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Biomedical subjects

B T Andrews

Publications and source records attributed to B T Andrews.

At least 55 records · Page 3Linked to original sources
PubMed1988

Intradural arachnoid cysts of the spinal canal associated with intramedullary cysts.

Five patients had intradural arachnoid cysts of the thoracic spinal canal associated with syringomyelia or posttraumatic intramedullary spinal cord cysts. Three cases were diagnosed 6 to 18 years after spinal surgery and two 14 to 17 years after spinal cord trauma. In each case, delayed progression of symptoms led to the identification of the lesions. The diagnosis was assisted by the use of myelography and delayed computerized tomography scanning in two cases and by magnetic resonance imaging in all five. In each case, the arachnoid cyst appeared to compress the spinal cord or nerve roots; in three cases, the syrinx cavities appeared to exert a significant mass effect. In the two trauma-related cases, the intramedullary cysts were small and may have represented areas of cystic myelomalacia. In four cases, intraoperative real-time ultrasonography helped to localize the arachnoid and intramedullary cavities. All five patients were treated by fenestration of the arachnoid cyst; additional peritoneal shunting of the cyst was performed in one case and of the intramedullary cavity in three. In one patient, the two lesions appeared to have a balancing effect; after drainage of the arachnoid cyst, the syrinx cavity expanded and had to be treated separately. The neurological deficits were reduced in four patients and stabilized in one. Intradural arachnoid cysts and intramedullary cysts may occur together as a late complication of spinal surgery or spinal cord trauma, and either or both lesions may cause delayed neurological deterioration.

Adult↗
PubMed1988

The effect of intracerebral hematoma location on the risk of brain-stem compression and on clinical outcome.

The clinical findings and computerized tomography (CT) brain scans of 45 patients with supratentorial intracerebral hematomas were evaluated to determine the effect of hematoma location on the clinical course and outcome of the disease. The lesions were frontal in 18 patients, temporal or temporoparietal in 17, and parieto-occipital in 10. No patient with a frontal or parieto-occipital hematoma had clinical signs of transtentorial herniation at admission or subsequently, whereas seven (41%) of those with temporal or temporoparietal lesions had signs of herniation (p less than 0.05); three of these seven patients had an abnormal mental status, ipsilateral anisocoria, and lateralizing motor findings at admission, and four developed these signs within 12 hours after admission, necessitating urgent surgical intervention. The mean volume of the lesions estimated from the CT scans was similar in the three groups (frontal 47 +/- 28 cc; parieto-occipital 53 +/- 26 cc; temporal/temporoparietal 41 +/- 21 cc). None of the six patients with temporal or temporoparietal hematomas smaller than 30 cc had signs of tentorial herniation, compared with seven (64%) of 11 patients with larger hematomas (p less than 0.05); in six of these seven cases, the hematoma was caused by head injury. Patients with a temporal or temporoparietal hematoma had a worse outcome than those in the other two groups, and no patient with signs of tentorial herniation had a good outcome. Patients with temporal or temporoparietal hematomas appear to be at greater risk of brain-stem compression, especially if the lesion is larger than 30 cc and caused by head injury, than are those with hematomas in other sites. In such cases, prompt surgical intervention should be considered.

Adolescent↗
PubMed1988

Suprasellar meningiomas: the effect of tumor location on postoperative visual outcome.

