O. Wayne Houser

Arterial Fibromuscular Dysplasia

Fibromuscular dysplasia is a nonatherosclerotic, noninflammatory vascular disease that involves primarily the renal and internal carotid arteries and less often the vertebral, iliac, subclavian, and visceral arteries. Although its pathogenesis is not completely understood, humoral, mechanical, and genetic factors as well as mural ischemia may play a role. The natural history is relatively benign, with progression occurring in only a minority of the patients. Typical clinical manifestations are renovascular hypertension, stroke, subarachnoid hemorrhage, abdominal angina, or claudication of the legs or arms. In patients with symptoms, percutaneous transluminal angioplasty has emerged as the treatment of choice in most involved vascular beds.

Intracranial dural arteriovenous malformations.

Abstract Twenty-eight patients with dural arteriovenous malformations, mostly located along the cranial base and in the occipitomastoid region, were studied angiographically. It was often possible to define a relationship between the clinical syndrome and the angiographic pattern of venous drainage. Intracranial hemorrhages occurred in those patients in whom the venous drainage of the arteriovenous malformation was limited to the pial veins, while the syndrome of a cavernous sinus fistula was present when retrograde venous drainage from the anomaly extended through the distensible ophthalmic veins. If the venous outflow was antegrade through the usual channels, the clinical syndrome reflected only the presence and volume of the arteriovenous shunt.

Cortical Tuber Count: A Biomarker Indicating Neurologic Severity of Tuberous Sclerosis Complex

The relationship between the number of cortical tubers observed by magnetic resonance imaging (MRI) and the severity of cerebral dysfunction of tuberous sclerosis patients has been examined in a meta-analysis of the published literature. The literature review has identified five independent studies for examining the association. These studies consistently reveal that the cortical tuber count detected on MRI scans is increased among those with more severe cerebral disease. Severity of the cerebral dysfunction is measured by the seizure status and its control and by the developmental status and the level of mental retardation. Meta-analysis demonstrates that within a study population, the MRI-detected cortical tuber count is six times more likely to be above the median count for tuberous sclerosis patients with severe cerebral dysfunction (poor seizure control or moderate-severe retardation or both) than more mildly affected tuberous sclerosis patients. Similarly, across studies, moderately to severely affected patients are five times more likely to have greater than seven MRI-detected cortical tubers than those more mildly affected. These associations are both statistically significant and strong. The cortical tuber count is a biomarker that reasonably predicts the severity of cerebral dysfunction of tuberous sclerosis. Cortical tubers of tuberous sclerosis form in the early gestational period. The embryologic disruption determining the clinical severity of the cortical dysfunction of tuberous sclerosis is set in the early gestational period. (J Child Neurol 1997;12:85-90).

An Evaluation of the Quantitative and Radiation Features of a Scanning X-Ray Transverse Axial Tomograph: The EMI Scanner

Evaluation of the EMI Scanner, an x-ray transverse axial tomograph, has shown that the unit provides numerical values which are linearly related to the 73 keV attenuation coefficient values with an agreement of better than one half of one per cent. Precision of these determinations has also been shown to be 0.5%. Independence of spatial location and accurate resolution of objects as small as 6 mm have been demonstrated. An adjacency effect at a bone-brain matter interface was measured. Radiation exposures arc comparable to those received in many diagnostic roentgenologic procedures.

Prospective Study of the Effectiveness and Durability of Carotid Endarterectomy

In a series of 252 consecutive patients who underwent 282 carotid endarterectomies, we conducted clinical and angiographic follow-up for 2 to 6 years (mean, 3.2 years). Digital subtraction angiography (DSA) was done postoperatively in 95% of cases. Clinical follow-up was achieved in 97% of cases, and DSA follow-up was obtained in 66% of cases. The overall group had a 1% operative minor morbidity (three cases of minimal new neurologic deficit), no major morbidity, and a 0.7% mortality (one death from stroke and one from myocardial infarction). Complications correlated well with the patients preoperative risk category. During follow-up, 10 minor strokes, only 1 of which was attributable to the reconstructed artery, and 10 transient ischemic attacks, 3 of which were presumably related to recurrent stenosis, occurred. Asymptomatic mild to moderate restenosis of the internal carotid or common carotid artery was identified in 10% of follow-up DSAs and severe stenosis or occlusion in 3%. Stenosis in the opposite common carotid or internal carotid artery progressed in 48 cases (26% of follow-up DSAs and ultrasound studies), and 10 of these became symptomatic. An actuarial analysis of patients who had endarterectomy indicated that the cumulative probability of ipsilateral stroke was 1.5% at 1 month and 2% at 5 years. The cumulative probability of ipsilateral stroke, transient ischemic attack, or reversible ischemic neurologic deficit was 4% at 1 month and 8% at 5 years or less than 1% per year after the first month, with censoring at the time of the second surgical procedure.

