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Biomedical subjects

G W Kindt

Publications and source records attributed to G W Kindt.

At least 19 recordsLinked to original sources
PubMed1999

Bilateral partial laminectomy: a treatment for lumbar spinal stenosis and midline disc herniation.

BACKGROUND: Lower back pain is extremely common; most patients' symptoms improve with conservative treatment. This leaves only a small percentage of patients with persistent symptoms that are amenable to surgery. Various decompressions have been performed to remedy compressive conditions of the spine, with a wide range of results. METHODS: We retrospectively reviewed 152 patients with lumbar spinal stenosis or midline disc herniations surgically treated with bilateral partial laminectomy. Short-term follow-up was available for 138 patients (2 weeks to 2 months) and long-term follow-up was available for 88 patients (1-6 years, mean 3.5 years). Clinical outcome was determined by chart review and the use of a standardized questionnaire. Preoperative and postoperative back and leg pain, ambulation, employment status, and satisfaction were assessed. RESULTS: Overall improvement postoperatively was noted in 88% of the spinal stenosis patients and 91% of the midline disc herniations at long-term follow-up. Average hospital stays for the spinal stenosis group and the midline disc herniation group were 3.7 days and 2.8 days, respectively. Only two patients had undergone subsequent fusions of their lumbar spine after bilateral partial laminectomy. CONCLUSION: We believe that less radical resection of laminae and spinous processes better preserves the spine's natural architecture and may contribute to improved postoperative stability. This may reduce the number of patients needing concomitant or subsequent fusion, with its associated morbidity. As surgeons push for less radical or less invasive surgical techniques to obtain the same or better postoperative results, the bilateral partial laminectomy is a good alternative to total laminectomy.

Adult↗
PubMed1998

Induced hypervolemia and inotropic support for acute cerebral arterial insufficiency: an underused therapy.

BACKGROUND: Hypervolemia and induced systemic hypertension are generally considered the standard approach to the treatment of vasospasm. Despite evidence in favor of its efficacy, this therapy is used rarely in acute cerebrovascular occlusion. We present a case supporting this treatment paradigm. CASE DESCRIPTION: A patient developed aphasia and hemiplegia 8 h after carotid endarterectomy caused by embolic occlusion of the middle cerebral artery. Hyperdynamic/hypervolemic therapy was instituted. Serial angiograms filmed over the next 8 h demonstrated reperfusion of the hemisphere, through collateral flow. The patient's symptoms resolved. CONCLUSIONS: We believe this case demonstrates the effectiveness of hypervolemia and inotropic support in the treatment of acute embolic stroke by inducing dilatation of the leptomeningeal collateral circulation.

Acute Disease↗
PubMed1998

Outcome after urgent surgery for grade IV subarachnoid hemorrhage.

BACKGROUND: Outcome after subarachnoid hemorrhage (SAH) in patients presenting with poor clinical grade has historically been dismal. As a result, many poor-grade patients have been excluded from early, aggressive surgery. We present a consecutive series of 27 patients with acute (less than 24 h since clinical onset) Grade IV SAH treated with early surgery. METHODS: All patients were treated with immediate ventricular drainage, rigid hemodynamic control, early angiography and surgery within 24 h of presentation. Patients were followed for a minimum of 6 months and their outcomes categorized using a four-tiered scale: 1) independent and working, 2) impaired but independent, 3) severely impaired and dependent, and 4) dead. RESULTS: Seven patients died within 48 h of admission. The remaining 20 patients survived to discharge. At the time of discharge eight of these patients were considered to be impaired but independent and twelve were considered severely impaired and dependent. At follow-up, seven patients were independent and working, six were impaired but independent, five were severely impaired and dependent, and two severely impaired patients had subsequently died. CONCLUSIONS: We conclude that urgent surgery for poor-grade SAH can produce quality survival for a higher percentage of patients than is historically reported with delayed surgery.

Adult↗
PubMed1997

Pineal region choroid plexus papilloma treated with stereotactic radiosurgery: a case study.

The treatment of a patient with a third-ventricular choroid plexus papilloma is described. This relatively unusual lesion was treated with stereotactic radiosurgery. Follow-up at 17 months demonstrates substantial reduction in tumor volume and an excellent clinical outcome. The treatment of this patient suggests that radiosurgery may be an effective alternative to open surgical resection.

Adult↗
PubMed1992

Tungsten treatment prevents tumor necrosis factor-induced injury of brain endothelial cells.

