What is asymmetric crying facies (ACF)?
Asymmetric crying facies (ACF) is a congenital anomaly occurring in one out of 160 live births.
When the baby cries, the mouth is pulled downward on one side while not moving on the other side. This facial weakness only affects the lower lip. It occurs on the left side in nearly 80 per cent of cases. ACF is different from unilateral facial palsy in that the face appears symmetric at rest and the eye and forehead muscles are unaffected.
Congenital ACF is also called congenital unilateral lower lip palsy (CULLP).
In cases of congenital ACF, there is a 10 per cent risk of associated major anomalies. Such anomalies are most common in the cardiovascular system (44 per cent). ACF with associated heart defects is known as Cayler syndrome. Other anomalies can also affect the neck and face, or the genito-urinary system.
What causes asymmetric crying facies (ACF)?
There are two main reasons for a newborn to show facial weakness in the lower lip.
- Compression to the one of the branches of the facial nerve during delivery: this is a common type of birth trauma. It may be due, for example, to pressure from a bone in the mother’s pelvis during childbirth. ACF is then said to be acquired.
- Developmental problems in the womb: when ACF is congenital (present at birth and not acquired during birth), it is induced by an anomaly in the development of the child during pregnancy: either incomplete development (‘hypoplasia’) or absence (‘agenesis’) of three depressor muscles of the lip. However, the two most important are called depressor anguli oris and depressor labii inferioris on one side of the mouth. The depressor anguli oris is the muscle that joins up the lower jaw to the corners of the mouth and controls the downward motion of the lip.
Please note that it is not always possible to distinguish whether the cause of ACF is due to birth trauma or of a congenital nature.
Congenital ACF appears to be a genetic condition. It is most probably caused by alterations (mutations) in an individual’s genes. Genes are units of heredity transferred from the parents to their biological children. They are stored in thread-like structures called chromosomes. Every human cell typically contains in its nucleus 23 pairs of chromosomes, and thousands of genes are encoded on each chromosome.
Patients with Cayler syndrome (ACF with cardiac defects) show the deletion of a small piece of chromosome 22 (known as ‘22q11.2 deletion syndrome’). This is particular to Cayler syndrome and a few other conditions, and it doesn’t apply to all people with congenital ACF – most of whom do not have any associated complication.
What are the symptoms of asymmetric crying facies (ACF)?
Babies with ACF display the following traits:
- When the baby cries or grimaces, the mouth is pulled downward on one side while not moving on the other side.
- There may be slight thinning of the lip on the affected side and turning inwards.
- The face looks symmetrical at rest.
- Forehead movement (wrinkling) is not affected.
- Eye closure is normal on both sides.
- Sucking is normal and there is no drooling.
- The depth of the nasolabial folds (creases that run from each side of the nose to the corners of the mouth) is the same on both sides.
- Both nostrils dilate normally when breathing.
How is asymmetric crying facies (ACF) diagnosed?
When a newborn shows signs of ACF, it is important to establish if the facial weakness was acquired during birth trauma, or if it is congenital. (See ‘Causes’ above.) A thorough physical examination will look for asymmetry of the jaws and non-parallelism of the gums that are clues to nerve compression as the cause of facial weakness – in which case a search for other anomalies is not indicated.
If a developmental cause is suspected, electromyography (a technique for evaluating and recording the electrical activity produced by muscle cells when activated) and ultrasound scan (an imaging technique that uses high frequency sound waves to create images of organs and structures inside the body) may be used to confirm underdevelopment (or absence) of the depressor anguli oris and depressor labii inferioris muscles.
In cases of congenital ACF, further investigation is recommended to rule out any other associated malformations. A number of anomalies can be excluded by careful physical examination. In some cases it may be decided to perform a FISH test (‘fluorescence in situ hybridization’): this test ‘maps’ the genetic material in a person’s cells and is used to visualise specific genes or portions of genes. A FISH test will look for chromosomal abnormalities such as the deletion of a small piece of chromosome 22 that has been reported in patients with Cayler syndrome (ACF with heart defects).
What is the treatment for asymmetric crying facies?
In cases of ACF acquired during birth trauma, the asymmetry noticeable when the baby cries or smiles should show signs of improvement within a month. It eventually disappears in the great majority of cases.
Facial asymmetry tends to become less noticeable in children with congenital ACF as they grow up. If it remains an issue, surgery can provide a good outcome. Surgical treatment options could be available: a) reurotomy, of the marginal mandibular branch of the facial nerve on the unaffected side, so the good side of the lip can also become paralysed and better symmetry, especially during smiling, can be achieved, b) myotomy or partial myectomy of the lip depressor muscles on the unaffected side, causes also lack of movement on the good side of the lower lip, and can provide symmetry, or c) reanimation of the lower lip on the paralysed side with the transfer of the anterior belly of the digastric muscle, a small muscle under the chin, that can take place with one or two operations and aims to give movement to the paralysed side and achieve symmetry on the lower lip.
Where the asymmetry of muscle pull is mild or surgery is unfavourable to the family, botulinum toxin therapy by tiny injection can provide muscle balance across the mouth and smile.
Whenever there are associated complications such as heart or kidney defects, the child should be followed up by a team of relevant specialists.
Last reviewed: 20-07-2017 || Next review due: 20-07-2020