Characterization of intrathecal cerebrospinal fluid geometry and dynamics in cynomolgus monkeys (macaca fascicularis) by magnetic resonance imaging

Recent advancements have been made toward understanding the diagnostic and therapeutic potential of cerebrospinal fluid (CSF) and related hydrodynamics. Increased understanding of CSF dynamics may lead to improved detection of central nervous system (CNS) diseases and optimized delivery of CSF based CNS therapeutics, with many proposed therapeutics hoping to successfully treat or cure debilitating neurological conditions. Before significant strides can be made toward the research and development of interventions designed for human use, additional research must be carried out with representative subjects such as non-human primates (NHP). This study presents a geometric and hydrodynamic characterization of CSF in eight cynomolgus monkeys (Macaca fascicularis) at baseline and two-week follow-up.

Results showed that CSF flow along the entire spine was laminar with a Reynolds number ranging up to 80 and average Womersley number ranging from 4.1–7.7. Maximum CSF flow rate occurred ~25 mm caudal to the foramen magnum. Peak CSF flow rate ranged from 0.3–0.6 ml/s at the C3-C4 level. Geometric analysis indicated that average intrathecal CSF volume below the foramen magnum was 7.4 ml. The average surface area of the spinal cord and dura was 44.7 and 66.7 cm² respectively. Subarachnoid space cross-sectional area and hydraulic diameter ranged from 7–75 mm² and 2–3.7 mm, respectively. Stroke volume had the greatest value of 0.14 ml at an axial location corresponding to C3-C4.

Cerebellar tonsil ectopia measurement in type I Chiari malformation patients show poor inter-operator reliability

Background

Type 1 Chiari malformation (CM-I) has been historically defined by cerebellar tonsillar position (TP) greater than 3–5 mm below the foramen magnum (FM). Often, the radiographic findings are highly variable, which may influence the clinical course and patient outcome. In this study, we evaluate the inter-operator reliability (reproducibility) of MRI-based measurement of TP in CM-I patients and healthy controls.

Methods

Thirty-three T2-weighted MRI sets were obtained for 23 CM-I patients (11 symptomatic and 12 asymptomatic) and 10 healthy controls. TP inferior to the FM was measured in the mid-sagittal plane by seven expert operators with reference to McRae’s line. Overall agreement between the operators was quantified by intraclass correlation coefficient (ICC).

Results

The mean and standard deviation of cerebellar TP measurements for asymptomatic (CM-Ia) and symptomatic (CM-Is) patients in mid-sagittal plane was 6.38 ± 2.19 and 9.57 ± 2.63 mm, respectively. TP measurements for healthy controls was 0.48 ± 2.88 mm. The average range of TP measurements for all data sets analyzed was 7.7 mm. Overall operator agreement for TP measurements was relatively high with an ICC of 0.83.

Conclusion

The results demonstrated a large average range (7.7 mm) of measurements among the seven expert operators and support that, if economically feasible, two radiologists should make independent measurements before radiologic diagnosis of CM-I and surgery is contemplated. In the future, an objective diagnostic parameter for CM-I that utilizes automated algorithms and results in smaller inter-operator variation may improve patient selection.

Cardiac-Related Spinal Cord Tissue Motion at the Foramen Magnum is Increased in Patients with Type I Chiari Malformation and Decreases Postdecompression Surgery

OBJECTIVE

Type 1 Chiari malformation (CM-I) is a craniospinal disorder historically defined by cerebellar tonsillar position greater than 3-5 mm below the foramen magnum (FM). This definition has come under question because quantitative measurements of cerebellar herniation do not always correspond with symptom severity. Researchers have proposed several additional radiographic diagnostic criteria based on dynamic motion of fluids and/or tissues. The present study objective was to determine if cardiac-related craniocaudal spinal cord tissue displacement is an accurate indicator of the presence of CM-I and if tissue displacement is altered with decompression.

METHODS

A cohort of 20 symptomatic patients underwent decompression surgery. Fifteen healthy volunteers were recruited for comparison with the CM-I group. Axial phase-contrast magnetic resonance imaging (PC-MRI) measurements were collected before and after surgery at the FM with cranial-caudal velocity encoding and 20 frames per cardiac cycle with retrospective reconstruction. Spinal cord motion (SCM) at the FM was quantified based on the peak-to-peak integral of average spinal cord velocity.

