp rises of 20 to 25 CT units (500 scale) are seen on the time–density curves. Samples of while matter are usually no more than 2 CT units. When larger cursor samples of 220 to 255 pixels including cortex and white matter are examined, the time – density curves represent a combination of these two patterns. Comparison between symmetrical areas in the two hemispheres generally shows parallel curves in controls. The studies provide high resolution cerebral perfusion images. In ischemia secondary to ipsilateral carotid stenosis, there is depression of the up-slope and a depressed and late peak. Infarctions show a flat perfusion curve. Several patterns in brain tumors are illustrated. The study, simple to perform, adds significant perfusion information to the previously static CT examination of the brain.

Distinction Between Obstructive and Atrophic Dilatation of Ventricles in Children

Abstract The computed tomography (CT) scans of 92 Infants and children were reviewed. Thirty-three had proven atrophy, and 44 had proven obstructive hydrocephalus. Twelve CT measurements were made, and the results were subjected to computer analysis. The pathologic patients were divided into three groups by ventricular size index: mild (33–39%), moderate (40–46%), and severe (greater than 46%) enlargement. Obstructive patients showed much greater measurements for the temporal horn diameter and the frontal horn radius. The angle of the frontal horn was narrower in the obstructed group than in the atrophic patients. As expected, there were significantly more sulci visualized in the atrophic group than in the obstructed group. Three of these four parameters were directly related to concentric expansion of the ventricles in the presence of obstructive hydrocephalus. This is contrasted with passive dilatation of the ventricular system with preservation of the normal ventricular configuration in atrophy. The temporal horn diameter, frontal horn radius, the angle of the frontal horn, and the number of sulci all distinguish between obstruction and atrophy with individual probabilities of <0.05. When used together, they assure a high probability of separating obstruction from atrophy. Preliminary data suggest that these findings may have application in adults, but the number of confirmed observations has been too small for statistical analysis.

A preliminary investigation of the role of dynamic computed tomography in renovascular hypertension.

This preliminary report describes the application of dynamic computed tomography (CT) to the study of the kidney. The study is a simple, rapid, noninterventional test that gives time–density perfusion curves for the renal cortices as compared with aortic perfusion. In normal subjects, renal cortical time–density curves almost parallel the aortic time–density curve. In theory, decreases in perfusion in the kidney should show a renal cortical perfusion curve that is flattened and no longer parallel to the aortic curve. An experimental model for renal infarction was developed in the dog. Time–density curves taken from the infarcted area do show a depressed renal perfusion curve, with a lower peak than the curve for the contralateral kidney. Dynamic CT may be useful in screening human subjects for possible renovascular hypertension.

Atypical Findings in Adrenoleukodystrophy

: Computed tomography (CT) in a child with typical clinical and biochemical features of adrenoleukodystrophy (ALD) revealed striking pathologic enhancement in the centra semiovalia, posterior corpus callosum, and corticospinal tracts within the internal capsules, cerebral peduncles, and basis pontis. Central calcifications were detected within otherwise typical symmetrical low attenuation lesions in the periatrial white matter. These findings further expand the spectrum of CT abnormalities in ALD and may represent a link between the recently described Type 1 and Type 11 CT patterns.

Positron emission tomography: Comparison of clinical utility in temporal lobe and extratemporal epilepsy

Abstract Sixty consecutive patients admitted for possible surgical treatment of intractable epilepsy underwent 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) as part of a standardized presurgical protocol. Patients were classified as having temporal lobe or extratemporal epilepsy based on all available information excluding PET. Of 35 patients categorized as having temporal lobe epilepsy, 27 (77%) had unilateral temporal lobe hypometabolism that always correlated with electrophysiologic localization of the seizure focus. In 19 patients categorized as having extratemporal epilepsy, only six (32%) had an abnormal PET study and in only one patient did PET assist in subsequent localization of the seizure focus. Four patients with extratemporal epilepsy had falsely localizing information obtained on PET. The results of this study demonstrate that PET is of less clinical utility in the presurgical evaluation of patients with extratemporal epilepsy as compared to patients with temporal lobe epilepsy.

Role of computed tomography in the radiological evaluation of painful radiculopathy after negative myelography: foraminal neural entrapment.

Thirty-five patients with an unremarkable or a negative water-soluble contrast myelogram and a diagnosis of foraminal neural entrapment made or more firmly established by computed tomography (CT) were detected in evaluating 950 patients presenting for myelography. The CT criterion of foraminal neural entrapment was the presence of a mass displacing epidural fat and encroaching on the neural intervertebral foramen or lateral recess so as to compromise an emerging nerve root. The entrapment (confirmed operatively) was due to a laterally prolapsed disc (16 cases), superior articular hypertrophy (4 cases), lateral recess stenosis (3 cases), posterolateral vertebral bone lipping (2 cases), tumors (6 cases), postoperative scarring (2 cases), spondylolisthesis (1 case), and synovial cysts that encroached on the neural foramina (1 case). CT is an important additional investigation in patients with a painful radiculopathy and a negative or equivocal water-soluble contrast myelogram.

Rapid Development of Cerebral Atrophy Due to Perinatal Herpes-Simplex Encephalitis

: A case of neonatal herpes simplex virus (HSV) encephalitis is reported in which diffuse cerebral hemorrhagic lesions were seen in the neonatal period. Severe progressive cortical atrophy with parenchymal calcification developed over the subsequent 9 months, resulting in a striking computed tomography (CT) appearance. The range of CT findings in neonatal HSV encephalitis is reviewed, and differential diagnostic considerations in the present case are discussed.

Assessment of Craniocervical Junction and Atlantoaxial Relation Using Metrizamide-Enhanced CT in Flexion and Extension

Metrizamide-enhanced computed tomographic (CT) myelography has made it easier to define the relation of the spinal cord to the vertebral canal. A flexion-extension metrizamide-enhanced CT technique has been developed to study the craniocervical junction that refines evaluation of the relation between the spinal cord and the foramen magnum, atlas, and axis. This technique was used to study 15 adults who had had a structurally normal examination of the upper cervical cord and foramen magnum. The average movement of the upper cervical cord was shown to be 1 mm. The advantages of the flexion-extension metrizamide-enhanced CT examination were evident in 10 other patients who had a variety of craniocervical junction pathologies.