Marcus Gunn Phenomenon

Disease Overview

Marcus Gunn phenomenon is a rare condition present at birth (congenital) where one upper eyelid moves when the jaw moves.¹ This often looks like an involuntary “wink” or lift of the eyelid when a person chews, sucks, or moves their jaw in certain ways. Parents may first notice this movement when their baby is feeding.²

The exact cause is unknown, but experts believe it happens due to a miswiring between the nerves that control jaw movement and the muscles that lift the eyelid which is known as synkinesis.³ It usually affects just one eye, but in rare cases, both eyes can be involved.⁴

Many people with Marcus Gunn phenomenon don’t need treatment, especially if the eyelid movement is mild. However, if the condition affects vision or is a cosmetic concern, surgery may be an option.

This condition was first identified in 1883 by Dr. Robert Marcus Gunn, a Scottish eye doctor. It is considered part of a group of nerve-related eye movement disorders called congenital cranial dysinnervation disorders (CCDD).⁴

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Synonyms

• jaw winking syndrome
• jaw-winking syndrome
• jaw-blinking
• mandibulo-palpebral synkinesis-ptosis syndrome
• Marcus Gunn syndrome
• Marcus-Gunn syndrome
• Maxillopalpebral synkinesis
• pterygoid-levator synkinesis
• Marcus-Gunn jaw winking phenomenon (MGP)
• Marcus Gunn Jaw winking syndrome (MGJWS)
• Marcus Gunn ptosis
• Marcus Gunn jaw winking trigemino-oculomotor synkinesis
• Maxillopalpebral synkinesis

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Signs & Symptoms

The unique characteristic of Marcus Gunn phenomenon is that the affected eyelid lifts quickly when the jaw moves, such as during chewing, sucking, smiling, or even swallowing.⁵  This “wink” tends to be more noticeable when looking downward.⁴ It results in drooping of one upper eyelid (unilateral blepharoptosis).

Parents often notice the eyelid movement while their baby is breastfeeding or bottle-feeding.

Common signs and symptoms include:^2,4,6,7

• Mild-to-moderate blepharoptosis usually affecting one side
• Jaw-winking movement (eyelid lifts) when:
  • The mouth opens
  • The jaw moves to the opposite side
  • Chewing
  • Sucking
  • Jaw protrusion (moving the jaw forward)
  • Clenching teeth
  • Swallowing
    • Wink worsens when looking down

Marcus Gunn phenomenon is sometimes linked to other eye conditions:⁴

• Amblyopia (lazy eye) which may result from the droopy eyelid blocking vision or from crossed eyes (strabismus) causing low vision
• Strabismus (in about 50-60% of cases) which is misalignment of the eyes and can be vertical or horizontal
  • Vertical misalignment (typically) where the affected eye points in a lower direction than the other
  • Horizontal misalignment where the affected eye points inward or outward compared to the other eye (rare)
• Superior rectus palsy, a weakness of the muscle lifting the eye (seen in about 25% of cases)
• Double elevator palsy, another type of vertical eye movement limitation, (in about 25% of cases)
• Anisometropia, a significant difference in vision between the two eyes (seen in 5-25% of cases)

Although most cases are detected in infancy, the syndrome can present at any age.  Most cases affect only one side (unilateral) and it’s more common on the left side. Bilateral cases (both eyelids affected) are very rare.⁴

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Causes

Marcus Gunn phenomenon is considered as one of the congenital cranial dysinnervation disorders (CCDD)⁴ which involve abnormal connections between cranial nerves, often resulting in synkinetic activation of specific muscles. A synkinetic movement or “simultaneous movement” is a neurological phenomenon where a voluntary facial muscle movement unintentionally triggers involuntary contractions in other facial muscles.

Normally, the levator palpebrae superioris muscle, responsible for raising the upper eyelid, is innervated by the oculomotor nerve (CN III), specifically its superior branch. The muscles of the jaw, including those involved in chewing, are innervated by the mandibular nerve, a branch of the trigeminal nerve. In Marcus Gunn phenomenon, these nerves are miswired, leading to a synkinetic movement where moving the jaw also causes the eyelid to move.⁸

In a few cases, the synkinetic movement occurs between the internal pterygoid and the levator palpebrae superioris (LPS) muscles. The internal pterygoid muscle is innervated by the medial pterygoid nerve, a branch of the mandibular nerve. In such cases, the eyelid elevates by closing the mouth and clenching the teeth.

It is not known why the abnormal connection occurs.^4,9 This miswiring likely occurs during early fetal development, so Marcus Gunn phenomenon a congenital (present from birth) condition.

