Changes in cerebrospinal fluid magnesium levels in patients undergoing spinal anaesthesia for hip arthroplasty: does intravenous infusion of magnesium sulphate make any difference? A prospective, randomized, controlled study

BACKGROUND

Most investigators have attributed the reduced postoperative pain or anaesthetic drug requirements in patients receiving i.v. magnesium sulphate (MgSO(4)) infusion during spinal or general anaesthesia to central N-methyl-d-aspartate (NMDA) receptor magnesium (Mg) activity. In this study, we investigated how cerebrospinal fluid (CSF) Mg concentrations change after spinal anaesthesia, and whether peripherally infusing MgSO(4) influences central Mg levels.

METHODS

Forty-five patients undergoing continuous spinal anaesthesia for hip arthroplasty were randomly assigned to receive either i.v. MgSO(4) at a dose of 50 mg kg(-1) diluted in 100 ml 0.9% saline solution followed by 15 mg kg(-1) h(-1) for 6 h or saline at the same volume [mean (sd) 64 (10) ml]. The changes in CSF and serum total and ionized Mg concentrations were assessed at six time points before and after spinal anaesthesia. Secondary outcome variables included serum and CSF electrolytes and proteins.

RESULTS

Thirty-five patients completed the study. We found that spinal anaesthesia reduced total and ionized Mg concentrations in CSF by about 10%. Increasing serum Mg concentration over 80% of the baseline value left CSF Mg levels unchanged.

CONCLUSIONS

Spinal anaesthesia unexpectedly reduced CSF total and ionized Mg concentrations in patients undergoing hip arthroplasty, although the mechanism is unclear. The dose used for peripheral MgSO(4) infusion in this study had no influence on central Mg concentrations in neurologically healthy patients undergoing spinal anaesthesia. If CSF Mg concentration is a reliable marker of Mg brain bioavailability, peripherally infused MgSO(4) during spinal anaesthesia is unlikely to influence central NMDA receptor activity.

ITalian Observational Study of the management of mild-to-moderate Post-Operative Pain (ITOSPOP)

BACKGROUND

The multicenter observational ITalian Observational Study on the management of mild-to-moderate PostOperative Pain (ITOSPOP) was carried out in 24 hospitals to describe current postoperative pain management in Italy and the intensity of pain experienced by patients during the first 48 hours after surgery.

METHODS

Adult patients, after surgery expected to result in mild-moderate postoperative pain, underwent six evaluations. The primary endpoint was the level of organization and standardization of postoperative pain management. Secondary objectives included the intensity of postoperative pain, and an assessment of incident pain, postoperative analgesic and concomitant treatment administration.

RESULTS

Only 16.7% hospitals had an acute pain service and 41.7% hospitals applied a standardized protocol for postoperative pain management. The majority (>60%) of the 1952 patients monitored underwent all six assessments, >70% of which were performed by a physician. The proportion of patients with moderate pain decreased during the study period, but almost 10% of patients still experienced moderate pain at study end. Mild pain was reported by 50% of the patients for the entire study duration. At the final assessment, 5% of patients still presented with incident pain frequently interfering with daily activities. Most patients were treated with analgesics, but 20% of patients did not receive any pain medications despite experiencing pain.

CONCLUSION

The level of organization and standardization of postoperative pain management in Italian hospitals remains low. Postoperative analgesic treatment remained suboptimal and almost two-thirds of patients continued to experience pain.

Effects on growth and metabolism of growth hormone treatment for 3 years in 36 children with Prader-Willi syndrome

BACKGROUND/AIMS

Prader-Willi syndrome (PWS) is a complex genetic disorder whose many manifestations include obesity and short stature. Diabetes, osteoporosis, and scoliosis are common. We evaluated the effects of human growth hormone (hGH).

METHODS

A prospective cohort study of 36 children (1-15 years of age) with genetically confirmed PWS who were given hGH (mean dose 0.033 ± 0.006 mg/kg/day) for 36 months. At baseline and once yearly, we evaluated growth, insulin-like growth factor-1 (IGF-1), body composition, bone mineral density (BMD), glucose tolerance, serum lipids, and spinal radiographs.

RESULTS

Height gain over the 3-year period was 1.2 SD score. Lean body mass increased significantly during each treatment year. Total body fat decreased by 5.42 and 1.17% in the 1st and 2nd years, respectively. BMD remained unchanged during therapy. IGF-1 and homeostasis model assessment index of insulin resistance increased, and glucose intolerance was found in 22.7% of patients at baseline and 0% at 3 years. None of the patients had diabetes. Their lipid profile improved. Scoliosis was present in 27.8% of the patients at baseline and 47.2% at 3 years.

CONCLUSION

GH treatment in children with PWS has multiple beneficial effects on growth and body composition. Tolerance is good, with an improvement in glucose metabolism, although IGF-1 levels and insulin resistance parameters should be monitored closely. The high rate of scoliosis warrants monitoring by a pediatric orthopedic surgeon.