The authors reviewed 38 cases of suprasellar meningioma to determine the correlation between tumor site and postoperative visual outcome. Progressive visual loss, the most frequent initial complaint (94.7%), occurred over a mean of 24 1/2 months, was most often unilateral (18 patients) or bilateral but asymmetrical (14 patients), and was severe (20/200 vision or worse) in 23 patients; 24 patients had visual field abnormalities. Computerized tomography or magnetic resonance studies clearly delineated the lesions but did not appear to permit earlier diagnosis. Eleven patients had tumors limited to the tuberculum sellae; the tumor extended from the tuberculum sellae onto the planum sphenoidale in nine patients, into one optic canal in eight, onto the diaphragma sellae in seven, and onto the medial sphenoid wing in three. Patients with tumors affecting the optic canal had severe unilateral visual loss more often than those with tumors at other sites. Tumors limited to the tuberculum sellae were most often completely resected; postoperative recovery of vision was also most frequent in patients with tumors at this site. Tumors involving the diaphragma sellae or the medial sphenoid wing were least often completely removed and most likely to be associated with postoperative visual deterioration. Overall, 42% of patients had improved vision postoperatively, 30% remained unchanged, and 28% were worse. After a mean follow-up period of 38 months, 24 patients are doing well, four have significant visual disability, and three are blind or doing poorly. Two patients died of causes unrelated to their tumor. Three patients have had tumor recurrence.

Adult↗
PubMed1988

Levels of endogenous opioids and effects of an opiate antagonist during regional cerebral ischemia in rats.

Changes in endogenous opioid concentrations and the effect of treatment with the opiate receptor antagonist WIN 44,441-3 (WIN) were evaluated after middle cerebral artery occlusion (MCA-O) in rats. Animals treated with WIN at doses of 0.4 to 400 micrograms/kg 15 min, 3 hr and 6 hr after MCA-O had significantly higher mean arterial blood pressure than saline controls (P less than .05). Twenty-four hours after MCA-O, WIN-treated rats had significantly greater recovery of EEG activity and higher neurological scores than the controls; these actions were greatest at a dose of 40 micrograms/kg (P less than .01). The neurological outcome correlated with recovery of the ipsilateral EEG (P less than .01). The mortality rate 24 hr after occlusion and the infarct size were not significantly different from controls. At 1 hr after MCA-O, there were no significant differences in regional concentrations of endogenous opioid peptides (dynorphin, Leu-enkephalin and beta-endorphin) between the injured and uninjured hemispheres. These are the first studies to evaluate the effects of an opiate antagonist over a wide dose range in cerebral ischemia. Dose-related beneficial actions were found with regard to several, but not all, outcome measures. The absence of regional opioid changes after regional ischemia, in contrast to previous studies of spinal cord ischemia and brain trauma, was unexpected, but may reflect limited regional and temporal sampling.

Animals↗
PubMed1987

Measurement of lactate accumulation by in vivo proton NMR spectroscopy during global cerebral ischemia in rats.

In vivo 1H NMR spectral editing techniques were used to monitor cerebral lactate production during remotely controlled temporary forebrain ischemia in rats. The lactate/N-acetylaspartate (NAA) ratio correlated with survival after ischemia and subsequent reperfusion. The lactate/NAA ratio that predicted death after ischemia in rats was estimated to be approximately 1.3.

Animals↗
PubMed1987

Implications of systemic hypotension for the neurological examination in patients with severe head injury.

Thirty-six patients admitted with severe head injury and various degrees of systemic hypotension were studied to determine the effect of hypotension on the validity of the neurological examination in reflecting mechanical brain compression. All patients had clinical signs of transtentorial herniation or upper brainstem compression and underwent immediate bilateral placement of exploratory burr holes for the diagnosis and removal of intracranial hematomas. All patients were initially hypotensive: 10 were in cardiac arrest, 7 had a systolic blood pressure (SBP) less than 60 torr, and 19 had SBP of 60-90 torr. The median score on the Glascow coma scale was 3 (range 3-8). Although 4 of the 10 cardiac arrest patients had anisocoria, only one (10%) had an intracranial hematoma. Among the seven patients with severe hypotension, only two had anisocoria and neither had and intracranial hematoma; one patient in this group (14%) had a hematoma that was diagnosed at autopsy. In contrast, intracranial hematomas were discovered by burr-hole placement and evacuated in 13 (68%) of 19 patients with initially moderate hypotension, including seven (78%) of nine patients with anisocoria. Anisocoria was associated with mechanical brain compression from an intracranial hematoma significantly more often in patients with an initial SBP of 60-90 torr than in those with initial cardiac arrest or SBP less than 60 torr (chi-square p less than 0.05). Intracranial hematomas were significantly more frequent among patients with SBP of 60-90 torr than among those with a lower SBP or initial cardiac arrest (P less than 0.01). Thirty-three of 36 patients died; each of the three survivors had an initial SBP of 60-90 torr, and hematomas were removed in two. In head-injured patients with SBP greater than 60 torr, clinical signs of tentorial herniation or upper brainstem dysfunction remain valid indicators of possible mechanical compression; the high percentage of patients with acute intracranial hematomas in this group warrants immediate diagnostic burr-hole exploration. In patients with severe initial hypotension (SBP less than 60 torr) or cardiac arrest, clinical findings of brainstem dysfunction cannot be relied upon to indicate mechanical compression, and computed tomography scanning should be done immediately after resuscitation to determine the need for surgical exploration.

