The symptom complex of fluctuating unilateral motor, sensory or sensorimotor deficits simultaneously affecting the face, arm, and leg (i.e. clinically localized to the internal capsule) is referred to as capsular warning syndrome (CWS). While the exact pathogenesis is not fully understood and with the syndrome being rare (~1.5% of transient ischemic attacks (TIA)), its often poor prognosis with a 7-day risk of subsequent stroke equating 60% necessitates both clinicians and radiologists to be cognizant of this entity. 

With a history of incidental intracranial atherosclerotic disease (IAD) and lacunar infarction of the right recurrent artery of Heubner (performed at St. Elsewhere and not reacted upon) as visualized on brain computed tomography CT performed due to minor head trauma three years before, the patient later presented to the ER with repetitive sensorimotor deficits in the left side of the face, left arm and left leg i.e. description fitting CWS. MRI stroke protocol (DWI, T2-WI, T2*-WI and T2 FLAIR) performed in ER setting revealed no acute changes including absence of diffusion restriction, indicating intermediate risk of subsequent complete stroke. Ultrasonography with pulse-wave Doppler (PWUS) of the extracranial cervical vessels and consultation by a cardiologist performed in a subacute setting were without evidence of cervical large vessel or cardiac disease. 

Cholesterol lowering drugs and antiplatelet therapy were initiated and the patient was asymptomatic at both one- and two-year follow up.

With diagnostic workup, as well as therapy, in CWS dependent on local/national guidelines, these must be tailored individually and are beyond the scope of this discussion.

Key points:

• the symptom complex of fluctuating unilateral motor, sensory or sensorimotor deficits simultaneously affecting the face, arm and leg, also referred to as capsular warning syndrome (CWS), carries a poor prognosis with a 7-day risk of subsequent stroke equating 60%, necessitating both clinicians and radiologists to be cognizant of this entity
• while MRI may be preferable owing to its higher sensitivity, timely (<7 days) cross-sectional imaging (by either CT or MRI) as well as risk-stratification and initiation of tailored therapy are of utmost importance to prevent a potentially devastating outcome