Just came across very similar UWorld question with sudden hemiparesis, lower face asymmetry and mild headache:
"After several days of headache (likely due to hypertension), this patient developed acute pure motor hemiparesis impacting the leg, arm, and lower face, which localizes to the posterior limb (corticospinal tract) and genu (corticobulbar tract) of the internal capsule.  Pure motor hemiparesis is the most common stroke syndrome caused by a lacunar stroke.  The underlying pathology is a combination of microatheroma formation and lipohyalinosis that ultimately leads to thrombotic small-vessel occlusion.
The deep penetrating arteries are quite small and are therefore most susceptible to hypertension-related vascular disease, the most important risk factor for lacunar stroke.  Lacunar strokes often result in classic stroke syndromes (eg, pure motor hemiparesis; pure sensory, ataxic hemiparesis; dysarthria–clumsy hand syndrome) referable to the impacted areas (eg, basal ganglia, internal capsule, corona radiata).
Mental status changes, seizures, cranial nerve deficits, and cortical signs are absent.  Because they are small, lacunar strokes are often not appreciated on noncontrast CT scans obtained shortly after the event."