Protective effects of steroids on the corticomicrocirculation injured by cold

Ibuprofen prevents altitude illness: a randomized controlled trial for prevention of altitude illness with nonsteroidal anti-inflammatories

STUDY OBJECTIVE

Acute mountain sickness occurs in more than 25% of the tens of millions of people who travel to high altitude each year. Previous studies on chemoprophylaxis with nonsteroidal anti-inflammatory drugs are limited in their ability to determine efficacy. We compare ibuprofen versus placebo in the prevention of acute mountain sickness incidence and severity on ascent from low to high altitude.

METHODS

Healthy adult volunteers living at low altitude were randomized to ibuprofen 600 mg or placebo 3 times daily, starting 6 hours before ascent from 1,240 m (4,100 ft) to 3,810 m (12,570 ft) during July and August 2010 in the White Mountains of California. The main outcome measures were acute mountain sickness incidence and severity, measured by the Lake Louise Questionnaire acute mountain sickness score with a diagnosis of ≥ 3 with headache and 1 other symptom.

RESULTS

Eighty-six participants completed the study; 44 (51%) received ibuprofen and 42 (49%) placebo. There were no differences in demographic characteristics between the 2 groups. Fewer participants in the ibuprofen group (43%) developed acute mountain sickness compared with those receiving placebo (69%) (odds ratio 0.3, 95% confidence interval 0.1 to 0.8; number needed to treat 3.9, 95% confidence interval 2 to 33). The acute mountain sickness severity was higher in the placebo group (4.4 [SD 2.6]) than individuals receiving ibuprofen (3.2 [SD 2.4]) (mean difference 0.9%; 95% confidence interval 0.3% to 3.0%).

CONCLUSION

Compared with placebo, ibuprofen was effective in reducing the incidence of acute mountain sickness.

Silicone rubber microangiography of injured acute spinal cord after treatment with methylprednisolone and vitamin E in rats

STUDY DESIGN

An experimental study of changes in the microvasculature of the injured spinal cord that occur with methylprednisolone and vitamin E treatment.

OBJECTIVE

To determine the effect of treatment with the methylprednisolone and vitamin E on the microvasculature of the traumatized spinal cord.

SUMMARY OF BACKGROUND DATA

Silicon rubber microangiography provided an excellent three-dimensional method for defining the distribution of vasculature in untreated and treated rats after injury. Therefore, silicone rubber microangiography was helpful for elucidating the pathophysiology of posttraumatic ischemia and hemorrhages in the spinal cord.

METHODS

In this study, 30 adult rats underwent laminectomy between C7 and T2 followed by extradural spinal cord clipping to produce the compression injury. A control group of 10 rats was left untreated, and 10 rats were treated with methylprednisolone (30 mg/kg bolus and 5.4 mg per hour for 24 hours). Another 10 rats were treated with methylprednisolone and vitamin E (100 U/kg per day). The animals were killed 4, 24, or 48 hours after injury. Silicon rubber microangiography was performed after injury to assess the vasculature of rats' spinal cord. Spinal cord injury causes rapid elevation of noradrenalin, adrenaline, and dopamine. Venous blood samples were taken from all animals before the silicone rubber microangiography was performed.

RESULTS

The compression of the spinal cord followed by postinjury treatment with the methylprednisolone and combination methylprednisolone and vitamin E resulted in a ischemic area smaller than that in the untreated group. Adrenaline, noradrenalin, and dopamine levels were less than those in the untreated group.

CONCLUSIONS

Findings showed that the addition of vitamin E to the methylprednisolone treatment made no difference in the extent of the ischemic area as compared with methylprednisolone treatment given alone. However, the statistical analysis did not show a significant difference between the treated and untreated groups.

[Clinical experiences and results of high-dosage methylprednisolone therapy in spinal cord trauma 1991 to 1993]

Studies in animals and especially the NASCIS II study illustrated the neuroprotective effects of methylprednisolone, but they are disputed. At the University Clinic of Traumatology, Vienna, 31 patients with spinal cord injuries were given methylprednisolone as a bolus of 30 mg/kg body weight followed by a maintenance dose of 5.4 mg/kg body weight/h for another 23 hours. Twenty-seven patients were stabilised within 8 hours, 2 patients were not operated on, because of their low prognosis. Two patients could be treated conservatively, because the spinal fractures were supposed to be stabile. Then follow-up studies of these patients were between 1 and 3.2 years. All patients (100%) with incomplete neurologic deficits (n = 18) showed a significant recovery and even 3 patients (23.1%) with primarily a complete tetraplegia (n = 13) showed a nearly entire recovery. Compared to these results we look back at 113 patients with complete and incomplete neurologic deficits who were treated at the I. University Clinic of Traumatology, Vienna, and would have got methylprednisolone following our current management procedures.

