Last updated:
6/16/2025
Years published: 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, for the preparation of this report.
Summary
Marin-Amat syndrome (MAS) is a rare form of acquired facial synkinesis where one or both eyelids close involuntarily when the mouth or jaw moves, typically while opening the mouth, chewing, or moving the jaw to the side.1
It typically occurs after facial nerve paralysis, most often due to Bell’s palsy, resulting from abnormal nerve regeneration, where misdirected nerve fibers cause mouth movement to activate the muscles that close the eyelids. This phenomenon is known as oculofacial synkinesis.1,2 Synkinesis refers to unwanted movement of the muscles of the face during attempted movement of other muscles.
It is often mistaken for a similar condition called Marcus Gunn phenomenon, but the two conditions are quite different in their causes and appearance.1,2
Treatment may include Botox injections and surgery.
People with Marin-Amat syndrome may have the following signs and symptoms:2,3
These symptoms often start after recovery from facial nerve paralysis. Some people may have additional eyelid drooping (ptosis) due to stretched muscles over time.
Marin-Amat syndrome (MAS) is caused by a problem in how the nerves in the face rewire and heal after being damaged, most often after Bell’s palsy.1,2 Bell’s palsy is a temporary paralysis of the facial muscles, usually on one side of the face, resulting from inflammation or damage to the facial nerve. It often appears suddenly, and can cause symptoms like drooping eye, difficulty smiling, and changes in taste.
MAS is considered a synkinesis, which means that a movement in one part of the face unintentionally causes movement in another part. In MAS, the eye closes involuntarily when the mouth or jaw moves, like when speaking, chewing, or opening the mouth wide.
MAS is usually caused by irregular regeneration of the facial nerve, known medically as cranial nerve VII (CN VII). This nerve controls most of the muscles used for facial expression. When this nerve is damaged, such as during Bell’s palsy or a facial injury, it can regrow incorrectly.1,3
This nerve miswiring creates what’s called oculofacial synkinesis, where eye and facial movements get mixed up.
In some people, the abnormal connections do not just happen within the facial nerve itself. There may also be aberrant links between the trigeminal nerve (cranial nerve V or CN V) which controls jaw muscles and the facial nerve (CN VII). This crossover leads to an increased tone in the eyelid-closing muscle, making the eye shut when the jaw moves laterally or opens. This kind of “undesired wink” is not only frustrating physically, but it can also cause major emotional and social discomfort for patients.1,3
While MAS is mostly considered a peripheral nerve system (PNS) issue, some cases may be linked to problems in the central nervous system (CNS) which includes the brain and spinal cord. For example, a stroke or brain lesion that affects the parts of the brain responsible for facial movement might also result in MAS.1,3
The CNS includes the brain and spinal cord, which are responsible for processing information and coordinating body functions. The PNS, on the other hand, consists of all other nerves in the body, acting as a communication network between the CNS and the rest of the body.
While it is less common, it’s important for doctors to consider CNS conditions, especially if there is no history of facial paralysis or if symptoms seem unusual.
In these cases, miscommunication doesn’t happen during the regrowth of the facial nerve, but rather because nerve signals from the brain get rerouted or disrupted, leading to the same kind of involuntary movements.1,3
This condition is not present at birth (not congenital), unlike the similar-sounding inverse Marcus Gunn phenomenon which is extremely rare and involves different nerve issues entirely.1,3
Marin-Amat syndrome (MAS) is very rare, and most cases are acquired after an episode of facial nerve paralysis like Bell’s palsy. Because it can look similar to other conditions that affect the nerves or the eyelids, it is sometimes underdiagnosed or mistaken for other disorders.1,3
It was first reported by Marin–Amat, a Spanish ophthalmologist, in 1918.4 While there is not a comprehensive registry or database that provides an exact count of all reported instances, several case reports and reviews have been published over the years, each contributing to the understanding of this uncommon syndrome.4,6
Diagnosis of MAS is usually made by a doctor examining facial movements, especially:1,2,7
Sometimes, a test called electromyography (EMG) may be used to measure how the muscles and nerves are working, although many cases are diagnosed just by observing symptoms. Electromyography (EMG) is a diagnostic test that measures the electrical activity of the muscles and the nerves and can detect problems with motor nerves, muscles, or the communication between them.
Treatment
Treating Marin-Amat syndrome (MAS) focuses on managing symptoms, as there is no cure for the abnormal nerve connection. The main options include:1,3,7.8
Each treatment comes with risks and benefits, and what works best may depend on the severity of symptoms and whether eyelid drooping is also present. Doctors sometimes try Botox first and then surgery for the best results. Careful preoperative electromyography study and detailed dynamic facial image analysis of both upper and lower lid OOM are very important to locate the synkinetic muscle.
People with Marin-Amat Syndrome (MAS) may need to be seen by several different specialists who should work together as a team in a coordinated way. Because MAS involves nerve dysfunction, muscle miscoordination and sometimes cosmetic or functional facial issues, the team of specialists may include neurologists, ophthalmologists, facial plastic surgeons, otolaryngologists and other health professionals such as physical and speech therapists.
Because MAS can cause emotional distress due to cosmetic appearance, psychological support may also be helpful. Counseling or support groups can help patients cope with self-image issues or social withdrawal caused by visible facial movements.
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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