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Biomedical subjects

I A Awad

Publications and source records attributed to I A Awad.

At least 109 records · Page 6Linked to original sources
PubMed1990

Intracranial dural arteriovenous malformations: factors predisposing to an aggressive neurological course.

The natural history of cranial dural arteriovenous malformations (AVM's) is highly variable. The authors present their clinical experience with 17 dural AVM's in adults, including 10 cases with an aggressive neurological course (strictly defined as hemorrhage or progressive focal neurological deficit other than ophthalmoplegia). Two of these 10 patients died prior to surgical intervention and a third was severely disabled by intracerebral hemorrhage. Six patients underwent surgical resection of their dural AVM, with preparatory embolization in two cases. One patient received embolization and radiation therapy without surgery. Six of the seven cases without an aggressive neurological course were treated conservatively, and the seventh patient underwent embolization of a cavernous sinus dural AVM because of worsening ophthalmoplegia. In order to clarify features associated with aggressive behavior, a comprehensive meta-analysis was performed on 360 additional dural AVM's reported in the literature with sufficiently detailed clinical and angiographic information. The location and angiographic features of 100 aggressive cases were compared to those of 277 benign cases. No location of dural AVM's was immune from aggressive neurological behavior; however, an aggressive neurological course was least often associated with cases involving the transverse-sigmoid sinuses and cavernous sinus and most often associated with cases at the tentorial incisura. Contralateral contribution to arterial supply and rate of shunting (high vs. low flow) did not correlate with aggressive neurological behavior as defined. Leptomeningeal venous drainage, variceal or aneurysmal venous dilations, and galenic drainage correlated significantly (p less than 0.05) with aggressive neurological presentation. The latter three angiographic features often coexisted in the same dural AVM. It is concluded that these features significantly increase the natural risk of dural AVM's, and warrant a more vigilant therapeutic strategy.

Adult↗
PubMed1990

Vascular pressures and cortical blood flow in cavernous angioma of the brain.

This study was designed to investigate the hemodynamic characteristics of cavernous angiomas of the brain. Five adult patients with a cavernous angioma underwent local cortical blood flow studies and vascular pressure measurements during surgery for the excision of the cavernous angioma. Clinical presentation included headache in four patients, seizures in four patients, and recurring diplopia in one patient. Magnetic resonance imaging demonstrated the cavernous angiomas in all patients and revealed an associated small hematoma in two. Four patients with a cerebral cavernous angioma were operated on in the supine position and the remaining patient, whose lesion involved the brain stem, was operated on in the sitting position. Mean local cortical blood flow (+/- standard error of the mean) in the cerebral cortex adjacent to the lesion was 60.5 +/- 8.3 ml/100 gm/min at a mean PaCO2 of 35.0 +/- 0.6 torr. Mean CO2 reactivity was 1.1 +/- 0.2 ml/100 gm/min/torr. The local cortical blood flow results were similar to established normal control findings. Mean pressure within the lesion in the patients undergoing surgery while supine was 38.2 +/- 0.5 mm Hg; a slight decline in cavernous angioma pressure occurred with a drop in mean systemic arterial blood pressure and PaCO2. Mean pressure in the cavernous angioma in the patient operated on in the sitting position was 7 mm Hg. Jugular compression resulted in a 9-mm Hg rise in cavernous angioma pressure in one supine patient but no change in the patient in the sitting position. Direct microscopic observation revealed slow circulation within the lesions. The hemodynamic features demonstrated in this study indicate that cavernous angiomas are relatively passive vascular anomalies that are unlikely to produce ischemia in adjacent brain. Frank hemorrhage would be expected to be self-limiting because of relatively low driving pressures.

Adult↗
PubMed1989

Internal carotid artery occlusion for cavernous segment aneurysm.

We review our recent experience with occlusion of the cervical internal carotid artery (ICA) in 15 patients with symptomatic aneurysms of the cavernous segment. All the patients were women and ranged in age from 38 to 74 years. Ten patients sought treatment initially for ophthalmoplegia, 9 for retro-orbital pain, 8 for facial paresthesia, and 3 for loss of vision. Two patients had symptoms of transient ocular or brain ischemia. The diameter of the aneurysm was greater than 3 cm in 10 patients. Ten patients underwent gradual occlusion of the ICA by Selverstone clamp under anticoagulation and monitoring of neurological status. One patient underwent ligation of a severely stenotic ICA under general anesthesia and electroencephalographic monitoring. Four patients underwent trapping of the aneurysm (after attempts at direct obliteration) under electroencephalographic and cerebral blood flow monitoring. Two patients with incompetent circle of Willis collaterals underwent prophylactic superficial temporal artery to middle cerebral artery bypass surgery prior to ICA occlusion. There was no postoperative clinical change in 9 patients. Ophthalmoplegia improved in 2 patients, and facial pain improved in 3. Three patients developed new extraocular muscle palsies within hours of ICA occlusion; these resolved in all patients by 1 week postoperatively. No change in aneurysm size was documented by serial postoperative computed tomographic or magnetic resonance imaging scans. After a follow-up of 5 to 6 years (range, 6 months-9 years), 11 patients have remained neurologically stable. Two patients experienced delayed transient worsening of visual or facial symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Patch angioplasty in carotid endarterectomy. Advantages, concerns, and controversies.

