Recovery of nerve conduction following microvascular decompression for trigeminal neuralgia

OBJECTIVE

To assess the function of trigeminal nerve before and after microvascular decompression for trigeminal neuralgia.

BACKGROUND

To date there is no direct evidence that microvascular decompression of the trigeminal root restores normal conduction in the nerve.

METHODS

The authors examined 10 patients with trigeminal neuralgia in whom preoperative MRI and MR angiography demonstrated neurovascular contact. During microvascular decompression, the trigeminal nerve was monitored by recording early scalp trigeminal evoked potentials immediately before, during, and after decompression. Direct recordings from the root entry zone were also performed.

RESULTS

In all patients preoperative scalp evoked potentials showed impaired conduction of the trigeminal root. Microvascular decompression was associated with immediate recovery of conduction in seven patients, demonstrated by both scalp evoked potentials and direct root recordings. All 10 patients were pain free postoperatively.

CONCLUSIONS

Improvement in trigeminal neuralgia following microvascular decompression is often associated with normalization of neurophysiologic data, suggesting recovery of nerve function. Rapid electrophysiologic recovery and pain relief following microvascular decompression argue that neither phenomenon is linked to remyelination. It is possible that the trigeminal evoked potentials might predict an effective microvascular decompression.

Classification of asthma severity: should the international guidelines be changed?

BACKGROUND

International guidelines recommend that, in addition to symptoms and medication requirements, measurements of forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) are necessary for the objective assessment of asthma severity. The guidelines suggest that parity exists between measurements of FEV1 and PEF when expressed as percentage of predicted normal values, and that asthma severity can be classified as mild, moderate or severe on the basis of FEV and PEF measurements of > 80%, 60-80% and < 60% of predicted values, respectively.

OBJECTIVE

To determine the relationship between measurements of FEV1 and PEF when expressed as percentage predicted values.

METHODS

A total of 1198 paired measurements of FEV1 and PEF were obtained from the medical records of a random sample of 25 adult asthmatic patients attending a hospital-based chest clinic. Measurements of lung function were expressed as a percentage of predicted normal values, using the European Respiratory Society prediction equations for PEF and FEV1. For the individual paired measurements, the mean differences between PEF and FEV percentage predicted were calculated. Measurements of lung function were used to determine asthma severity with <60%, 60-80%, and >80% predicted FEV1 and PEF values representing severe, moderate and mild asthma, respectively. The proportion of paired measurements in which differences in classification resulted from the use of FEV1 or PEF percentage predicted values was then calculated.

RESULTS

In asthma of differing severity, there was considerable variability between measurements of FEV1 and PEF when expressed as percentage predicted values; calculation of the FEV1% predicted resulted in lower values than those of the PEF percentage predicted, with a mean difference of -17.2% (95% CI -16.3%, -18.1%). There was agreement in classification of asthma severity in only 49.9% (598/1198) of paired measurements. Different prediction equations, while variably altering the degree of misclassification, did not correct the basic differences in the assessment of asthma severity dependent on the use of FEV or PEF.

CONCLUSION

FEV1 and PEF values, expressed as percentage predicted, are not equivalent. Pending further evaluation, the authors suggest that published asthma guidelines should avoid the assumption of parity between these two measurements.

Risk of lung cancer associated with residential radon exposure in south-west England: a case-control study