Adolescent↗
PubMed1987

Staged treatment of arteriovenous malformations of the brain.

Twenty-eight patients treated for arteriovenous malformations (AVMs) of the brain had staged therapy consisting of multiple surgical procedures or endovascular embolization followed by surgical treatment. There were 10 men and 18 women, aged 15 to 60 years (mean, 34 years). The clinical symptoms were those associated with intracranial hemorrhage in 13 patients, progressive neurological deficit not due to hemorrhage in 6, intractable headache in 5, and seizures in 4. Four groups were identified based upon the reason for staging therapy. Thirteen patients with large high flow AVMs (Group A) had staged treatment because of the risk of normal perfusion pressure breakthrough. The initial afferent artery occlusion was accomplished surgically in 9 patients and by endovascular embolization in 4. Postoperatively, no patient in this group had malignant cerebral edema or intracranial hemorrhage suggestive of normal perfusion pressure breakthrough, but 1 patient had an intraventricular hemorrhage after initial embolization. In 9 patients (Group B), the AVM had a complex multiple arterial supply that precluded resection from a single operative exposure. Seven had supratentorial AVMs, and 2 had AVMs of the posterior fossa. In 6 of these cases, the AVM was located in the midline and received bilateral arterial input. Six patients had staged surgical procedures, and 3 had an initial endovascular embolization followed by operation. Two patients had intracerebral hemorrhages, one after an initial surgical procedure and another after initial embolization. In 4 patients (Group C), the AVM had a major dural component that was treated separately from the parenchymal component. In 3 of these patients, embolization through the external carotid artery satisfactorily obliterated the dural component; in the remaining patient, a persistent internal carotid supply necessitated resection of the dural malformation. The parenchymal component was excised surgically in 2 patients. Two patients (Group D) had separate surgical procedures to treat an aneurysm associated with a parenchymal AVM. Overall, 19 of 28 patients had complete excision and 9 had partial obliteration of their AVMs. Late follow-up of 27 patients at a mean of 18.6 months showed that 16 patients were in excellent condition and 8 were in good condition. Three patients were in poor condition with debilitating neurological deficits. One patient had a delayed intracranial hemorrhage 22 months after incomplete obliteration of her AVM. Staged treatment of selected AVMs of the brain may avoid the occurrence of normal perfusion pressure breakthrough.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

Unilateral normal perfusion pressure breakthrough after carotid endarterectomy: case report.

The authors report a case of unilateral malignant cerebral edema that occurred after the removal of a high grade atheromatous lesion of the ipsilateral internal carotid artery. A form of unilateral normal perfusion pressure breakthrough caused by postischemic impairment of cerebrovascular autoregulation and exacerbated by systemic hypertension is thought to have contributed to this complication. Control of the hypertension and treatment of the cerebral edema with mannitol and dexamethasone led to a complete neurological recovery.

Aged↗
PubMed1987

Sequential in vivo measurement of cerebral intracellular metabolites with phosphorus-31 magnetic resonance spectroscopy during global cerebral ischemia and reperfusion in rats.

