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Biomedical subjects

M L Walker

Publications and source records attributed to M L Walker.

At least 37 records · Page 2Linked to original sources
PubMed1997

Personality disorders in adolescents with major depression, substance use disorders, and coexisting major depression and substance use disorders.

This study examined the presence of personality disorders in adolescent inpatients with major depression (MDD; n = 45), substance use disorders (SUD; n = 27), or both disorders combined (MDD-SUD; n = 42). A consecutive series of patients were given structured diagnostic interviews for Axes I and II disorders. The groups did not differ with regard to age, gender, ethnicity, socioeconomic status, psychiatric history, or global assessment of functioning. Borderline personality disorder was diagnosed more frequently in the MDD-SUD group than in the MDD or the SUD groups.

Adolescent↗
PubMed1997

Reduced cerebral vasomotor reactivity as an indicator of postoperative confusion.

Surgical intervention in elderly patients carries a high risk. A frequent problem with surgery in these patients is the occurrence of a temporary confusional state, which increases both the risk of postoperative complications and the need for intensive care. We hypothesised that, in part, temporary confusional state results from cerebral hypoxia occurring in response to blood pressure fluctuations during surgery. To assess whether disruption of autoregulation of cerebral blood vessels plays a role in temporary confusional state, we studied 31 patients over 55 years of age, using the Doppler-carbon dioxide test. We determined whether vasomotor reactivity could be used diagnostically to identify those patients most likely to experience temporary confusional state. Blood flow velocity in the middle cerebral artery was detected using Doppler ultrasound, and hypercapnia was induced by breathing carbon dioxide until an end-tidal concentration of 8.0% by volume was reached. Vasomotor reactivity was calculated on the basis of the changes in blood flow velocity in response to the increase in carbon dioxide. Temporary confusional state was assessed using the Syndrome Short Test (Syndrom-Kurztest). We found that resting blood flow velocity was inversely related to age (p < 0.05). In addition, there was a significant inverse correlation between vasomotor reactivity and temporary confusional state (p < 0.05). These data indicate that vasomotor reactivity, as measured by the Doppler-carbon dioxide test, is a reliable tool to identify patients at risk for postoperative psychological disturbances.

Aged↗
PubMed1997

Three-dimensional ultrasound angiography (power mode) for the quantification of carotid artery atherosclerosis.

Three-dimensional (3D) ultrasound angiography was performed to diagnose carotid artery atherosclerosis. Thirty-five patients (15 women, 20 men) with a history of cerebrovascular disease were examined using conventional color-coded Doppler ultrasound and 3D ultrasound angiography. Carotid stenosis was initially diagnosed using continuous-wave Doppler ultrasound. To determine intraobserver and interobserver reliabilities, 21 patients were evaluated using 3D ultrasound on three occasions. Sixty-five percent of patients were diagnosed with stenosis of more than 50%. Twenty-two percent of plaques had a smooth surface, 72.9% were ulcerated, and 5.1% were indeterminate. Data collection for 3D imaging required 5 minutes per patient, whereas image processing and plaque volume quantification required 30 minutes. Plaque volume ranged from 0.053 to 0.685 ml. The intraobserver and interobserver variabilities were 4.16 and 5.87%, respectively (r = 0.96, p < 0.0001; r = 0.89, p < 0.0001). 3D Color Doppler and 3D ultrasound angiography assessments of plaque volume differed by 8.5%. Plaques were more precisely differentiated using 3D ultrasound, and plaque volume quantification was less affected by echo shadowing after 3D reconstruction. In comparison to other techniques for the quantification of atherosclerotic lesions. 3D ultrasound angiography offers a more precise quantitative method for prospective, clinical studies of atherosclerosis.

Aged↗
PubMed1997

Astrocytoma and pineoblastoma arising sequentially in the fourth ventricle of the same patient. Case report and molecular analysis.

The sequential appearance of two different brain tumors in the same patient without intervening radiation or chemotherapy is a rare event, most often seen in hereditary cancer syndromes. We present one such case of sequential tumors, along with their molecular analysis. A 17-year-old male presented with a pilocytic astrocytoma arising in the fourth ventricle at the pontomedullary junction. Six and one half years later, a pineoblastoma was discovered in the fourth ventricle, rostral to the first tumor site. Both tumors were treated by gross-total surgical resection. Following resection of the pineoblastoma, the patient underwent craniospinal irradiation and systemic chemotherapy. Single-strand conformation polymorphism analysis showed that the patient had neither a germ-line mutation nor a somatic tumor mutation in the p53 tumor suppressor gene. Coupled with the lack of a family history of cancer, these data suggest that these were not manifestations of Li-Fraumeni syndrome, but rather two sporadic tumors which arose via a p53-independent mechanism.

Adolescent↗
PubMed1997

Experimental model: change in the posterior fossa with surgically induced spina bifida aperta in mouse.

