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Biomedical subjects

H R Winn

Publications and source records attributed to H R Winn.

At least 19 recordsLinked to original sources
PubMed1999

P-selectin blockade following fluid-percussion injury: behavioral and immunochemical sequelae.

Traumatic brain injury (TBI) can cause polymorphonuclear leukocyte (PMN) migration into brain parenchyma, mediating various cytodestructive mechanisms. We examined the effect of blocking leukocyte/endothelial cell adhesion molecules (CAMs) on the anatomic and behavioral sequelae in lateral fluid-percussion injury in rats. Monoclonal antibodies (MAb) directed against a functional (PB1.3) or nonfunctional (PNB1.6) epitope on endothelial P-selectin were used as treatments. Subjects were tested in the Morris water maze (MWM) at 7 and 14 days postinjury then immunohistochemistry was performed using antibodies that recognize ChAT, GFAP and OX-42. A second set of animals underwent myeloperoxidase (MPO) assay in the brain parenchyma and a third set was used to examine neutrophil migration using the MAb RP-3. Time in quadrant, but not escape latency or proximity improved with PB1.3 (p < 0.05). Similarly, PB1.3 reduced MPO levels after injury (p < 0.05), in the ipsilateral cortex. No significant difference occurred in neutrophil counts in cortex, corpus callosum, hippocampus, and thalamus between injured only rats and injured rats treated with PB1.3. Quantitative analysis of cholinergic cells in the medial septum showed a protective effect by PB1.3. Densitometry readings of GFAP and OX-42 immunolabeling revealed no discernible differences between the treated and untreated injured rats. Qualitatively, there was no difference in microglia or astrocyte response to treatment. Treatment with P-selectin blockade in brain-injured rats may reduce PMN migration into brain, help preserve cholinergic immunolabeling of medial septal nucleus neurons, and may alleviate mnemonic deficits.

Animals↗
PubMed1999

Resolution of central pain after embolization of an arteriovenous malformation. Case report.

The authors describe a patient with right-sided central pain resulting from a left parietal arteriovenous malformation (AVM). The AVM was treated with staged embolization and stereotactic radiosurgery, and its obliteration was documented on follow-up angiographic studies. Surprisingly, the patient noted complete resolution of her pain syndrome after embolization, which is an extremely rare result. Central pain and its proposed mechanisms are discussed.

Angiography, Digital Subtraction↗
PubMed1998

Suppression of somatosensory evoked potentials by nitric oxide synthase inhibition in rats: methodological differences.

We have previously shown that topically applied N(G)-nitro-L-arginine (L-NNA), a nitric oxide synthase (NOS) inhibitor, suppressed both somatosensory evoked potentials (SEPs) and vascular responses during sciatic nerve stimulation in rats. Due to the normal tight coupling between cerebral blood flow and neuronal activity, we surmise that the vascular response attenuation may be secondary to the SEP decrease. However, a recent study, in which SEPs were recorded with a 'non-contact' electrode placed longitudinally across the cranial window without touching the cortex, did not find a SEP decrease following NOS inhibition. In the present study, we compared SEPs recorded with 'contact' and 'non-contact' electrodes. Regardless of stimulation methods (sciatic nerve or hindpaw), an electrode in contact with the pial surface overlying the hindlimb somatosensory cortex recorded a steady SEP decline during I-NNA application. In contrast, a 'non-contact' electrode did not detect a significant SEP change in the presence of I-NNA. The present results thus confirm the attenuation of SEPs by NOS inhibition.

Animals↗
PubMed1998

Selective loss of hippocampal long-term potentiation, but not depression, following fluid percussion injury.