Studies of underground miners occupationally exposed to radon have consistently demonstrated an increased risk of lung cancer in both smokers and non-smokers. Radon exposure also occurs elsewhere, especially in houses, and estimates based on the findings for miners suggest that residential radon is responsible for about one in 20 lung cancers in the UK, most being caused in combination with smoking. These calculations depend, however, on several assumptions and more direct evidence on the magnitude of the risk is needed. To obtain such evidence, a case-control study was carried out in south-west England in which 982 subjects with lung cancer and 3185 control subjects were interviewed. In addition, radon concentrations were measured at the addresses at which subjects had lived during the 30-year period ending 5 years before the interview. Lung cancer risk was examined in relation to residential radon concentration after taking into account the length of time that subjects had lived at each address and adjusting for age, sex, smoking status, county of residence and social class. The relative risk of lung cancer increased by 0.08 (95% CI -0.03, 0.20) per 100 Bq m(-3) increase in the observed time-weighted residential radon concentration. When the analysis was restricted to the 484 subjects with lung cancer and the 1637 control subjects with radon measurements available for the entire 30-year period of interest, the corresponding increase was somewhat higher at 0.14 per 100 Bq m(-3) (95% CI 0.01, 0.29), although the difference between this group and the remaining subjects was not statistically significant. When the analysis was repeated taking into account uncertainties in the assessment of radon exposure, the estimated increases in relative risk per 100 Bq m(-3) were larger, at 0.12 (95% CI -0.05, 0.33) when all subjects were included and 0.24 (95% CI -0.01, 0.56) when limited to subjects with radon measurements available for all 30 years. These results are consistent with those from studies of residential radon carried out in other countries in which data on individual subjects have been collected. The combined evidence suggests that the risk of lung cancer associated with residential radon exposure is about the size that has been postulated on the basis of the studies of miners exposed to radon.

Impact of the change in Connecticut syringe prescription laws on pharmacy sales and pharmacy managers' practices

We assessed the impact of the 1992 change in Connecticut syringe prescription laws on pharmacy sales and pharmacy managers' sales practices. A mail survey was conducted in 1994 of all current pharmacy managers in the five largest cities in Connecticut (Hartford, New Haven, Waterbury, Bridgeport, and Stamford) and a random sample of those practicing in all other areas. Of these, 89.3% of the pharmacies in the five largest cities and 85.1% in the other areas had ever sold syringes without a prescription since the July 1992 law went into effect. Most pharmacists identified safety issues as very important in their personal decision about the sale of syringes without a prescription. Although the purpose of the change in the prescription law was to provide expanded access to sterile syringes by injection drug users (IDUs), only 31.4% of the managers who were allowed to sell in all instances and 18.1% of those who sold at their discretion were very willing to sell syringes to IDUs. In the logistic regression model of pharmacies with a sell-in-all-instances policy, the perceived benefit of the sale of syringes on health and community well-being was the only influence independently associated with managers support for nonprescription sales. Overall, managers reported they did not know what other pharmacists thought (40.4%) or did (42.9%) regarding the sale of syringes. When pharmacists had discretion over syringe sales, managers' beliefs about what other Connecticut pharmacists thought and did about the nonprescription sale of syringes remained a significant influence on the degree of support for sales. Most pharmacies implemented and maintained policies permitting the sale of syringes without a prescription. Several issues, including risk of discarded contaminated syringes around pharmacies and in the community and reluctance to sell to IDUs, reduced pharmacists willingness to sell syringes. Efforts to incorporate pharmacists as active partners in HIV prevention in IDUs should promote the sale of syringes without a prescription to IDUs as acceptable public health practice.

Dysaesthetic neck pain with syncope

Neurogenic dysaesthetic pain in the neck following surgery for tumours in the neck is rare. Rarer still is the combination of pain following surgery with syncope. We looked at four patients who had tumours within the neck excised and then went on to develop neurogenic dysaesthetic neck pain associated with syncope. Distinction is made between neurogenic dysaesthetic pain following neck surgery and glossopharyngeal neuralgia which has been previously reported in association with neck surgery and also glossopharyngeal neuralgia with syncope. Spinal cord stimulation was used successfully to treat the dysaesthetic pain and syncope in three of the patients while the fourth patient died from the effects of his tumour. Medical practitioners may wish to consider spinal cord stimulation in relation to treating neurogenic dysaesthetic neck pain with syncope.