Familial cases with autosomal dominant inheritance have been described in the medical literature but are very rare.⁴ Most isolated Marcus Gunn phenomenon cases occur sporadically without a known genetic cause.¹⁰

Marcus-Gunn phenomenon can also occur as part of several syndromes caused by different gene variants including:¹⁰

• Congenital fibrosis syndrome of the extraocular muscles (CFEOM) caused by variants in the KIF21A gene or by variants in the TUBB3 gene which affects eye movement development
• Arthrogryposis multiplex congenita (a condition causing joint contractures) caused by TUBB3 gene variants
• Congenital central hypoventilation syndrome caused by  ZC4H2 gene variants or PHOX2B gene variants
• CHARGE syndrome (a disorder with multiple birth defects) caused by CHD7 gene variants

Additionally, chromosomal abnormalities like 22q11.2 microduplication (duplication of the part of chromosome 22) and 7q11.23 gene deletion have been reported in complex Marcus Gunn phenomenon cases.

While Marcus Gunn phenomenon is typically congenital, there are a few reports of acquired cases after ocular trauma or complicated eye surgeries. In these situations, abnormal nerve regeneration may create a similar jaw-winking reflex.⁴

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Affected populations

Marcus Gunn phenomenon is rare, with around 300 documented cases worldwide.¹¹ It affects males and females equally.^11,12

The condition is usually noticed when parents observe the eyelid movement while the baby is breastfeeding or bottle-feeding.¹²

Among children with congenital ptosis (droopy eyelid present at birth), 2-13% are diagnosed with Marcus Gunn phenomenon.⁴

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Disorders with Similar Symptoms

Symptoms of the following disorders may be similar to those of Marcus Gunn phenomenon. Comparisons may be useful for a differential diagnosis.⁴

• Oral-facial-digital syndrome type III can mimic many symptoms of Marcus Gunn phenomenon but also involves more severe and extensive cranial, facial and finger malformations.
• Congenital fibrosis syndrome of the extraocular muscles, where there is an inability to move both eyes in certain directions (ophthalmoplegia), droopy eyelids (ptosis) and eyes that are fixed in an abnormal position.
• Myasthenia gravis, characterized by weakness of the muscles, especially the eye muscles (ptosis)

Marin-Amat syndrome presents similarly but causes the eyelid to close instead of open with jaw movement, leading to its designation as the “inverse Marcus-Gunn phenomenon” It is classified as a form of Marcus Gunn phenomenon.

Marcus Gunn phenomenon may also occur as part or rare eye conditions:⁴

• Pseudo inferior oblique overaction. an abnormal upward turning of the affected eye
• Morning Glory anomaly, a rare optic nerve abnormality
• Duane retraction syndrome, an eye movement disorder where the eye retracts or has limited movement
• Retinitis pigmentosa, less commonly.

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Diagnosis

Doctors diagnose Marcus Gunn phenomenon by observing the distinctive eyelid movement when the jaw moves.⁴^,5 They may also check for related eye conditions like lazy eye (amblyopia) or misaligned eyes (strabismus). ⁷

A full eye exam usually includes:⁷

• Vision testing to check for amblyopia
• Pupil (the black opening in the middle of the eye) response check to see how the eyes react to light
• Cycloplegic refraction using special drops to measure vision differences between the eyes
• Eye movement tests to look for strabismus or weak eye muscles

• Eyelid function tests to measure how much the eyelid moves and how severe the drooping is; ptosis evaluation where eyelid droop is measured with the jaw still and after covering one eye briefly to break visual focus
  • Mild ptosis: ≤2 mm
  • Moderate ptosis: 3 mm
  • Severe ptosis: ≥4 mm

The amount of “jaw-winking” is also measured:⁴

• Mild – eyelid lifts 2 mm or less
• Moderate – eyelid lifts 2–5 mm
• Severe – eyelid lifts more than 5 mm

Doctors also check for Bell’s phenomenon, which is whether the eyes roll upward when closed as this reflex can be weak in certain conditions.

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Standard Therapies

Treatment

For many people with Marcus Gunn phenomenon, treatment isn’t needed. The jaw-winking movement may become less noticeable with age, and mild cases might not cause any significant issues.⁶ However, if the ptosis (droopy eyelid) is severe or causes vision problems (like amblyopia), or is a cosmetic concern, treatment options including surgery, can be considered.⁶

Before considering surgery, it’s crucial to treat amblyopia (lazy eye) if it’s present. This might involve:

• Occlusion therapy which involves patching the stronger eye to force the weaker eye to work harder

• Use of glasses or contact lenses to correct vision differences between the eyes

Clinical photos may be taken to monitor the condition over time.⁴

Close follow-up is essential to ensure the therapy is working and the child’s vision develops properly.⁴

Surgery is considered if the eyelid droop is severe, interferes with vision, or if the jaw-winking movement is very noticeable.⁷^,¹⁰ Doctors usually wait until the child is at least 1–2 years old because anesthesia is safer after infancy.⁴

There are different surgical options to treat droopy eyelids (ptosis), depending on how severe it is.⁴