We investigated the early effects of in vivo fluid percussion injury (FPI) on hippocampal synaptic potentials and excitability. In vitro field potential recordings and immunocytochemistry were performed in the CA1 region in slices from naïve, post-FPI, or sham-operated rats. The following electrophysiological and morphological parameters were affected following FPI: (1) threshold for population spike generation was increased suggesting that post-FPI neurons were hypoexcitable; (2) long-term potentiation (LTP) could not be induced in injured hippocampi; (3) GFAP and inducible NO synthase (iNOS) immunoreactivity were enhanced post-FPI; and (4) following injury, synaptophysin immunoreactivity was enhanced in CA1 stratum radiatum. The effects of FPI on synaptic plasticity were LTP-specific, since long-term depression (LTD) could be equally induced and maintained in post-FPI, sham-operated and control slices. Sham-operated slices were characterized by synaptic excitability indistinguishable from naïve controls, but displayed decreased ability for LTP production and expressed high levels of iNOS. We conclude that FPI causes a selective loss of LTP, possibly due to a previous potentiation induced by trauma as reflected by the increased expression of synaptic proteins. Sham surgical procedures were, however, not without effects on long-term potentiation itself; the latter effects appear to be mediated by an increased production of NO. Our study demonstrates for the first time that hippocampal slices can be used to investigate the correlates of in vivo FPI. Furthermore, we describe LTP-specific deficits in post-traumatic brain injury, suggesting that FPI can selectively erase one of the two main NMDA-dependent forms of synaptic plasticity in the hippocampus.

Animals↗
PubMed1998

Two cases of esophageal carcinoma metastatic to the pineal region with a review of the literature.

BACKGROUND: Metastasis to the pineal region is rare, and there are no previously reported cases of esophageal carcinoma metastatic to the pineal region. CASE DESCRIPTION: We now present two cases of solitary esophageal carcinoma metastatic to the pineal region. In each case there was no evidence of disease progression at the primary site at the time of presentation, and neurologic symptoms were the first indication of recurrent disease. Both patients underwent infratentorial/supracerebellar resection of the pineal lesions and were subsequently referred for radiation therapy. CONCLUSIONS: These two cases emphasize that metastatic disease must be a likely differential consideration in a patient with a CNS lesion and a history of previous malignancy, even if the lesion is in an unusual location.

Adenocarcinoma↗
PubMed1998

Increases in metabolism of valproate and excretion of 6beta-hydroxycortisol in patients with traumatic brain injury.

AIMS: The objectives of this study were to determine the effect of brain trauma on the multiple pathways of metabolism of valproate and to evaluate the use of the urinary 6beta-hydroxycortisol to cortisol ratio in predicting changes in hepatic metabolism induced by brain injury. METHODS: Fourteen patients with severe head injuries received a 15 mg kg(-1) loading dose and a maintenance dose of valproate to maintain therapeutic plasma concentrations. A minimum of one steady state trough blood sample and one dosage interval urine were collected during days 3-6 and during days 7-14 post-injury. Total and unbound valproate plasma concentrations were determined by gas chromatography-flame ionization detection (GC-FID) with and without ultrafiltration. Urinary valproate metabolites were measured by gas chromatography/mass spectrometry (GC-MS) (n = 10). Urinary 6beta-hydroxycortisol and cortisol concentrations were determined by high performance liquid chromatography (h.p.l.c.) (n = 14). Total intrinsic clearance (CL[int]) for valproate and individual formation clearances (CL[f]) to its major metabolites were calculated. Data obtained during baseline (days 3-6) were averaged for each patient and were compared with averaged data obtained from days 7 to 14 using a paired t-test. RESULTS: Statistically significant increases in the CL(int), CL(f) of VPA glucuronide, 2-ene-VPA, and 4-OH-VPA pathways and the 6beta-hydroxycortisol to cortisol ratio were found. The percent change in the 6beta-hydroxycortisol to cortisol ratio correlated significantly with the changes in the CL(int) of valproate. CONCLUSIONS: Brain trauma results in induction of multiple pathways of valproate metabolism and increases in the 6beta-hydroxycortisol to cortisol ratio, suggesting a non-specific enzyme induction in response to head injury.

Adult↗
PubMed1998

Balloon angioplasty for the treatment of vasospasm: results of first 50 cases.