Mapping radon-prone areas by lognormal modeling of house radon data

Results of radon measurements in houses are generally distributed approximately lognormally, whether large or small areas are considered. The properties of the lognormal distribution allow the proportion of houses above a threshold level to be estimated even when there are insufficient data to calculate the proportion directly. In this paper the properties of the data set of radon measurements made in UK houses with etched-track radon detectors are examined, with the purpose of using them to map radon-prone areas. Individual results are normalized depending on the average outdoor temperature during the measurement to estimate the annual average radon level. For certain types of maps, results may also be normalized to estimate the radon level in a standard house or mixture of house types on the same site. Methods to use the lognormal model to estimate the geometric mean radon concentration and geometric standard deviation for data grouped by area have been developed. These data are then used to map radon-prone areas of England and Wales.

Liposomally-encapsulated ricin toxoid vaccine delivered intratracheally elicits a good immune response and protects against a lethal pulmonary dose of ricin toxin

A small study was performed to examine whether the instillation of ricin toxoid vaccine into the lungs of Porton rats offered protection from lethal effects of subsequent intratracheal challenge with ricin toxin. Further the immune response to liposomally-encapsulated vaccine and the protection offered was compared with vaccine either adsorbed to Alhydrogel adjuvant or as a simple aqueous solution. The formaldehyde-treated ricin toxin vaccine (RTV) was administered at two dose levels, 500 and 100 micrograms kg-1 body weight to groups of rats, on two occasions by intratracheal instillation. Liposomally-encapsulated vaccine (LRTV) produced a higher titre of ricin-specific antibodies than Alhydrogel-vaccine (ARTV) and vaccine solution. When challenged with 3 LD50 of ricin by intratracheal instillation 7 weeks after the second vaccine instillation, all rats in both LRTV dose groups survived with minimal signs of incapacitation. Analysis of antibody secretion by spleen cells, 14 days post challenge, showed that the IgG isotype in the LRTV group was significantly higher than that in the ARTV and RTV groups and also that the proportion of specific IgA in lung fluid was higher in the LRTV group than in the ARTV and RTV groups. The results of this study indicate that effective vaccinations against inhaled ricin could be achieved with liposomally-encapsulated ricin toxoid, via the lung and should be investigated further.

Increased urinary albumin and retinol-binding protein in type I diabetes. A study of identical twins

OBJECTIVE

Indexes of early renal glomerular and tubular dysfunction have been demonstrated in type I diabetes, but it remains uncertain whether such changes are genetically determined or are secondary to the disease process. We therefore undertook to study whether early markers of renal dysfunction are a consequence of type I diabetes or inherited.

RESEARCH DESIGN AND METHODS

We estimated both urinary albumin excretion (UAE) and urinary retinol-binding protein (RBP) in 51 identical twin pairs discordant for type I diabetes and in 51 matched control subjects.

RESULTS

UAE and RBP were significantly higher in the diabetic twins than in their nondiabetic co-twins (P < 0.0001 and P < 0.0002, respectively). Seven diabetic twins had elevated UAE, but none of the nondiabetic co-twins did. In a subgroup of 44 twins with normal UAE (albumin excretion rate < 20 micrograms/min), diabetic twins had both a higher albumin excretion function (median [range]; 0.64 [0.18-2.74] mg/mmol creatinine) than their nondiabetic co-twins (0.48 [0.24-1.40], P < 0.01) and higher levels of RBP excretion (10.4 [4.0-167.0] micrograms/mmol creatinine) than their nondiabetic co-twins (7.5 [0.97-23.0], P < 0.05). Values between twins of a pair were significantly correlated for RBP (r = 0.36, P < 0.05) but not for UAE (r = 0.13).

CONCLUSIONS

These results suggest that in type I diabetes, an index of renal tubular function (RBP), but not glomerular function (UAE), is influenced by shared genetic and nongenetic factors. Type I diabetes can affect renal tubular function even when glomerular function is normal. We conclude that neither the increased UAE nor urinary RBP found in type I diabetes is inherited independently of the diabetes process.

Electrical spinal-cord stimulation for painful diabetic peripheral neuropathy

BACKGROUND

Conventional treatment for painful peripheral diabetic neuropathy is largely symptomatic and often ineffective, with unacceptable side-effects. We tested electrical spinal-cord stimulation for the management of chronic neuropathic pain.