RESULTS

Tissue motion for the presurgical group was significantly greater than controls (P = 0.0009). Motion decreased after surgery (P = 0.058) with an effect size of -0.151 mm and a standard error of 0.066 mm. Postoperatively, no statistical difference from controls in bulk displacement at the FM was found (P = 0.200) after post hoc testing using the Tukey adjustment for multiple comparisons.

CONCLUSIONS

These results support SCM measurement by PC-MRI as a possible noninvasive radiographic diagnostic for CM-I. Dynamic measurement of SCM provides unique diagnostic information about CM-I alongside static quantification of tonsillar position and other intracranial morphometrics.

Differences in the potencies of inhaled steroids are not reflected in the doses prescribed in primary care in New Zealand

OBJECTIVE

To determine whether the average doses of inhaled beclomethasone, fluticasone and budesonide prescribed in primary care reflect the relative potencies of these medicines.

METHODS

Retrospective analysis of 95,540 prescriptions for inhaled steroids written by 293 general practitioners in Auckland, New Zealand, between November 1995 and June 1998. In addition, 177 general practitioners were presented with two case histories describing patients with uncontrolled asthma who were not on treatment with inhaled steroids. They were asked which medicine they would prescribe and in what dose.

RESULTS

The average daily doses prescribed were 600 microg for fluticasone, 747 microg for beclomethasone and 1184 microg for budesonide. The average dose of fluticasone was 80% of that for beclomethasone. In May 1997, when 4.5% of the prescriptions for inhaled steroids were for fluticasone, the average doses of fluticasone and beclomethasone were 632 microg and 760 microg, respectively. By May 1998, when 23% of prescriptions were for fluticasone, the average doses of fluticasone and beclomethasone were little changed at 610 microg and 726 microg, respectively. In response to the two case histories, the average doses of fluticasone chosen were 71% and 77% of the doses of beclomethasone.

CONCLUSIONS

The average prescribed dose of fluticasone was 80% of that for beclomethasone, even though fluticasone is at least twice as potent as beclomethasone. Similar findings were observed when the general practitioners responded to the case histories. The high doses of fluticasone prescribed may be due to a failure to appreciate that fluticasone is twice as potent as beclomethasone and to the availability of high strength preparations of fluticasone, i.e. 250 microg per actuation.

Economic outcomes of antipsychotic agents in a Medicaid population: traditional agents vs. risperidone

Clinical trials reveal that the newer atypical antipsychotic agents are more effective and have fewer side effects than traditional agents. However, these newer agents have a higher acquisition cost than traditional agents. This study assessed the differential impact of risperidone and traditional agents on the total schizophrenia-related cost of care for Medicaid patients suffering from schizophrenia. This was a retrospective longitudinal pretest-posttest analysis of Medicaid claims data covering January 1992 to August 1996. Continuously eligible patients (n = 150) with a documented diagnosis of schizophrenia were evaluated. Medical claims were analyzed for patients treated with traditional antipsychotics for at least 12 months and then switched to risperidone and followed for at least 12 months. Patients who failed on at least one traditional agent and who remained on other traditional agents throughout the study timeframe served as a control group. Monthly costs per patient were estimated using mixed model linear regression with age and gender serving as covariates. The total monthly costs per patient for the risperidone and traditional cohorts were similar ($1,050.52 and $946.24, respectively; p = .5438) during the pretest phase of the study. For patients treated with risperidone, drug costs were $177.35 higher (CL0.95 +/- $7.64; p = .0001) per patient per month in the posttest period compared with the pretest period. However inpatient hospital costs were $312.04 lower (CL0.95 +/- $146.76; p = .001) per patient per month in the posttest period compared with the pretest period. In addition, physician costs were $9.55 lower (CL0.95 +/- $5.31; p = .0004) per patient per month in the posttest period. The difference from the pretest to posttest period for outpatient mental health clinic costs was statistically similar. For those in the risperidone cohort, total estimated costs decreased by $204.87 per patient per month during treatment with risperidone (CL0.95 +/- $161.01; p = .0127). Over the same time-frame, total costs increased $160.68 per patient per month (CL0.95 +/- $196.04; n.s.; p = .1082) in the control cohort. While the mean monthly drug cost was significantly higher during treatment with risperidone, this increase was offset by cost reductions elsewhere in the system.