There is much controversy in the literature regarding the precise role of patch angioplasty in carotid endarterectomy. Our report summarizes the theoretical and experimental considerations, including the hemodynamic effects and biologic behavior of the graft, associated with this technique. We present a detailed review of the literature regarding the clinical efficacy of patch angioplasty in carotid endarterectomy, including the early results, the late results, and the incidence and nature of carotid restenosis. We address concerns about the use of patch angioplasty, including the duration of cross-clamping, potential problems with the graft and suture-line disruption, and graft atherogenesis. We conclude that most recent literature indicates that patch angioplasty decreases acute complications (notably carotid occlusion) after carotid endarterectomy and prevents or delays carotid restenosis. As pressure increases to achieve a minimal rate of perioperative morbidity, many surgeons are expected to adopt patch angioplasty in more of their cases. However, in the absence of conclusive results from a prospective randomized study, opinion will continue to be divided regarding the routine versus the selective use of patch grafting in carotid endarterectomy. We present criteria for randomized trials of this technique.

Animals↗
PubMed1989

Intracranial meningiomas in the aged: surgical outcome in the era of computed tomography.

Seventy-five patients older than 60 years of age underwent surgical resection of intracranial meningiomas during a 10-year period at a single institution. All patients had a computed tomographic scan preoperatively, and all were followed for at least 3 months postoperatively. There were 50 patients 61 to 70 years of age (Group A), and 25 patients older than 70 years (Group B). Sixteen patients (21%) were asymptomatic, and no patient was severely disabled preoperatively. Operative morbidity and mortality and outcome at 3 months were assessed and correlated with age, preoperative neurological status, and tumor size and location. Operative mortality was 6.6% (6% in Group A; 8% in Group B). Perioperative morbidity (including medical and surgical complications and worsening in neurological status) was 48% (46% in Group A; 52% in Group B). Neurological status 3 months after surgery was improved by at least one grade as compared to before surgery in 40% of patients (38% in Group A; 44% in Group B), unchanged in 29% (34% in Group A; 20% in Group B), and worsened in 31% (28% in Group A; 36% in Group B). While nearly half of the patients were asymptomatic 3 months after surgery, 11 patients (15%) had died or remained seriously disabled. Outcome at 3 months correlated significantly with low neurological grade preoperatively and with a tumor location over the cortical convexity. There was no significant correlation with age or tumor size. We conclude that resection of intracranial meningiomas is associated with significant morbidity and mortality in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Incidental lesions noted on magnetic resonance imaging of the brain: prevalence and clinical significance in various age groups.

With the advent of magnetic resonance imaging (MRI) of the brain, a large number of incidental lesions (ILs) are being identified. The prevalence and clinical significance of these ILs are not known. The MRI and clinical records of 86 consecutive patients who underwent technically satisfactory brain imaging at a large urban referral center were reviewed. Patients with definite or probably demyelinating disease were excluded. Incidental lesions were defined as parenchymal areas of increased signal intensity on T2-weighted imaging, which could not be directly explained by the patient's current clinical diagnosis, neurological status, or computed tomographic (CT) scan. The ILs were noted and graded according to size, multiplicity, and location and were correlated with age, clinical presentation, CT scan findings, and risk factors for cerebrovascular disease. One or more IL were identified in 22% of patients under 40 years of age, in 57% of patients 41 to 60 years of age, and in 90% of patients over 60 years of age. Large patches of confluent ILs were not encountered in any patient less than 40 years of age; they were present in 10% of patients 41 to 60 years of age, and in 30% of patients over 60 years of age. The incidence of severity of ILs correlated significantly with age (P less than 0.0005) and with risk factors for cerebrovascular disease (P less than 0.02). Patients with most severe ILs also had areas of vague periventricular leukomalacia on the CT scan. The clinical significance of incidental MRI lesions in various age groups is discussed in detail.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Extracranial-intracranial bypass surgery: a critical analysis in light of the International Cooperative Study.

