Duane Retractio..

Neurophthalmologic condition associated with abnormal ocular movement, usually not accompanied by other congenital anomalies.

Stilling Turk Duane Syndrome.

Duane retraction syndrome (DRS) is an unusual form of congenital strabismus and accounts for 1 to 4% of children with strabismus. It is slightly more common in females than in males (about 60:40), often is bilateral (2057%), and is significantly more frequent in the left eye (about 3-4:1). Reported frequencies vary widely.

Approximately 56 to 90% are sporadic cases. In the residual cases, a positive family history with autosomal dominant transmission has been suggested, although some cases with most likely autosomal recessive inheritance have been reported. Several gene defects can account for hypoplastic or absent brainstem motor neurons and aberrant innervation and therefore have been linked to DRS. Defects have been mapped to loci 2q31, 4q27-31, 8q12.2-q21.1, and 22pter-22q11.2, to mention a few.

Innervation of the lateral rectus muscle emanates from axons of oculomotor nuclei, which supposedly supply the medial rectus muscle. The abducens nucleus may be hypoplastic or even absent. Attempted adduction of the eye basically results in simultaneous contractions of the lateral and the medial rectus muscle, with the net effect being retraction of the globe. At the same time, the palpebral fissure narrows and horizontal eye movement is limited (depending on the type of DRS, abduction is severely compromised). A teratogenic event (e.g., thalidomide exposure) between days 20 and 35 of gestation has been held responsible for the genetic defect.

Severe limitation of horizontal eye movement accompanied by narrowing of the palpebral fissure and eyeball retraction with attempted adduction leads to the diagnosis of DRS.

Different classifications have been suggested for DRS. The following classification is based on EMG findings:

• Type I: Abduction is more compromised than adduction, which results in globe retraction and narrowing of the palpebral fissure, whereas abduction results in widening of the palpebral fissure. Adduction, but not abduction, shows EMG activity in the lateral rectus muscle. This type accounts for 70 to 90% of cases.
• Type II: Adduction is absent or limited with exotropia of the affected eye. Attempted adduction results in globe retraction. Adduction and abduction result in EMG activity in the lateral rectus muscle.
• Type III: Both adduction and abduction are severely limited. Attempted adduction results in globe retraction and narrowing of the palpebral fissure. EMG activity can be recorded for the lateral and the medial rectus muscles during attempted abduction and abduction.

In addition to the described horizontal restrictions of eye movement, vertical eye movement anomalies are possible.

A few other anomalies have been reported in conjunction with DRS, including other ocular anomalies such as anisometropia, amblyopia (both in approximately 15% of DRS patients), anisocoria, ptosis, and nystagmus. Conductive hearing loss and sensorineural hearing loss (each in approximately 5% of cases) have been reported. Furthermore, DRS has been described ...

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