Cerebrospinal fluid and plasma ascorbate concentrations following subarachnoid haemorrhage.

ABSTRACT

Background: Ascorbate, the biologically active form of vitamin C, is the primary neural anti-oxidant. Ascorbate concentrations have never been quantified following aneurysmal subarachnoid haemorrhage (aSAH). Objective: To quantify plasma and cerebrospinal fluid (CSF) ascorbate concentrations in patients following SAH. Design Setting Participants Main Outcome Measures: Cohort study in which plasma and CSF ascorbate concentrations were measured longitudinally in 12 aSAH patients admitted to a quaternary referral intensive care unit and compared to one-off samples obtained from 20 pregnant women prior to delivery in a co-located obstetric hospital. Data are median [interquartile range] or median (95 % confidence intervals). Results: Forty-eight plasma samples were obtained from the 12 aSAH patients (eight females, age 62 [53-68] years). Eight participants with extra-ventricular drains provided 31 paired CSF-plasma samples. Single plasma and CSF samples were obtained from 20 pregnant women (age 35 [31-37] years). Initial plasma and CSF ascorbate concentrations post aSAH were less than half those in pregnant controls (plasma aSAH 31 [25-39] µmol/L vs. comparator 64 [59-77] µmol/L; P < 0.001 and CSF 116 [80-142] µmol/L vs. 252 [240-288] µmol/L; P < 0.001). Post aSAH there was a gradual reduction in the CSFplasma ascorbate ratio from ∼41 to ∼11. Six (50 %) patients developed vasospasm and CSF ascorbate concentrations were lower in these patients (vasospasm 61 (25, 97) vs. no vasospasm 110 (96, 125) µmol/L; P = 0.01). Conclusion: Post aSAH there is a marked reduction in CSF ascorbate concentration that is most prominent in those who develop vasospasm.