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Biomedical subjects

R L Grubb

Publications and source records attributed to R L Grubb.

At least 55 records · Page 3Linked to original sources
PubMed1989

Influence of cerebral hemodynamics on stroke risk: one-year follow-up of 30 medically treated patients.

The importance of hemodynamic factors in the pathogenesis and treatment of ischemic cerebrovascular disease is not clear. We have investigated the relationship between cerebral hemodynamics and the subsequent risk of stroke in 30 medically treated patients with symptomatic occlusion or greater than 75% intracranial stenosis of the carotid arterial system. Positron emission tomography (PET) was used to evaluate the regional hemodynamic status of the cerebral circulation. Clinical follow-up to 1 year post-PET was available for all patients. The incidence at 1 year of all strokes was 1/9 for patients with normal hemodynamics and 1/21 for patients with abnormal hemodynamics. The 1-year incidence of ipsilateral ischemic stroke was 1/9 for hemodynamically normal patients and 0/21 in the abnormal group. The 21 patients in the abnormal group fulfilled entry criteria for the Extracranial-Intracranial Bypass Trial. The 0/21 incidence of ipsilateral ischemic stroke at 1 year was compared with the 1-year rate of 0.109 for the 714 medically treated patients from the Bypass Trial. We were able to reject with better than 90% certainty (p = 0.089) the hypothesis that our sample of patients came from a population with an ipsilateral ischemic stroke rate of 0.109 or greater. Thus, in this small sample, we found no evidence that PET evidence of abnormal cerebral hemodynamics identifies a subgroup of patients at higher risk for early stroke if treated medically with antithrombotic drugs.

Aged↗
PubMed1989

Selective shunting during carotid endarterectomy based on two-channel computerized electroencephalographic/compressed spectral array analysis.

The reliability of selective shunting based on computerized electroencephalographic (EEG) monitoring has not been addressed. In this study, 103 carotid endarterectomies were performed with selective shunting based on a two-channel computerized EEG monitor that processed the on-line, raw electroencephalogram (EEG) to produce a compressed spectral array (CSA). Ischemic EEG events were identified by amplitude attenuation of the raw EEG and/or loss of high-frequency activity on the CSA. Fourteen patients (13.6%) received a bypass shunt, and postoperative neurological examinations showed 97 patients (94.2%) to be intact. A correlation between total (cumulative) ischemic EEG time and the postoperative neurological exam was demonstrated (P less than 0.0001). Six postoperative deficits (5.8%) occurred, five in patients whose computerized EEGs demonstrated an ischemic EEG event late during carotid clamping, when it was no longer possible to place a shunt. The sixth deficit was found in a patient whose EEG did not demonstrate any patient whose EEG did not demonstrate any signs of cerebral ischemia. Five of these six new deficits resolved within 12 hours, and only one persisted for 72 hours, when the patient died of a pulmonary embolism (cerebral infarction and mortality rate of 1%). These results appear to demonstrate that two-channel monitoring of both the CSA and the unprocessed (raw) EEG simultaneously can be used as a reliable indicator of whether a bypass shunt is required during carotid cross-clamping in all patients, regardless of their preoperative neurological history or angiographic findings.

Brain Damage, Chronic↗
PubMed1989

Management of neurovascular complications in extended skull base surgery.

Combined oncologic approaches to the skull base now permit resection of extensive basicranial neoplasms. Despite advances in microsurgical techniques, disabling or life-threatening complications are still encountered in such surgery. Successful management of these sequelae is dependent upon meticulous intraoperative care and compulsive postoperative clinical assessment. Perioperative neurovascular complications were recorded in 154 consecutive skull base procedures. The most frequent severe complication was cerebral edema, which occasionally required surgical intervention. Dysphagia was the most common complication noted in the late postoperative period. Based upon this review, the management and methods found to minimize the incidence of various perioperative neurovascular complications related to extended skull base surgery are described.

Brain Edema↗
PubMed1989

Clinical results of extracranial-intracranial bypass surgery in patients with hemodynamic cerebrovascular disease.

