What are the causes of a 3rd nerve palsy?
The third cranial nerve comprises of two major components: outer parasympathetic fibers which innervate ciliary muscles and sphincter pupillae and inner somatic fibers that supply levator muscles of eye lid and extra ocular muscles. The damage is known as palsy. It can be the result of: vascular ischemia, trauma, and an intracranial neoplasm, hemorrhage, congenital or idiopathic. Diabetics and hypertensive patients are specifically prone to these. If the defect is supranuclear pathway level conjugate paresis of both eyes occurs. The lesion at nuclear level is basically caused by vascular diseases. Demyelination or tumors. If the lesion is at basilar portion unilateral palsy is common. Intraorbital portion is usually due to trauma and Tolosa- Hunt syndrome.
