Asymmetric crying facies (ACF), a condition observed in approximately 1 out of every 160 live births, is a congenital anomaly characterized by an uneven movement of the mouth when a baby cries. Specifically, one side of the mouth is pulled downwards, while the other side remains relatively still. This facial weakness exclusively affects the lower lip and is more frequently observed on the left side in about 80% of cases. It’s crucial to distinguish ACF from unilateral facial palsy; in ACF, the face appears symmetrical at rest, and the muscles controlling the eyes and forehead are unaffected.
Congenital ACF is also clinically referred to as congenital unilateral lower lip palsy (CULLP).
In cases where ACF is congenital, it’s important to note a potential 10% risk of associated major anomalies. These anomalies are most commonly found within the cardiovascular system, accounting for around 44% of cases. When ACF is present alongside heart defects, it is classified as Cayler syndrome. Beyond cardiovascular issues, other anomalies may involve the neck, face, or the genitourinary system.
Unpacking the Causes Behind Asymmetric Crying Facies (ACF)
When a newborn exhibits facial weakness affecting the lower lip, there are primarily two categories of causes to consider in the medical diagnosis of ACF:
- Birth Trauma: Compression of a facial nerve branch during delivery is a common cause of birth trauma. This pressure, potentially from the mother’s pelvic bones during childbirth, can lead to what’s termed acquired ACF.
- Congenital Development Issues: Congenital ACF, present from birth and not due to birth trauma, stems from developmental anomalies during pregnancy. These anomalies involve either the underdevelopment (hypoplasia) or absence (agenesis) of specific lip depressor muscles. The key muscles involved are the depressor anguli oris and depressor labii inferioris on one side of the mouth. The depressor anguli oris muscle is responsible for connecting the lower jaw to the corners of the mouth and controlling the downward motion of the lip.
It’s important to note in Acf Medical Diagnosis that differentiating between birth trauma-induced ACF and congenital ACF isn’t always straightforward.
Congenital ACF is believed to have a genetic basis, likely resulting from alterations (mutations) in an individual’s genes. Genes, the units of heredity passed from parents to offspring, reside within chromosomes. Human cells typically contain 23 pairs of chromosomes in their nucleus, with each chromosome encoding thousands of genes.
Cayler syndrome, the specific presentation of ACF accompanied by cardiac defects, has been linked to the deletion of a small segment of chromosome 22 (known as ’22q11.2 deletion syndrome’). This genetic deletion is specific to Cayler syndrome and a few other conditions and is not universally present in all cases of congenital ACF. The majority of individuals with congenital ACF do not experience any other related complications.
Identifying Symptoms of Asymmetric Crying Facies (ACF)
Infants with ACF present with a distinct set of symptoms, crucial for ACF medical diagnosis:
- Asymmetrical Mouth Movement During Crying: When the infant cries or grimaces, the mouth pulls down on one side while the other side shows limited to no movement.
- Subtle Lip Thinning: The affected side of the lip might appear slightly thinner and may turn inwards.
- Facial Symmetry at Rest: The face appears balanced and symmetrical when the baby is not crying or expressing emotion.
- Unaffected Forehead Movement: Wrinkling of the forehead is normal and symmetrical.
- Normal Eye Closure: Both eyes close completely and equally.
- Typical Sucking and No Drooling: Feeding and swallowing functions are unaffected, with no excessive drooling.
- Symmetrical Nasolabial Folds: The depth of the nasolabial folds, the creases extending from the nose to the mouth corners, is equal on both sides.
- Normal Nostril Dilation: Both nostrils expand normally during breathing.
The Diagnostic Process for Asymmetric Crying Facies (ACF)
When a newborn exhibits signs of ACF, a key step in ACF medical diagnosis is to determine whether the facial weakness originated from birth trauma or is congenital. (Refer to ‘Causes’ section). A comprehensive physical examination is conducted to identify any asymmetry in the jaws or non-parallelism of the gums, which can indicate nerve compression due to birth trauma. In such cases, further investigation for other anomalies is typically not required.
However, in cases suggestive of congenital ACF, further investigation is advisable to rule out any associated malformations. A thorough physical examination can exclude certain anomalies. In some instances, a FISH test (‘fluorescence in situ hybridization’) may be recommended. This genetic test maps the genetic material within a person’s cells, allowing visualization of specific genes or gene segments. A FISH test can detect chromosomal abnormalities, such as the 22q11.2 deletion associated with Cayler syndrome (ACF with heart defects).
Treatment Strategies for Asymmetric Crying Facies
For ACF cases resulting from birth trauma, the facial asymmetry evident during crying or smiling usually shows improvement within the first month and typically resolves entirely.
In children with congenital ACF, facial asymmetry tends to become less noticeable as they age. If the asymmetry persists and remains a concern, surgical intervention can be considered. Surgical options include:
a) Neurotomy: Severing the marginal mandibular branch of the facial nerve on the unaffected side. This induces paralysis on the stronger side, potentially leading to improved symmetry, especially during smiling.
b) Myotomy or Partial Myectomy: Cutting or partially removing the lip depressor muscles on the unaffected side. This also reduces movement on the stronger side, aiming for symmetry in the lower lip.
c) Lower Lip Reanimation: Transferring the anterior belly of the digastric muscle, a small muscle under the chin, to the paralyzed side. This procedure, potentially requiring one or two operations, aims to restore movement to the paralyzed side and achieve lower lip symmetry.
For milder cases of muscle pull asymmetry or when surgery is not preferred, botulinum toxin therapy, administered via small injections, can help balance muscle activity across the mouth and improve smile symmetry.
In situations where ACF is accompanied by complications like heart or kidney defects, ongoing follow-up with a team of relevant specialists is crucial for comprehensive care.
Sources
http://smj.sma.org.sg/4808/4808cr1.pdf
http://www.ncbi.nlm.nih.gov/pubmed/17572570
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Last reviewed: 03-09-2024 || Next review due: 03-09-2025
