What is the definition of Marcus Gunn Phenomenon?
Marcus Gunn phenomenon is a rare condition characterized by movement of the upper eyelid in a rapid rising motion (a "wink") each time the jaw moves. The wink phenomenon may be elicited by opening the mouth, thrusting the jaw to the side, jaw protrusion, chewing, smiling, or sucking. It is usually present at birth and may occur with other eye abnormalities (such as strabismus) or vision problems. Although it usually affects one eye, it can affect both eyes in rare cases. The exact cause is not known. Marcus Gunn phenomenon is generally sporadic, but familial cases have been reported. Treatment is not always needed but may include surgery in more severe cases.
What are the alternative names for Marcus Gunn Phenomenon?
- Maxillopalpebral synkinesis
- Familial Marcus Gunn phenomenon (subtype)
- Marcus Gunn syndrome
What are the symptoms for Marcus Gunn Phenomenon?
Signs and symptoms of Marcus Gunn phenomenom (MGP) may include the following:
- Mild-to-moderate drooping of the eyelids (blepharoptosis), usually on one side (unilateral)
- Synkinetic (involuntary) upper eyelid movement after almost any movement of the lower jaw including: mouth opening, chewing, sucking, jaw protrusion, clenching teeth together, and swallowing
- Worsening of symptoms when looking down
- Decreased vision due to amblyopia ("lazy eye")
- Strabismus ("crossed eyes")
These symptoms are usually first noticed in infancy while bottle or breast feeding.
What are the current treatments for Marcus Gunn Phenomenon?
While it may not be needed in every case, people with Marcus Gunn phenomenon may benefit from surgery. Children with Marcus Gunn phenomenon need to be regularly monitored for amblyopia. If not addressed by age 7 to 10 years of age, amblyopia may become untreatable. Untreated severe ptosis can also result in vision loss. Other associated eye problems, such as horizontal strabismus, vertical strabismus, and double elevator palsy typically need to be addressed before considering how to manage Marcus Gunn phenomenon itself. These related eye problems may be corrected with eyeglasses, surgery, and/or medications.
Surgery for Marcus Gunn phenomenon may be considered for ptosis or jaw winking that is considered cosmetically significant, or causing amblyopia. Depending on the degree of ptosis and severity of jaw winking, several surgical techniques have been proposed. For mild Marcus Gunn phenomenon, management has included observation, levator muscle resection, and the Fasanella-Servat procedure.
More detailed information about treatment of Marcus Gunn phenomenon is available on Medscape Reference's Web site and can be viewed here.
Is Marcus Gunn Phenomenon an inherited disorder?
People with Marcus Gunn phenomenon usually have no family history of the disorder and do not pass it down to their children. However there have been reported cases where more than one family member has the disorder, but so far the genetic cause in these families is unknown. Sometimes, people with Marcus Gunn phenomenon are also born with other birth defects. In these cases, a chromosome or gene mutation may be found.
Since there are different causes of Marcus Gunn phenomenon and in most cases the cause is unknown, it is difficult to predict if it can be passed down in a family. If a gene or chromosome mutation is found, the risk of passing the Marcus Gunn phenomenon down to children will depend on the mutation.