The importance of hemodynamic factors in the pathogenesis and treatment of cerebrovascular disease remains uncertain. The extracranial-intracranial (EC-IC) bypass trial has been criticized for failing to identify and separately analyze those patients with chronic reduction in regional cerebral perfusion pressure (rCPP) who might be most likely to benefit from surgery. Positron emission tomography (PET) measurements of regional cerebral blood flow (rCBF) and blood volume (rCBV) were performed on 29 patients with symptomatic occlusion or intracranial stenosis of the carotid arterial system prior to undergoing EC-IC bypass surgery. Twenty-four patients had evidence of reduced rCPP (increased rCBV/rCBF ratio) distal to the arterial lesion. Of 21 patients who survived surgery without stroke, three suffered ipsilateral ischemic strokes during the 1st postoperative year. A nonrandomized control group of 23 nonsurgical patients' with similar clinical, arteriographic, and PET characteristics experienced no ipsilateral ischemic strokes during the 1st year following PET. Based on these results in 44 patients, the probability that successful surgery reduces the occurrence of ipsilateral ischemic stroke 1 year later was calculated. This probability ranged from 0.045 for a 50% reduction to 0.168 for a 10% reduction. Thus, there was little evidence to suggest that measurements of cerebral hemodynamics can identify a group of patients who would benefit from EC-IC bypass surgery.

Blood Volume↗
PubMed1989

Use of computerized electroencephalographic monitoring during aneurysm surgery.

The clinical usefulness of intraoperative electroencephalographic (EEG) monitoring of cerebral perfusion during aneurysm surgery has received little attention, primarily due to problems with electrode placement over the operative site, which is the area of maximal risk. In this report, 27 patients undergoing surgery for anterior circulation aneurysms were monitored intraoperatively with a two-channel computerized EEG complex using a bilateral frontal-occipital montage. In 16 patients, a normal EEG pattern was observed throughout surgery; all 16 awoke neurologically intact and their postoperative angiograms did not reveal cerebral vasospasm. In the other 11 patients, one of two patterns of persistent EEG abnormalities was identified. 1) In six of these patients a marked attenuation of EEG activity was observed ipsilaterally which coincided with various intraoperative events including brain retraction, hypotension, and aneurysm dissection/clipping. Five of these six patients awoke with new neurological deficits which persisted beyond 12 hours in two, both of whom had angiographically proven vasospasm 24 hours after surgery. 2) In the remaining five patients, a distinct abnormal EEG pattern consisting of marked hyperactivity in the delta, theta, and alpha frequency ranges was observed ipsilaterally. Four of these five patients had a poor neurological outcome and vasospasm on their angiogram 24 hours after surgery. Thus, EEG monitoring which spans the operative area during aneurysm surgery is practicable and appears to be of value in the detection of compromised cerebral perfusion during aneurysm surgery. The possible significance of the two abnormal EEG patterns identified in this report is discussed.

Cerebral Angiography↗
PubMed1988

Posterior segmental spinal instrumentation (PSSI) with posterolateral decompression and debulking for metastatic thoracic and lumbar spine disease. Limitations of the technique.

Twenty-five patients with metastatic thoracic and lumbar spine disease were initially treated by the authors with posterolateral debridement and decompression, along with posterior segmental spinal instrumentation. Ten patients had marked paresis, nine had signs of spinal cord or cauda equina compression without paresis, and all patients had pain severe enough to prevent sitting/standing/walking. The posterior approach was used in these patients instead of an anterior one because of translocation (4), three-column disease (16), three or more vertebral bodies involved (13), disease at two separate locations (2), and inability to tolerate an anterior approach (3). All patients had maintenance of spinal alignment for the length of follow-up or until their ultimate demise. Good pain relief was achieved in 19 of 25 patients. Six of ten patients with significant paresis recovered. Four patients developed recurrent spinal cord compression within 12 months postoperative from regrowth of tumor that was not controlled by radiotherapy or chemotherapy. Six of the 25 patients were not significantly palliated by the technique.

