Duane Syndrome

What is Duane Syndrome?

Duane syndrome is a congenital strabismus eye movement disorder. Duane syndrome is characterized by horizontal eye movement limits (adduction or abduction). In people with Duane syndrome, when they move their eyes in toward their nose, their eyeballs retract and their eye openings narrow. Sometimes when the eyes look inward they move upward or downward instead. It is usually diagnosed before ten years of age.

Duane syndrome was first described by ophthalmologists Jakob Stilling, Siegmund Turk and Alexander Duane.

Duane syndrome falls into the category of misalignment of the eyes. It falls under the sub classification of eye misalignment that varies with gaze directions. It also falls into the sub-heading Congenital Cranial Dysinnervation Disorders (CCDD’s). CCDD’s are neuromuscular disorders that are congenital and result from developmental errors. These disorders involve one or more cranial nerves or nuclei with flawed innervation.

Duane syndrome is classified into three types: Type 1, Type 2 and Type 3. Duane syndrome is also known as Duane reaction syndrome (DRS), DR syndrome, Duane radial ray syndrome (DRRS), Duane’s retraction syndrome, eye retraction syndrome, retraction syndrome and Stilling-Turk-Duane syndrome. ^{[1, 2, 3, 4]}

What Causes Duane Syndrome?

Duane syndrome is caused by mis-wiring of the eye muscles. Duane syndrome most likely happens around the sixth week in uterus. It is due to the abnormal development of the eye nerve muscles. The sixth cranial nerve that controls eye muscle movement to rotate the eyes out towards the ear does not develop normally. It is not known why this happens but it is the misdirection of the nerve fibers that results in opposite muscles being supplied by the same nerve.

Most cases of Duane syndrome are sporadic. Ten percent of people with Duane syndrome have familial links. There have been both recessive and dominant forms documented. It has been known to skip generations in dominant cases and has been seen to range in severity in the same family. Most cases of Duane syndrome with familial ties are not associated with other anomalies.

Some genetic and environmental causes are known to play a role in Duane syndrome. Duane syndrome has been found in autosomal recessive disorders that include deafness, vascular malformations, facial weakness and learning disabilities. How common is Duane syndrome? It affects around one in a thousand people. ^{[1, 3, 4]}

Signs and Symptoms

• Type 1 Duane Syndrome
  • Ability to turn the eyes toward the ears is affected
  • Ability to move the eyes inward toward the nose is normal/near normal
  • Eye openings narrow and the eyeballs retract when looking in towards the nose
  • When looking outward toward the ears the opposite happens
• Type 2 Duane Syndrome
  • Ability to move the eyes inward toward the nose is affected
  • Ability to move the eyes outward toward the ears is normal/near normal
  • Eye openings narrow and the eyeballs retract when looking in towards the nose
• Type 3 Duane Syndrome
  • Ability to move the eyes inward toward the nose is affected
  • Ability to move the eyes outward toward the ears is affected
  • Eye openings narrow and the eyeballs retract when looking in towards the nose

Sub groups A, B and C describe the eyes when looking straight

• Group A
  • Esotropia (affected eye is turned inward toward the nose)
• Group B
  • Exotropia (affected eye is turned outward toward the ear)
• Group C
  • Eyes are straight when looking ahead in primary position

Type 1 of Duane syndrome happens seventy eight percent of the time. Type 2 of Duane syndrome happens seven percent of the time. Type 3 of Duane syndrome happens fifteen percent of the time.

Involvement of both eyes is less common than one eye only. Eighty to ninety percent of cases involve only one eye. When one eye is affected, the left eye is affected in seventy two percent of the time. In ten percent of Duane syndrome cases, there is also reduced visual acuity in an eye.

Major abnormalities associated with Duane syndrome are: skeletal issues, ear problems, eye problems, nervous system problems and renal issues. Duane syndrome is also associated with better defined syndromes like Okihiro’s, Wildervanck, Holt-Oram, Goldenhar and Mobius syndromes. ^[3]

Epidemiology

One to five percent of people in the general population will acquire strabismus. One percent of all people with strabismus will acquire Duane syndrome. There are no racial preferences for Duane syndrome. Female to male ratio for Duane syndrome is three to two.

Forty percent of people with Duane syndrome develop Esotropia (one or both eyes that turn inward) and tight medial rectus muscles. So therefore, thirty percent of people have compensatory head positions so they can achieve binocular single vision. ^[2]

How is Duane Syndrome Treated?

• A thorough ophthalmologist examination is required for a diagnosis of Duane syndrome
• Assessment of the neck, chest, spine, palate, hands and hearing is needed as well to rule out associated disorders
• Cannot be cured, missing cranial nerve can’t be replaced
• Most individuals do not need surgery
• Duane syndrome surgery aims to make the eye more central in location
• Medial rectus recession surgery, weakening these muscles can improve crossed eye appearance but not improve abductions
• Surgery of lateral transposition of vertical muscles can improve eye range of motion
• Surgery indications below:
  • Reduce a significant deviation in the looking straight position
  • Eliminate a significant abnormal head position
  • Eliminate a significant upward or downward eye position
  • Lazy eye can be treated with occlusion
• Investigational therapies may be available as well ^{[3. 4]}

^{Surgery to correct Duane syndrome}

Duane Syndrome Life Expectancy

People with Duane syndrome are expected to have a normal life expectancy.

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Reference List:

1. American Association for Pediatric Ophthalmology and Strabismus, Available from: https://www.aapos.org/terms/conditions/46

2. Medscape from E Medicine, Available from: http://emedicine.medscape.com/article/1198559-overview

3. National Organization for Rare Diseases, Available from: https://rarediseases.org/rare-diseases/duane-syndrome/

4. Wikipedia, Available from: https://en.wikipedia.org/wiki/Duane_syndrome

5. YouTube, Available from: https://www.youtube.com/watch?v=UWXLLAMD2W4 AND

https://www.youtube.com/watch?v=9pkru5Ii1nw

6. Reddit, Available from: https://www.reddit.com/r/mildlyinteresting/comments/18x18y/i_have_duanes_syndrome_which_causes_my_left_eye/?st=iv8naf3s&sh=f1a52557

7. Oculist.com, Available from: http://www.oculist.net/downaton502/prof/ebook/duanes/pages/v6/v6c096.html