Isolated Pupillary-sparing Cranial Nerve III Palsy from a Subgaleal Abscess.

Cranial nerve (CN) III palsy is rarely caused by intraorbital compression, let alone from a subgaleal abscess. We present a case of a hypertensive 55-year-old man with an acute isolated pupillary-sparing left CN III palsy from a left subgaleal abscess with associated pterional osteomyelitis and frontotemporal mass. This is the first reported such case and the third reported case of a chronic spontaneous subgaleal abscess. A seemingly routine case of an acute, pupillary-sparing, isolated CN III palsy from hypertension turned out to be a rare case in terms of etiology of the palsy and of the source of the abscess.