Cranial mononeuropathy VI

Definition

Cranial mononeuropathy VI is a nerve disorder that causes double vision.

Causes, incidence, and risk factors

Cranial mononeuropathy VI is a damage to the sixth cranial (skull) nerve. This nerve, also called the abducens nerve, helps controls eye movement.

Abducens nerve disorders are often associated with diabetic neuropathy, trauma, infections (such as meningitis or sinusitis), infarction (tissue damage from loss of blood flow), brain aneurysms, tumors, or increased intracranial pressure (pressure within the skull).

In some cases, no cause can be found.

Because their are common nerve pathways through the skull, other cranial nerves (such as the third or fourth cranial nerve) may be also affected.

Symptoms

Symptoms may include double vision when looking to one side (unilateral injury). In some cases, there is pain or headaches.

Signs and tests

Testing of eye movement shows that one eye has difficulty looking to the side and the other eye moves normally. An eye examination shows the eyes do not align -- either at rest, or when looking in the direction of the weak eye.

A complete medical and neurological examination must be done to determine if other parts of the nervous system are affected. Depending on the suspected cause, a patient may undergo blood tests, a head imaging study such as an MRI or CT scan, and possibly a lumbar puncture (spinal tap).

Treatment

In some cases, corticosteroids may reduce swelling and relieve pressure on the nerve. In other cases, the condition disappear without treatment. If the cause can be identified, symptoms may be treated and relieved. Close control of blood sugar levels in diabetics may be beneficial.

Until the nerve heals, an eye patch may alleviate double vision.

Expectations (prognosis)

The outcome depends on the underlying cause. Treatment of the underlying cause may improve the condition. Improvement may occur even if the cause is never determined.

Complications

Some complications include permanent vision changes.

Calling your health care provider

Call your health care provider if double vision occurs.

Prevention

No specific prevention is available, although patients with diabetes may reduce the risk by controlling their blood sugar.

Illustrations

Central nervous system

Page Content:

Abducens palsy; Lateral rectus palsy ; abducens nerve palsy