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Biomedical subjects

L A Hayman

Publications and source records attributed to L A Hayman.

At least 55 records · Page 3Linked to original sources
PubMed1984

Interdural cyst of the lumbosacral region.

The purpose of this report is to call attention to the clinical, myelographic, and computed tomographic appearance of a very rare type of dural cyst within the lumbosacral spinal canal. We report this condition in three unrelated boys who presented with symptoms of cauda equina compression. Our experience suggests that these cysts are congenital in origin. Anatomically, the cyst wall consisted of a dura-like layer without arachnoid. There was a small ventral defect allowing incomplete communication with the compressed subarachnoid space. Cerebrospinal fluid-like fluid accumulated within the interdural cyst as a result of this communication. Treatment consisted of obliteration of the point of entry between cyst and subarachnoid space in all cases and partial cyst wall excision in one case. After operation, the two patients who had presented with long-standing sphincter disturbance had partial improvement in function and the child with a pain syndrome was completely relieved of symptoms.

Cauda Equina↗
PubMed1984

Correlation of CT cerebral vascular territories with function: 3. Middle cerebral artery.

Schematic displays are presented of the cerebral territories supplied by branches of the middle cerebral artery as they would appear on axial and coronal computed tomographic (CT) scan sections. Companion diagrams of regional cortical function and a discussion of the fiber tracts are provided to simplify correlation of clinical deficits with coronal and axial CT abnormalities.

Brain↗
PubMed1983

Diazepam prophylaxis of contrast media-induced seizures during computed tomography of patients with brain metastases.

The effect of 5 mg of intravenous diazepam (Valium) on contrast media-associated seizure incidence was studied in a randomized controlled trial involving 284 patients with known or suspected brain metastases undergoing cerebral computed tomography. Of these patients, 188 were found to have brain metastases, and it is estimated that for this subgroup prophylactic diazepam reduces the risk of contrast-associated seizure by a factor of 0.26. Seizures occurred in three of 96 patients with metastases on diazepam and in 14 of 92 patients with metastases but without diazepam. Factors related to increased risk of contrast media-associated seizures are: (1) prior seizure history due to brain metastases and/or prior contrast, (2) progressive cerebral metastases, and (3) prior or concurrent brain antineoplastic therapy. Factors not related to an increased risk of these seizures are: (1) contrast media dosage, chemical composition, or osmolarity, (2) computed tomographic appearance of metastases, and (3) type of primary malignancy. Concomitant therapeutic levels of diphenylhydantoin (Dilantin) do not protect completely against contrast media-associated seizures. Pathophysiology of contrast media-associated seizures is discussed in view of the risk factors determined by this study.

Aged↗
PubMed1982

Familial cavernous angiomas: natural history and genetic study over a 5-year period.

In a kindred of 122 individuals we found 5 individuals with cerebral vascular malformation, 3 representing typical cavernous angiomas. The condition was inherited as an autosomal dominant trait with variable expressivity. Forty-three relatives were examined prospectively by cranial computed tomography (CCT) and lesions were found in 15; 7 were followed prospectively with CCT scans for 5 years. Angiography in 5 of these cases failed to demonstrate the lesion. In 3 patients with previously normal CCT scans a change in blood volume or membrane permeability allowed visualization of the lesion on contrast scans. In 2 individuals, both parents of affected children, a normal CCT scan was found. This emphasizes the limitations of CCT in detecting this disorder. Biochemical and red blood cell immunological genetic linkage studies were done in 36 persons. No linkage was found with any of the markers. The natural history of this disorder, characterized by marked clinical and radiographic variation in site of lesion, and the timing and severity of intracranial hemorrhage, make it a useful model for investigating contributing factors and consequences of intracranial hemorrhage in general. For at-risk and affected patients early and sequential CCTs are necessary. Familial cavernous angioma should be included in the differential diagnosis of all young persons presenting with cerebrovascular impairment, seizures, intracranial calcifications or hemorrhage.