Economic outcomes associated with the use of risperidone in a naturalistic group practice setting

The purpose of this cohort pilot study was to compare the resource utilization and economic outcomes associated with the use of risperidone versus haloperidol in a naturalistic setting. Patient charts from a large psychiatric group practice were reviewed, and hospital billing data were obtained. Patients meeting the inclusion criteria were placed into one of two cohorts depending on their medication history. Thirty patients treated with risperidone met the selection criteria, and a random quota sampling technique was used to allow for a matched control cohort of 30 patients treated with haloperidol. In the haloperidol and risperidone cohorts, 24 and 28 patients, respectively, were evaluated statistically. Mean utilization rates and costs per patient per month for each service were estimated by using regression analysis. Patients in the risperidone cohort had significantly fewer hospitalizations than did those in the haloperidol cohort (P = 0.004). Likewise, risperidone patients had significantly lower hospitalization costs than haloperidol patients (P = 0.005). Conversely, patients treated with risperidone visited the physician more frequently than did those treated with haloperidol (P = 0.0005). Estimated mean total monthly costs were $123.34 lower (95% confidence interval = $464, $217) per patient in the risperidone cohort than in the haloperidol cohort ($1,636.11 vs $1759.45; P = 0.4693). Significant reductions in hospital costs in the risperidone cohort offset higher medication and physician costs. Overall, total monthly costs were similar for the two cohorts.

Gastrointestinal illness in managed care: healthcare utilization and costs

Identification of inefficiencies is a first step to improving the quality of gastrointestinal (GI) care at the most reasonable cost. This analysis used administrative data to examine the healthcare utilization and associated costs of the management of GI illnesses in a 2.5 million-member private managed care plan containing many benefit designs. An overall incidence of 10% was found for GI conditions, with a preponderance in adults (patients older than 40 years) and women. The most frequently occurring conditions were abdominal pain, nonulcer peptic diseases, lower GI tract diseases, and other GI tract problems. These conditions, along with gallbladder/biliary tract disease, were also the most costly. Claims submitted for care during GI episodes averaged $17 per member per month. Increasing severity of condition was associated with substantial increases in utilization and costs (except for medication use). For most GI conditions, approximately 40% of charges were for professional services (procedures, tests, and visits) and 40% of charges were for facility admissions. The prescription utilization analysis indicated areas where utilization patterns may not match accepted guidelines, such as the low use of anti-Helicobacter pylori therapy, the possible concomitant use of nonsteroidal anti-inflammatory drugs in patients with upper GI diseases, and the use of narcotics in treating patients with lower GI disease and abdominal pain. Also, there was no clear relationship between medication utilization and disease severity. Thus, this analysis indicated that GI disease is a significant economic burden to managed care, and identified usage patterns that potentially could be modified to improve quality of care.

Impact of risperidone on the use of mental health care resources

OBJECTIVE

The effects of risperidone treatment on health care utilization and treatment costs were examined among patients with treatment-refractory schizophrenia or schizoaffective disorder.

METHODS

Data from the Santa Clara County Mental Health Department were used to measure inpatient and ambulatory services and outpatient medications related to the treatment of mental disorders. Data for 139 patients were analyzed for periods before and after initiation of risperidone treatment. A mean +/- SD of 14 +/- 2.1 months of data were available in both the before and after periods, for a mean total study period of 28 months.

RESULTS

The patients' mean age was 40 years (range, 18 to 78 years), and 46 percent were women. After the start of risperidone treatment, days in acute care inpatient facilities were reduced by 26 percent, and days in residential treatment were reduced by 57 percent. These reductions were accompanied by an increase in the use of lower-cost services, such as community living, treatment planning, and partial hospital-day treatment. There was a 3.4 percent increase in total psychiatric health care costs after initiation of treatment with risperidone.

CONCLUSIONS

Overall, risperidone treatment resulted in a shift or resource utilization from provider-delivered services to pharmaceutical care without a significant change in total health care cost.

Comparing dihydroergotamine mesylate and sumatriptan in the management of acute migraine. A retrospective cost-efficacy analysis

The annual cost of managing migraine totals billions of US dollars. This retrospective economic analysis of a clinical trial comparing subcutaneous dihydroergotamine mesylate (DHE) with subcutaneous sumatriptan in the treatment of acute migraine is appropriate because, although each product has been shown to be efficacious, the acquisition cost of sumatriptan is over 3 times that of DHE. Total costs in each treatment group were calculated and applied independently to 11 clinical trial efficacy measures. Three of the efficacy measures showed no statistically significant difference between treatment arms, leading to a decision to use the less expensive DHE. In 4 of the efficacy measures. DHE was the obvious choice because it is more efficacious and less expensive. For the final 4 efficacy measures, where sumatriptan is more efficacious and more expensive, incremental cost-efficacy ratios were calculated to determine the additional expenditure required to achieve outcomes associated with quick relief. Depending on the efficacy variable chosen and the assumptions used in the model, the incremental cost-efficacy ratios ranged from $US4000 to $US6700 per year (1993 dollars) for each additional patient who is successfully treated with sumatriptan compared with DHE. Therefore, in a population of 100 migraineurs, an additional 13 to 22 patients would achieve these short term benefits of sumatriptan, although it would cost an additional $US88 395 annually, given the assumptions made. Because each product has unique advantages, we conclude that the more cost-efficacious product is dependent on the outcome of interest and the amount that the patient or provider is willing to pay to achieve that outcome.

