PubMed Health⌕ Search

Biomedical subjects

J Howieson

Publications and source records attributed to J Howieson.

At least 19 recordsLinked to original sources
PubMed1995

Detection of discrete white matter lesions after irreversible compression of MR images.

PURPOSE: To validate the use of techniques of irreversible compression of images, which can be performed using a block-based discrete cosine transform technique as defined by the Joint Photographic Experts Group, before they can be used in clinical applications, by evaluating the effect of compression on the ability of observers to detect discrete white matter lesions on MR images of the brain. METHODS: Sixty T2- and intermediate-weighted spin-echo images were compressed with varying degrees of coefficient quantization with compression ratios from 1:1 to more than 40:1, randomized, and evaluated by three observers blinded to the degree of compression. RESULTS: No significant difference in the number of lesions detected was apparent until compression ratios reached 40:1, despite a significant subjective loss in perceived image quality at 20:1. Only small (< or = 5 mm) lesions were missed at the highest degree of compression. No significant differences were observed in the detection of confluent periventricular white matter disease at any degree of compression tested. CONCLUSIONS: The use of high degrees of irreversible compression of MR images may be acceptable for diagnostic tasks.

Brain↗
PubMed1994

Neurologic evaluation of the optimally healthy oldest old.

OBJECTIVE: Individuals aged 85 years or older (the "oldest old") are the fastest-growing age group in the United States. Because there is little information characterizing expected neurologic function in this group, our goal was to determine clinical neurologic traits characteristic of the optimally healthy oldest old. DESIGN: Standardized neurologic evaluation findings of optimally healthy persons older than 84 years compared with those of equally healthy control subjects aged 65 to 74 years. SETTING: Community-based, longitudinal aging study. PARTICIPANTS: Community-residing, consecutively recruited volunteers who were screened for the absence of chronic disease or medication use. MAIN OUTCOME MEASURE: Standardized neurologic examination coded into ordinal or interval variables. RESULTS: Significant between-group differences were greatest for tests of mental status, sensory function (ie, smell, hearing, vibratory discrimination, and stereognosis), oculomotor function, distal movement speed, and balance. Discriminant function analysis suggests that of these changes, membership in the oldest group is best predicted by poor performance on clinical tests of balance (heel-toe walking and one-leg balancing with eyes closed), smell, and visual pursuit. CONCLUSIONS: Many neurologic signs appear with aging that cannot be attributed to disease, even in the very old. Deficits in balance, olfaction, and visual pursuit discriminate best between the aging changes of the healthy very old and changes seen in younger elderly persons.

Aged↗
PubMed1993

Neurologic function in the optimally healthy oldest old. Neuropsychological evaluation.

We examined cognition on a wide range of standardized neuropsychological tests in two groups of optimally healthy, elderly volunteers. One was composed of community-dwelling, functionally independent individuals aged 84 years and older, and the other group was nearly 20 years younger. The effect of aging was greatest on visual perceptual and constructional tasks rather than on memory tasks. Many cognitive functions were relatively well preserved in the optimally healthy oldest old.

Aged↗
PubMed1986

Therapeutic efficacy of multiagent chemotherapy with drug delivery enhancement by blood-brain barrier modification in glioblastoma.

Reversible osmotic blood-brain barrier (BBB) modification was used in 38 patients with glioblastoma to enhance the delivery of chemotherapeutic agents. The patients ranged in age from 14 to 70 years (mean, 43), and all had prior surgery and radiation; 5 had also received systemic chemotherapy. Karnofsky Performance Status (KPS) scores ranged from 60 to 100% (mean, 79) on admission to the treatment program. Barrier modification was achieved by intracarotid or intravertebral artery infusion of mannitol, and a chemotherapy regimen of methotrexate, cytoxan, and procarbazine was given in conjunction with barrier modification. The 38 glioblastoma patients were compared to two control groups of patients with glioblastoma; these encompassed 14 patients treated with surgery and radiation and 8 treated with surgery, radiation, and systemic chemotherapy. Survival analysis using the Cox Proportional Hazards Regression Model (corrected for age, sex, presence or absence of necrosis, and functional status) showed that patients receiving chemotherapy with BBB modification had a statistically significant (P = 0.0006) longer expected survival (17.5 months) than the control groups (12.8 and 11.4 months, respectively). Presently 16 patients of the barrier-enhanced treatment group are alive at 5 to 42 months from diagnosis (median, 20) with KPS scores ranging from 40 to 90% (median, 65). The neurological complications seen included a stroke-like syndrome in 3 patients (1 with decreased motor movement in the hand, 1 with marked hemiparesis, and 1 with hemiplegia), transient exacerbation of preexisting neurological deficits lasting 2 to 3 days, and a 15% incidence of seizures during or within 24 hours of the BBB modification. In 2 of the 38 patients, radiographic documentation of central nervous system tumor regression concurrent with the development of new tumor nodule(s) in portions of the brain distant from the region of osmotic BBB opening was seen. These studies indicate that chemotherapeutic drug delivery to tumors (as well as surrounding brain) can be augmented by osmotic BBB modification and that such therapy can result in a prolongation of survival.