Results, Complications, and Follow-Up of 415 Bypass Operations for Occlusive Disease of the Carotid System

Selected patients with acute or continuing ischemic symptoms from occlusions or inaccessible stenotic lesions of the internal carotid artery or middle cerebral artery have been considered candidates for a carotid artery-middle cerebral artery bypass procedure at our institution since July 1974. We report herein an 8-year experience through June 1982 with 415 operations in 403 patients in whom a branch of the superficial temporal artery was anastomosed to a branch of the middle cerebral artery. Patients selected for operation usually had had more than one form of ischemic symptom. The primary indication for operation was transient ischemic attacks, and the most common vascular pathologic condition was internal carotid artery occlusion. Preoperatively, 183 patients were taking antiplatelet agents and 157 were taking anticoagulants. Neurologic function 6 months postoperatively was equal to or better than the function preoperatively in 95% of survivors. The bypass pedicle was patent in 99% of patients studied. The mortality and morbidity associated with the surgical procedure varied on the basis of the patients preoperative neurologic condition but were 1% and 4%, respectively, for the entire group at 30 days postoperatively. Of the 54 deaths during the entire follow-up period, 27 were cardiogenic and 6 were from ischemic stroke. On the basis of patient-months of follow-up, stroke was 8 times more likely to occur within 6 months after operation than thereafter.

Computed Tomography and Radionuclide Imaging in the Evaluation of Ischemic Stroke

One hundred forty-one patients with cerebral or cerebellar infarction were examined by computed tomography (CT) as soon after the ictus as possible. The examination was repeated in 7 days, and a radionuclide brain scan was performed. The overall detection rate for ischemic infarction was approximately equal for both techniques, ranging from 58% for radionuclide scanning to 66% for the delayed CT. Almost half of the supratentorial infarcts examined by CT on the day of the ictus were demonstrated. Mass effect was observed as early as the first day and as late as the 25th day.

Computed tomography in the evaluation of subdural hematomas.

Computed tomographic (CT) scans used in the diagnosis and management of subdural hematomas were analyzed with respect to their contribution to angiography and surgery. There has been a progressive increase in the use of CT in evaluating post-traumatic and postoperative subdural hematomas at the Mayo Clinic. At present, 40% of all patients undergo operation on the basis of the CT findings alone. False-positive diagnoses revealed at surgery have decreased to less than 4%. Erroneous negative interpretations have involved 10% of all patients whose diagnosis was subdural hematoma. Criteria for the interpretation of scans have been established.

Magnetic resonance imaging in a routine clinical setting.

The results of magnetic resonance imaging (MRI) examinations in the first 1,000 consecutive patients who were studied by this technique at our institution were reviewed to determine the disease states encountered, the sensitivity and accuracy of results, and the value of the examination as compared with computed tomography and other imaging procedures. The MRI device was a 0.15-tesla resistive magnet that used a variety of saturation recovery, spin echo, and inversion recovery pulse sequences to produce images. MRI was found equal to or superior to other imaging techniques in most cases. Exceptions included organs or body regions that are prone to excessive respiratory or vascular motion, lesions that necessitate exquisite spatial resolution for diagnosis, and lesions in which angulation of the viewing plane is necessary for optimal depiction. Fresh blood and calcification within a lesion were also difficult to detect with use of MRI.

Imaging of Cranial Chordomas

The clinical, pathologic, and imaging characteristics of clival chordomas in 14 patients who underwent magnetic resonance examinations were evaluated. Magnetic resonance imaging (MRI) was compared with skull series, tomography, computed tomography (CT), and magnification angiography in the diagnosis of clival chordomas. Although all examinations were highly sensitive for the detection of clival chordomas, MRI was the best single study because of its ability to image in orthogonal planes, its excellent soft-tissue contrast, and its demonstration of the relationship between the neoplasm and regional vital structures, particularly the brainstem, cavernous sinus, cranial nerves, and neighboring vessels. The deficiencies of MRI are poor visualization of tumoral calcification and osseous destruction--findings that are better identified on CT. In all 14 cases, MRI revealed the neoplasms to be black on inversion-recovery, gray on partial-saturation, and white on T2-weighted pulse sequences. Three chordomas had a speckled signal void pattern, typical of tumor calcification.