METHODS

Ten diabetic patients who did not respond to conventional treatment (mean age 51 [SD 9.3] years, six with type II diabetes, mean duration of diabetes 12 [6.3] years, mean duration of neuropathy 5 [2.1] years) were studied. The electrode was implanted in the thoracic/lumbar epidural space. Immediate neuropathic pain relief was assessed by visual analogue scale (VAS) after connecting the electrode, in a random order, to a percutaneous electrical stimulator or to a placebo stimulator. Exercise tolerance was assessed on a treadmill.

FINDINGS

Eight subjects had statistically significant pain relief with the electrical stimulator (p < 0.02) and were therefore converted to a permanent system. Statistically significant relief of both background and peak neuropathic pain was achieved at 3 months (n = 7, p = 0.016), at 6 months (n = 7, p = 0.03), and at the end of the study (14 months, n = 7, background pain p = 0.06, peak pain p = 0.03). One patient died 2 months after the start of the study of unrelated cause while continuing to benefit from treatment and another patient ceased to benefit at 4 months. McGill pain questionnaire scores with the stimulator turned off did not change significantly from baseline scores, indicating that the severity of the underlying pain was unaltered. However, with the stimulator turned on, there was a statistically significant (p < 0.05) improvement in all four components of the score, by the end of the study. At the end of the study, six patients continued to gain significant pain relief and used the stimulator as the sole treatment for their neuropathic pain. For example, median background and peak pain scores at the end of study, were, respectively, 77 and 81 with the stimulator off and 23 and 20 with the stimulator on. Exercise tolerance significantly improved at 3 months (n = 7, median % increase 85 [IQR, 62-360], p = 0.015) and at 6 months (n = 6, 163 [61-425], p = 0.0007). Electrophysiological tests, vibration perception-threshold, and glycaemic control were unchanged.

INTERPRETATION

Electrical spinal-cord stimulation offers a new and effective way of relieving chronic diabetic neuropathic pain and improves exercise tolerance. The technique should be considered in patients with neuropathic pain who do not respond to conventional treatment.

Management of asthma in the hospital emergency department

The use of asthma assessment and management protocols enables many of the clinical problems associated with the treatment of asthma in hospital emergency departments to be overcome. Their implementation also serves an educational function when used by the junior medical staff who are usually delegated responsibility for the care of asthmatic patients in the emergency department.

Nurses' views of the decision not to resuscitate a patient

The decision not to resuscitate a patient is a complex issue and there is little guidance for nurses on how such a decision is made. The aim of this study was, therefore, to explore the views and working practices of staff in relation to current guidelines and theories, using a situational analysis. Overall, the staff seemed to meet the criteria outlined in the guidelines, although there was little awareness of the guidelines. Nurses in the clinical area should be both educated in the recommendations for practice and should be consulted and involved in developing such recommendations.

Substrate metabolism in humans: 1995 A.S.P.E.N. research workshop

BACKGROUND

The 1995 A.S.P.E.N. Research Workshop was held at the annual meeting in Miami Beach, Florida, on January 15, 1995. The workshop focused on substrate metabolism in humans.

METHODS

State-of-the-art presentations on the regulation of energy, carbohydrate, lipid, and protein metabolism during health and disease were made by the preeminant leaders in the field. The presentations concentrated on in vivo studies performed in humans and included both recently published and unpublished data.

RESULTS

Using sophisticated research methodology, such as nuclear magnetic resonance spectroscopy, compartmental modeling, stable isotope tracers, microdialysis, and abdominal vein catheterization, the investigators presented data that clarified unresolved issues, challenged many previously held dogmas, and raised new questions for future investigations in human intermediary metabolism.

CONCLUSIONS

This workshop demonstrated that in vivo investigation remains the best approach for providing physiologically relevant data in humans. An understanding of normal human physiology and the metabolic alterations caused by disease is critical for optimal nutritional and metabolic management of patients.