On the basis of experimental studies on mouse embryos in which spina bifida development of the brain ventricular system. Mouse embryos were exposed and surgically treated at gestation day 12 to produce spina bifida aperta, and operated embryos were cultured exo utero in the peritoneal cavity of the pregnant dam. Embryos were harvested at gestation day 14. Open neural tube defects resulted in 7 out of 10 embryos surviving surgery. Histological examination revealed that the sizes of ventricles in both the supra- and infratentorial compartments were greatly reduced in embryos with spina bifida aperta compared with control embryos. This result supports the hypothesis that leakage of cerebrospinal fluid through the opening of the caudal spine may be a major cause of brain abnormalities in patients with myelomeningocele.

Animals↗
PubMed1997

Choroid plexus papilloma and cysts in the Aicardi syndrome: case reports.

Two female infants with callosal agenesis, infantile spasms, chorioretinal lacunae, optic disc colobomas and cortical heterotopias were diagnosed with Aicardi syndrome. A choroid plexus papilloma was found in one patient, and choroid plexus cysts were found in the other. Choroid plexus lesions are common findings in the Aicardi syndrome and are discussed in this paper.

Agenesis of Corpus Callosum↗
PubMed1997

Controlled study of psychiatric comorbidity in psychiatrically hospitalized young adults with substance use disorders.

OBJECTIVE: The purpose of this study was to examine DSM-III-R axis I and axis II comorbidity in psychiatrically hospitalized young adults with substance use disorders. METHOD: Structured diagnostic interviews were given to 117 consecutive inpatients. Seventy patients with substance use disorders and 47 patients without substance use disorders were compared. RESULTS: High rates of co-occurrence of axis I disorders were observed, but no disorder coexisted in the group with substance use disorders at a significantly higher rate than in the group without substance use disorders. Among axis II disorders, borderline personality disorder was diagnosed significantly more frequently in the group with substance use disorders. CONCLUSIONS: Significant additional diagnostic co-occurrence, defined as comorbidity, was observed only between borderline personality disorder and substance use disorders. The use of a relevant psychiatric comparison group allows for finer distinctions between covariation based on shared severity and comorbidity possibly based on shared pathophysiology.

Adolescent↗
PubMed1997

The role of "one-shot" intravenous pyelogram in evaluation of penetrating abdominal trauma.

The role of limited "one-shot" intravenous pyelogram (IVP) in patients sustaining proximity penetrating trauma is not well defined, although formal IVP remains the "gold standard" for evaluating possible urological injuries. This retrospective review evaluates the efficacy and usefulness of limited one-shot IVP in penetrating abdominal trauma patients who are suspected of having urological injuries. The charts of 40 patients with penetrating abdominal trauma who had one-shot IVP performed in the emergency room at presentation were reviewed. Of the total, 36 patients had gunshot wounds and only 4 patients had stab wounds. Mean Penetrating Abdominal Trauma Index was 15.7, with 47.5 per cent of patients in shock. Only 2 out of 10 urological injuries were detected by one-shot IVP. The positive predictive value of limited one-shot IVP was only 20 per cent, with sensitivity 25 per cent and specificity 76.2 per cent. The results of the one-shot IVP did not influence the decisions for laparotomy in any of the 35 (87.5%) patients who underwent exploratory laparotomy. In the two patients with positive one-shot IVPs who had urological injuries, the decision to operate was again determined by the presence of other associated intra-abdominal injuries. Eighty per cent of patients with normal one-shot IVP findings had renal injuries not detected by one-shot IVP, and 20 per cent of patients with abnormal IVP findings had no intraoperative evidence of renal injury. The presence of gross hematuria appeared to correlate with the presence of significant urological injuries. We therefore conclude that limited one-shot IVP is of no significant value in assessing penetrating abdominal trauma patients who subsequently undergo exploratory laparotomy for other associated intra-abdominal injuries, and indeed, the delay imposed, before definitive operative intervention in potentially unstable patients, is unjustified.

Abdominal Injuries↗
PubMed1997

Delayed presentation of popliteal artery pseudoaneurysm following blunt trauma.

Popliteal artery pseudoaneurysms are not uncommon. They may result from penetrating or blunt trauma, arterial reconstructive surgery, invasive diagnostic or surgical orthopedic procedures, and perigenicular neoplasia. We report two patients with popliteal artery pseudoaneurysm diagnosed 3 months and 3 weeks, respectively, after blunt trauma. These two patients as well as many patients reported in the literature had palpable distal pulses and no obvious clinical signs of arterial injury following various forms of trauma. Arteriography in these circumstances is usually abandoned because of the low yield and the possible risk of complications. However, as we illustrate in this report, noninvasive diagnostic modalities such as duplex ultrasound and magnetic resonance arteriography are both safe and accurate for early detection of popliteal artery pseudoaneurysm. Once diagnosed, standard vascular reconstruction should be performed to prevent potential complications.

Adult↗
PubMed1996

Determination of an arylacetamide antiarrhythmic in rat blood and tissues using reversed-phase high-performance liquid chromatography.