• Mild cases:
  • Müller muscle and conjunctival resection where the surgeon removes a small part of the eyelid’s internal muscles to lift it slightly (1–3 mm)
  • Fasanella-Servat procedure where the surgeon removes part of the tarsus (a supportive eyelid structure) along with other tissues to improve lifting
• Moderate to severe cases:
  • Levator resection where the surgeon tightens the eyelid muscle for better lifting
  • Frontalis suspension where the surgeon connects the eyelid to the forehead muscle so the forehead helps lift the eyelid

If the jaw-wink is too severe, surgeons may disable or remove the levator muscle to stop the abnormal movement.⁷

Like any surgery, eyelid procedures have risks, including:⁷

• Under-correction or over-correction where the eyelid may still droop or be lifted too high
• Difficulty closing the eye (lagophthalmos) where the eye may not fully close, leading to dryness
• Asymmetry, when the eyelids may not look perfect even after surgery
• Suture granuloma, which is a small lump of tissue may form around the stitches
• Corneal exposure (dry eye issues) where the cornea (front surface of the eye) can become dry and irritated

Regular follow-ups help monitor healing and address any complications.⁴

New ideas are emerging to improve Marcus Gunn phenomenon treatment. Researchers suggest exploring:^7,10

• Botulinum toxin (Botox) injections targeting the jaw muscles by reducing the jaw-triggered eyelid lift or wink
• Neuromuscular retraining exercises to help retrain nerve and muscle function
• Deep learning and facial recognition to assist with rehabilitation and improve outcomes
  • Deep learning is a type of artificial intelligence (AI) that helps computers learn patterns and make decisions on their own, and facial recognition is a technology that helps computers identify people by their faces.

Most people with Marcus Gunn phenomenon have a good prognosis. With careful monitoring and appropriate treatment, amblyopia can be successfully managed, and surgical outcomes can improve both function and appearance.⁴

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Clinical Trials and Studies

Information on current clinical trials is posted on the Internet at https://clinicaltrials.gov/. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]

Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/

For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/

For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/

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References

1. Gorlin RJ, Cohen MM Jr, Levin LS. (1990). Syndromes of the Head and Neck, 3rd ed. Oxford University Press, London, UK; 604-05.
2. Hwang JM, Park SH. A case of Marcus Gunn jaw winking and pseudo inferior oblique overaction. Am J Ophthalmol. 2001 Jan;131(1):148-50. doi: 10.1016/s0002-9394(00)00705-4
3. Kodsi S. Marcus Gunn jaw winking with trigemino-abducens synkinesis. J AAPOS. 2000 Oct;4(5):316-7. doi: 10.1067/mpa.2000.107903.
4. Senthilkumar VA, Tripathy K. Marcus Gunn Jaw-Winking Syndrome. [Updated 2023 Aug 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan- Available from: https://www.ncbi.nlm.nih.gov/books/NBK559058/ Accessed April 24, 2025.
5. Wong JF, Thériault JF, Bouzouaya C, Codère F. Marcus Gunn jaw-winking phenomenon: a new supplemental test in the preoperative evaluation. Ophthalmic Plast Reconstr Surg. 2001 Nov;17(6):412-8. doi: 10.1097/00002341-200111000-00005. 
6. Bartkowski SB, Zapala J, Wyszyńska-Pawelec G, Krzystkowa KM. Marcus Gunn Jaw-Winking Phenomenon: management and results of treatment in 19 patients. J Craniomaxillofac Surg. 1999 Feb;27(1):25-9. doi: 10.1016/s1010-5182(99)80006-7. 
7. Roque BL. Marcus Gunn Jaw-winking Syndrome. Medscape. January 24, 2023. https://emedicine.medscape.com/article/1213228-overview Accessed April 24, 2025.
8. Landau WM. Clinical neuromythology. I. The Marcus Gunn phenomenon: loose canon of neuro-ophthalmology. Neurology. 1988 Jul;38(7):1141-2. 10.1212/wnl.38.7.1141
9. McKusick VA, Ed. Online Mendelian Inheritance In Man (OMIM). Marcus Gunn Phenomenon. The Johns Hopkins University. Entry Number;154600: Last Edit Date 02/13/2006. https://omim.org/entry/154600 Accessed April 24, 2025.
10. Zhuang S, Qi Q, Lin M, Li J. Progress in MGJWS: A 74-Year Review of Marcus Gunn Jaw-Winking Syndrome. Journal of Child Neurology. 2024;40(2):132-147. doi:10.1177/08830738241282698
11. Newell FW. (1991). Ophthalmology: Principles and Concepts, 7th ed. Mosby Year Book, St. Louis, MO; 168.
12. Ziga N, Biscevic A, Pjano MA, Pidro A. Marcus Gunn Jaw-Winking Syndrome: a Case Report. Med Arch. 2019 Aug;73(4):282-284. doi: 10.5455/medarh.2019.73.282-284.

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