Adolescent↗
PubMed1988

Anterior cervical disc herniation. Case report.

A 39-year-old man with an extrinsic esophageal lesion was found to have an anterior herniation of a soft degenerated cervical disc. Only two cases of symptomatic anterior cervical disc herniation have been reported previously. Dysphagia produced by anterior cervical osteophytes is more common and is a recognized clinical entity. Asymptomatic anterior cervical disc herniation may play a key role in the pathogenesis of anterior cervical osteophytes.

Adult↗
PubMed1987

The effect of hemodynamically significant carotid artery disease on the hemodynamic status of the cerebral circulation.

Although the presence of a hemodynamically significant carotid artery lesion is commonly used as an indicator of impaired cerebral circulation, the effect of such lesions on cerebral perfusion pressure and cerebral blood flow has never been determined accurately. We used positron emission tomography (PET) to study 19 patients with unilateral hemodynamically significant carotid artery disease (greater than 66% diameter reduction) and no evidence of cerebral infarction. According to PET measurements in the cerebral hemisphere distal to the lesion, 7 patients had normal cerebral hemodynamics, 8 had reduced perfusion pressure with normal blood flow, and 4 had reduced blood flow. Neither the percent stenosis nor the residual lumen diameter in the carotid artery was a reliable indicator of the hemodynamic status of the cerebral circulation. However, a significant relationship was found between the PET measurements of cerebral hemodynamics and the arteriographic circulation pattern (p = 0.006). The role of hemodynamic factors in the pathogenesis and treatment of cerebrovascular disease cannot be determined from the severity of carotid artery disease alone.

Aged↗
PubMed1986

Aneurysmal bone cyst of the cervicothoracic spine: computed tomographic evaluation of the value of preoperative embolization. Case report.

In this report, the management of an aneurysmal bone cyst in the cervicothoracic region of an 8-year-old girl is described. Aneurysmal bone cyst is a histologically benign lesion that is often extremely vascular. In the spine, it can cause extensive bone destruction and compress neural structures. Because this lesion may involve all parts of a vertebra, full delineation of the lesion before its excision is important in planning the surgical approach. The value of preoperative embolization to reduce tumor vascularity, allowing total excision, and the improved radiological evaluation of this lesion with computed tomographic scanning are demonstrated.

Angiography↗
PubMed1986

Treatment of chronic subdural hematoma by twist-drill craniotomy with continuous catheter drainage.

The case records of 114 patients were reviewed to ascertain the efficacy of bedside twist-drill craniotomy and continuous closed-system catheter drainage for the treatment of chronic subdural hematomas. Ninety-eight (86%) patients achieved an excellent outcome, and seven (6%) had no significant improvement. The total mortality from all cases was 8% in this group. Successful catheter drainage of the chronic subdural hematoma was accomplished by either one or two catheter placements in 102 (90%) patients. Twelve patients required additional operative procedures. The mean duration of hospitalization for the study group was 16 days. No infections occurred in these patients. Remission of the clinical syndrome did not require the radiographic resolution of the chronic subdural hematoma.

Adult↗
PubMed1985

Muteness of cerebellar origin.

Acute bilateral damage to large areas of both cerebellar hemispheres including the dentate nuclei led to temporary loss of speech in six children. In each case muteness was unassociated with motor paralysis, loss of higher cognitive functions, or cranial nerve dysfunction. Muteness lasted one to three months. All patients were severely dysarthric during recovery. We conclude that transient muteness may result from acute bilateral cerebellar injury.

Cerebellar Diseases↗
PubMed1985

Cerebral blood flow and cerebral metabolic rate of oxygen requirements for cerebral function and viability in humans.

