Duane syndrome

Last revised by Rohit Sharma on 22 Mar 2024

Duane syndrome, also known as Duane retraction syndrome, is a rare congenital disease characterized by non-progressive strabismus. It is caused by a variable degree of abnormal development of one or both 6th cranial nerves (CN VI).

It presents during childhood and it accounts for less than 5% of cases of strabismus 1.

Three types of Duane syndrome are described, each with a different clinical presentation 4,5:

  • type I: most common

    • strabismus with esotropia at rest

    • head tilt to affected side

    • absent to markedly restricted abduction

    • normal to mildly restricted adduction

    • induced ptosis on adduction

  • type II

    • strabismus with exotropia at rest

    • head tilt to unaffected side

    • normal to mildly restricted abduction

    • absent to markedly restricted adduction

    • induced ptosis on adduction

  • type III 

    • strabismus with either esotropia or exotroptia at rest

    • head tilt to the affected side

    • absent to markedly restricted abduction

    • absent to markedly restricted adduction

    • induced ptosis on adduction

The majority of cases are unilateral, but it can be bilateral in up to 20% of patients.

Duane syndrome results from absent or abnormal development of the abducens nerve or nucleus 4,5. Thus, the lateral rectus muscle becomes abnormally innervated by branches from the oculomotor nerve 4,5.

Most cases (90%) are sporadic, however, a minority of cases may have a genetic bases 5. Pathogenic variants in the CHN1, MAFB, or SALL4 genes have been implicated in inherited forms 5. Syndromic associations are also present, as aforementioned.

MRI findings consist of the following 2,3:

  • hypoplasia/atrophy of the lateral rectus muscle

    • the degree of atrophy is variable as the lateral rectus muscle may be reinnervated by aberrant branches from the 3rd cranial nerve (CN III)

  • hypoplasia or absence of CN VI

Hypoplasia of other extra-ocular muscles have been described, depending on the type of the disease, especially the superior oblique muscle (types I and II) 3.

Management can be non-surgical (e.g. wearing prisms) or surgical (e.g. correcting strabismus) 5.

The condition is named after Alexander Duane (1858-1926), American ophthalmologist, who described it in 1905 6.

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