Can perfusion CT unmask postictal stroke mimics? A case-control study of 133 patients.

OBJECTIVE:To study the diagnostic value of volume perfusion CT (VPCT) in patients with transient focal neurologic deficits following and during epileptic seizures, that mimic symptoms of stroke. METHODS:A retrospective case-control study was performed on 159 patients who presented with a seizure and received an emergency VPCT within the first 3.5 hours of admission, after being misjudged to have an acute stroke. The reference test was a clinical-based, EEG-supported diagnostic algorithm for seizure. RESULTS:We included 133 patients: 94 stroke-mimicking cases with postictal focal neurologic deficits ("Todd phenomenon," n = 67) or ongoing seizure on hospital admission ("ictal patients," n = 27), and 39 postictal controls without focal neurologic deficits. Patients with Todd phenomenon showed normal perfusion (64%), hypoperfusion (21%), and hyperperfusion (14%) on early VPCT. Ictal patients displayed more hyperperfusion compared to postictal patients (p = 0.015). Test sensitivity of hyperperfusion for ictal patients is 38% (95% confidence interval [CI] 20.7%-57.7%), specificity 86% (95% CI 77.3%-91.7%), positive predictive value is 42% (95% CI 27.5%-58.7%), and the negative predictive value 83% (95% CI 78.6%-86.9%). A cortical distribution was seen in all hyperperfusion scans, compared to a cortico-subcortical pattern in hypoperfusion (p < 0.001). A history of complex focal seizure and age were associated with hyperperfusion (p = 0.046 and 0.038, respectively). CONCLUSION:VPCT can differentiate ictal stroke mimics with hyperperfusion from acute ischemic stroke, but not postictal patients who display perfusion patterns overlapping with ischemic stroke. CLASSIFICATION OF EVIDENCE:This study provides Class IV evidence that VPCT accurately differentiates ictal stroke mimics from acute ischemic stroke.