Volume Perfusion CT Helps Differentiate Ictal Stroke Mimics, but Not Postictal, From Acute Ischemic Stroke

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Patients were initially misjudged to have presented with an acute stroke instead of an epileptic seizure.
Patients were initially misjudged to have presented with an acute stroke instead of an epileptic seizure.

According to a study published in Neurology, volume perfusion CT (VPCT) may be a reliable tool for differentiating patients with ictal stroke mimics with hyperperfusion from those with ischemic stroke.

An electronic hospital database in Aachen, Germany, was used to sample a total of 133 patients with a new epileptic seizure who underwent a VPCT examination within a 3.5-hour period of hospital admission. Patients were initially misjudged to have presented with an acute stroke instead of an epileptic seizure. Witness description was used to diagnose epileptic seizure if automatisms, diminished consciousness, head deviation or tonic gaze, oral foaming, and/or aura were present. Patients in the analysis also underwent venous blood sampling within a 30-minute period following admission.

A total of 94 patients presented with stroke mimics with postictal focal neurologic deficits (n=67) or ongoing seizure (n=27) at time of hospital admission. In addition, there were 39 postictal control cases without focal neurologic deficits. Stroke-mimicking cases with postictal focal neurologic deficits were characterized as having normal perfusion (64%), hypoperfusion (21%), and hyperperfusion (14%) on early VPCT examination. The researchers found that ictal patients had significantly greater hyperperfusion when compared with postictal patients (positive predictive value, 42% [95% CI, 27.5%–58.7%]; negative predictive value, 83% [95% CI, 78.6%–86.9%]; P =.015).

The test sensitivity, specificity, positive predictive value, and negative predictive value of hyperperfusion for ictal patients was 38% (95% CI, 20.7%–57.7%), 86% (95% CI, 77.3%–91.7%), 42% (95% CI, 27.5%–58.7%), and 83% (95% CI, 78.6%–86.9%), respectively. All hyperperfusion scans demonstrated a cortical distribution compared with hypoperfusion scans which featured primarily a cortico-subcortical pattern (P <.001). Hyperperfusion was associated with a history of complex focal seizure (P =.046) and age (P =.038).

Limitations of the study included the retrospective nature of data collection as well as the inclusion of only German patients.

Despite its diagnostic utility, findings from this study highlighted the limitation of VPCT for differentiating patients with acute ischemic stroke from postictal patients, since the latter typically demonstrate “normal perfusion or a cortical-subcortical hypoperfusion.”

For the identification of postictal stroke mimics, the researchers noted that “a solid anamnesis, clinical and laboratory examination, absence of early ischemic changes on NCT, and normal CTA remain the primary instruments.”

Reference

Van Cauwenberge MGA, Dekeyzer S, Nikoubashman O, Dafotakis M, Wiesmann M. Can perfusion CT unmask postictal stroke mimics? A case-control study of 133 patients [published online October 17, 2018]. Neurology. doi: 10.1212/WNL.0000000000006501

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