Table of Contents
Introduction
Marcus Gunn first described Marcus Gunn syndrome in 1883. It is defined as congenital ptosis (droopy eyelid since birth) and synkinetic movement (a neurologic movement that causes ptosis) of the upper eyelid during mastication. It is a condition when the upper eyelid droops over the eyelid. It can be acquired (occur during lifetime) or congenital (since birth). Spontaneous remission is associated with the acquired form, and the congenital form exists without improvement. There is no gender predisposition and thus affects males and females equally. Although it may be bilateral, it is generally unilateral.
Winking of the eye consists of either momentary upper eyelid retraction or elevation of ipsilateral pterygoid muscle with an equal or higher level than the normal fellow eyelid upon stimulation and is followed by a rapid return to a lower position. Winking is usually higher in downgaze. As a result, the rapid, abnormal motion of the eyelid is one of the most disturbing aspects of the jaw-winking syndrome. However, the outcome of treatment is overall good in all stages.
What Are the Causes of Marcus Gunn Jaw Winking syndrome?
Other names of Marcus Gunn syndrome are Marcus Gunn ptosis, Marcus Gunn jaw winking trigemino-oculomotor synkinesis, and pterygoid-levator synkinesis. Abnormal nerve innervation is the abnormal nerve supply that can lead to this syndrome between the motor branches of two nerves. One of the nerves is called the trigeminal nerve, which controls the muscles of mastication; the superior branch of the oculomotor nerve, which regulates the eye muscles, is the other one. After surgical treatment of the eyes, trauma, syphilis, and brain tumors can also develop disorders.
What Are the Signs and Symptoms Associated With Marcus Gunn Jaw Winking Syndrome?
Ocular Signs and Symptoms:
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Blepharoptosis - It is defined as when the upper eyelid droops over the eye. It is usually unilateral. Upper eyelid movement is seen during mouth opening, chewing, swallowing, and teeth clenching.
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Strabismus - The condition known as strabismus causes the eyes to not point in the same direction.
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Amblyopia - Amblyopia is also called lazy eyes. Abnormal visual development can lead to a reduction of vision in one eye.
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Anisometropia - It is a condition where both eyes have varying refractive power.
Systemic Symptoms:
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Cleft lip and cleft palate.
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Kidney stones.
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Charge syndrome consists of coloboma (a disorder in which normal tissue in and around the eyes is missing), heart defects, choanal atresia (narrowing of the nasal cavity that causes difficulty breathing), growth retardation, and genital and ear abnormalities.
How to Diagnose Marcus Gunn Jaw Winking Syndrome?
Clinical History: Diagnosis is based on the above signs and symptoms.
1. Measurement of Jaw Wink:
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Mild is less than two millimeters.
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Moderate range from two to five millimeters.
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Severe more than six millimeters.
2. Test to Evaluate Abnormal Oculocardiac Reflex - This abnormal reflex is associated with this syndrome. There is a reduction in heart rate because of the pressure exerted on the extraocular muscles.
3. Visual Acuity - Visual acuity (ability to identify details and shape of the objects) is also checked to rule out lazy eyes in infants.
- Pupillary Examination - A pupil examination is done to evaluate this syndrome.
- Cycloplegic Refraction - Cycloplegic refraction is done to diagnose anisometropia, where the refractive error is different in both eyes.
- Fundus Evaluation - Examination of the fundus, extraocular motility test, and cover test are done to check for superior rectus muscle palsy.
- Head Position - Because of ptosis, the child may lift their chin for better vision. If a child is not trying to lift the chin in the presence of ptosis, then it is imperative to exclude amblyopia.
- Marginal Reflex Distance (MRD) - MRD is evaluated when the eyes are in primary gaze. MRD1 is defined as the estimation of the measurement of the corneal reflex to the central margin of the upper lid. MRD2 is the estimation of the corneal reflex to the central margin of the lower lid. MRD3 estimates the corneal reflex to the central margin of the upper lid and is measured when the patient watches in extreme upgaze. It is also used to evaluate the measurement of levator palpebrae superioris resection in ptosis surgery.
- Levator Function - The levator function is the distance from the upper eyelid that travels from downgaze to upgaze. It is measured when the frontalis muscle is held rigidly in the brow region.
4. Classification of Levator Function:
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Normal (when the distance is at least 15 millimeters).
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Good (when the distance is 12 to 14 millimeters).
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Fair (when the distance is 10 to 11 millimeters).
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Poor (when the distance is less than or equal to four millimeters).
5. Measurement of Eyelid Position - The measurement of eyelid position is also carried
out in the downgaze position of the eyelid, and the presence of any lid lag is evaluated
during the measurement.
What Is the Treatment of Marcus Gunn Jaw Winking Syndrome?
1. Medical Therapy: If a patient is diagnosed with amblyopia which is loss of vision in one eye, treatment is done with the help of occlusion therapy and correction of anisometropia, which is unequal refractive power in both eyes, before going for ptosis surgery. Regular follow-up is advised for the patients.
2. Surgical Therapy: Different surgical procedures are performed to correct jaw wink ptosis and movement of eyelids, such are sling operations and partial excision of the levator muscle without dissecting the muscle. An appropriate technique should be used based on the severity of the jaw wink ptosis. Surgery complications include under correction, overcorrection, lagophthalmos (abnormal closure of eyelids), suture granuloma (benign granulomatous growth in response to the foreign body), inflammation, infection, and lazy eyes, which is called amblyopia. Six-month follow-up is advised for the patients. Photographs help monitor the patients.
Conclusion
Marcus Gunn syndrome is an autosomal dominant condition (a genetic condition that can pass from parent to child) in which there is upward jerking of the upper eyelid. Synkinesis is seen during chewing, swallowing, clenching of teeth, and sucking. Although Marcus Gunn syndrome is evident at birth, parents notice a winking phenomenon while feeding infants. Satisfactory results are obtained using medical and surgical approaches. Follow-ups are generally advised to the patients to monitor their condition.
