« RETURN TO FAQs

What is a cranial nerve palsy?

What is a cranial nerve?

The brainstem connects the spinal cord to the brain.  The brainstem performs spinal-cord like functions for the head.  The cranial nerves emanate from the brainstem.  They provide sensory and motor functions that deal with the special senses (olfaction, sight, hearing, equilibrium, and taste).

Which cranial nerves pertain to the eyes?

The second cranial nerve is called the optic nerve.  It is the conduit of visual information from the eye to the brain.  The third cranial nerve is called the oculomotor nerve.  It is involved with eye movement, eyelid movement, and the function of the pupil and lens.  The fourth cranial nerve is called the trochlear nerve and the sixth cranial nerve is called the abducens nerve.  They each innervate an eye muscle involved in eye movement.  The fifth cranial nerve is called the trigeminal nerve and this nerve provides facial sensation (including corneal sensation).

What is a cranial nerve palsy?

 A palsy is a lack of function of a nerve.  Palsy refers to a complete weakness, whereas a paresis is a partial weakness.  In the case of a cranial nerve that has multiple functions (such as the oculomotor nerve), it is possible to have a complete (all the various functions affected) or partial palsy (some of the functions affected).

What are some causes of a cranial nerve palsy?

A cranial nerve palsy can be congenital, traumatic, or due to vascular disease (ex. Hypertension, diabetes, strokes).  They can also be due to aneurysms, infections, migraines, tumors, or elevated intracranial pressure.  The age of the patient, as well as clinical findings, will help point the physician toward the correct diagnostic tests needed to determine the etiology.

What are the symptoms of a cranial nerve palsy?

3^rd, 4^th, and 6^th nerve palsies can limit eye movements and produce diplopia.  The orientation of the diplopia will be different based on which cranial nerve is affected.  Also ptosis (droopy eyelid) and mydriasis (dilated pupil) can occur with a 3^rd nerve palsy.

Is there any treatment?

Please refer to the specific FAQ sections on 3^rd, 4^th, and 6^th nerve palsies for specific recommendations and information (located on this website).  In general, some cases may resolve spontaneously.  In other cases, diplopia may be relieved with prism glasses, occlusion therapy, botulinum toxin, or surgery.  The best treatment will be determined by the Ophthalmologist after a thorough evaluation.