Neurologycommon
A 79-year-old man on apixaban for atrial fibrillation is brought in by his wife. Over three weeks he has become slower, sleeps much of the day, has twice lost the thread of conversations, and has been unsteady walking with two near-falls. She recalls that four weeks ago he struck his head on a kitchen cupboard, without losing consciousness, and had a headache for a day. He has no fever and no urinary symptoms. Examination: Glasgow Coma Scale 14 (confused), mild drift of the right arm when held outstretched, brisk right-sided reflexes, and a normal gait apart from unsteadiness.
Which one of the following is the most likely diagnosis?