Phosphorus-31 magnetic resonance (31P MR) spectroscopy was used to obtain serial in vivo measurements of cerebral adenosine triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi), and intracellular pH levels in rats during temporary global cerebral ischemia and reperfusion. Three groups of 4 rats each that recovered from permanent bilateral vertebral artery occlusion were placed in a MR spectrometer and subjected to remotely controlled bilateral carotid artery occlusion lasting 6, 15, or 30 minutes followed by 1 hour of reperfusion. Four additional rats that developed systemic hypotension (2 during a 6-minute occlusion and 2 during a 15-minute occlusion) were also studied. 31P MR spectra were obtained in each rat before, during, and after ischemia. Rats in which MR spectra showed metabolic recovery underwent a second occlusion followed by reperfusion and sacrifice. In the 12 normotensive rats, metabolic alterations began within 3 minutes after the onset of global ischemia. By the end of the occlusion period, cerebral ATP had decreased by 20 to 100% in 10 rats and PCr had decreased by 15 to 75% in all 12; Pi increased by 25 to 240%. The mean intracellular pH decreased from 7.33 to 6.9 +/- 0.6. The degree of metabolic deterioration during ischemia was not related to the duration of occlusion. During reperfusion, ATP, PCr, Pi, and intracellular pH returned to normal in 4 rats; 5 rats had partial metabolic recovery, and 3 had minimal or transient metabolic recovery followed by progressive deterioration. All rats that developed systemic hypotension had a decrease in ATP, PCr, and intracellular pH and an increase in Pi during the initial occlusion. Each had transient partial recovery in ATP during reperfusion, and 2 had slight recovery of PCr. The onset of hypotension was followed by depletion of these metabolites, progressive increase in Pi, and progressive intracellular acidosis. All rats that deteriorated metabolically after reversal of carotid occlusion died by the end of the reperfusion period or soon after. The 8 rats that recovered from the first occlusion were subjected to a second period of ischemia, during which each rat showed severe depletion of metabolites. During the second reperfusion, only 1 rat showed significant metabolic recovery, which lasted only 30 minutes and was followed by progressive deterioration. Severe global cerebral ischemia was associated with a progressive decline in both ATP and PCr, whereas less complete ischemia seemed to be characterized by stabilization or recovery of ATP and continued depression of PCr.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1987

Intraoperative anaphylaxis after irrigation with bacitracin: case report.

We report a case of anaphylaxis caused by irrigation with a bacitracin solution during lumbar laminectomy. The patient had been exposed to bacitracin during a previous anterior cervical discectomy. We recommend avoiding the use of irrigation solutions containing bacitracin in patients with previous systemic exposure to this antibiotic.

Aged↗
PubMed1986

Variant aneurysms of the fenestrated basilar artery.

Two cases of aneurysm occurring on a fenestrated basilar artery are reported. One patient had a saccular aneurysm in the typical location at the vertebrobasilar junction at the proximal end of the fenestrated basilar segment. The aneurysm sac projected dorsally into the brain stem. The other patient had a blister-like aneurysm distal to a fenestration of the terminal basilar artery. The development of a distal aneurysm on a fenestrated basilar artery is predictable based on the reported morphology of the vessel wall in this vascular anomaly.

Adult↗
PubMed1986

Cerebral salt wasting after pituitary exploration and biopsy: case report.

We report a case of hyponatremia associated with volume depletion after pituitary exploration and biopsy. The presence of clinical dehydration precluded diagnosis of the syndrome of inappropriate secretion of antidiuretic hormone. The absence of a hypoadrenal state and the patient's response to volume reexpansion were consistent with a diagnosis of primary cerebral salt wasting.

Adult↗
PubMed1986

Is computed tomographic scanning necessary in patients with tentorial herniation? Results of immediate surgical exploration without computed tomography in 100 patients.

