Lumbar puncture (LP) may precipitate cerebral venous thrombosis (CVT), but it is unclear if LP is deleterious in patients with CVT. We aimed to assess the safety of LP in the International Study on Cerebral Veins and Dural Sinus Thrombosis prospective cohort.

In 624 patients with CVT, we compared the prognosis of patients submitted or not to LP. The primary outcome was 'death or dependency at 6 months', as evaluated by the modified Rankin Scale (mRS; mRS = 3-6, with adjustment for variables associated with poor prognosis); secondary outcomes were: 'worsening after admission'; 'acute death'; and 'complete recovery at 6 months' (mRS = 0-1). We analyzed the same outcomes in subgroups of patients with brain lesions on the admission computer tomography/magnetic resonance imaging.

LP was performed in 224 patients (35.9%). There was no difference in frequency of 'death or dependency at 6 months' between patients with or without LP [13.4% vs. 14.4%; odds ratio (OR) = 0.9, 95% confidence interval (CI) 0.6-1.5; P = 0.739]. LP was not associated with 'worsening after hospitalization' [21.5% vs. 23.5%; OR = 0.9, 95% CI 0.6-1.3; P = 0.577], 'acute death' [3.6% vs. 3.3%; OR = 1.1, 95% CI 0.5-2.7; P = 0.844] or 'complete recovery' [79.9% vs. 76.6%; OR = 1.2, 95% CI 0.8-1.7; P = 0.484]. In the subgroups of patients with brain lesions, the prognoses were not different between patients submitted or not to LP.

LP was not associated with the functional outcome of patients with CVT, suggesting that LP was not harmful in these patients. These results should not be generalized to patients with large brain lesions and risk of herniation where LP is contraindicated.