PubMed Health⌕ Search

Biomedical subjects

F W Sharbrough

Publications and source records attributed to F W Sharbrough.

At least 19 recordsLinked to original sources
PubMed1992

Magnetic resonance image-based hippocampal volumetry: correlation with outcome after temporal lobectomy.

We developed a magnetic resonance imaging (MRI)-based technique for measuring the volume of the hippocampal formation. In this study, the relationship between volumes of the hippocampal formation and outcome (i.e., postoperative seizure control) after anterior temporal lobectomy for intractable epilepsy was analyzed in 50 consecutive patients in whom the surgical specimen did not contain an epileptogenic mass lesion. Outcome was classified as either satisfactory or unsatisfactory. A significant relationship was found between outcome and volume of the operated hippocampal formation (p = 0.012), as well as a derived volumetric measure (nonoperated minus operated volume of the hippocampal formation) (p = 0.004). The association between outcome and nonoperated volume was borderline (p = 0.057). Thirty-four (97%) of 35 patients in whom the volumetric study and electroencephalography (EEG) concordantly lateralized the seizure disorder had satisfactory postoperative seizure control. Conversely, only 7 (42%) of 12 patients in whom the volume study was nonlateralizing and 1 (33%) of 3 in whom the EEG and volume study were discordant has a satisfactory outcome. We regard our MRI-based study of hippocampal formation volume as a noninvasive surrogate for the identification of moderate or severe mesial temporal sclerosis. The technique is a useful adjunct in a multidisciplinary, preoperative epilepsy evaluation when T2-weighted MRIs do not reveal an epileptogenic mass lesion. The reasons for the usefulness of this imaging technique are: (1) It is an independent source of information on seizure lateralization, (2) it will provide information as to expected postoperative outcome, and (3) it may aid in appropriately selecting patients for invasive preoperative monitoring studies.

Adult↗
PubMed1992

MRI in the presurgical evaluation of patients with frontal lobe epilepsy and children with temporal lobe epilepsy: pathologic correlation and prognostic importance.

We performed magnetic resonance imaging (MRI) using a high-field strength magnet (1.5 T) in two series of 53 patients with intractable partial epilepsy of frontal lobe or temporal lobe origin who subsequently received ablative surgery for their seizure disorder. In the first series of patients the pathologic correlation and prognostic importance of an MRI-identified lesion in the frontal lobe were assessed. Twenty-five percent of the patients with negative MRI studies and 67% of patients with neuroimaging abnormalities restricted to the frontal lobe, were seizure-free at a minimum duration of follow-up of 1 year. None of the patients with a multilobar MRI-detected abnormality was seizure-free postoperatively. In the second study the sensitivity and specificity of MRI-based hippocampal volumetry was determined in pediatric patients with partial epilepsy of temporal lobe origin unrelated to foreign-tissue pathology. Hippocampal formation atrophy in the epileptic temporal lobe was identified in 63% of patients. The sensitivity and specificity of hippocampal volumetry was 100% in patients with mesial temporal sclerosis. The presence of an MRI-detected epileptogenic lesion in the frontal lobe and hippocampal formation atrophy in the temporal lobe may correlate with the underlying pathology and affect the identification of potential candidates for epilepsy surgery.

Adolescent↗
PubMed1992

Surgical outcome in computer-assisted stereotactic resection of intra-axial cerebral lesions for partial epilepsy.

A retrospective analysis was performed in 30 patients who underwent computer-assisted stereotactic resection of intra-axial mass lesions with intractable partial epilepsy. Mean follow-up was 4.1 years (2-5.5), mean age 21 years (3-45) and mean duration of seizures 8.4 years (1-26). Pathology consisted of vascular malformations in 11, glial neoplasms in 11, cortical dysplasia in 4 and gliosis in 3, and no diagnostic abnormality was found in 2 patients. The location of the lesions in some cases may have precluded a standard craniotomy and cortical resection, e.g. precentral gyrus (5), post-central gyrus (5) and deep-seated left posterior temporal region (4). Operative morbidity involved 3 patients who developed motor or language deficits. Four patients were lost to follow-up. Thirteen patients out of 26 (50%) were class I, 3 (12%) were class II, 4 (15%) were class III and 6 (23%) were class IV. These findings suggest that stereotactic lesion resection in selected cases (e.g. where lesions are located in eloquent brain regions) can be useful in providing a histological diagnosis of the epileptogenic foci and result in a favorable reduction in seizure activity without the need for a standard cortical resection.

Adult↗
PubMed1992

Identification of the epileptic focus: magnetic resonance imaging.

Magnetic resonance imaging (MRI) is the most sensitive and specific structural imaging technique available to demonstrate focal epileptogenic lesions in patients with intractable partial epilepsy. MRI may be useful in the selection of candidates for surgical treatment of epilepsy. The studies may also assist in the implantation of depth electrodes and in the stereotactic resection of epileptogenic lesions. More recent applications of this neuroimaging modality in the surgical treatment of epilepsy include pre-operative hippocampal formation of volume measurements and postoperative quantitative determinations of cortical resections.

Brain↗
PubMed1979

Stimulus-induced EEG complexes and motor spasms in subacute sclerosing panencephalitis.

Patients with subacute sclerosing panencephalitis (SSPE) typically present with spontaneous periodic, stereotyped electroencephalographic (EEG) complexes and motor spasms, which are not usually affected by sensory stimuli. This report describes two patients with SSPE in whom the EEG complexes and the motor movements occurred mainly in response to afferent stimuli. Various forms of stimuli were effective in precipitating the movements and EEG complexes, particularly when the stimulus was unexpected or startled the patient. During sleep, the EEG complexes spontaneously occurred in a more periodic fashion, typical of SSPE, but afferent stimuli were still effective in evoking the EEG complexes and associated motor spasms.

Adolescent↗
PubMed1978

Effects of hypothermia on the human brainstem auditory response.

Latency measurements between three potentials (waves I, III, and IV/V) of the human brainstem auditory response can allow early detection of certain posterior fossa lesions. The diagnostic use of these interwave latencies requires knowledge of what factors may prolong them in the absence of disease. Hypothermia appears to be one such factor--in 5 neurologically and audiometrically normal patients, mean esophageal temperatures as high as 34.5 degrees C resulted in prolongations of central auditory conduction time. Interwave latency prolongations that were abnormal relative to an age-matched normal population were seen at 32.1 degrees +/- 0.3 degrees C in patients with both spontaneous and induced hypothermia, and these abnormalities disappeared after rewarming to normothermia. Hypothermia often accompanies intoxication and coma and should therefore be considered when brainstem auditory response abnormalities are being interpreted in these two clinical conditions.

Adult↗
PubMed1978

Movement-activated central fast rhythms: an EEG finding in action myoclonus.

Five patients with relatively mild but disabling action myoclonus displayed a subtle and heretofore unemphasized electroencephalographic manifestation of action myoclonus consisting of low-voltage, central fast activity somatotopically related to the extremity being used. The importance of recognizing this rhythm lies in its association with milder forms of action myoclonus which resemble other types of movement disorders, the difficulty in recognizing this rhythm unless special tests are carried out, and the beneficial response of anticonvulsant therapy if the nature of the movement is realized.

Adolescent↗
PubMed1977

Anterior shift of the dominant EEG rhytham during anesthesia in the Java monkey: correlation with anesthetic potency.

EEG amplitude dominance in awake man is posterior. During EEG monitoring in patients, the authors observed the abrupt appearance of anterior amplitude dominance during induction of anesthesia with halothane, enflurane, or thiopental. This EEG change is coincident with loss of eyelid reflex and loss of ability to respond to command. This EEG change was studied with several anesthetics in five Java monkeys to determine alveolar anesthetic concentration at which it occurred and to observe the effects of various stimuli on it. EEG recordings were obtained after equilibration at each level with increasing concentrations of halothane, enflurane or isoflurane in oxygen and each agent again in 30 per cent N2O, in separate experiments in the same animals. EEG amplitude dominance became anterior in each animal with each anesthetic and combination at concentrations less than MAC, which was also determined in the same experiments. At lower concentrations, stimulation at equilibrated anesthetic concentrations resulted in abrupt EEG return to posterior amplitude dominance. The end-tidal anesthetic concentration at which persistence of anterior EEG dominance was seen after stimulation was approximately 0.4 MAC for each anesthetic and combination tested. This is interpreted as support for physical solution-lipid solubility theories of anesthetic action. In addition, an EEG change common to various anesthetics may increase the clinical usefulness of EEG monitoring. It is speculated that this EEG change may signal loss of awareness. If so, observance of sustained anterior EEG amplitude dominance may provide assurance of obliteration of awareness during anesthesia.

Anesthetics↗
PubMed1977

Physiological considerations important for the management of vasospasm.