Exposure to recombinant human tumor necrosis factor-alpha (TNF-alpha) or calcium ionophore (A23187) for 4 h increased (P less than 0.05) lactate dehydrogenase (LDH) release from cultured bovine brain endothelial cells (EC). In contrast, treatment with endotoxin or interleukin-1 did not increase (P greater than 0.05). LDH release from brain EC. Pretreatment with tungsten decreased (P less than 0.05) xanthine oxidase activity in brain EC and decreased (P less than 0.05) LDH release from brain EC following exposure to TNF. Our results suggest that TNF-alpha injures brain microvascular EC and that this effect may be mediated by xanthine oxidase.

Animals↗
PubMed1992

Loss of cerebral regulation during cardiac output variations in focal cerebral ischemia.

Focal cerebral ischemia was induced in anesthetized macaque monkeys by unilateral middle cerebral artery occlusion. The effect of blood volume expansion by a colloid agent and subsequent exsanguination to baseline cardiac output (CO) on local cerebral blood flow (CBF) was measured by the hydrogen clearance technique in both ischemic and nonischemic brain regions. Cardiac output was increased to maximum levels (159% +/- 92%, mean +/- standard error of the mean) by blood volume expansion with the colloid agent hetastarch, and was then reduced a similar amount (166% +/- 82%) by exsanguination during the ischemic period. Local CBF in ischemic brain regions varied directly with CO, with a correlation coefficient of 0.89 (% change CBF/% change CO), while CBF in nonischemic brain was not affected by upward or downward manipulations of CO. The difference in these responses between ischemic and nonischemic brain was highly significant (p less than 0.001). The results of this study show a profound loss of regulatory control in ischemic brain in response to alterations in CO, thereby suggesting that blood volume variations may cause significant changes in the intensity of ischemia. It is proposed that CO monitoring and manipulation may be vital for optimum care of patients with acute cerebral ischemia.

Animals↗
PubMed1991

Generation of superoxide anion by brain endothelial cell xanthine oxidase.

Bovine brain endothelial cells (EC) that were isolated and propagated in pure culture had increased (greater than 20-fold) levels of xanthine oxidase and xanthine dehydrogenase activity compared to whole brain homogenate. Brain EC also released superoxide anion (O2-) into the extracellular medium. Treatment of EC with tungsten decreased (P less than 0.05) both XO activity and O2- release. XO appears to be highly concentrated in cerebral vascular endothelium and may be an important source of O2-.

Animals↗
PubMed1989

Effects of crystalloid and colloid infusions on intracranial pressure and computerized electroencephalographic data in dogs with vasogenic brain edema.

This experiment was designed to study the effects of intravascular volume expansion with crystalloid and colloid agents on intracranial pressure (ICP) and computerized electroencephalographic (EEG) data in dogs with cerebral vasogenic edema. A liquid nitrogen cold lesion was produced in the right parietal lobes of 30 anesthetized mongrel dogs. ICP data from an intraventricular catheter, hemodynamic data, and EEG power data were recorded continuously during the course of the experiment. Six hours after creation of the liquid nitrogen cold lesion, each dog was infused with one of the following treatments: 1) no treatment (control); 2) 5% dextrose in water (D5W) (30 ml/kg/h); 3) 0.9% NaCl (30 ml/kg/h); 4) hetastarch (10 ml/kg/h); and 5) hetastarch (30 ml/kg/h). The animals were treated for 2 hours, killed, and the brains examined and measured for water content. During the D5W infusion, ICP increased significantly (141%) but the EEG power data did not change. During the normal saline infusion, ICP increased significantly (91%) and the EEG power data showed marked deterioration. Both hetastarch infusions produced no change in ICP and demonstrated an improvement in the EEG power data (P less than 0.001). These data suggest that crystalloid infusions may have profound deleterious effects in the presence of brain edema, but colloids do not, and should be considered in the fluid management of patients with cerebral edema.

Animals↗
PubMed1988

Thrombosed arteriovenous malformations: a type of occult vascular malformation. Magnetic resonance imaging and histopathological correlations.