Adolescent↗
PubMed1982

Maximizing the harvest of contrast enhancing lesions in multiple sclerosis.

Transient contrast enhancing lesions can be seen with CT in patients with MS, particularly during acute exacerbations. Conventional 40 gm iodine enhancement technique followed by immediate postinfusion scanning was compared with high dose (80 gm iodine) enhancement technique followed by a 1-hour delayed CT scan; delayed high dose technique (DHD) in nine exacerbations. New lesions, totaling 36 in all, were observed in each case with the DHD technique. With time, the borders expanded in 98% of lesions, thus confirming in vivo that a defective blood-brain barrier (BBB) underlies this phenomenon.

Adult↗
PubMed1981

Protocol for delayed contrast enhancement in computed tomography of cerebral neoplasia.

One hundred cranial computed tomograms of adults with known or suspected intracranial neoplasm were analyzed retrospectively. Rapid high-dose intravenous contrast infusion (84.6 g l) was followed by immediate and 1 1/2-hour delayed scans. Delayed images afforded more information than the initial series in 67% of cases. 11.5% false-negative examinations (i.e., no tumor reported) would have resulted if studies were terminated after the immediate post-infusion scans. No patient experienced clinically detectable renal compromise.

Adult↗
PubMed1981

Delayed high dose contrast CT: identifying patients at risk of massive hemorrhagic infarction.

A prospective clinical study was done on 20 patients referred for computed tomography within 28 hr of a cerebral ischemic event. The patients were scanned before, immediately after, and 3 hr after a high dose of intravenous contrast medium was administered to produce prolonged high blood iodine levels. In seven patients the delayed scan demonstrated a heretofore undescribed type of contrast enhancement which represents the early massive vasogenic edema seen in experimental animals before confluent hemorrhagic infarction. Four of the seven patients developed hemorrhagic infarction. None of the remaining 11 patients with cerebral infarctions and conventional postenhancement CT patterns showed hemorrhage on follow-up CT scans or at autopsy. Two patients with transient ischemic attacks had normal CT scans. It may now be possible to predict patients in whom there is high probability of hemorrhagic infarction before blood appears on CT. Treatment of these patients should probably be aimed at preventing the devastating effects of the vasogenic edema. We speculate that heparinization or bypass surgery to reestablish circulation may be contraindicated in this group.

Adult↗
PubMed1981

Correlation of CT cerebral vascular territories with function: II. Posterior cerebral artery.

This paper presents schematic displays of the cerebral territories supplied by branches of the posterior artery as they would appear on axial and coronal computed tomographic (CT) scan sections. Companion diagrams of regional cortical function and a discussion of the fiber tracts are provided to simplify correlation of clinical deficits with coronal and axial CT abnormalities. Illustrations of the vascular supply and functional relay points (nuclei) of the thalamus are provided.

Brain↗
PubMed1981

Central nervous system leukemia and lymphoma: computed tomographic manifestations.

Computed tomographic (CT) abnormalities in the brain were identified in 31 of 405 patients with leukemia or lymphoma. Abnormalities included neoplastic masses (15), hemorrhage (nine), abscess (two), other brain tumors (four), and methotrexate leukoencephalopathy (one). CT was normal in 374 patients including 148 with meningeal disease diagnosed by cerebrospinal fluid cytologic examination. Prior to treatment, malignant masses were isodense or of greater density with varying amounts of edema. Increase in size or number of the masses indicated worsening. Response to radiation and chemotherapy was manifested by development of a central low density region with an enhancing rim. CT findings correlated with clinical and cerebrospinal fluid findings. The differential diagnosis of the various abnormalities is considered.

Cerebral Hemorrhage↗
PubMed1980

Cerebral embolism: local CBF and edema measured by CT scanning and Xes inhalation.