This study was undertaken to determine the minimum CBF and CMRO2 required by the human brain to maintain normal function and viability for more than a few hours. Positron emission tomography (PET) was used to perform regional measurements in 50 subjects with varying degrees of cerebral ischemia but no evidence of infarction. There were 24 normal subjects, 24 subjects with arteriographic evidence of vascular disease of the carotid system, and two subjects with reversible ischemic neurological deficits due to cerebral vasospasm. Minimum values found in the 48 subjects with normal neurological function were 19 ml/100 g-min for regional cerebral blood flow (rCBF) and 1.3 ml/100 g-min for regional cerebral metabolic rate of oxygen (rCMRO2). Minimum values for all 50 subjects with viable cerebral tissue were 15 ml/100 g-min for rCBF and 1.3 ml/100 g-min for rCMRO2. Comparison of these measurements with values from 20 areas of established cerebral infarction in 10 subjects demonstrated that 80% (16/20) of infarcted regions had rCMRO2 values below the lower normal limit of 1.3 ml/100 g-min. Measurements of rCBF, regional cerebral blood volume, and oxygen extraction fraction were less useful for distinguishing viable from infarcted tissue. These data indicate that quantitative regional measurements of rCMRO2 with PET accurately distinguish viable from nonviable cerebral tissue and may be useful in the prospective identification of patients with reversible ischemia.

Adult↗
PubMed1985

Regional cerebral blood flow and metabolism in reversible ischemia due to vasospasm. Determination by positron emission tomography.

Regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO2) were measured by positron emission tomography (PET) in four patients with subarachnoid hemorrhage and hemiparesis due to cerebral vasospasm. With resolution of the vasospasm, two patients recovered and two remained hemiparetic. Contralateral to the hemiparesis, rCBF was slightly higher in the two patients who eventually recovered (15.0 and 16.2 ml/100 gm/min) than in the two who remained hemiparetic (12.0 and 11.7 ml/100 gm/min). The rCMRO2 measurements showed similar differences, with values of 1.34 and 2.60 ml/100 gm/min in the patients who recovered, and 0.72 and 1.66 ml/100 gm/min in those who did not. These preliminary findings indicate that with PET studies it may be possible to prospectively differentiate patients with neurological deficits due to reversible ischemia from patients with irreversible infarction.

Adult↗
PubMed1984

Physiological responses to focal cerebral ischemia in humans.

Positron emission tomography (PET) was used to investigate the regional hemodynamic and metabolic changes that accompany focal reductions in cerebral blood flow to ischemic but uninfarcted regions of the brain. Studies were performed on 7 patients chosen from a larger group of subjects with transient ischemic attacks and normal computed tomographic findings, specifically because their PET studies showed decreased blood flow to the symptomatic hemisphere rather than symmetrical flow to the two hemispheres. In regions with decreased blood flow, the cerebral metabolic rate for oxygen was also decreased, but to a lesser degree. Cerebral blood volume, vascular mean transit time, and fractional extraction of oxygen from blood were all increased. These findings indicate that cerebral oxygen metabolism was maintained in the face of decreased blood flow by local compensatory mechanisms that included dilation of intraparenchymal blood vessels and increased transfer of oxygen from blood to tissue. Such knowledge of the physiological characteristics of ischemic, uninfarcted brain is important if PET is to be used clinically to differentiate reversible cerebral ischemia from irreversible infarction.

Aged↗
PubMed1984

Cerebral blood volume, blood flow, and oxygen metabolism in cerebral ischaemia and subarachnoid haemorrhage: an in-vivo study using positron emission tomography.

A characteristic sequence of metabolic and haemodynamic changes has been shown to occur in the brain as cerebral perfusion pressure is reduced in experimental animals. Increased cerebral blood volume (CBV) occurs initially, followed by a fall in blood flow (CBF) and, finally, a fall in oxygen metabolism (CMRO2). By measuring CBV, CBF, and CMRO2 with positron emission tomography in patients with vasospasm associated with subarachnoid haemorrhage and in patients with arteriosclerotic occlusion or stenosis of extraparenchymal cerebral arteries, we have demonstrated the presence of similar changes distal to such lesions in man. These findings suggest the presence of a local decrease in perfusion pressure. This study demonstrates the utility of positron emission tomography in the assessment of cerebral circulation and metabolism in man. Measurements of regional CBV must be included for a complete assessment of the dynamics of the cerebral circulation.

Blood Volume↗