Adult↗
PubMed1985

Late stenosis of a superficial temporal-middle cerebral artery bypass: angiographic and histological findings.

The course of a patient with an initially widely patent superficial temporal artery-middle cerebral artery (STA-MCA) bypass and an enlarged donor vessel is presented. Over 17 months, the STA became markedly stenotic. Serial angiography is correlated with autopsy histological findings showing severe atherosclerotic changes throughout the donor vessel. The potential causative factors, both medical and surgical, are discussed and the appropriate literature is reviewed. Parallels are drawn from the cardiac bypass experience. The bypass itself may have precipitated or accelerated intimal hyperplasia, which stenosed (and may have eventually occluded) the vessel. Is this phenomenon more frequent than we realize?

Cerebral Angiography↗
PubMed1983

Acoustic tumors: atypical features and recent diagnostic tests.

About one-third of patients with acoustic tumor (AT) initially seek medical attention for nonaudiologic complaints. The nonspecific early symptoms of AT require the inclusion of AT in many neurologic differential diagnoses. Advances in electrophysiologic and radiographic tests have allowed earlier diagnosis of AT at a time when abnormal physical findings other than hearing loss are present in less than half of patients. The availability of brainstem auditory evoked response testing, fourth-generation CT, and air-CT cisternography have changed the approach to the diagnosis of AT. Neurologists should be cognizant of recent diagnostic advances.

Brain Stem↗
PubMed1983

Osmotic blood-brain barrier modification: clinical documentation by enhanced CT scanning and/or radionuclide brain scanning.

Results of initial clinical trials of brain tumor chemotherapy after osmotic blood-brain barrier disruption are promising. In general, the procedure is well tolerated. The major complication has been seizures. In this report, data are presented which indicate that the etiology of these seizures is related to the use of contrast agent (meglumine iothalamate) to monitor barrier modification. A series of 19 patients underwent a total of 85 barrier modification procedures. Documentation of barrier disruption was monitored by contrast-enhanced computed tomographic (CT) scanning, radionuclide brain scanning, or a combination of both techniques. In 56 procedures (19 patients) monitored by enhanced CT, seizures occurred a total of 10 times in eight patients. Twenty-three barrier modification procedures (in nine of these 19 patients) documented by nuclear brain scans alone, however, resulted in only one focal motor seizure in each of two patients. In eight of the 19 patients who had seizures after barrier disruption and enhanced CT scan, four subsequently had repeat procedures monitored by radionuclide scan alone. In only one of these patients was further seizure activity noted; a single focal motor seizure was observed. Clearly, the radionuclide brain scan does not have the sensitivity and spatial resolution of enhanced CT, but at present it appears safer to monitor barrier modification by this method and to follow tumor growth between barrier modifications by enhanced CT. Four illustrative cases showing methods, problems, and promising results are presented.

Adult↗
PubMed1982

[EEG in newborn infants with intracranial hemorrhages: a comparison with clinical findings and CT scan].

This study was undertaken to evaluate the usefulness of the EEG in neonates with intracranial hemorrhage (ICH) and to correlate the EEG with clinical findings and the CT-scan. Thirty-eight infants with intraventricular hemorrhage (IVH) and/or subarachnoid hemorrhage (SAH) had EEG examinations. Repetitive sharp waves were present in IVH (48%) and also seen in SAH (33%). They did not differentiate between IVH and SAH, nor were they related to the grade of IVH. The repetitive character of these wave forms suggest that it may be a type of seizure discharge. The value of the EEG in neonatal ICH lies not in the diagnosis of ICH and its extend. This can be done much better with CT-scan and ultrasound. But the EEG is valuable in the recognition of electrical seizure activity which should lead to early anticonvulsive therapy. Depressed background EEG activity was seen in all non-survivors and in all children with major neurological damage. Normal background activity in spite of seizure discharge was favorable prognostic criterion. The prognosis depends on the gestational age, clinical findings and morphological changes. The EEG reflects the actual cerebral function and can add to a more differentiated prognostic evaluation.