A method was developed for quantification of (+)-trans-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzo[b-] thiophene-4-acetamide (compound I), an antiarrhythmic drug, in rat whole blood, heart, brain, liver and skeletal muscle. Blood and tissue samples were homogenized and purified by chemical extraction. Chromatographic separations were achieved using reversed-phase high-performance liquid chromatography (HPLC) coupled with UV detection (215 nm). Drug recoveries from the extraction procedure ranged from 77 to 90%. Within- and between-day reproducibility of peak area (coefficient of variation) ranged from 1.1 to 15.7%. The detection limit was 80-200 ng/ml (in a 500-microliters extracted solution) depending on the type of biological sample. This method was used in a pharmacokinetic study of compound I disposition in rats after a bolus intravenous dose of 3.1 mg/kg.

Animals↗
PubMed1996

Gender differences in personality disorders in psychiatrically hospitalized young adults.

We examined gender differences in DSM-III-R personality disorders in psychiatrically hospitalized young adults. Structured diagnostic interviews were reliably performed on a consecutive series of 118 inpatients. Men were significantly more likely to meet criteria for cluster A, schizotypal, and antisocial personality disorders. To reduce variability due to axis I heterogeneity, we retested for gender differences in a subgroup of patients with major depression. Depressed men were more likely to meet criteria for cluster A, schizotypal, and cluster C personality disorders. Women were not observed to have a higher frequency of any personality disorder than men in either study group.

Adult↗
PubMed1996

Basilar artery blood flow during head rotation in vertebrobasilar ischemia.

PATIENTS AND METHODS: Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography. RESULTS: In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver. CONCLUSION: These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.

Adult↗
PubMed1996

Fatal air bag mediated craniocervical trauma in a child.

This case report describes a 5-year-old child who sustained fatal craniocervical injuries as the result of an inflating automobile air bag. Although air bags have in general been shown to reduce the severity of injury to occupants of vehicles involved in front-end collisions, a growing number of incidents suggests that in some instances the air bag system itself may cause injuries, some of which can be serious or even fatal. Small children and infants in infant seats travelling in the front passenger seat appear to be particularly at risk. The increasing number of reports of air bag mediated injuries highlights the need for changes in both system design and possibly the threshold speed required for air bag deployment.

Air Bags↗
PubMed1996

Spinal stenosis after total lumbar laminectomy for selective dorsal rhizotomy.

Knowledge of long-term outcome and complications of selective dorsal rhizotomy is limited due to the relatively recent introduction of the procedure. We describe 2 patients with cerebral palsy who developed lumbar spinal stenosis several years after selective dorsal rhizotomy. These patients also had substantial lateral trunk sway during gait and walked for several years with limited assistive devices. This abnormal gait pattern in combination with the changes from the selective dorsal rhizotomy may lead to the development of spinal stenosis.

Cerebral Palsy↗
PubMed1996

Cerebrovascular disease assessed by color-flow and power Doppler ultrasonography. Comparison with digital subtraction angiography in internal carotid artery stenosis.

BACKGROUND AND PURPOSE: An understanding of carotid atherosclerosis is important to further our knowledge regarding the etiology of cerebral ischemia, and therefore it is necessary to accurately visualize carotid stenosis. The purpose of the present study was to compare different imaging techniques to determine their advantages and disadvantages in the diagnosis and quantification of middle- and high-grade internal carotid artery stenosis. In particular, we were interested in evaluating the effectiveness of the new ultrasound technique power Doppler. METHODS: Fifty-four patients with greater than 50% extracranial internal carotid artery stenosis, as determined by continuous-wave Doppler, were recruited prospectively to serve as subjects. All subjects were examined with color-flow Doppler, power Doppler, and digital subtraction angiography to enable visualization of carotid stenosis and plaque surface morphology. RESULTS: Thirty-four middle-grade stenoses (50% to 69%), 32 high-grade stenoses (70% to 99%), and 7 complete occlusions of the internal carotid artery were diagnosed with the use of digital subtraction angiography. Power Doppler visualized stenosis significantly more frequently and accurately than color-flow Doppler. Color-flow Doppler tended to overestimate and underestimate in patients with both middle- and high-grade stenosis. Power Doppler was superior to both color-flow Doppler and angiography with regard to differentiation of plaque surface morphology. CONCLUSIONS: This study demonstrates that power Doppler is an important, noninvasive imaging technique that has several advantages over color-flow Doppler in diagnosing carotid artery stenosis and visualizing plaque surface. Power Doppler, used in concert with other ultrasound techniques, should enable a more accurate detection and treatment of cerebrovascular disease.

Aged↗
PubMed1996

Gender differences in personality disorders in psychiatrically hospitalized adolescents.

OBJECTIVE: The authors examined gender differences in DSM-III-R personality disorders in adolescent psychiatric inpatients. METHODS: Structured diagnostic interviews were reliably performed with a series of 138 consecutively admitted adolescent inpatients. To reduce variability due to heterogeneity of axis I diagnoses, a subgroup of 87 patients with major depression was retested for gender differences. RESULTS: Females were significantly more likely than males to meet the criteria for borderline personality disorder. Narcissistic personality disorder was diagnosed only in males. A similar pattern was observed in the subgroup of patients with major depression. CONCLUSIONS: The findings suggest potentially important gender differences in personality disorders in adolescent inpatients.

Adolescent↗