Table of Contents - This Web Page
Duane syndrome, also called Duane retraction syndrome (DRS), is a group
of eye muscle disorders that cause abnormal eye movements. People with
Duane syndrome have difficulty rotating one or both eyes outward
(abduction) or inward (adduction).
Six muscles, which control the movement of the eye, are attached to the
outside wall of the eye. In each eye, there are two muscles that move
the eye horizontally. The lateral rectus muscle pulls the eye out
towards the ear and the medial rectus muscle pulls the eye in towards
the nose. There are four other muscles, which move the eye up or down
and at an angle. Each eye muscle receives the command for movement from
the cranial nerves that exit the brain.
Duane syndrome is often characterized by whether the primary
abnormality is a reduced ability to turn the affected eye(s) outward
(type I), inward (type II), or both (type III). Type I is the most
common form of Duane syndrome.
In Duane syndrome, the sixth cranial nerve that controls the lateral
rectus muscle (the muscle that rotates the eye out towards the ear)
does not develop properly. Why the nerve does not develop is not yet
understood. Thus, the problem is not primarily with the eye muscle
itself, but with the nerve that transmits the electrical impulses to
the muscle. There is also irregular innervation of a branch from the
third cranial nerve, which controls the medial rectus muscle (the
muscle that rotates the eye toward the nose). This is why abnormalities
may be found in both left gaze and right gaze.
Duane syndrome affects girls more often than boys. In addition the left
eye is more likely than the right eye to be affected. The reason for
this is not known. Around 20 % of Duane syndrome patients have both
eyes affected. No particular race or ethnic group is more likely to be
affected.
Duane retraction syndrome is present from birth, even if it is not
recognized during infancy. An abnormal head posture and strabismus are
often visible in old photographs taken in early childhood.
In 90% of cases, the patient has no family history of Duane syndrome.
Ten percent of patients will have an affected family member and these
tend to be cases where both eyes are involved. There is currently no
test that can determine whether a patient has a hereditary form.
The problem with the 6th cranial nerve is usually an isolated condition
and the child is usually otherwise completely normal. Occasionally,
Duane syndrome may be found in association with other eye problems,
including disorders of other cranial nerves, nystagmus ( an involuntary
back-and-forth movement of the eyeball), cataract, optic nerve
abnormalities, microphthalmos (abnormally small eye), and crocodile
tears.
The problem with the cranial nerve is usually an isolated condition and
the child is otherwise completely normal. However, some patients with
Duane syndrome have other problems, such as hearing impairment,
Goldenhar Syndrome, spinal and vertebral abnormalities. There is also
an increased frequency of Duane syndrome in patients with thalidomide
Embropathy.
Treatment for Duane syndrome is indicated for one of three reasons: