Congenital Unilateral Lower Lip Palsy(Asymmetric Crying Facies)
Compassionate evaluation and specialized treatment to restore facial symmetry for children and adults.
What is Congenital Unilateral Lower Lip Palsy?
Congenital Unilateral Lower Lip Palsy (CULLP), frequently referred to clinically as Asymmetric Crying Facies (ACF), is a rare congenital condition present at birth. It is characterized by an inability to pull down one corner of the mouth, which becomes highly noticeable when the infant cries or smiles.
In most cases, ACF is caused by the underdevelopment (hypoplasia) or complete absence (agenesis) of a specific facial muscle called the depressor anguli oris. Less commonly, it may involve the depressor labii inferioris muscle. Because the rest of the facial nerve and muscles function normally—allowing the child to blink, close their eyes, and wrinkle their forehead—this condition is distinct from total facial nerve paralysis.
While the facial asymmetry itself is primarily a cosmetic concern, roughly 10% of infants with ACF may have associated congenital abnormalities, particularly structural heart defects (a condition known as Cayler cardiofacial syndrome). Therefore, a comprehensive pediatric evaluation is standard protocol upon diagnosis.
Information supported by NORD.
A Note to Parents
Discovering your newborn has facial asymmetry can be frightening. However, it is important to know that isolated Asymmetric Crying Facies does not cause pain, does not affect brain development, and does not progress or worsen over time.
Unlike acquired nerve injuries, there is no urgent "window" where surgery must be performed immediately to save the nerve. We can carefully plan the timing of any intervention based on the severity of the asymmetry and the developmental stage of your child.
Recognizing the Clinical Signs
The visual presentation of ACF is highly characteristic, allowing experienced specialists to often diagnose it visually.
The "Crying" Asymmetry
When the baby cries, the healthy side of the lower lip pulls down normally, while the affected side remains flat or slightly elevated. This creates a distinct, lopsided appearance.
Normal Upper Face
Crucially, the upper face functions perfectly. The child can fully close both eyes tightly and wrinkle their forehead symmetrically. This distinguishes ACF from complete facial nerve paralysis.
Normal Sucking & Swallowing
Because the lips and mouth muscles required for feeding are not deeply affected, most infants with isolated ACF can breastfeed or bottle-feed without significant difficulty.
Customized Treatment Options
Historically, children with CULLP were simply told to "live with it." Today, modern facial plastic surgery offers elegant solutions to restore a balanced smile. Treatment timing is individualized—some families choose early intervention, while others wait until adolescence.
A highly effective, non-surgical approach often utilized in older children, teenagers, and adults. By injecting a small amount of botulinum toxin into the depressor anguli oris muscle on the healthy side of the face, we intentionally weaken the overactive pull. This creates a beautifully balanced, symmetrical lower lip when smiling or speaking. Treatments must be repeated every 3 to 6 months to maintain the effect.
Frequently Asked Questions
Why Choose Revitalis?
Dr. Nate Jowett is a world-renowned expert in facial reanimation. With dual fellowship training in Germany and at Harvard Medical School, he brings a unique engineering and microsurgical background to treating complex facial nerve disorders.
Whether you are days into a diagnosis or have lived with incomplete recovery for years, Dr. Jowett offers the full spectrum of care, from medical management to cutting-edge surgical reconstruction, to help you regain your smile and confidence.
Selected References
- Dual-Vector Gracilis Muscle Transfer for Smile Reanimation with Lower Lip Depression. Ein L, Hadlock TA, Jowett N. Laryngoscope. 2021 Aug; 131(8):1758-1760. doi: 10.1002/lary.29476. PMID: 33660858.
- Effect of Weakening of Ipsilateral Depressor Anguli Oris on Smile Symmetry in Postparalysis Facial Palsy. Jowett N, Malka R, Hadlock TA. JAMA Facial Plast Surg. 2017 Jan 01; 19(1):29-33. doi: 10.1001/jamafacial.2016.1115. PMID: 27658020.
- Motor and Sensory Rehabilitation of the Lower Lip. Mohan S, Jowett N. Operative Techniques in Otolaryngology-Head and Neck Surgery. 2020; 31(1):45-54.
- A General Approach to Facial Palsy. Jowett N. Otolaryngol Clin North Am. 2018 Dec;51(6):1019-1031. doi: 10.1016/j.otc.2018.07.002. PMID: 30119926.