Cranial mononeuropathy IIIThird cranial nerve palsy; Oculomotor palsy; Pupil-involving third cranial nerve palsy; Mononeuropathy - compression type
Cranial mononeuropathy III is a nerve disorder. It affects the function of the third cranial nerve. As a result, the person may have double vision and eyelid drooping.
Mononeuropathy means that only one nerve is affected. This disorder affects the third cranial nerve in the skull. This is one of the cranial nerves that control eye movement. Causes may include:
Mononeuropathy is damage to a single nerve, which results in loss of movement, sensation, or other function of that nerve.
- Brain aneurysm
- Abnormal 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 growths (especially tumors at the base of the brain and pituitary gland)
In rare cases, people with migraine headaches 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.
A migraine is a type of headache. It may occur with symptoms such as nausea, vomiting, or sensitivity to light and sound. In many people, a throbbi...
People with diabetes may also develop a neuropathy of the third nerve.
A neuropathy of the third nerve
This diabetic type of cranial mononeuropathy III is a complication of diabetes. It causes double vision and eyelid drooping.
Symptoms may include:
- Double vision, which is the most common symptom
- Drooping of one eyelid (ptosis)
- Enlarged pupil that does not get smaller when a light shines on it
- Headache or eye pain
Other symptoms may occur if the cause is a tumor or swelling of the brain. Decreasing alertness is serious, because it could be a sign of brain damage or impending death.
Exams and Tests
An eye examination may show:
- Enlarged (dilated) pupil of the affected eye
- Eye movement abnormalities
- Eyes that are not aligned
Your health care provider will do a complete examination to find out if other parts of the nervous system are affected. Depending on the suspected cause, you may need:
- Blood tests
- Tests to look at blood vessels to the brain (cerebral angiogram, CT angiogram, or MR angiogram)
Cerebral angiography is a procedure that uses a special dye (contrast material) and x-rays to see how blood flows through the brain.
- MRI or CT scan of the brain
A head MRI (magnetic resonance imaging) is an imaging test that uses powerful magnets and radio waves to create pictures of the brain and surrounding...
- Spinal tap (lumbar puncture)
You may need to be referred to a doctor who specializes in vision problems related to the nervous system (neuro-ophthalmologist).
Some people get better without treatment. Treating the cause (if it can be found) may relieve the symptoms.
Other treatments to relieve symptoms may include:
- Corticosteroid medicines to reduce swelling and relieve pressure on the nerve (when caused by a tumor or injury)
- Eye patch or glasses with prisms to reduce double vision
- Pain medicines
- Surgery to treat eyelid drooping or eyes that are not aligned
Some people will respond to treatment. In a few others, permanent eye drooping or loss of eye movement will occur.
Causes such as brain swelling due to a tumor or stroke, or a brain aneurysm may be life threatening.
When to Contact a Medical Professional
Call your provider if you have double vision and it does not go away in a few minutes, especially if you also have eyelid drooping.
Quickly treating disorders that could press on the nerve may reduce the risk of developing cranial mononeuropathy III.
Rucker JC, Thurtell MJ. Cranial neuropathies. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 104.
Central nervous system - illustration
The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Central nervous system
Review Date: 5/30/2016
Reviewed By: Amit M. Shelat, DO, FACP, Attending Neurologist and Assistant Professor of Clinical Neurology, SUNY Stony Brook, School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.