Joseph R. Thompson

Cerebral vasoconstriction in toxemia

Three patients with toxemia developed acute neurologic deterioration postpartum. In all, cerebral angiography revealed widespread arterial vasoconstriction. Cerebral vasoconstriction may be an important cause of neurologic complications in toxemia.

CT and angiographic correlation of severe neurological disease in toxemia of pregnancy

SummaryTwo patients with severe cerebral symptoms of toxemia of pregnancy were examined using computed tomography (CT) and angiography. CT disclosed extensive areas of low attenuation within the cerebral hemispheres. Angiography revealed constriction and narrowing of proximal and peripheral vessels suggesting vasculitis with extensive areas of impaired regional cerebral blood flow. A review of the known pathology and the theories regarding the pathophysiology of the cerebral effects of toxemia is presented.

Cerebral blood flow and carbon dioxide reactivity in children with bacterial meningitis

We examined total and regional cerebral blood flow (CBF) by stable xenon computed tomography in 20 seriously ill children with acute bacterial meningitis to determine whether CBF was reduced and to examine the changes in CBF during hyperventilation. In 13 children, total CBF was normal (62 +/- 20 ml/min/100 gm) but marked local variability of flow was seen. In five other children, total CBF was significantly reduced (26 +/- 10 ml/min/100 gm; p less than 0.05), with flow reduced more in white matter (8 +/- 5 ml/min/100 gm) than in gray matter (30 +/- 15 ml/min/100 gm). Autoregulation of CBF appeared to be present in these 18 children within a range of mean arterial blood pressure from 56 to 102 mm Hg. In the remaining two infants, brain dead within the first 24 hours, total flow was uniformly absent, averaging 3 +/- 3 ml/min/100 gm. In seven children, CBF was determined at two carbon dioxide tension (PCO2) levels: 40 (+/- 3) mm Hg and 29 (+/- 3) mm Hg. In six children, total CBF decreased 33%, from 52 (+/- 25) to 35 (+/- 15) ml/min/100 gm; the mean percentage of change in CBF per millimeter of mercury of PCO2 was 3.0%. Regional variability of perfusion to changes in PCO2 was marked in all six children. The percentage of change in CBF per millimeter of mercury of PCO2 was similar in frontal gray matter (3.1%) but higher in white matter (4.5%). In the seventh patient a paradoxical response was observed; total and regional CBF increased 25% after hyperventilation. Our findings demonstrate that (1) CBF in children with bacterial meningitis may be substantially decreased globally, with even more variability noted regionally, (2) autoregulation of CBF is preserved, (3) CBF/CO2 responsitivity varies among patients and in different regions of the brain in the same patient, and (4) hyperventilation can reduce CBF below ischemic thresholds.

Neuroradiology of Tuberous Sclerosis in Children

A retrospective study of tuberous sclerosis in 45 children aged six months to 14 years was done. Positive neuroradiologic findings were present in all, often before the clinical diagnosis was suspected. Pneumoencephalography revealed definite nodules in almost all cases; mild ventricular dilatation was also a common finding. Children are less likely to have intracranial calcification than adults, but the incidence of these calcifications increases with age.

Occlusion of the intradural vertebrobasilar artery

SummaryThe diagnosis of occlusion of the intradural vertebrobasilar artery (OIDVBA) was made by means of cerebral angiography in 22 patients. The clinical presentation, course and followup were studied in conjunction with the angiographic findings in each case and the following conclusions made. OIDVBA is not rare. It occurs one-fourth as often as occlusion of the carotid artery. The correct diagnosis is not made clinically before angiography in the majority of patients. Complete visualization of the neck and intracranial vasculature is necessary to document the occlusion. Atherosclerotic thrombosis is the most common type of occlusive lesion. The most common predisposing factors are atherosclerosis, hypertensive cardiovascular disease, diabetes mellitus, and developmental vertebrobasilar hypoplasia. Most patients with occlusion are in the 7th and 8th decades of life and transient attacks of vertebrobasilar ischemia precede the occlusion in one-half of the cases. Emboli usually lodge in the terminal portion of the basilar artery whereas thrombotic occlusions tend not to be located in a characteristic segment. A majority of patients diagnosed angiographically survive their OIDVBA, but most distal occlusions result in death, often following several weeks of coma. In the surviving majority, disturbance of gait, impairment of vision, and symptoms of transient vertebrobasilar ischemia are the most common sequelae.