OBJECTIVE: To report the results of the first 50 consecutive patients with vasospasm secondary to subarachnoid hemorrhage treated with balloon angioplasty after failure of medical management. METHODS: Retrospective uncontrolled study of 50 consecutive patients treated with balloon angioplasty between February 1988 and July 1992. Forty-six had objective clinical deterioration despite maximal medical therapy, whereas four were treated on the basis of rapidly accelerating transcranial Doppler velocities and decreased regional blood perfusion detected by technetium-99m-exametazime brain single photon emission computed tomography. All patients had evidence of marked vasospasm demonstrated by angiography. Thirty-two (64%) and 46 (92%) patients underwent angioplasty within 12 and 18 hours, respectively. RESULTS: Of the patients with clinical evidence of vasospasm-induced ischemia, 28 (61%) showed sustained neurological improvement within 72 hours of angioplasty. Three (6%) patients deteriorated within 72 hours after angioplasty, with two (4%) patients dying immediately after angioplasty as a result of vessel rupture and the other patient's Glasgow Coma Scale score decreasing by 2. Two additional patients in poor condition with Hunt and Hess Grade V at the time of angioplasty subsequently died during hospitalization. Two other patients died as a result of unclipped aneurysms that subsequently bled 4 and 12 days after angioplasty, respectively. The improvement demonstrated clinically, angiographically, and by transcranial Doppler after angioplasty was sustained, with only one patient requiring subsequent angioplasty of a previously dilated segment (total, 170 vessel segments dilated). Two patients developed vasospasm in previously undilated segments. CONCLUSION: Timely balloon angioplasty can reverse delayed ischemic deficit caused by vasospasm in patients for whom medical therapy has failed.

Angioplasty, Balloon↗
PubMed1998

Accuracy of continuous jugular bulb oximetry in the intensive care unit.

OBJECTIVE: To address the accuracy of a bedside jugular bulb oxygen saturation (SjO2) catheter monitor (Baxter-Edwards, Santa Ana, CA) versus in vitro co-oximetry measurements in the intensive care unit (ICU). METHODS: By prospective protocol, we compared blood gas measurements with simultaneously recorded continuous bedside oximetric monitor values for 31 ICU patients with traumatic brain injury undergoing jugular bulb catheter monitoring. For suboptimal fiberoptic light signal quality indices, the catheter was repositioned, flushed, or both before drawing the sample for in vitro measurement. Laboratory and bedside monitor data were examined for association using the chi2 and paired t tests and a linear regression model. RESULTS: We assessed 195 samples (median, 5 per patient; range, 1-14) who were monitored an average of 3.4 (range, 1-6) days. The in vivo monitor (range, 32-94%) and in vitro co-oximetry (range, 38-93%) values had acceptable correlation (y = 0.94x + 4.4, r2 = 0.80). For bedside monitor detection of jugular bulb desaturation (SjO2 < 50% for 10 min), the kappa statistic was 0.35, the sensitivity was 45 to 50%, and the specificity was 98 to 100%. CONCLUSION: Continuous ICU SjO2 monitoring correlates significantly with in vitro values, but less so than previously described during intracranial surgery. Although sensitivity of the bedside monitor to detect confirmed desaturations remains an issue, the high specificity indicates that it is less of a concern that patients may be misdiagnosed as having desaturations resulting in unnecessary interventions. Nonetheless, suspected jugular bulb desaturation should be verified before taking therapeutic actions.

Adolescent↗
PubMed1998

Risks and benefits of diagnostic angiography after aneurysm surgery: a retrospective analysis of 597 studies.