The ability of extracranial-intracranial bypass surgery to alter favorably the natural history of ischemic cerebrovascular disease remains in question. A recently completed prospective randomized multicenter cooperative trial failed to confirm the hypothesis that the procedure prevents further cerebral ischemia in patients with atherosclerotic internal carotid artery or middle cerebral artery disease. We analyze findings of the study in detail, including possible effects on the natural history of the disease beyond the immediate perioperative period. Potential sources of bias that may have unpredictably affected the study are discussed. These include observational bias (patient and therapist not blinded), "randomization-to-treatment" bias (high morbidity after randomization but before operation), and "prerandomization" or allocation bias (patients in the study representing a selected sample of the population with cerebrovascular disease). The extensive analysis of secondary subgroups with small numbers of patients is discussed in light of the statistical methods used. Two particular classes of patients not addressed in the study who might benefit from the procedure are defined. They are patients failing the best available medical therapy and patients with clearly documented hemodynamic compromise. Possible indications for bypass surgery are suggested for the various lesions in light of the trial and of recent reports on the natural history and pathophysiology of ischemic cerebrovascular disease. Selected cases illustrating these indications are presented.

Adult↗
PubMedDate not supplied

Extent of resection in temporal lobectomy for epilepsy. I. Interobserver analysis and correlation with seizure outcome.

The extent of resection was assessed in 45 temporal lobectomies for medically intractable epilepsy with mapped temporal lobe foci. Postoperative magnetic resonance imaging (MRI) in the coronal plane was used to quantify the extent of resection of superior lateral, inferior lateral, basal, and medial structures, including the amygdalohippocampal complex. A new 20-compartment model of the temporal lobe was used for this assessment. Blinded interobserver variability was minimal. Intraoperative measurements and maps routinely overestimated the actual extent of resection, especially of medial structures. One year after surgery, 70% of patients remained seizure-free (except for auras). Seizure-free outcome was accomplished despite varying degrees of resection, but was more likely achieved with more extensive resections in all compartments. Among patients with mesiobasal foci, seizure-free outcome correlated significantly with extent of resection of amygdalohippocampal complex. We conclude that assessment of extent of resection by postoperative MRI provides an objective basis of evaluating outcome after temporal lobectomy. It allows a rational approach to understanding of operative failures and is potentially useful in comparing efficacy of various surgical approaches.

Epilepsy↗
PubMedDate not supplied

Extent of resection in temporal lobectomy for epilepsy. II. Memory changes and neurologic complications.

We present correlations of extent of temporal lobectomy for intractable epilepsy with postoperative memory changes (20 cases) and abnormalities of visual field and neurologic examination (45 cases). Postoperative magnetic resonance imaging (MRI) in the coronal plane was used to quantify anteroposterior extent of resection of various quadrants of the temporal lobe, using a 20-compartment model of that structure. The Wechsler Memory Scale-Revised (WMS-R) was administered preoperatively and postoperatively. Postoperative decrease in percentage of retention of verbal material correlated with extent of medial resection of left temporal lobe, whereas decrease in percentage of retention of visual material correlated with extent of medial resection of right temporal lobe. These correlations approached but did not reach statistical significance. Extent of resection correlated significantly with the presence of visual field defect on perimetry testing but not with severity, denseness, or congruity of the defect. There was no correlation between postoperative dysphasia and extent of resection in any quadrant. Assessment of extent of resection after temporal lobectomy allows a rational interpretation of postoperative neurologic deficits in light of functional anatomy of the temporal lobe.

Aphasia↗
PubMedDate not supplied

Intractable epilepsy and structural lesions of the brain: mapping, resection strategies, and seizure outcome.

Forty-seven patients with structural brain lesions on neuroimaging studies and partial epilepsy intractable to medical therapy were studied. Prolonged noninvasive interictal and ictal EEG recording was performed, followed by more focused mapping using chronically implanted subdural electrode plates. Surgical procedures included lesion biopsy, maximal lesion excision, and/or resection of zones of epileptogenesis depending on accessibility and involvement of speech or other functional areas. The epileptogenic zone involved exclusively the region adjacent to the structural lesion in 11 patients. It extended beyond the lesion in 18 patients. Eighteen other patients had remote noncontiguous zones of epileptogenesis. Postoperative control of epilepsy was accomplished in 17 of 18 patients (94%) with complete lesion excision regardless of extent of seizure focus excision. Postoperative control of epilepsy was accomplished in 5 of 6 patients (83%) with incomplete lesion excision but complete seizure focus excision and in 12 of 23 patients (52%) with incomplete lesion excision and incomplete focus excision. The extent of lesion resection was strongly associated with surgical outcome either in itself (p less than 0.003), or in combination with focus excision. Focus resection was marginally associated with surgical outcome as a dichotomous variable (p = 0.048) and showed a trend toward significance (p = 0.07) only as a three-level outcome variable. We conclude that structural lesions are associated with zones of epileptogenesis in neighboring and remote areas of the brain. Maximum resection of the lesion offers the best chance at controlling intractable epilepsy; however, seizure control is achieved in many patients by carefully planned subtotal resection of lesions or foci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Natural history of recurrent seizures after resective surgery for epilepsy.