Dexamethasone as prophylaxis for acute mountain sickness. Effect of dose level

Rapid exposure of unacclimatized persons to high altitude causes the syndrome acute mountain sickness (AMS). Prophylactic treatment with frequent high doses of dexamethasone has been shown to prevent AMS. To determine whether lower, less frequent doses were effective in preventing AMS, 28 men between the ages of 18 and 32 were exposed to a simulated altitude of 4,570 m for 45 h in a hypobaric chamber on two occasions while taking one of three doses of dexamethasone (4 mg, 1 mg, or .25 mg every 12 h) or a placebo in a double-blind, crossover design. The 4-mg dose of dexamethasone reduced the incidence of AMS symptoms compared with placebo and the other dose levels. Dexamethasone did not alter fluid balance or plasma volume changes, but treatment with 1 mg and 4 mg suppressed cortisol secretion. There was no evidence of adrenal cortical suppression after treatment with dexamethasone or placebo 48 h after discontinuing altitude exposure and drug treatment. The results indicate that 4 mg of dexamethasone twice daily is an effective prophylactic treatment for AMS, while lower doses are relatively ineffective.

Dexamethasone and local cerebral glucose utilization in freeze-traumatized rat brain

Local cerebral glucose utilization (LCGU) was studied using the 14C-deoxyglucose method in dexamethasone-treated rats with focal cortical freezing lesions. Widespread depression of LCGU, which developed with time after the lesion in untreated animals, was significantly diminished by dexamethasone(0.25 mg/kg/day) started either 6 to 18 hours before or 4 or 24 hours after the lesion. The effect of dexamethasone was most striking in cortical areas of the traumatized hemisphere, where the depression was most profound in untreated animals. Thus, three days after the lesion, average LCGU in these regions was 47% and 72% of normal in untreated and pretreated rats, respectively. Dexamethasone also affected LCGU bilaterally in subcortical structures and in white matter. The results suggest that dexamethasone modified the widespread depression in functional state of the rat brain that developed in response to injury. Since the spatial distribution and time course of the observed changes in LCGU did not parallel those of cerebral edema, these effects of dexamethasone do not appear to be mediated by effects on the edematous process.

Microvascular perfusion and metabolism in injured spinal cord after methylprednisolone treatment

The purpose of this study was to determine the effect of treatment with the synthetic glucocorticoid, methylprednisolone, on the microvasulature and metabolism of the traumatized spinal cord. Spinal cords of cats were compressed with a 170-gm weight for 5 minutes and were treated with either high-dose methylprednisolone (HDMP, 15 mg/kg/24 hrs) or megadose methylprednisolone (MDMP,60 mg/kg/24 hrs). Animals were sacrificed at 2, 8, or 24 hours following injury. Treatment with HDMP resulted in substantial preservation of injured spinal cord microvascular perfusion at 8 hours as compared with injured untreated cats. Compression trauma caused a partial derangement of energy metabolism and a shift toward anaerobic glycolysis in both treated and untreated groups for the entire 24-hour postinjury period. Tissue levels of adenosine triphosphate, phosphocreatine, and total adenylates in the HDMP-treated cats sacrificed at 8 hours after trauma were significantly elevated over untreated controls, but those in the 2- and 24-hour groups were not. Concentration of energy intermediates in MDMP-treated cat were either equal to or below those of injured untreated animals al all three postinjury time period. The postinjury metabolite pattern and concentrations seen in this study possibly result from differing levels of blood flow and neuronal activity in the injured untreated, HDMP-, and MDMP-treated spinal cords. Better tissue perfusion in the HDMP-treated cats might be expected to result in an improved tissue energy state in these animals. However, intensive high-dose glucocorticoid treatment has been demonstrated to augment spinal cord monosynaptic and polysynaptic reflex transmission and primary afferent excitability. Furthermore, acute single intravenous dose studies have shown this direct neuronal action to be dose-related. Thus, additional high-energy phosphate molecules that may be reformed as a result of HDMP treatment were perhaps used as the energy source for any increased neuronal activity caused by steroid administration. The beneficial effects of glucocorticoid treatment in experimental spinal cord trauma might derive from preserved cellular structural integrity. This could result in increased levels of neuronal activity, energy utilization, and production in treated as compared with untreated tissue.