INTRODUCTION: Cerebral angiography performed after aneurysm surgery can identify causes of morbidity and mortality that may be corrected. The risks and benefits of angiography that is performed after aneurysm surgery, however, have not been clearly defined. We therefore reviewed our experience with postoperative angiography to determine its dangers and benefits. METHODS: During 10 years, 543 consecutive patients received treatment for cerebral aneurysms. A retrospective analysis of 597 diagnostic angiograms obtained after aneurysm surgery for 494 of these patients was performed. RESULTS: Catheter-induced vessel spasm and dissection, occurring most frequently in the internal carotid artery, were observed in seven (1.2%) and six (1%) studies, respectively. No angiography-associated strokes were identified. No association between age, smoking, hypertension, blood pressure, atherosclerosis, or severe vasospasm and angiographic complications was observed. Aneurysm remnants were identified in 36 (5.7%) of the 637 aneurysms that were surgically treated. Atherosclerosis (P < 0.01) or multiple clip applications (P < 0.01) were significantly associated with aneurysm remnants. Angiographic vessel occlusion was observed in 28 (5.7%) patients and resulted in stroke in 14 of these patients. Vessel occlusion was significantly associated with increasing aneurysm size (P < 0.001), atherosclerosis (P < 0.001), temporary clips (P < 0.001), multiple clips (P=0.03), multiple clip applications (P=0.001), and a new postoperative neurological deficit (P=0.002). Severe vasospasm and newly identified aneurysms were observed in 51 and 16 patients, respectively. CONCLUSION: Angiography after aneurysm surgery is safe and can be routinely performed. Angiography after aneurysm surgery should be particularly considered for patients with large aneurysms or cerebrovascular atherosclerosis and for those who develop new postoperative neurological deficits.

Adolescent↗
PubMed1998

An illuminating retractor for intracranial microneurosurgery.

During certain microneurosurgical procedures, the illumination provided by current coaxial microscope light sources is suboptimal. One potential solution is the surgical light blade (SLB), a malleable retractor incorporating a flat fiberoptic bundle along its surface. The SLB provides intense illumination within the surgical field without decreasing the amount of limited operating space. A prototype of the SLB was tested in six patients. Results suggest that with further development the SLB could become useful for intracranial microneurosurgery.

Brain Diseases↗
PubMed1998

Relationship between intracranial pressure and the development of vasospasm after aneurysmal subarachnoid hemorrhage.

The relationship between intracranial pressure (ICP) and the development of vasospasm after subarachnoid hemorrhage caused by the rupture of an intracranial aneurysm was investigated. Eleven patients were divided into high (6 cases) and low (5 cases) ICP groups based on ICP data obtained during the perioperative period by continuous ICP monitoring. Transcranial Doppler ultrasonography was performed every 24 hours for 7 days and the severity, distribution, and duration of vasospasm were assessed. The high ICP group tended to have severe, prolonged, and diffuse vasospasm compared with the low ICP group. However, only duration of vasospasm was statistically different. The relationship between cerebral perfusion pressure (CPP) and the development of vasospasm was also examined. CPP had a less significant effect than ICP although similar tendencies for high ICP and low CPP were observed. High ICP worsens vasospasm and treatment for decreasing ICP with perioperative ICP monitoring has potential for avoiding the development of vasospasm.

Adult↗
PubMed1998

Comparison of balloon angioplasty and papaverine infusion for the treatment of vasospasm following aneurysmal subarachnoid hemorrhage.

OBJECT: The purpose of this study was to test the hypothesis that balloon angioplasty is superior to papaverine infusion for the treatment of proximal anterior circulation arterial vasospasm following subarachnoid hemorrhage (SAH). Between 1989 and 1995, 125 vasospastic distal internal carotid artery or proximal middle cerebral artery vessel segments were treated in 52 patients. METHODS: Blood flow velocities of the involved vessels were assessed by using transcranial Doppler (TCD) monitoring in relation to the day of treatment with balloon angioplasty or papaverine infusion. Balloon angioplasty and papaverine infusion cohorts were compared based on mean pre- and posttreatment velocity at 24 and 48 hours using the one-tailed, paired-samples t-test. Balloon angioplasty alone was performed in 101 vessel segments (81%) in 39 patients (75%), whereas papaverine infusion alone was used in 24 vessel segments (19%) in 13 patients (25%). Although repeated treatment after balloon angioplasty was needed in only one vessel segment, repeated treatment following papaverine infusion was required in 10 vessel segments (42%) in six patients because of recurrent vasospasm (p < 0.001). Seven vessel segments (29%) with recurrent spasm following papaverine infusion were treated with balloon angioplasty. Although vessel segments treated with papaverine demonstrated a 20% mean decrease in blood flow velocity (p < 0.009) on posttreatment Day 1, velocities were not significantly lower than pretreatment levels by posttreatment Day 2 (p = 0.133). Balloon angioplasty resulted in a 45% mean decrease in velocity to a normal level following treatment (p < 0.001), a decrease that was sustained. CONCLUSIONS: Balloon angioplasty is superior to papaverine infusion for the permanent treatment of proximal anterior circulation vasospasm following aneurysmal SAH.