Serial CT scans were made in baboons after cerebral embolization during stable Xe inhalation for measuring local values for CBF and lambda (brain-blood partition or solubility coefficients), followed by iodine infusion for detecting blood-brain barrier (BBB) damage. Supplementary 133Xe CBF measurements were made at corresponding intervals. Persistent zones of zero flow surrounded by reduced flow were measured predominantly in subcortical regions, which showed gross and microscopic evidence of infarction at necropsy. Overlying cortex was relatively spared. Reduced lambda values attributed to edema appeared within 3--5 minutes and progressed up to 60 minutes. Damage to BBB with visible transvascular seepage of iodine began to appear 1--1 1/2 hours after embolism. In chronic animals, lambda values were persistently reduced in areas showing histologic infarction. Contralateral hemispheric CBF increased for the first 15 minutes after embolism, followed by progressive reduction after 30 minutes (diaschisis).

Afferent Pathways↗
PubMed1980

Delayed high iodine dose contrast computed tomography: cranial neoplasms.

A one-year prospective study was done involving 78 patients with a suspected intracranial neoplasm. Immediate and delayed high dose (DHD) contrast (with 80 g of iodine) postinfusion computed tomographic scans were compared in 15 cases of primary and 32 cases of metastatic neoplasm. The one-hour delayed scan was as diagnostic as the immediate scan in all patients. In 10 cases, additional lesions were demonstrated on the DHD scan. Results suggest that DHD should replace conventional contrast scans in evaluating patients for neoplasia.

Adult↗
PubMed1980

Renal consequences of rapid high dose contrast CT.

A retrospective study of renal deterioration after high doses (80 g l) of intravenous contrast medium was done of 286 adult patients. The incidence, duration, and severity of renal deterioration were compared with those reported in a series of 377 similar patients after low dose contrast infusion (43 g l). No statistically significant difference between these groups was seen in nondiabetics with a preinfusion serum creatinine below 4.5 mg/dl. A prospective study of fractional excretions in 35 patients receiving high dose infusion demonstrated no additional subtle renal damage in 34 patients. One patient developed a transient rise in serum creatinine that was identical to the course of renal deterioration after 43 g of iodine. It is concluded that the severity and duration of renal deterioration was not affected by the dose of contrast material (43--80 g iodine).

Adult↗
PubMed1980

Local cerebral blood flow measured by CT after stable xenon inhalation.

A safe, practical, clinically applicable, noninvasive method for measuring local cerebral blood flow (LCBF) using inert xenon (Xes) and a 60 sec CT scanner has been developed in the baboon. Direct measurement of expired Xes concentration after short inhalation (4--7 min) of 40% Xes and the use of computer-programmed autoradiographic formulas allow accurate, reproducible measurements of LCBF using serial 60 sec scans of regions as small as 0.04 cm3. LCBF measurements are possible with a single 1 min scan. The method reduces radiation exposure, obviates a costly fourth-generation scanner, avoids anesthetic effects of Xes, and reduces the 30 min/scan saturation period. It is less expensive than emission tomography and minimizes problems of overlap and Compton scatter inherent in 133Xe and positron-emission blood flow measurements. Regions of zero perfusion are demonstrable in three dimensions. Tissue solubility and partition coefficients, as well as LCBF, are measured in vivo with high resolution and reproductibility so that minor regional changes in physical properties of tissue that alter solubility are measured. These enhance the potential clinical usefulness of CT scanning.

Administration, Intranasal↗
PubMed1980

Correlation of CT cerebral vascular territories with function: I. Anterior cerebral artery.

Schematic displays of the cerebral territories supplied by branches of the anterior cerebral artery as they would appear on axial and coronal CT scan sections are presented. Companion diagrams of regional cerebral function are also provided to simplify correlation of clinical deficits with coronal and axial CT abnormalities. Selected examples illustrate that these facilitate more detailed and precise CT interpretation in clinical practice.

Brain Mapping↗