Brain Damage, Chronic↗
PubMed1981

CT scans of long-term survivors of various childhood malignancies.

Forty-two children with various systemic malignancies in continuous remission for 1 to 3 years after the completion of chemotherapy had CT scans with normal ventricular dimensions, similar to a noncancer "control" population. Seventeen of these patients had acute lymphocytic leukemia (ALL) treated either with prophylactic cranial irradiation and intrathecal methotrexate [7] or intrathecal methotrexate alone [10] and the remaining 25 patients had soft tissue sarcomas. Sixteen other patients with sarcomatous meningitis had enlarged ventricles while on chemotherapy. Nine had ALL. Seven had soft tissue sarcomas, none of whom received any prior CNS irradiation or intrathecal chemotherapy. In this retrospective study no evidence of hydrocephalus or significant white matter hypodensity was detected in long-term survivors of childhood cancer, regardless of whether prophylactic intrathecal chemotherapy and/or cranial irradiation was given. Direct involvement of the CNS with meningeal cancer was the most important association with ventriculomegaly.

Adolescent↗
PubMed1978

Normal CAT scans in craniopharyngioma.

Three patients with symptoms of headache and vision loss had normal routine CAT scans, with and without injection of contrast medium, as their initial diagnostic procedure. Subsequent pneumoencephalography revealed large suprasellar masses, which at operation were found to be partially cystic craniopharyngiomas. The findings emphasize the existence of craniopharyngiomas that are isodense with brain and may not be detected on routine CAT scan. When a patient's clinical presentation suggests chiasmal or sellar abnormalities, the pneumoencephalogram remains the most accurate diagnostic procedure.

Adult↗
PubMed1977

Long-term therapy of myoclonus and other neurologic disorders with L-5-hydroxytryptophan and carbidopa.

We evaluated the therapeutic effect of L-5-hydroxytryptophan (L-5HTP), the precursor of serotonin (5-hydroxytryptamine), combined with carbidopa, a peripheral decarboxylase inhibitor, in patients with intention myoclonus and examined the serotonin metabolites in spinal fluid, blood and urine before and during therapy. In 18 patients with intention myoclonus due to anoxia or other brain damage, 11 derived more than 50% overall improvement during treatment with L-5HTP and carbidopa. Spinal-fluid 5-hydroxyindoleacetic acid was 35% lower in patients with intention myoclonus than in controls (P less than 0.05). Therapy with L-5HTP and carbidopa increased the concentration of serotonin metabolites in urine and spinal fluid. We postulate that a deficiency of brain serotonin is causally related to intention myoclonus and that the therapeutic effect of L-5HTP and carbidopa may be due to the repletion of serotonin in regions of the brain where serotoninergic neurons have degenerated.

5-Hydroxytryptophan↗
PubMed1977

"Disappearing" spinal cord compression: oncolytic effect of glucocorticoids (and other chemotherapeutic agents) on epidural metastases.

Four patients suffering spinal cord compression resulting from epidural metastases were treated with adrenocorticosteroid hormones. For 2 patients, prompt relief of symptoms followed glucocorticoid therapy alone and was associated with marked shrinkage or disappearance of the metastasis, a direct oncolytic effect of the steroids. For the other 2 patients, glucocorticoids combined with other chemotherapeutic agents caused disappearance of the extradural tumor. For 1 patient, failure to recognize the oncolytic effects of the chemotherapy led to an unnecessary surgical procedure, and for a second patient an unnecessary operation was narrowly averted. Thus, for certain patients, glucocorticoids may occasionally have a marked oncolytic effect on epidural metastatic tumors.

Adolescent↗
PubMed1977

The rate of CSF formation in man: preliminary observations on metrizamide washout as a measure of CSF bulk flow.

Metrizamide, a nonionic, water-soluble contrast agent, was injected into the ventricular system of 3 patients with indwelling ventricular catheters and subcutaneous cerebrospinal fluid reservoirs. A first-order rate constant, k, for metrizamide washout from the right lateral ventricle was determined with reference to mean ventricular metrizamide concentration on serial CAT scans; right ventricular volume, V, was estimated after metrizamide injection by multiplying the appropriate ventricular area on consecutive CAT slices by the nominal slice thickness. The rate of right lateral ventricular CSF formation, If, in our 3 patients was calculated as k X V and ranged from 0.083 to 0.103 ml per minute.

Adult↗