Adult↗
PubMed1998

Methylprednisolone or tirilazad mesylate administration after acute spinal cord injury: 1-year follow up. Results of the third National Acute Spinal Cord Injury randomized controlled trial.

OBJECT: A randomized double-blind clinical trial was conducted to compare neurological and functional recovery and morbidity and mortality rates 1 year after acute spinal cord injury in patients who had received a standard 24-hour methylprednisolone regimen (24MP) with those in whom an identical MP regimen had been delivered for 48 hours (48MP) or those who had received a 48-hour tirilazad mesylate (48TM) regimen. METHODS: Patients for whom treatment was initiated within 3 hours of injury showed equal neurological and functional recovery in all three treatment groups. Patients for whom treatment was delayed more than 3 hours experienced diminished motor function recovery in the 24MP group, but those in the 48MP group showed greater 1-year motor recovery (recovery scores of 13.7 and 19, respectively, p=0.053). A greater percentage of patients improving three or more neurological grades was also observed in the 48MP group (p=0.073). In general, patients treated with 48TM recovered equally when compared with those who received 24MP treatments. A corresponding recovery in self care and sphincter control was seen but was not statistically significant. Mortality and morbidity rates at 1 year were similar in all groups. CONCLUSIONS: For patients in whom MP therapy is initiated within 3 hours of injury, 24-hour maintenance is appropriate. Patients starting therapy 3 to 8 hours after injury should be maintained on the regimen for 48 hours unless there are complicating medical factors.

Activities of Daily Living↗
PubMed1998

Management of cerebral aneurysms. How can current management be improved?

In the present article, we have reviewed potential avenues for improvement in the care of and present management of patients with cerebral aneurysms. Opportunities exist in areas of prevention, systems approach and organization of centers, physician and patient education, screening, and advances in surgical and endovascular therapy. All such advances, however, depend on rigorous academic evaluation. This issue represents a review of the current management of cerebral aneurysms, hopefully providing a basis for future improvements in the treatment of these lesions.

Case Management↗
PubMed1998

Management of the ruptured aneurysm.

Rupture of cerebral aneurysms is a complex and devastating pathophysiologic event. The successful management of aneurysm rupture requires a dedicated multidisciplinary team. This article reviews pathophysiology; clinical grading that can be used to predict outcome and guide therapy; factors that may affect outcome such as rebleeding, poor clinical grade, intracerebral hemorrhage, intraventricular hemorrhage, and acute hydrocephalus; preoperative care and assessment; pharmacological therapy; anesthetic, surgical, and endovascular considerations; and postoperative care following aneurysm rupture.

Aneurysm, Ruptured↗
PubMed1998

Surgical approaches to basilar bifurcation aneurysms.

Basilar bifurcation aneurysms are technically challenging and their treatment is often associated with greater morbidity than aneurysms located in the anterior circulation. These lesions can be treated using surgical, endovascular, or a combination of techniques. Several surgical approaches have evolved to treat basilar bifurcation aneurysms; none, however, is suitable for all aneurysms in this location. This article reviews the natural history, clinical presentation, evaluation, and selection of treatment approach and details various surgical techniques. The use of endovascular techniques is reviewed briefly.

Basilar Artery↗