Atopic status in patients with brittle and non-brittle asthma: a case-control study

BACKGROUND

Sensitization to inhaled and ingested allergens is an important process in determining the subsequent clinical expression of asthma. Allergen exposure has also been reported to be associated with admission to hospital with acute severe asthma. Patients with brittle asthma, characterized by widely variable peak expiratory flow are at increased risk of life-threatening episodes but the role of atopy in these patients is unknown.

OBJECTIVE

To determine the atopic status of patients with brittle asthma using a case-control design.

METHODS

We have assessed the atopic status by skin-prick tests to 19 common allergens, and total and specific immunoglobulin E (IgE) in 29 patients with well characterized brittle asthma and an age, sex and treatment-matched control group without brittle asthma.

RESULTS

Mean weal diameters were higher in brittle compared to non-brittle asthma for grass pollen (4.64 vs 2.17; P = 0.01), horse hair (6.28 vs 2.64; P = 0.02), feathers (2.96 vs 1.52; P = 0.01), wheat (1.48 vs 0.66; P = 0.001) and chocolate (1.09 vs 0.41; P = 0.05). Mean radioallergosorbent (RAST) scores to house dust mite were also greater in brittle asthma patients (19.3 vs 7.65; P = 0.05). Patients with brittle asthma also exhibited a significantly greater degree of atopy when weal diameters to all 19 allergens were summated to produce an atopy score (brittle 44.35 vs non-brittle 23.72; P = 0.04). There were no significant differences between the two groups in either the number of positive skin tests (using a 4 mm definition of skin-test positivity), total IgE or RASTs (using a weak +ve score to define positivity). However, the use of differing definitions of atopy (1, 2, 3, 4 and 5 mm skin test weal diameters) resulted in marked intra-group variation in atopic status in both brittle and non-brittle asthma patients.

CONCLUSIONS

The greater degree of atopy seen may be an important factor in patients with brittle asthma. The varying interpretations of the classification of what constitutes the presence or absence of atopy, based on mean weal diameters of skin-prick tests, or from IgE or RAST positivity shows that there is considerable potential variation in the degree of difference between the two groups depending on what criteria are used. Although internationally agreed definitions of atopic status have been devised a more rigorous application, or review of these guidelines needs to accompany future epidemiological studies of allergic sensitization.

Effects of the normal nocturnal rise in cortisol on carbohydrate and fat metabolism in IDDM

Plasma cortisol concentrations increase approximately three- to five-fold during sleep in healthy humans. To determine the effects of the normal nocturnal rise in cortisol on carbohydrate and fat metabolism independent of changes in endogenous insulin secretion, we studied the disposition of a mixed meal in individuals with insulin-dependent diabetes mellitus (IDDM) in whom the normal nocturnal rise in cortisol had been either prevented or mimicked by using metyrapone and a constant or variable hydrocortisone infusion. Insulin was infused intravenously on both occasions in amounts sufficient to create relative postprandial insulin deficiency. The nocturnal rise in cortisol resulted in an approximately 30 mg/dl greater (P < 0.001) peak postprandial glycemic excursion due to greater (P < 0.01) systemic glucose appearance and inappropriately low (P < 0.05) tissue glucose uptake. The latter was most evident when postprandial glucose concentrations in the presence and absence of the nocturnal rise in cortisol were matched by means of an exogenous glucose infusion to avoid the confounding effects of differences in glycemia. The nocturnal rise in cortisol also resulted in increased (P < 0.01) incorporation of 14CO2 into glucose (an index of gluconeogenesis), decreased (P < 0.05) carbohydrate oxidation, and increased (P < 0.05) rates of palmitate appearance, lipid oxidation, and beta-hydroxybutyrate concentrations. Thus the normal nocturnal rise in cortisol, independent of changes in insulin secretion, is an important regulator of postabsorptive and postprandial carbohydrate, fat, and ketone body metabolism in humans.

