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Biomedical subjects

W Logan

Publications and source records attributed to W Logan.

At least 19 recordsLinked to original sources
PubMed2005

Comparing language lateralization determined by dichotic listening and fMRI activation in frontal and temporal lobes in children with epilepsy.

We investigated the relationship between ear advantage scores on the Fused Dichotic Words Test (FDWT), and laterality of activation in fMRI using a verb generation paradigm in fourteen children with epilepsy. The magnitude of the laterality index (LI), based on spatial extent and magnitude of activation in classical language areas (BA 44/45, 21/22, 39) differed significantly for patients classified with unilateral left, compared to bilateral, language representation based on FDWT scores. Concordance with fMRI was higher for those classified with unilateral left, than bilateral language representation on the FDWT. Of note, asymmetry in temporal lobe, rather than frontal lobe, activation was more strongly related to the LI from the dichotic listening test. This study shows that the FDWT can provide a quick and valid estimate of lateralization in pre-surgical candidates, which can be readily adopted for other clinical or research purposes when an estimate of language dominance is desired.

Brain Mapping↗
PubMed1997

Combined utility of functional MRI, cortical mapping, and frameless stereotaxy in the resection of lesions in eloquent areas of brain in children.

We studied 16 children with lesions in the eloquent brain to determine if the amalgamation of information from functional magnetic resonance imaging (fMRI), frameless stereotaxy, and direct cortical mapping and recording could facilitate the excision of these lesions while minimizing potential neurological deficits. The mean age of the children was 10 years. Fourteen children presented with seizures. All lesions were located in or near eloquent cerebral cortex. fMRI was successful in all patients in delineating the relationship between the lesion and regions of task-activated cortex. The ISG wand was utilized in all cases for scalp and bone flap placement, and for intraoperative localization of the lesion. Direct cortical stimulation or recording of phase reversals with somatosensory evoked potentials helped delineate the central sulcus and language cortex in patients with lesions near the motor or language cortex. Intraoperative electrocorticography (ECoG) was utilized in all patients who presented with seizures to guide the extent of resection of the epileptiform cortex. Ten children had benign cerebral neoplasms, nine of which were totally resected. The other diagnoses included vascular malformations, Sturge-Weber, tuberous sclerosis, Rasmussen's encephalitis, and primitive neuroectodermal tumor. Only 1 patient with a left Rolandic AVM developed a new neurological deficit postoperatively. Thirteen of fourteen patients who presented with seizure disorders were rendered either seizure free or improved in terms of seizure control postoperatively. Follow-up has ranged from 12 to 18 months, with a mean follow-up of 15 months. We conclude that the techniques of fMRI, frameless stereotaxy, direct cortical stimulation and recording can be utilized in sequence to accurately localize intracerebral lesions in eloquent brain, and to reduce the morbidity of resecting these lesions in children.

Adolescent↗
PubMed1986

Visual and auditory neurotoxicity in patients receiving subcutaneous deferoxamine infusions.

Of 89 patients receiving nightly subcutaneous deferoxamine for transfusion-dependent thalassemia major or Diamond-Blackfan anemia, 13 presented with visual loss or deafness of acute onset or both. Detailed ophthalmologic, audiologic, and evoked-potential studies uncovered abnormalities caused by neurotoxicity in 27 more. Four patients with visual loss had optic neuropathy, with a marked decrease in acuity, loss of color vision, and delayed visual evoked potentials. Five asymptomatic patients had changes in the pigment of the retinal epithelium. The hearing loss was characterized by a high-frequency sensorineural deficit, which necessitated hearing aids in six patients. When deferoxamine was stopped, recovery of vision was complete in 2 patients and partial in 2, and in 22 patients with abnormal audiograms, reversal of the hearing deficit was complete in 4 and partial in 1. An analysis of the clinical data showed that members of the affected group were younger, had lower serum ferritin values, and were self-administering higher doses of deferoxamine per kilogram of body weight. Significantly lower doses of deferoxamine were being taken by patients without abnormalities than by those with visual symptoms, abnormal audiograms, or prolonged evoked potentials (P less than 0.001, less than 0.006, and less than 0.04, respectively). The data implicate high-dose deferoxamine as a central factor in the pathogenesis of the neurotoxicity. We strongly recommend careful regulation of the deferoxamine dosage and serial audiovisual monitoring in all patients receiving the drug.

Adolescent↗
PubMed1984

Carotid and coronary arterial disease. A rational approach.

One hundred thirty-four patients referred for myocardial revascularization had oculoplethysmography/carotid phonoangiography (OPG/CPA) evaluations as a screening test for possible carotid arterial disease. On the basis of preoperative neurologic symptoms or hemodynamically positive OPG/CPA studies, 52 patients had carotid arteriography. Forty-six patients with coexistent carotid and coronary arterial occlusive disease were identified. Twenty-nine had a previous history of central nervous system (CNS) dysfunction, while ten patients (20%) were asymptomatic. Twenty-two patients had "staged" coronary artery bypass grafts (CABG) and carotid endarterectomy (CE) procedures, while 24 had simultaneous CABG/CE. Of the staged patients, one fatal myocardial infarction occurred after CE but prior to CABG; two patients experienced neurologic deficits after CABG yet prior to CE. Twenty-four patients had simultaneous CE/CABG, and no cardiac or neurologic complications occurred. All patients undergoing cardiovascular surgery should have preoperative noninvasive carotid screening studies performed. If OPG/CPA studies indicate a hemodynamically significant lesion, arteriography is indicated. When OPG/CPA studies are negative, yet a history consistent with previous CNS dysfunction is present, a digital intravenous arteriogram is performed. In the presence of coexistence severe coronary and extracranial carotid stenotic or ulcerative plaque disease, simultaneous CE/CABG is advocated.

Arterial Occlusive Diseases↗
PubMed1983

Methylphenidate hydrochloride given with or before breakfast: II. Effects on plasma concentration of methylphenidate and ritalinic acid.

Methylphenidate HCl (Ritalin) is often prescribed for the treatment of hyperactivity and is usually administered orally 30 minutes to 1 hour before meals, based on an assumption that meals may interfere with the absorption or metabolism of the drug. Seven boys who were taking methylphenidate regularly for the treatment of hyperactivity were hospitalized and given their established dose of the drug intravenously or orally, either with breakfast or in a fasted state. Blood samples were taken to determine the pharmacokinetics of the drug in each condition. Few differences between the "fed" and "fasted" states were noted, but the statistically significant differences indicated that meals accelerate rather than impede the absorption of methylphenidate.

Adolescent↗
PubMed1982

Screening for breast cancer in a high-risk series.

A unique cohort of women at increased risk of breast cancer because of prior X-ray treatment of acute mastitis and their selected high-risk siblings were offered periodic breast cancer screening including physical examination of the breasts, mammography, and thermography. Twelve breast cancers were detected when fewer than four would have been expected based on age-specific breast cancer detection rates from the National Cancer Institute/American Cancer Society Breast Cancer Demonstration Detection Projects. Mammography was positive in all cases but physical examination was positive in only three cases. Thermography was an unreliable indicator of disease. Given the concern over radiation-induced risk, use of low-dose technique and of criteria for participation that select women at high risk of breast cancer will maximize the benefit/risk ratio for mammography screening.

Adult↗