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

Cranial mononeuropathy VI is 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
• Increased intracranial pressure (pressure within the skull)

In some people, no cause is found.

Because there are common nerve pathways through the skull, the disorder may affect other cranial nerves (such as the third or fourth cranial nerve).

Symptoms may include double vision when looking to one side (unilateral injury). Pain or headaches may also occur.

Tests typically show that one eye has trouble looking to the side, while the other eye moves normally. An examination shows the eyes do not align -- either at rest, or when looking in the direction of the weak eye.

Your health care provider will perform a complete medical and neurological examination to determine the possible affect on other parts of the nervous system. Depending on the suspected cause, you may need blood tests, a head imaging study (such as an MRI or CT scan), and possibly a lumbar puncture (spinal tap).