Seizures persist or recur in 20-60% of patients after resective surgery for intractable partial epilepsy. Further information about the natural course of these seizures is lacking in the literature. During one decade of epilepsy surgery at a single institution, we identified 72 patients with recurrent postoperative seizures after resective procedures for epilepsy. Prospectively compiled seizure diaries, hospital records, and outpatient office records were reviewed and supplemented by telephone communications to assess subsequent seizure frequency. Follow-up data was available ranging from 6 months to 7 years 5 months (mean 3 years 5 months). The likelihood of persistent seizures and recurrent intractability was examined with life-tables. Seizures recurred within the first postoperative year in 86% of patients and were similar to preoperative events in 74% of patients. After the first seizure recurrence, there was 80% likelihood of persistent seizures in the next 6 years and 40% likelihood of intractability (more than one seizure a month despite optimal medical therapy). The interval until recurrence within the first postoperative year did not affect the likelihood of subsequent seizures or intractability. Late seizure recurrence (after the first year) was not associated with any instances of subsequent intractability. Recurrent seizures after extratemporal resections were more likely to become persistent and intractable than seizures recurring after temporal resections. This information provides rational prognostication and assists in counseling patients with recurrent seizures after resective surgery for intractable epilepsy.

Adolescent↗
PubMedDate not supplied

Differences of in vitro electrophysiology of hippocampal neurons from epileptic patients with mesiotemporal sclerosis versus structural lesions.

In vitro electrophysiologic studies of animal hippocampal slice models of epilepsy have generated hypotheses regarding cellular pathophysiologies associated with epileptogenesis. We tested some of these hypotheses using in vitro intracellular recordings of hippocampal neurons from patients with intractable temporal lobe epilepsy. We compared the electrophysiology of hippocampal neurons from 14 patients with mesiotemporal sclerosis with hippocampal neurons from 7 epileptic patients with structural lesions near the hippocampal biopsy. Both spontaneous and stimulus-evoked synaptic function and action potential firing patterns were observed. Presumed pyramidal neurons from sclerotic hippocampus were significantly less likely to display stimulus-evoked inhibitory postsynaptic potentials (IPSPs) and were more likely to fire spontaneously in bursts of action potentials than were hippocampal neurons from patients with structural lesions. No significant differences were detected in spontaneous postsynaptic potentials, spontaneous rhythmic synaptic events, spontaneous or anode break action potentials, stimulus-evoked excitatory postsynaptic potentials, or stimulus-evoked action potential bursts. Cellular membrane parameters were similar in the two groups, including resting membrane potential, action potential amplitude, action potential half-width, action potential threshold, input resistance, time constant, input/output relationship, and afterhyperpolarization amplitude.

Action Potentials↗
PubMedDate not supplied

Incidental subcortical lesions identified on magnetic resonance imaging in the elderly. I. Correlation with age and cerebrovascular risk factors.

Patchy subcortical foci of increased signal intensity are frequently identified on magnetic resonance imaging (MRI) in the elderly. The incidence and clinical correlates of these lesions remain unknown. In this report, 240 consecutive MRI scans performed over a 6-month period were reviewed (excluding patients with recent brain trauma or known demyelinating disease). Subcortical incidental lesions (ILs) were identified, which could not be accounted for by the patient's current clinical diagnosis, neurological status, or CT scan. The ILs were graded according to size, multiplicity, and location. The incidence and severity of ILs increased with advancing age (p less than 0.0005). Among patients over 50 years of age, the incidence and severity of ILs were correlated with a previous history of history of ischemic cerebrovascular disease (p less than 0.05) and with hypertension (p less than 0.05). Multivariable regression analysis identified age, prior brain ischemia, and hypertension as the major predictors of ILs in the elderly. Diabetes, coronary artery diseases, and sex did not play a significant role. With the exception of cerebrovascular disease, there was no association between ILs and any particular clinical entity, including dementia. It is concluded that subcortical parenchymal lesions are frequent incidental findings on MRI in the elderly, and may represent an index of chronic cerebrovascular diseases in such patients.

Age Factors↗