Fibrodysplasia (myositis) ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare hereditary connective tissue disorder. Patients with FOP develop progressive ossification of muscle and connective tissue associated with pain and disability. Onset is typically in childhood, and congenital anomalies of the feet are an early sign of this condition. Pain and stiffness of the spine or an inflammatory mass are common presenting features of FOP. Involvement of the spine often leads to complete fusion mimicking ankylosing spondylitis. Studies of twins and families suggest that FOP is a genetically inherited autosomal dominant trait with complete penetrance but variable expressivity. While radionuclide imaging and computed tomography are very sensitive for new bone formation and greatly assist the diagnosis of FOP, unfortunately, effective therapy is unavailable. We present twins with FOP and review the clinical, radiographic, and genetic manifestations of this disorder.

Stereotactic radiosurgery for glioblastoma multiforme: report of a prospective study evaluating prognostic factors and analyzing long-term survival advantage

PURPOSE

Prospective evaluation of the toxicity and efficacy of radiosurgery with external beam radiotherapy in the management of newly diagnosed glioblastoma.

METHODS AND MATERIALS

From 5/89 to 12/92, 31 out of 51 patients with glioblastoma multiforme underwent radiosurgery, in addition to 54 Gy in 1.8 Gy/fraction following biopsy (n = 12) or resection (n = 19). Eligibility required supratentorial glioblastoma, tumor not > 4 cm in > 1 axis, age > 18 years, and location > 1 cm from optic chiasm. Patient characteristics were: age 20-78 years (median = 57); 22 male, 9 female; Karnofsky score 20-90 (m = 70), and volume of 2.3-59.7 c.c. (m = 17.4). Eighteen patients were treated with 1 collimator, 5 with 2, 7 with 3, and 1 with 4; peripheral isodoses were 40-90% (m = 72.5) and minimum and maximum tumor dose ranges were 10-20 (m = 12) and 15-35 Gy (m = 18.75). Patients were followed clinically and radiographically every 8-12 weeks to analyze survival, quality of life, and toxicity.

RESULTS

With a follow-up of 12-171 weeks, 8 out of 31 (26%) patients are alive. Median survival is 42 weeks. Twelve and 24-month actuarial survival are 38 and 28%. Comparison of the 2-year survival with previous Radiation Therapy Oncology Group patients was carried out using a nonparametric recursive partitioning technique and the observed vs. expected values are 28 vs. 9.7% (p < 0.05). Extent of resection and performance status were associated with improved survival in a multivariate analysis. No significant acute toxicity was encountered. Four patients (13%) developed clinically significant necrosis verified by biopsy or positron emission tomography scan at 9-59 weeks after radiosurgery.

CONCLUSION

The improvement in median survival in broadly selected glioblastoma patients treated with radiosurgery is difficult to determine, but the 2-year survival may be superior. Future randomized trials of radiosurgery are recommended, and ad hoc use of this modality should be discouraged.

The determination of IgG subclass concentrations in serum by enzyme-linked immunosorbent assay: establishment of age-related reference ranges for cord blood samples, children aged 5-13 years and adults

We describe a simple enzyme-linked immunosorbent assay for the measurement of immunoglobulin G (IgG) subclasses in serum. The microtitre plate is coated directly with diluted samples, standards or controls, blocked with phosphate-buffered saline containing 1% Tween to prevent non-specific protein binding to the plate, and each subclass assigned with specific mouse monoclonal antibody. The specific antibody is detected with alkaline-phosphatase linked anti-globulin and the colour development of the paranitrophenyl phosphate indicator reagent is measured at 405 nm until the highest concentration of standard gives an absorbance in excess of 1.4. Coefficients of variation measured at three concentration levels were less than 7% for within-assay variation and less than 10% for between-assay variation. Regression analysis of total IgG with the sum of the measured IgG subclasses gave a correlation coefficient of 0.932 (P < 0.001). The assay has been used to establish age-related reference ranges for serum IgG subclasses; these are found to be slightly different from those established for radioimmunodiffusion methods. Our study does not confirm the previously reported absence of IgG4 in normal individuals.