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Cranial mononeuropathy III

Third 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.

Causes

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:

  • Brain aneurysm
  • Infections
  • 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.

People with diabetes may also develop a neuropathy of the third nerve.

Symptoms

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:

You may need to be referred to a doctor who specializes in vision problems related to the nervous system (neuro-ophthalmologist).

Treatment

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

Outlook (Prognosis)

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.

Prevention

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

References

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.

Stettler BA. Brain and cranial nerve disorders. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 95.

Tamhankar MA. Eye movement disorders: third, fourth, and sixth nerve palsies and other causes of diplopia and ocular misalignment. In: Liu GT, Volpe NJ, Galetta SL, eds. Liu, Volpe, and Galetta's Neuro-Ophthalmology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 15.

    • Central nervous system and peripheral nervous system

      Central nervous system and peripheral 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 and peripheral nervous system

      illustration

      • Central nervous system and peripheral nervous system

        Central nervous system and peripheral 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 and peripheral nervous system

        illustration

      Review Date: 4/30/2018

      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, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

      The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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