Review question

Do corticosteroids reduce inflammation in the membrane of the brain caused by parasites?

Background

Eosinophilic meningitis is an inflammation of the membrane covering the brain, the causes of which can be broadly categorised into infectious and non-infectious. Among the infectious aetiologies, Angiostrongylus cantonensis, a rat lung worm, is the major cause of eosinophilic meningitis. It occurs principally in South-East Asia and throughout the Pacific basin. However, this parasite has spread beyond the Pacific basin and is now found in regions of North America due to infected ship rats. Severe headache, which is self limiting, is the main complaint. The headache is probably due to an immune response to the dead parasites. Other signs and symptoms include neck stiffness and pain, visual disturbances, nausea, vomiting, paraesthesia and hyperaesthesia. Corticosteroids are drugs that reduce inflammation, which can occur in eosinophilic meningitis due to dead larvae.

Study characteristics

We conducted a systematic review and meta-analysis of randomised controlled trials of corticosteroids for treating eosinophilic meningitis. The evidence is current to December 2014. We found only one randomised controlled trial that matched our criteria. This trial included 129 patients (63 in the treatment group, prednisolone 60 mg/day, divided into three doses for two weeks and 66 in the control group, placebo). However,19 patients were lost to follow-up.

Key results

The included study showed that the median time to resolution of headaches was lower in the group treated with prednisolone (10.5 days versus 25 days) and the number of patients who still had headaches after 14 days was lower in the prednisolone group compared to the control (9.1% versus 45.5%). There were statistically significant differences, which favoured the treatment group, in other outcomes including the frequency of acetaminophen (paracetamol) use (median of number of times used) amongst those who still had headaches after 14 days of prednisolone treatment and the mean time until complete disappearance of headache. The number of patients who needed repeat lumbar puncture was also smaller in the treatment group. There were no reported adverse effects from prednisolone in the treatment group. Corticosteroids significantly help relieve headache in patients with eosinophilic meningitis, who have a pain score of four or more on a visual analogue scale.

Quality of the evidence

Given the lack of allocation concealment and blinding (especially in a trial with subjective outcomes), and the attrition (loss of participants), we graded our evidence as moderate quality.