The physiological mechanisms of known importance in the control of cerebral blood flow (CBF) and smooth muscle contraction and relaxation are reviewed. The pathophysiology of vasospasm following subarachnoid hemorrhage (SAH) is correlated with an alteration of these mechanisms. It is emphasized that smooth muscle relaxation is an energy-dependent process and that vasodilators require a functional smooth muscle membrane that may be severely impaired in ischemia or subarachnoid hemorrhage. The temporal profile of ischemia from spasm is correlated with the pathophysiology of altered metabolism of smooth muscle. The relevance of this complication to the timing of aneurysm surgery in 337 cases operated by one surgeon is considered along with various drug regimens suggested for its management.

Albuterol↗
PubMed1977

Carotid endarterectomy: results, complications, and monitoring techniques.

A system of grouping patients according to preoperative evaluation of risk of carotid endaterectomy is presented. The primary complications of this surgical procedure were myocardial infarction and residual mild to severe neurologic deficit. Neurologically stable patients without medical or angiographically determined risk factors (group 1) have a risk of 1%. Neurologically stable patients without medical risk but with angiographically determined risks (group 2) have a risk of 2%. Neurologically stable patients with significant medical illness and with or without angiographically determined risks (group 3) have a risk of 7%, primarily related to cardiac disease. Neurologically unstable patients (group 4) have a 6% risk for a neurologic deficit. Current monitoring techniques using continuous electroencephalograms, cerebral blood flow measurements, and arterial stump pressure are considered. The prevention and management of complications are presented in some detail.

Adenosine Triphosphate↗
PubMed1977

Detection and localization of occult lesions with brainstem auditory responses.

Seven vertex-positive potentials--the brainstem auditory response--can be recorded from the human scalp within 10 milliseconds of an appropriate acoustic stimulus. The first of these potentials is generated in the acoustic nerve, the third in the pons, and the fifth in the midbrain. Measurement of the relative latencies and amplitudes of these potentials allowed detection of subclinical lesions in 37 (53 percent) of 70 patients with suspected multiple sclerosis who had no signs or symptoms of brainstem involvement by the disease. Abnormalities in the brainstem auditory response provided the first evidence of the pressence of multiple lesions in 14 (35 percent) of 40 patients with suspected multiple sclerosis who had clinical evidence of only a single spinal or cerebral lesion. Response abnormalities also suggested the presence of tumors of the posterior fossa in three patients with nonspecific symptoms and normal neurologic examinations, the test indicated the need for contrast studies, which then led to the correct diagnosis of infratentorial neoplasm.

Acoustic Stimulation↗
PubMed1976

Internal carotid artery stump pressure and cerebral blood flow during carotid endarterectomy: modification by halothane, enflurane, and innovar.

Carotid endarterectomy requires temporary surgical occlusion of the involved carotid artery. During occlusion, the minimally acceptable (critical) internal carotid artery stump pressure is reported to be 50 torr, whereas for regional cerebral blood flow (rCBF), a critical range is reported to be 18-24 ml/100 g/min. During 90 carotid endarterectomies, rCBF and stump pressure were measured and the EEG continuously monitored. A positive correlation between rCBF and stump pressure (i.e., when both were either above or below their respective critical values) was observed in only 58 per cent of the cases. In 28 per cent stump pressures of less than 50 torr were observed despite rCBF's above 24 ml/100 g/min and normal EEG's. In 8 per cent stump pressures were more than 50 torr but rCBF's were less than 18 ml/100 g/min and EEG changes of ischemia were commonly observed. In the remaining 6 per cent rCBF's were marginal (18-24 ml/100 g/min) while stump pressures were more than 50 torr and EEG changes were not observed. The relationship between stump pressure and rCBF was influenced by the anesthetic. In the absence of transient ischemia during occlusion (that is, rCBF greater than 18 ml/100 g/min), halothane and enflurane anesthesia were associated with significantly higher rCBF's and lower stump pressures than was neuroleptanesthesia. Pre-occlusion and post-occlusion rCBF measurements also demonstrated cerebral vasodilation by halothane and enflurane (halothane greater than enflurane) and vasoconstriction by neuroleptanesthesia. It is concluded that stump pressure is an unreliable index of CBF during carotid occlusion and that its relationship to CBF is considerably influenced by the anesthetic.

Blood Flow Velocity↗
PubMed1976

Electroencephalographic evaluation in Sturge-Weber syndrome.

The most consistent electroencephalographic finding in 16 cases of Sturge-Weber syndrome was a unilateral reduction of background amplitude in the waking record. Comparable asymmetries were noted in those patients in whom sleep recording also was done. Physiologic responses (to hyperventilation and photic driving) usually were decreased on the involved side. These hemispheric electroencephalographic abnormalities are detectable in infancy even before the characteristic intracranial calification develops. Epileptiform activity, when focal, was limited to the involved hemisphere.

Adolescent↗