Abstracts

Seizures are a common manifestation of cerebral venous thrombosis (CVT). They are commoner in venous than in arterial strokes. Though seizures after arterial strokes have been extensively studied, there is no similar published data on venous stroke and seizures. The exact mechanism of seizures in arterial or venous stroke is not established. Among arterial strokes, large cortical infarcts are associated with increased seizure risk compared to subcortical infarcts and hemorrhage is associated with a greater seizure risk than ischemic stroke. As an extrapolation it may be true that the high incidence of seizures in CVT is due to the cortical location of venous infarcts. Venous infarcts are often hemorrhagic, which may independently increase seizure risk.
We studied the pattern of brain imaging in patients of CVT with and without seizures to establish whether the higher incidence of seizures in venous stroke is due to venous infarcts because of 1) their cortical location and /or 2) their hemorrhagic component.
Data of 72 consecutive patients admitted over 4 years was retrospectively analysed. All had been clinically suspected to have CVT and confirmed on MRI/MRV or CT scan of the brain. Parenchymal brain changes on CT/MRI were classified as i) normal ii) non -hemorrhagic infarcts iii) hemorrhagic infarcts. The brain imaging patterns were compared in the groups with and without seizures. Odds ratios were calculated for the risk of seizures with and without infarcts and for hemorrhagic versus non hemorrhagic infarcts.
The risk of seizures was compared in two groups according to symptom duration i)[lt]/= 15days ii)[gt]15 days
[/italic][/underline] Seizures were noted in 39 of 72 cases (54.2[italic][underline]%)[/italic][/underline]. Of those patients with seizures, 24 (61.5 %) had parenchymal infarcts. Seizures were commoner in CVT in the presence of a venous infarct (OR 8.67, 95%CI 6.62-9.72). [/italic][/underline] : Thirtyone patients (43.1%) had brain infarcts. All infarcts except two were cerebral cortical infarcts. These were located in the thalamus and cerebellum. The patients with thalamic and cerebellar infarcts did not have seizures. [/italic][/underline] in patients with seizures, 19 of 24 infarcts (79.2%) were hemorrhagic .Seven of the 33 patients (21.2 %) without seizures had infarcts on neuroimaging, Of these majority were hemorrhagic (6 of 7) . Presence of hemorrhage in an infarct did not increase the seizure risk (OR 0.63,95% CI -0.88-2.14) .
The risk of seizures was higher in acute ([lt]/=15days) than chronic CVT (OR 2.21.95% CI 0.69-7.15)
Seizures are commoner in arterial than venous strokes. Brain infarcts on imaging increases the likelihood of seizures in patients with CVT. Most infarcts in CVT are cortical in location. Though hemorrhagic infarcts are commoner than non hemorrhagic infarcts in venous stroke, hemorrhagic component in an infarct does not independently increase seizure risk. Seizures are commoner in acute than in chronic CVT.