Osteoporosis: the need for comprehensive treatment guidelines

Osteoporosis is a debilitating disease that results in nearly 1.3 million fractures per year in the United States. The cost of treating these fractures has been estimated to be as high as $10 billion per year. These costs are expected to more than double during the next 50 years unless comprehensive programs of prevention and treatment are initiated. Both pharmacologic and nonpharmacologic interventions (eg, diet and exercise) have been shown to have a significant impact on the incidence of osteoporosis, depending on the time of their application. Unfortunately, osteoporosis is often not diagnosed until after fractures have occurred, when it may be too late for treatment to have a major impact. To be most effective, therapy should be started early, before serious bone loss has occurred. Because of its efficacy and relatively low acquisition cost, long-term hormone replacement therapy (HRT) is considered first-line pharmacologic therapy for the prevention of osteoporosis. However, for various reasons, less than 25% of US women who might benefit from HRT are receiving it. Aside from HRT, the only other products approved by the US Food and Drug Administration for the treatment of osteoporosis are salmon calcitonin and alendronate. Several other agents are under development, including sustained-release fluoride and other products in the bisphosphonate class. The development and adoption of early detection programs and treatment guidelines are crucial to help ease the economic burden of osteoporosis. These guidelines should incorporate preventive measures such as diet and exercise, risk assessment through proper screening programs, and the appropriate use of pharmaceutical products. The purpose of this paper is to discuss relevant economic issues associated with osteoporosis and discuss the need for a management algorithm that could be used to more efficiently prevent and treat this disease. We conclude that further modeling is needed to determine which programs and treatments are most cost-effective within each at-risk subgroup. As clinicians better understand the need for preventive care and the advantages of the various pharmacologic therapies, patients with osteoporosis will receive higher-quality and more efficient medical care.

A literature review comparing the economic, clinical, and humanistic attributes of dihydroergotamine and sumatriptan

The value of different pharmaceuticals in treating migraine is frequently based on clinical efficacy only. This article assumes a broader perspective and compares the clinical, economic, and humanistic attributes of two antimigraine medications, dihydroergotamine (DHE) and sumatriptan, based on a literature review. DHE is an established product with over 40 years of use in the treatment of migraine. Sumatriptan is a new product with a higher acquisition cost than DHE. Because sumatriptan costs more than DHE, the question must be asked. "Does sumatriptan provide advantages that offset this price differential?" This question reflects the growing concern among payers and patients over the cost and effectiveness of therapies. However, it is not easily answered. Direct comparative data are not available, and data sources are different for the two products. Moreover, the products are currently marketed in different dosage forms--intramuscular for DHE and subcutaneous for sumatriptan. The literature reviewed indicates that the clinical attributes of the two products are similar, with each having slightly different advantages and disadvantages. However, the DHE literature is generally limited to uncontrolled studies, whereas the sumatriptan literature reports the results of rigorously designed, randomized, double-blind, placebo-controlled clinical trials. Published data on the products' economic and humanistic attributes are limited. We concluded that the literature does provide important, albeit limited, data on the economic, clinical, and humanistic attributes of DHE and sumatriptan that permit restricted comparisons. The limitations of the data highlight the need for comparative studies of these products' multidimensional attributes both in controlled clinical trials and under actual practice conditions.

Rapid identification of gene sequences for transcriptional map assembly by direct cDNA screening of genomic reference libraries

We have used the direct cDNA screening protocol to identify sequences transcribed in cerebral cortex from a reference library of human Xq28. To derive coding sequences from these genomic clones, we first identified fragments containing transcribed sequences and subjected these to exon trapping or to partial sequencing and analysis by Grail. In a preliminary analysis of three clones, coding sequences from two novel genes expressed in brain were identified. This method allows the rapid identification of coding sequences of genes expressed in specific tissues without recourse to cDNA libraries. The approach is amenable to large scale applications and should be useful for isolating candidate disease genes and in particular for assembling integrated transcriptional maps from large genomic regions.