Thrombosed arteriovenous malformations (AVMs) are the predominant type of occult vascular malformation and do not seem to differ significantly in clinical or radiographic presentation from other types of occult vascular malformations. Thrombosed AVMs and occult vascular malformations occasionally present with symptoms secondary to subacute or occult hemorrhage that requires operation. The histopathology of thrombosed AVMs and occult vascular malformations does not seem to have prognostic significance. Five patients with histologically verified thrombosed AVMs are reported. Two patients had previous incomplete resection of histologically proven thrombosed AVMs and presented with recurrence and bleeding. Two patients presented with seizures and headaches, and one patient presented with hemiparesis and headache. All histology specimens had evidence of hemorrhage. The pathological findings of these lesions seem variable; two specimens contained a mixture of cavernous angioma and AVM. Two previously resected lesions had been defined histologically as thrombosed AVMs. Successful excision of the lesions was accomplished in four patients, and one patient had stereotactic biopsy. The magnetic resonance imaging characteristics of lesions seem to add a degree of specificity over computed tomography and angiography. We have found that the literature poorly describes the natural history and histology of these lesions. Conservative management for seizures and headaches due to thrombosed AVMs may not be warranted because of a propensity for hemorrhage and recurrence.

Adult↗
PubMed1986

Phase I clinical trial of intracarotid bis-chloroethylnitrosourea (BCNU) and 2' dioxy-5-fluorouridine (FUDR) in malignant astrocytomas.

Systemic chemotherapy has been of limited benefit in the treatment of intracranial neoplasms, due, in part, to the inability to deliver effective drug doses to the neoplasm without systemic toxicity. We have completed a clinical trial of intracarotid BCNU and FUDR using an implantable pump in patients with unilateral malignant astrocytomas (Grade III and IV) in the hope of obtaining better tumor control with less systemic toxicity. Six patients had in-dwelling catheters placed in the internal carotid artery attached to a percutaneous refillable pump (Infusaid 400). The treatment program consisted of bolus BCNU 400 mg every 6 weeks and FUDR by continuous infusion at dosages ranging from 0.5 mg/24 h to 2.5 mg/24 h. The maximum tolerable dose of FUDR was 1 mg/24 h with ipsilateral mucositis and conjunctivitis being dose limiting factors. Flow studies demonstrated significant perfusion of the ipsilateral eye and surrounding face secondary to ophthalmic artery collaterals. No patient had systemic toxicity and the lowest WBC encountered was 2 400 with normal differential and platelets.

Aged↗
PubMed1986

Blood volume expansion with hetastarch in acute ischaemic stroke: the effects on local cerebral blood flow and computer mapped EEG.

Focal cerebral ischaemia was induced in seven anaesthetized monkeys by unilateral middle cerebral artery (MCA) occlusion. Local cerebral blood flow (CBF) and computer mapped EEG (CME) changes were then studied as blood volume and cardiac output (CO) were varied. CO was increased by colloidal volume expansion and decreased by exsanguination. Local CBF fell to 24 +/- 9% of control values in ischaemic areas following MCA occlusion and increased to 43 +/- 19% of control values (p less than 0.01) when CO was increased by 130 +/- 70% with colloid infusion. Local CBF to nonischaemic regions was not altered significantly by blood volume expansion. Exsanguination led to return of CO to control levels and was associated with reduction of local CBF in ischaemic regions to 24 +/- 12% of control values (p less than 0.05). CME showed bifrontal or ipsilateral slow wave foci (delta) following MCA occlusion. Blood volume expansion brought about a marked reduction of this slow wave activity and exsanguination led to recurrence of the slow wave foci. This data demonstrated that colloidal blood volume expansion induced an increase in local CBF and improved neuroelectric status of ischaemic brain following MCA occlusion. It was also shown that a reduction of blood volume and cardiac output resulted in a reduction in local CBF and a worsening of neuroelectric status in ischaemic areas. This study supports the contention that blood volume and cardiac output maintenance is extremely important in the management of acute ischaemic stroke.

Animals↗
PubMed1986

Acute middle cerebral artery occlusion: experience with volume expansion therapy.

Five consecutive patients with acute neurological deficits after middle cerebral artery (MCA) occlusion were given emergency treatment with colloidal volume expansion. In each case, the diagnosis was confirmed promptly by computed tomography and cerebral angiography. Aggressive volume expansion therapy was started 2 to 18 hours (mean, 11 hr) after the onset of the neurological deficit. The mean colloidal volume used was 920 ml/day for an average of 4 days. During volume expansion, the mean cardiac output increased 57% from 4.6 +/- 0.6 to 7.2 +/- 1.9 litres/min (P less than 0.05). The mean hematocrit decreased 19% from 46 +/- 3% to 37 +/- 4% (P less than 0.01). The mean arterial blood pressure remained stable, and the pulmonary artery wedge pressure was maintained at less than 15 mm Hg. Three patients improved dramatically with volume expansion therapy and have returned to their previous life-styles. Two patients made partial recoveries and manage at home with nursing care. The three patients who improved dramatically were young (aged less than 34) and, when compared to the older patients, they had greater increases in cardiac output (67% vs. 19%). No major complications or deaths were attributed to the volume expansion therapy. We propose that intravascular volume expansion and its concomitant augmentation of the cardiovascular dynamics may be effective in the treatment of acute neurological deficits after acute MCA occlusion.