Computed tomographic (CT) scans are performed on virtually all patients with severe head injury at the time of admission. Because of the time involved in obtaining these studies, the evacuation of significant intracranial mass lesions is delayed. To avoid such delays, the authors performed burr-hole exploration for the diagnosis of intracranial hematomas before CT scans were obtained in 100 consecutive head-injured patients with clinical signs of tentorial herniation or upper brain stem dysfunction upon admission to the emergency room. Patients in whom a hematoma was discovered had a craniotomy for evacuation of the clot; those in whom the exploration was negative had a CT brain scan immediately after operation. Burr-hole exploration revealed extracerebral mass lesions in 56 patients. In 38 patients, the exploration was negative, and postoperative CT scanning showed no significant hematoma. Of 6 patients in whom the CT scan demonstrated extraaxial hematomas requiring surgical evacuation, 4 had subdural hematomas that were missed because the exploration was incomplete; 1 patient had an epidural hematoma and 1 had a subdural hematoma contralateral to a craniotomy on the side of a positive initial burr-hole exploration. Our results indicate that the relatively small subgroup of head-injured patients with early tentorial herniation or upper brain stem compression have a high incidence of immediate extraaxial hematomas and a low incidence of intracerebral hematomas. This is particularly true of patients over 30 years of age and those who suffer low speed trauma, such as falls and vehicle-pedestrian accidents.

Adult↗
PubMed1986

A new microclip for vascular occlusion. Technical note.

A new microclip for use on blood vessels 300 mu to 1 mm in diameter is described. This clip is suitable for either temporary or permanent occlusion and has been used in experimental applications. Potential clinical applications are described.

Surgical Instruments↗
PubMed1985

Subarachnoid hemorrhage from a peripheral intracranial aneurysm associated with malignant glioma: report of a case.

The case of a patient who initially presented with a subarachnoid hemorrhage from an aneurysm of the distal left middle cerebral artery is reported. The aneurysm was later found to have occurred within a malignant glioma. Histological analysis showed tumor infiltrating the wall of the aneurysm. A causal relationship between growth of the tumor and development and rupture of the aneurysm is postulated.

Brain Neoplasms↗
PubMed1985

Extracranial-intracranial arterial bypass for middle cerebral artery stenosis and occlusion. Operative results in 65 cases.

Forty-seven patients with middle cerebral artery (MCA) stenosis and 18 patients with MCA occlusion underwent extracranial-intracranial arterial bypass procedures. Patients presented with a history of transient ischemic attacks (TIA's), reversible ischemic neurological deficits, TIA's after initial stroke, stroke-in-evolution, or completed stroke. Angiography revealed that the MCA stenosis ranged from 70% to over 95%. Two patients (4.3%) in the stenosis group had a perioperative stroke (within 30 days of operation). There was no perioperative mortality. In the occlusion group, no patient had a perioperative stroke, and one patient (5.5%) died from a non-neurological disease. The TIA's resolved completely in 90% of the patients with stenosis and in 91.6% of those with occlusion. No patient with MCA stenosis had a late ipsilateral stroke, although five had a contralateral or vertebrobasilar stroke. One patient with MCA occlusion had a late ipsilateral stroke. The bypass patency rate at late follow-up review was 100%. The results of intracranial-extracranial arterial bypass procedures appear to be similar for patients with either stenosis or occlusion of the MCA. Symptomatic relief of TIA's was excellent and, in two patients with progressive stroke-in-evolution, the deficit was stabilized. The incidence of postoperative ipsilateral stroke was low in patients with TIA's alone or with TIA's after an initial stroke, but among patients with completed stroke, improvement was confined to slight reduction in the neurological deficit.

Adult↗
PubMed1984

Neuroepithelial cysts of the posterior fossa: pathogenesis and report of two cases.

We present two cases of simple neuroepithelial cyst--one at the cerebellopontine angle and the other in the pontine brain stem--in which a basement membrane was detected. The pathogenesis of these cysts, their diagnosis using computed tomography-metrizamide cisternography and nuclear magnetic resonance imaging, and their surgical treatment by fenestration and drainage are discussed.

Adult↗