The 'FLAIR Motor Sign': FLAIR Signal Abnormality in Precentral Cortex is Useful to Diagnose Adult Global Hypoxic-Ischemic Brain Injury Following Cardiac Arrest.

Purpose: The precentral cortex normally demonstrates lower signal intensity compared to remainder of the neocortex on 2D fluid attenuated inversion recovery (FLAIR) images. Loss of this normal hypointensity bilaterally can be seen in patients with adult hypoxic-ischemic brain injury (HIBI). We have named this the 'FLAIR motor' sign (FMS). The performance of this sign for detection of HIBI is evaluated in this case-control study.

Methods: MRI studies of 74 consecutive patients with clinical evidence of HIBI following cardiac arrest formed the 'case' group. Controls comprised of normal MRI studies of an equal number of age and gender matched patients. Two fellowship-trained neuro-radiologists reviewed the MRI studies in a blinded randomized fashion and recorded the presence or absence of 'FLAIR motor' sign.

Results: Average time from cardiac arrest to MRI was 7.12 days (range: 1-25 days). The average sensitivity and specificity of 'FLAIR motor' sign for HIBI was 86.49% and 100% respectively. The sign demonstrated excellent inter-reader agreement (kappa >0.8).

Conclusion: The loss of the normal hypointensity in bilateral pre-central cortex on 2D-FLAIR images is a specific and reliable MRI sign of HIBI in the subacute phase following cardiac arrest in adults.