Acute Disease↗
PubMed1986

Pulsatile versus nonpulsatile blood flow in the treatment of acute cerebral ischemia.

The effects of pulsatile and nonpulsatile perfusion on local cerebral blood flow (CBF) and on computerized mapping (CME) of electroencephalograms (EEG) in nonischemic and ischemic brain were studied using a canine stroke model. Nine anesthetized mongrel dogs were placed on normothermic right atrial-femoral artery cardiopulmonary bypass at a flow of 100 ml/kg/minute. Local CBF measurements and CME data were collected during nonpulsatile perfusion and maximal pulsatile perfusion. The stroke model was then produced, and local CBF measurements and CME data were again collected during nonpulsatile and pulsatile perfusion. In the nonischemic brain, local CBF increased 19%, from 32 +/- 10 to 38 +/- 11 ml/100 g/minute (P less than 0.01), when perfusion was changed from nonpulsatile flow (pulse pressure less than 4mm Hg) to pulsatile flow (pulse pressure 39 +/- 11 mm Hg). In the ischemic brain, local CBF increased 55%, from 11 +/- 5 to 17 +/- 7 ml/100 g/minute (P less than 0.01), when perfusion was changed from nonpulsatile (pulse pressure less than 3 mm Hg) to pulsatile (pulse pressure 36 +/- 7) flow. EEG power data, expressed as a power ratio index (PRI = low frequency power/high frequency power), improved significantly, from 110 +/- 33 to 101 +/- 41 (P less than 0.01) with pulsatile perfusion. These data demonstrate the importance of pulsatile blood flow in ischemic brain.

Acute Disease↗
PubMed1985

Modification of focal cerebral ischemia by cardiac output augmentation.

Intravascular volume expansion has been employed successfully for treatment of ischemic stroke from cerebral vasospasm and from cerebrovascular occlusive disease. The physiologic mechanism responsible for this success has not previously been delineated in controlled experimentation. The objective of this investigation was to delineate the effects of cardiac output and of hemodilution in a primate model of focal cerebral ischemia. Two groups of anesthetized rhesus monkeys received extensive cardiovascular monitoring, and local cerebral blood flow (lCBF) was determined in both ischemic and nonischemic brain regions by the hydrogen clearance method. Both groups were subjected to unilateral middle cerebral artery occlusion. One group then underwent blood volume expansion with Dextran 40 (cardiac output augmentation), and one group underwent isovolemic hemodilution with Dextran 40, cardiac output being maintained constant. Significant increases in lCBF occurred in ischemic regions only and occurred only in response to augmentation of cardiac output. Isovolemic hemodilution failed to produce any changes in lCBF. This investigation indicates that ischemic brain regions are selectively vulnerable to alterations in cardiac output, these effects being independent of alterations in blood pressure. Blood viscosity changes may play only a minor role. This study strongly suggests an important role of intravascular volume expansion and cardiac output augmentation in treatment of acute ischemic stroke.

Animals↗
PubMed1985

High altitude: an unusual cause of neurological deterioration in a patient with an arteriovenous malformation.

High altitude associated with neurological deterioration is an unusual presentation for an arteriovenous malformation (AVM). A case report of a man with a left temporal occipital AVM who developed symptoms that were markedly intensified by exposure to high altitude is presented. The AVM was removed surgically, and all symptoms resolved. The pathogenesis of this unusual AVM symptom complex is discussed in this report.

Altitude↗
PubMed1985

Topographic electroencephalographic study with power ratio index mapping in patients with malignant brain tumors.

A variant of electroencephalogram (EEG) power spectral mapping called power ratio index (PRI) mapping was used to monitor 15 patients with malignant brain tumors. This index is generated by dividing the low frequency (delta, theta) power by the high frequency (alpha, beta) power. Because the nonparoxysmal effect of a brain tumor on the EEG is reflected as a relative loss of high frequency power and a gain in low frequency power, utilization of the PRI has the effect of placing the epicenter of the "power dysfunction" coincident with the epicenter of the tumor.

Adult↗