Health Encyclopedia

Cranial mononeuropathy III - compression type

Definition

Cranial mononeuropathy III is a problem with the function of the third cranial nerve, which is located behind the eye.

Alternative Names

Third cranial nerve palsy; Oculomotor palsy; Pupil-involving third cranial nerve palsy

Causes, incidence, and risk factors

Cranial mononeuropathy III - compression type is a mononeuropathy, which means that only one nerve is affected. It affects the third cranial (oculomotor) nerve, one of the cranial nerves that controls eye movement. Local tumors or swelling can press down on and damage the nerve.

Causes may include:

Brain aneurysms
Disorders such as mononeuritis multiplex
Infections
Poorly formed blood vessels (vascular malformations)
Sinus thrombosis
Tissue damage from loss of blood flow (infarction)
Trauma (from head injury or caused accidentally during surgery)
Tumors or other lesions (especially tumors at the base of the brain and pituitary gland)

Rarely, people with migraine headaches may have a temporary problem with the oculomotor nerve. This is probably due to a spasm of the blood vessels. In some cases, no cause can be found.

Symptoms

Double vision
Drooping of one eyelid
Headache or eye pain

Other symptoms may occur if the cause is a tumor or trauma. Decreasing consciousness is a serious sign, because it could indicate brain damage or death.

Signs and tests

An eye examination may show:

Enlarged (dilated) pupil of the affected eye
Eye movement abnormalities
Eyes that are not aligned (dysconjugate gaze)

A complete medical and nervous system (neurological) examination can show whether any other parts of the body are affected.

Other tests may include:

Blood tests
CT angiogram
CT scan
MRI
Spinal tap (lumbar puncture)

Treatment

Some cases may get better without treatment. Treating the cause (if it can be found) may relieve the symptoms in many cases.

Treatment may include:

Corticosteroid medications to reduce swelling and relieve pressure on the nerve
Surgery to treat eyelid drooping or eyes that are not aligned
Wearing an eye patch or prisms

Expectations (prognosis)

Some cranial nerve dysfunctions will respond to treatment. A few cases result in some permanent loss of function. If the problem is caused by brain swelling due to a tumor or stroke, those conditions may be life-threatening.

Complications

Permanent eyelid drooping
Permanent vision changes

Calling your health care provider

Call the local emergency number (such as 911) or go to the emergency room if you have:

Double vision
No feeling in or control over parts of your body
Signs of changed consciousness
Unusual headache

Prevention

Quickly treating disorders that could press down on the nerve may reduce the risk of developing cranial mononeuropathy III.

Review Date:2/13/2008
Reviewed By:Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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