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Biomedical subjects

R L Grubb

Publications and source records attributed to R L Grubb.

At least 19 recordsLinked to original sources
PubMed1992

Computerized electroencephalographic monitoring and selective shunting: influence on intraoperative administration of phenylephrine and myocardial infarction after general anesthesia for carotid endarterectomy.

During carotid endarterectomy (CEA), phenylephrine infusions are commonly used to induce hypertension during carotid clamping in an attempt to increase collateral cerebral blood flow and prevent cerebral ischemia. Although this practice appears to increase the incidence of intraoperative myocardial ischemia during CEA when general anesthesia is employed, whether the limited use of phenylephrine infusions in specific instances of cerebral ischemia, as shown on an electro-encephalogram, results in low perioperative rates of both myocardial infarction (MI) and cerebral infarction remains unclear. We studied 171 CEAs done under general anesthesia performed with selective shunting based on the identification of cerebral ischemia by a two-channel computerized electroencephalographic monitor. The use of a phenylephrine infusion was restricted to the following instances of cerebral ischemia: 1) ischemia associated with hypotension that did not resolve within 2 minutes of decreases in anesthetic administration and treatment with fluid and/or colloid; 2) ischemia poorly or slowly responsive to shunt placement, accompanied by either hypo- or normotension; and 3) ischemia poorly or slowly responsive to removal of the carotid clamp, accompanied by either hypo- or normotension. Two non-Q wave MIs (1.2%) occurred, both nonfatal. There were two cerebral infarctions (1.2%) and three deaths not related to MI (1.8%). Based on these findings, in order to decrease the incidence of both MI and cerebral infarction after general anesthesia for CEA, we recommend the restrictive use of phenylephrine-induced hypertension for specific instances of slowly or poorly reversible cerebral ischemia, as shown on the electroencephalogram.

Adult↗
PubMed1991

Cerebral oxygen metabolism after aneurysmal subarachnoid hemorrhage.

Previous studies of cerebral oxygen metabolism and extraction in patients with subarachnoid hemorrhage (SAH) have yielded conflicting results. We used positron emission tomography (PET) to measure the regional cerebral metabolic rate for oxygen (rCMRO2), oxygen extraction fraction (rOEF), and cerebral blood flow (rCBF) 16 times in 11 patients with aneurysmal SAH. All studies were performed preoperatively; no patient had hydrocephalus or intracerebral hematoma on brain CT. Eight patients with no arteriographic vasospasm who were studied on days 1-4 post-SAH had a significant 25% reduction in global CMRO2 compared to age-matched controls, and no significant change in global OEF, suggesting a primary reduction in CMRO2 caused by SAH. Four patients studied seven times during arteriographic vasospasm had significantly increased rOEF with unchanged CMRO2 in arterial territories affected by arteriographic vasospasm compared to territories without vasospasm, indicative of cerebral ischemia without infarction. No brain regions studied with PET were infarcted on follow-up CT. We conclude that the initial aneurysm rupture produces a primary reduction in CMRO2, and that subsequent vasospasm causes ischemia.

Adult↗
PubMed1990

The perioperative management of the petrous carotid artery in contemporary surgery of the skull base.

Optimal techniques for the preoperative assessment and intraoperative management of the petrous carotid artery remain undefined. While purposeful "avoidance" of this structure may result in partial tumor removal, limited exposure of the petrous carotid artery may lead to inadvertent injury with life-threatening neurovascular sequelae. Twenty-five cases are reported in which surgical manipulation of the petrous carotid artery was necessary to accomplish total tumor removal or gain operative exposure to the skull base. A standard diagnostic radiographic assessment consisted of high-resolution computed tomography, magnetic resonance imaging, and a 4-vessel angiography. Preoperative balloon occlusion of the involved internal carotid artery was performed in four patients. Surgical approaches used in this series were broadly classified as: infratemporal-anterolateral (14), pterional-infratemporal (6), or pterional-anterolateral (5). Intraoperative management of the carotid artery consisted of total decompression in 19 cases, decompression with mobilization in four patients, and resection in two instances. Major neurovascular complications included one stroke and death caused by arterial occlusion, one stroke and death caused by arterial spasm, one stroke caused by brain edema, and one death related to a postoperative carotid hemorrhage. Other nonvascular complications included brain swelling, cranial nerve palsies, dysphagia, ataxia, cerebrospinal fluid fistulae, flap necrosis with wound infection, and pneumocephalus. Invasive and noninvasive methods are outlined for the preoperative assessment of the petrous carotid in cases of advanced skull base disease and intraoperative management options are detailed.

Adolescent↗
PubMed1990

Combined pterional-anterolateral approaches to cranial base tumors.

