DUANE SYNDROME:
Affecting just one tenth of a percent of the general population, this congenital disorder that limits movement of the eye(s) was first described by A. Duane, more than a century ago. Duane Retraction Syndrome (DRS) is congenital in nature, meaning that its presence is extant from birth, and in simplest terms, is characterized by the inability to move the eye out wards from the “straight ahead” position – – – an act more than ninety-nine percent of us perform perhaps dozens of times daily without conscious thought. Classified as one of the known extraocular muscle fibrosis syndromes, medical conditions which involve the muscles that move our eyes, DRS is believed by researchers to occur as an abnormality from between the third and eighth weeks of gestation, a period critical in the formation of ocular muscles and the cranial nerves which control them. Ocular muscles are required to perform what on the surface seems a “given,” the rotating of our eyes outward, but whether due to environmental factors or unknown genetic disorders, the connections among nerves which supply those muscles to the eyes during weeks three through eight fail to develop in the fetus who will be born with Duane Syndrome.
Decades of research have led medical scientists to believe that it is the absence of the cranial nerve VI, also known as the abducens nerve, which leads to DRS. The muscle this nerve is responsible for controlling is responsible itself for rotating the eye outward, and it is from this inability to pivot the eye toward the ear that the vast majority (seventy percent) of Duane Syndrome patients suffer. Thirty percent of those diagnosed have limited to zero ability in moving the eye(s) inward, toward the nose.
The lack of peripheral vision inherent in DRS patients is, as one might suspect, not without its hardships, and dangers. The activities occurring just outside the “straight ahead” field of vision most of us enjoy can often times be ignored; our brains and our eyes work in tandem, choosing what movement to ignore and what movement to include in our thought/sight process. DRS patients aren’t so enabled, but most compensate with what physicians have come to call “head turn,” a habit of turning the head so as to bring peripheral activity into “straight ahead” vision, an act borne of necessity for the safety of those who have no true peripheral vision.
Because physical manifestations of DRS can be witnessed as early as middle-infancy, most children are diagnosed with the syndrome long before reaching school age. Presenting as typically healthy infants otherwise, many times the most obvious symptom of Duane Syndrome in children can appear to be what parents mistake as “lazy eye” – – – one eye appearing to move in a direction independent of the other. This is not the case of course, but it most certainly can appear to be. In children with DRS Type I, where rotation outward toward the ear is either very limited or completely absent, the affected eye – – – in seventy-two percent of patients, the left – – – remains in the “straight ahead” position while the other eye, pivoting normally, appears to move too far inward toward the nose, giving the false impression of “lazy eye.”
(Contributor’s Note: This was our first concern, “lazy eye,” when we for the first time noticed something not quite right with our own toddler’s vision at around age two. His right eye appeared to wander at will, rotating toward his nose, while his left eye would remain fixed forward. It wasn’t until our family doctor referred us to a pediatric ophthalmologist that we became aware of Duane Syndrome, a position we share with most parents whose children are so diagnosed.)
Clinical evaluation for DRS most times includes family history and an eye examination, which usually encompasses measurements in head turns, eye alignment, range of motion in the eyes, visual sharpness, and retraction of the eyeballs. Because DRS can sometimes be associated with skeletal and neurological systems, an exam of the cervical and thoracic spine may be included in testing a child for DRS.
While there is currently no cure for Duane Syndrome and at this time, unfortunately, the absence of the nerve responsible for controlling eye muscles cannot be corrected, some treatments do offer help in reducing or even eliminating the head turning associated with it. Glasses cut with special prisms can drastically reduce or even completely eliminate the varying degrees of head turning. Cosmetic surgery is also a choice for many patients, performed when abnormalities in primary gaze are present. This surgery, while unable to fix the missing nerve, can most certainly keep the condition from worsening further and is a real consideration for those affected by Duane Syndrome.
For further help, information or support, please visit the MUMS Parent-to-Parent Network or the Yahoo! Duane’s Retraction Syndrome Support Group, both available online.
