James E. Knake

Atherosclerotic extracranial carotid artery aneurysms.

Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.

Descending spinal motor tract regeneration after spinal cord transection

In spite of evidence that mammalian axons do sprout in areas of central nervous system (CNS) injury and in some cases cross the gap in a transected spinal cord, the goal of useful regeneration after human cord injury remains elusive.’-6 Glial scars can be reduced and regenera t ion enhanced by a variety of methods,7-‘ but long motor tract regeneration in mammals has been claimed only by Freeman and associates.’ -2 Other investigators have not repeated their experiments, and the reliability of their endpoints of functional r e t u r n and electromyographic evidence of regeneration is disputed. Treatments have been successful in decreasing the amount of scar tissue, but the remaining scar always appears to inhibit regenerating axons. We investigated reports of those animnls in which cord regeneration did occur to search for a clue as to why it occurred in the simpler animals2 ’ -2 and in embryo^^^-^ but not in mature mammals.’ A remarkable parallel was recognized: Each group in which cord regeneration had been recorded was also known to accept skin hornograft~.~ 9 3 We decided to test the hypothesis that autoimmunity to brain antigens in those that do not produce regeneration in their spinal cords is a causal factor in their inability to regenerate. The newborn rat is still immunologically in the “plastic period” in which he can be made tolerant to foreign antigens by exposure to the antigens during the first two days of life.3 ’ 3 3 2 P a t e r ~ o n ~ ~ 3 3 4 has shown that rats exposed to emulsified spinal cord from animals of the same inbred strain on day 1 or 2 of life will have a decreased susceptibility to experimental allergic encephalomyelitis when they are challenged with spinal cord antigen in later adult life. We confirmed this ability to induce tolerance to spinal cord antigen in our own rats with similar experiments. This report will discuss our efforts to increase the potential for spinal cord regeneration in rats by methods that should be effective in inhibiting the development of homograft-type allergic responses to CNS antigen.

Gas as a mass: A symptomatic spinal canalicular collection

A symptomatic collection of spinal canalicular gas of degenerative origin was observed by computed tomography. Relief of symptoms followed gas aspiration. The collection involved the lateral recess. Such gas collections do not appear to represent benign, transient entities in all patients.

Real time ultrasound characteristics of the acute intracerebral hemorrhage as studied in the canine model

Real time intraoperative sonography is a valuable tool for visualizing subcortical mass lesions. Although most solid lesions are hyperechogenic, little is known about the ultrasound characteristics of intracerebral hemorrhage and subsequent hematoma formation. We sought to determine the sonographic characteristics of an acute intracerebral hematoma, to study its evolution, and to explore factors responsible for its echogenicity. Acute intracerebral hematomas were created in adult mongrel dogs using heparinized or unheparinized autologous whole blood injected under sonographic visualization into the centrum semiovale of 10 cerebral hemispheres. Different components of blood were also imaged in polyurethane test tubes (n = 56) immersed in a degassed, room temperature water bath. All studies were performed with continuous ultrasound recording using the ATL real time Neurosector scanner with the variable 3-, 5-, and 7.5-MHz transducer. Intracerebral hematomas were initially hypoechogenic, becoming hyperechogenic between 16 and 23 seconds after injection (average, 22 seconds). Full echogenicity was obtained between 40 and 213 seconds after injection (average, 91 seconds). There was no difference between the sonographic appearances of hematomas formed with whole blood and those formed with heparinized whole blood. In addition, we demonstrated the superior sensitivity of the 7.5-MHz frequency in visualizing intracerebral hematomas in vivo, as opposed to the 3- and 5-MHz frequencies. Whole blood, heparinized whole blood, and citrated whole blood were found to be highly echogenic in vitro. Phosphate-buffered saline, plasma, serum, and packed red blood cells (PRBCs) were hypoechogenic. Resuspended PRCBs in phosphate-buffered saline, plasma, or serum were echogenic. Our data suggest that hyperechogenicity is independent of the clotting mechanism and is related to blood stasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior cervical epidural abscess: The use of intraoperative spinal sonography

A case of acute cervical epidural abscess is presented. The use of intraoperative spinal sonography is discussed as a valuable adjunct in the evaluation and treatment of these uncommon lesions.

Iohexol versus metrizamide for lumbar myelography: Preliminary report of double-blind trial

Lumbar myelography was performed in 38 patients; 19 received iohexol (an investigational aqueous contrast agent) and 19 received metrizamide. Iohexol is stable in solution, which is not the case with metrizamide. There was no other significant difference in diagnostic utility or quality between the two media. However, there was considerable postmyelography morbidity in the metrizamide group, but no postmyelography morbidity in the iohexol group. Preliminary clinical evidence suggests that iohexol is significantly superior to metrizamide as a contrast agent for lumbar myelography.

ASPECTS OF INTERHEMISPHERIC SUBDURAL HEMATOMA, INCLUDING THE FALX SYNDROME

Two cases of interhemispheric subdural haematoma are reported. The first patient presented with a falx syndrome of contralateral hemiparesis, most marked in the lower extremity. The second patient had vertex headaches and was diagnosed with computerised tomography. Serial studies suggested that the interhemispheric haematoma may have migrated to a lateral position over the cerebral convexity.

OBSTRUCTIVE HYDROCEPHALUS SECONDARY TO AN ECTATIC BASILAR ARTERY

A 57 year-old white hypertensive male presented with a five-month history of progressive dementia and a clinical picture suggestive of normal pressure hydrocephalus. A CT scan and vertebral angiogram demonstrated an ectatic basilar artery obstructing the posterior third ventricle; the resulting hydrocephalus was relieved by a ventriculo-peritoneal shunt and the patients symptoms resolved completely.

AN EVALUATION OF THE PERFORMANCE CHARACTERISTICS OF DIFFERENT TYPES OF COLLIMATORS USED WITH THE EMI BRAIN SCANNER (MKI) AND THEIR SIGNIFICANCE IN SPECIFIC CLINICAL APPLICATIONS

The characteristics of various types of collimators have been studied systematically for the EMI Mark I brain scanner. The degree of collimation ranged from the 13-mm adjacent A and B slices to 3-mm separated slices. Multiple phantom studies (including variable density immiscible liquid interfaces) have been performed to evaluate the effect of collimation on (a) the line-spread function, (b) the change in effective absorption number, and (c) volume averaging. Effects associated with the technique settings involving the kVp, the mA, and the scan time were also investigated. The results of TLD dose measurements as a function of collimation are presented. The significance of collimation in specific clinical studies involving small, fairly well-circumscribed lesions is discussed.

ELECTROENCEPHALOGRAPHY IN BRAIN EDEMA (127 CASES OF BRAIN TUMOR INVESTIGATED BY CRANIAL COMPUTERIZED TOMOGRAPHY)

Cranial computerized tomography (CCT) in permitting visualization of cerebral edema in live patients, allows for the first time valid studies concerning the role of reactional edema in the generation of EEG abnormalities related to expanding processes. The authors analyze the results of EEG and CCT in 127 patients presenting cerebral tumor(s), 84 of which were accompanied by reactional edema. The study leads to the conclusion (also demonstrated by certain animal work) that edema per se is only rarely responsible (9.5%) for the EEG abnormalities.