The pathomorphology of spinal stenosis as seen on CT scans of the lumbar spine.

This study examines different morphologic measurements in the evaluation of patients with lumbar spinal stenosis. Preoperative CT scans from 24 patients who underwent surgery for central lumbar stenosis were analyzed. No correlation was observed between the size of the bony spinal canal and the size of the dural sac. A new measurement, the transverse area of the dural sac, is introduced. Normal values are provided. Correlation between the cross-sectional area of the dural sac and the anteroposterior diameter of the dural sac was excellent.

Role of computed tomography and myelography in the diagnosis of central spinal stenosis.

In order to evaluate radiographic methods for diagnosing central lumbar stenosis, we reviewed the computed tomography scans and myelograms of twenty-four patients who underwent surgical decompression for central lumbar stenosis. In the diagnosis of central lumbar stenosis, the measurement of the anterior-posterior diameter of the osseous canal by computed tomography was less reliable than the measurement of the dural sac by myelography. The dimensions of the canal derived from computed tomography provided a correct diagnosis in 20 per cent of the patients, while myelography was accurate 83 per cent of the time. The effectiveness of computed tomography was improved when the cross-sectional area of the dural sac was measured. We suggest that a narrow dural sac, demonstrated by myelography or by computed tomography, reliably indicates central spinal stenosis.

Pressure changes within the cauda equina following constriction of the dural sac. An in vitro experimental study.

In order to register pressure changes within the cauda equina, a highly sensitive pressure measuring catheter was inserted through a hole in the dural sac. Its tip was placed among the nerve roots of the cauda equina at levels L2, L3, and L4 in seven freshly removed human specimens. The cross-sectional area of the dural sac then was decreased gradually by constriction of a circular clamp. The inside diameter of the clamp and the corresponding area was determined when further reduction of the circumference of the clamp caused the first signs of a pressure increase, the critical size, among the nerve roots. The average critical size was 76.9 mm2 at the L2 level, corresponding to a diameter of 11.4 mm At the L3 level, the corresponding figures were 71.5 mm2 and 11.1 mm, and at the L4 level 64.8 mm2 and 10.6 mm, respectively. It seemed reasonable to assume that the critical sizes determined in this way could be threshold values below which a further constriction of the size of the dural sac would cause an impairment of the circulatory and/or the nerve function of the cauda equina.

Mycotic aneurysm of the internal carotid artery. A surgical emergency.

A 17-year-old man presented with signs of rupture of a high cervical internal carotid aneurysm. Following angiographic demonstration of the aneurysm, he was immediately treated by balloon catheter occlusion. Eight days later the ligation of the supraclinoid portion of the internal carotid on the left was prompted by the formation of blood clots and emboli from this segment. The patient tolerated both procedures well.

Interval appearance of glioblastomas not evident in previous CT examinations.

This communication presents our experience with eight patients who were initially evaluated as having normal cerebral computed tomographic (CT) scans. Follow-up scans ranging from 2 to 9 months later showed interval appearance of large contrast enhancing mass producing lesions. All eight of these patients turned out to have glioblastoma multiforme. This phenomenon of "false-negative" CT does not seem to be dependent on the type of equipment used or the age of the patient. Negative CT should not dissuade radiologists and clinicians from believing that a patient with appropriate symptoms and signs does indeed harbor a brain tumor.

Preoperative CT diagnosis of mesial temporal sclerosis for surgical treatment of epilepsy.

A computerized tomographic (CT) scanning technique has been devised by which the anatomy of the mesial temporal lobe can be examined in epileptics who are being considered for temporal lobectomy. Among 25 patients examined with this technique, 17 have had the anatomy of their mesial temporal lobe verified at craniotomy, showing close correlation between surgical findings and the high-resolution cerebrospinal fluid-enhanced CT scans. Atrophy was present in 4 patients, whereas chronic herniation of the mesial temporal structures over the free edge of the tentorium was present in 12; in 1 patient the structures were normal. The correlation of an anatomical lesion with an electroencephalographically (EEG) defined epileptogenic focus will improve the outcome of surgery for epilepsy. This CT technique aids in identifying the epileptogenic temporal lobe for patients in whom the focus is ambiguous by EEG criteria alone.

CT measurements of mesial temporal lobe herniation in epileptics.

The purpose of this study was to develop a quantitative method for describing preoperatively herniation of the mesial temporal lobe structures in epileptic patients. This was done by opacifying the CSF of the basal cisterns with metrizamide and measuring the position and contour of the mesial temporal lobe. The measurements were fitted to complex polynomial curves, which were then analyzed. The shapes of the curves, the surface area between the curves and the x axis, and the angles at which the curves intersected the x axis were all found to be reliable indicators of the presence or absence of herniation of the mesial temporal structures. In the 18 patients studied, chronic herniation of the mesial temporal lobe was found at the time of surgery in 13 cases and had been assessed correctly preoperatively with the aid of the polynomial curves in each instance.

Intracranial hemorrhage in premature infants: accuracy in sonographic evaluation.

The real-time high resolution mechanical sonographic sector scanner is a convenient and useful instrument for the detection of intracranial hemorrhage in premature infants. Experience with 27 infants with intracranial hemorrhage detected by sonography and confirmed by computed tomography (CT) or by autopsy is analyzed. The severity of the hemorrhage shown by those methods was graded by an accepted classification for standardized reporting. The extent of intraparenchymal and intraventricular hemorrhage was accurately assessed by sonography in all cases except for small amounts of blood in normal sized ventricles in five of 12 instances. Sonography also failed to detect subarachnoid hemorrhage in each of 13 cases. There were no known false-positive sonograms. From this experience the authors believe sonographic sector scanning should be the initial examination in all infants at high risk for intracranial hemorrhage. When the ventricles are of normal size, CT scanning is recommended to search for small intraventricular hemorrhage that may not be detected by sonography. For subarachnoid bleeding, CT is preferable to sonography.

Localization of stereotaxic centers by computerized tomographic scanning. Technical note.

A method is described for determining stereotaxic coordinates using computerized tomographic scanning and intraoperative ventriculography of the third ventricle.