A Cochrane review included 4 RCTs with a total of 1091 patients with bacterial meningitis. Three trials were conducted in children under 16 years, and one trial in adults and adolescents older than 14 years. The etiology of meningitis was not clear. One trial took place in Finland, one in South America, one in India and one in Malawi. All participants received broad-spectrum iv. antibiotic treatment. All compared glycerol (a water-soluble sugar alcohol) with a control; in 3 trials this was a placebo, and in one a small amount of 50% dextrose. Three trials included comparators of dexamethasone alone or in combination with glycerol. As dexamethasone appeared to have no modifying effect, the results were aggregated across arms where both treatment and control groups received corticosteroids and where both treatment and control groups did not. Compared to placebo, glycerol had little or no effect on death in people with bacterial meningitis (RR 1.09, 95% CI 0.89 to 1.33; 4 trials, n=1091); or on death and neurological disability combined (RR 1.04, 95% CI 0.86 to 1.25; 4 trials, n=1091). In the single trial in adults (n=265), glycerol was associated with increased mortality (RR 1.30, 95% CI 1.04 to 1.62; ). Glycerol had little or no effect on seizures during treatment for meningitis (RR 1.08, 95% CI 0.90 to 1.30, 3 trials, n=909). Glycerol reduced the risk of subsequent deafness (RR 0.60, 95% CI 0.38 to 0.93, 4 trials, n=741). Neither glycerol nor dexamethasone were associated with significant adverse effects.
Comment: The quality of the evidence is downgraded by imprecise results (small trials and few events, it is probable that the trials included patients with Haemophilus influenzae meningitis) and indirectness (differences in studied patients, one trial conducted in a developing country).