Progressive osseous heteroplasia: a model for the imprinting effects of GNAS inactivating mutations in humans

CONTEXT

Heterozygous GNAS inactivating mutations are known to induce pseudohypoparathyroidism type 1a when maternally inherited and pseudopseudohypoparathyroidism when paternally inherited. Progressive osseous heteroplasia (POH) is a rare disease of ectopic bone formation, and studies in different families have shown that POH is also caused by paternally inherited GNAS mutations.

OBJECTIVE

Our purpose was to characterize parental origin of the mutated allele in de novo cases of POH and to draw phenotype/genotype correlations according to maternal or paternal transmission of a same GNAS mutation.

DESIGN AND SETTING

We conducted a retrospective study on patients addressed to our referral center for the rare diseases of calcium and phosphorus metabolism.

PATIENTS AND METHODS

We matched 10 cases of POH with cases of pseudohypoparathyroidism type 1a carrying the same GNAS mutations.

MAIN OUTCOME MEASURES

The parental origin of the mutated allele was studied using informative intragenic polymorphisms and subcloning of PCR products.

RESULTS

Paternal origin of GNAS mutations was clearly demonstrated in eight POH cases including one patient with mutation in exon 1. Genotype/phenotype analyses suggest that there is no direct correlation between the ossifying process and the position of the inactivating GNAS mutation. It is, however, more severe in patients in whom origin of the mutation is paternal. Severe intrauterine growth retardation was clearly evidenced in paternally inherited mutations.

CONCLUSIONS

Clinical heterogeneity makes genetic counseling a delicate matter, especially in which paternal inheritance is concerned because it can lead to either a mild expression of pseudopseudohypoparathyroidism or a severe expression of POH.

Tetraplegia following parathyroidectomy in two long-term haemodialysis patients

We report two cases of postoperative iatrogenic tetraparesis, which occurred in different hospitals after surgery for parathyroidectomy. Both patients were on long-term haemodialysis. The prolonged neck extension usually required by this procedure was probably the main factor involved in the genesis of the spinal cord injury. Spinal abnormalities associated with chronic renal failure may have made these patients more vulnerable. In our opinion, it is advisable to investigate thoroughly any sign of spinal stenosis in patients who undergo any procedure requiring significant neck extension, particularly if on long-term haemodialysis.

Pamidronate treatment of children with moderate-to-severe osteogenesis imperfecta: a note of caution

BACKGROUND/AIMS

Bisphosphonates have been reported to decrease fractures related to osteogenesis imperfecta (OI). We assessed the efficacy and long-term safety of pamidronate therapy in patients with moderate-to-severe OI.

METHODS

We conducted an open-label uncontrolled study in 14 boys and 13 girls whose mean age was 6.8 years at baseline. Intravenous pamidronate, 1 mg/kg/day, was given for 3 consecutive days every 4 months for 2-6 years, with physical therapy and orthopedic surgery as appropriate. Mobility score, fracture rate, height, bone mineral density (BMD) and bone healing were evaluated throughout follow-up.

RESULTS

In 24 (89%) patients, the fracture rate decreased to <or=2/year and/or the mobility score improved. The remaining 3 (11%) patients continued to experience more than 2 fractures per year with mobility scores <2 despite significant BMD gains. Delayed radiographic fracture healing (>6 months) occurred in 8 (29.6%) patients; their BMD gains, baseline age and treatment duration were not significantly different from those in the other patients. Tolerance was good.

CONCLUSION

Pamidronate with physiotherapy and orthopedic management improved outcomes without delaying fracture healing in 19 (70%) of 27 patients. Delayed fracture healing occurred in 8/27 patients. Pamidronate should be reserved for severe OI with multiple fractures and/or flattened vertebras.

Genetic control of somatic embryogenesis induction in Eucalyptus globulus Labill

A reproducible protocol for somatic embryogenesis (SE) induction in Eucalyptus globulus from mature zygotic embryos is available since 2002. However, for the use of SE in tree breeding programs, the frequency of SE initiation needs to be improved and controlled, and this was investigated in 13 open-pollinated (OP) families over three consecutive years. A diallel mating design with five parent trees was used to study genetic control of SE induction. Results showed that SE induction varies across E. globulus families and over the years of seed production tested. Somatic embryogenesis was initiated on explants from 84% of the OP families tested in 2002 and 100% of the families tested in 2003 and 2004. The year 2003 gave best results for percentage of induction and total number of somatic embryos produced. Results concerning genetic control showed that SE induction is under the control of additive genetic effects, as 22.0% of variation in SE initiation was due to general combining ability (GCA) effect, whereas 6.4% was due to maternal effects. Neither specific combining ability (SCA) nor reciprocal effects were significant.