Prognostic implications of hyperglycemia and reduced cerebral blood flow in childhood near‐drowning

We retrospectively examined the clinical courses of 20 children with severe near-drowning and divided their outcomes into 3 groups: normal (4), persistent vegetative state (9), and dead (7). We reviewed serial blood glucose levels and cerebral blood flow measured by stable xenon computed tomography within the 1st 48 hours of admission to determine whether they were predictive of outcome. Total, frontal gray, frontal white, and temporal and parietal gray matter cerebral blood flows were significantly decreased in children who died compared with those who completely recovered. Only 1/2 the children surviving in a vegetative state had decreased flows compared with those who recovered. An elevated initial blood glucose was highly predictive of those patients who died (mean, 511 ± 110 mg%) or those with vegetative survival (465 ± 104 mg%) compared with those who recovered completely (238 ± 170 mg%). The predictive value of initial blood glucose alone (68%) or CBF alone (50%) was similar to that of clinical rating scales or immersion/resuscitation times. The combination of blood glucose with CBF improved predictability to 79%. Our results suggest that CBF measurements are predictive of eventual death but cannot differentiate normal from vegetative survival. Combining multiple laboratory studies may be of value in predetermining the eventual outcome in near-drowning.

Bacterial meningitis in children: pathophysiology and treatment.

Recent studies of the pathophysiology of bacterial meningitis have suggested that the development of neuronal injury is related to the release of vasoactive substances or alteration of blood-brain barrier permeability. Cerebral edema, increased intracranial pressure (ICP), systemic hypotension, decreased cerebral perfusion pressure, vascular inflammation, thrombosis, and a variety of other vascular changes may result in global or regional reductions in cerebral blood flow (CBF), which contribute to this insult. Approximately one-third of infants and children with bacterial meningitis will have markedly reduced CBF, and even in those children with normal total flow, regional hypoperfusion is common. Reduced CBF is associated with cerebral edema and a poor prognosis. A poor prognosis also is associated with reduced cerebral perfusion pressure. This occurs early in the course of meningitis and is primarily due to increased ICP rather than systemic hypotension. Autoregulation is preserved, suggesting that local ischemic tissue injury is more related to factors such as regional edema formation, focal vascular pathology, or specific intrinsic flow/metabolic abnormalities than to a reduction in systemic blood pressure. In contrast with other acute CNS insults, CBF/PCO2 reactivity is well preserved in many patients with meningitis; this raises the possibility that hyperventilation may cause further ischemic injury in those patients with marginal CBF. Although it is still unclear that treatment of increased ICP will affect outcome, we propose a treatment paradigm based on the results of neuroimaging studies and ICP measurements.

Intra- and inter-observer variability and accuracy in the determination of linear and angular measurements in computed tomography. An in vitro and in situ study of human mandibles.

The observer variability and accuracy of linear and angular computed tomography (CT) software measurements in the transaxial plane were investigated for the temporomandibular joint with the General Electric 8800 CT/N Scanner. A dried and measured human mandible was embedded in plastic and scanned in vitro. Sixteen observers participated in the study. The following measurements were tested: inter- and extra-condylar distances, transverse condylar dimension, condylar angulation, and the plastic base of the specimen. Three frozen cadaveric heads were similarly scanned and measured in situ. Intra- and inter-observer variabilities were lowest for the specimen base and highest for condylar angulation. Neuroradiologists had the lowest variability as a group, and radiology residents and paramedical personnel had the highest, but the differences were small. No significant difference was found between CT and macroscopic measurement of the mandible. In situ measurement by CT of condyles with structural changes in the transaxial plane was, however, subject to substantial error. It was concluded that transaxial linear measurements of the condylar processes free of significant structural changes had an error and an accuracy well within acceptable limits. The error for angular measurements was significantly greater than the error for linear measurements.

Occult spinal dysraphism in the geriatric patient.

Three patients in their seventies with occult spinal dysraphism are described. All three had tethered spinal cords, intrasacral meningoceles, and severe degenerative lumbar spondylopathy. The mechanism for the late development of symptomatology is related to an acquired lesion, degenerative spinal stenosis.

Computed tomography of condylar and articular disk positions within the temporomandibular joint

The computed tomograms of temporomandibular joints in 25 patients (41 joints) were retrospectively evaluated for condylar position and joint space with General Electric computer software. Computed tomography scans of the temporomandibular joint were made in the axial plane with the teeth in centric occlusion, and measurements were made from vertically reformatted images. Interarticular joint spaces were measured anterosuperiorly, superiorly, posterosuperiorly, and posteriorly from the condylar surfaces. This was repeated in five equidistant (3.1 mm) serial sagittal planes across the condyle, beginning and ending, on average, 2.5 mm from the lateral and medial condylar poles. Articular disk positions (anterolateral, anterior, anteromedial, medial, and normal) were correlated with condylar position. Significant differences between disk positions and joint spaces were found most frequently in the anterosuperior and the superior joint interval. When the disk was positioned normally, the anterosuperior joint space was consistent (1.5 to 2.0 mm) across the joint (standard deviation, 0.3 to 0.8 mm). The superior, the posterosuperior, and the posterior joint spaces in the normal joint were greater than the anterosuperior joint space. When the disk was anterior to the condyle, the anterosuperior joint interval was widened. When the disk was medial, the superior joint space was significantly wider than normal across the breadth of the condyle. In those joints in which the disk was anteromedial, there was an absence (0.2 mm) of joint space, and this occurred in all areas of the condyle except in its medial one fourth. In the internally deranged joint, joint space narrowing may be focal in nature.