Advanced tumors of the paranasal sinuses, parotid gland, orbit, parapharynx, and cranial cavity may invade the infratemporal fossa by direct extension or through natural anatomic pathways. The inability to control disease involving this region is reflected by the unacceptably high recurrence rates for both intracranial and extracranial neoplasms. Between 1983 and 1986, a pterional (or subtemporal) approach was combined with such conventional anterolateral procedures as a mandibulopharyngectomy, maxillectomy, orbitectomy, and parotidectomy in 13 patients with advanced skull base lesions. The tumor origin was extracranial in ten cases and intracranial in three patients. Seven of the neoplasms were malignant and six were histologically benign. Complete tumor removal was achieved in all patients. Repair of the ablative defect was achieved with a temporalis myogenous flap in ten patients, and primary closure or distant myocutaneous flaps in the remaining three patients. Postoperative complications included three lateral nasocutaneous fistulae secondary to temporalis myogenous flap necrosis and isolated cases of stroke, cerebral edema, pneumocephalus, and cerebrospinal fluid rhinorrhea. Twelve patients are alive without evidence of disease at a mean interval of 25 months. The remaining patient died from lung metastases 11 months after surgery.

Adolescent↗
PubMed1990

Meningiomas of the lateral skull base: neurotologic manifestations and patterns of recurrence.

The eradication of basicranial meningiomas by traditional surgical techniques is often hindered by neoplastic entanglement with critical neurovascular structures. Apparent, complete tumor resection is frequently followed by extensive, yet clinically silent, recurrent disease with local infiltration of bone, cranial nerves, and brain. Fifty-five cases of sphenoid wing or parasellar meningioma were analyzed to identify clinical manifestations suggestive of early tumor recurrence. Regrowth patterns were then defined according to preoperative radiographic and intraoperative surgical findings. Medial tumor regrowth, involving the cavernous sinus, caused neurapraxia of cranial nerves III, IV, or VI, with associated diplopia or ophthalmoplegia. Inferior (caudal) regrowth of disease involved the infratemporal fossa, pterygomaxillary space, or paranasal sinuses by bony erosion of the middle cranial fossa floor or through natural anatomic foramina and fissures. Such inferior extension was manifested clinically by facial hypesthesia, trismus, and referred otalgia caused by trigeminal nerve involvement and by autophony or serous otitis media related to eustachian tube obstruction. Posterior tumor regrowth occurred along the petrous bone and horizontal carotid canal, resulting in internal auditory meatus erosion and cerebellopontine angle extension with associated tinnitus, hearing loss, unsteadiness, and occasional facial twitching. While the clinical and radiographic evaluations of any patient with a suspected recurrent basicranial meningioma are critical in planning the method and magnitude of reoperation, an understanding of potential recurrence patterns can be used in devising more extensive, combined approaches that may allow complete tumor extirpation at the initial surgical intervention.

Adult↗
PubMed1990

Borderzone hemodynamics in cerebrovascular disease.

To investigate the possible existence of chronic selective hemodynamic impairment in the arterial borderzone regions of the brain, we used positron emission tomography (PET) to measure regional mean vascular transit time (rt, equal to the ratio of regional cerebral blood volume to cerebral blood flow) and regional oxygen extraction fraction (rOEF) in 32 patients with either severe internal carotid artery stenosis or occlusion and 11 normal controls. Twenty-four of the patients had had TIAs or amaurosis fugax from 1 to 60 days before PET; all had normal brain CT. We used a stereotactic localization method to locate the anterior and posterior borderzone regions of the middle cerebral artery (MCA) territory. We then calculated ratios of each borderzone to the ipsilateral MCA territory for both rt and rOEF. There was no significant difference from control ratios in any patient subgroup including those with greater than or equal to 75% stenosis or occlusion, those with or without contralateral greater than or equal to 50% stenosis, or those with abnormal hemodynamics in the MCA territory. We therefore found no evidence for selective borderzone hemodynamic impairment in this group of patients with severe carotid artery disease.

Adult↗
PubMed1990

Management of cerebrospinal fluid otorhinorrhea complicating the retrosigmoid approach to the cerebellopontine angle.

The retrosigmoid approach is currently used in the resection of small acoustic schwannomas or the vestibular nerve in selected patients with recurrent vertigo. Cerebrospinal fluid otorhinorrhea associated with the approach is often due to a failure to completely obliterate exposed air cells of the posteromedial and posterosuperior tracts of the temporal bone. A therapeutic protocol for managing a postoperative spinal fluid leak is outlined on the basis of these anatomic features and the status of the patient's hearing. If serviceable hearing has been preserved, the operative site is explored and incompletely obliterated or exposed cells are sealed with bone wax. If a leak persists, or if hearing is lost with the initial procedure, the mastoid cavity and middle ear cleft are obliterated with abdominal fat and the eustachian tube orifice occluded with Proplast through a facial recess approach.

Cerebellopontine Angle↗
PubMed1990

Control of bleeding in extended skull base surgery.

The resection of skull base neoplasms requires an intimate knowledge of basicranial vascular anatomy. Tumor distortion of surgical landmarks may increase the potential for inadvertent vascular injury with life-threatening intraoperative bleeding or delayed neurologic sequelae. Moreover, massive transfusion therapy may significantly alter the hemostatic mechanism in the perioperative period. On the basis of a review of hemorrhagic complications encountered in 154 consecutive skull base procedures, we describe techniques that are designed to avoid or efficiently control venous and arterial bleeding in extended skull base surgery. The management of complications resulting from blood replacement are reviewed.

Brain↗
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↗