Related Experiment Video
Updated: Jul 17, 2026
19:53
Single-stage Dynamic Reanimation of the Smile in Irreversible Facial Paralysis by Free Functional Muscle Transfer
Published on: March 1, 2015
Asymmetrical smiles corrected by botulinum toxin serotype A
1Department of Dermatology, University of Pennsylvania School of Medicine, and Medical Director, Dermatologic SurgiCenter, Philadelphia, Pennsylvania, USA. Avb@benedettoderm.com
Summary
Botulinum toxin A (BTX-A) injections effectively correct asymmetrical smiles caused by a hyperactive depressor labii inferioris muscle. This safe treatment provides long-lasting lip symmetry for at least six months.
Area of Science:
- Plastic Surgery
- Dermatology
- Facial Aesthetics
Background:
- Facial asymmetry, particularly an asymmetrical smile, can significantly impact patient aesthetics and self-perception.
- Identifying the underlying muscular cause is crucial for effective treatment planning.
Observation:
- Patients presenting with asymmetrical smiles were observed to have an exaggerated lowering of one side of the lower lip.
- This asymmetry was linked to a hyperkinetic (overactive) ipsilateral depressor labii inferioris muscle.
Findings:
- Injections of Botulinum toxin A (BTX-A) into the hyperkinetic depressor labii inferioris muscle successfully corrected lower lip asymmetry.
- Lip symmetry was achieved within one week and lasted for a minimum of six months, with longer durations after repeat treatments.
Implications:
- BTX-A offers a safe and effective therapeutic option for correcting smile asymmetry attributed to depressor labii inferioris hyperactivity.
- This minimally invasive treatment can restore facial balance and improve patient satisfaction.
Related Concept Videos
01:22Botulism
Botulism is a life-threatening neuroparalytic condition caused by botulinum neurotoxin, which is produced by the bacterium Clostridium botulinum, a Gram-positive, spore-forming, obligate anaerobe.In adults, the toxin enters the body in different ways: in foodborne botulism, the preformed toxin is absorbed in the intestine. In wound botulism, spores grow in injured tissue and release the toxin into the blood. Infant botulism differs mechanistically from adult forms. In infants, botulism commonly...
01:14Muscles for Facial Expressions
The craniofacial muscles are a collection of approximately 20 thin skeletal muscles situated beneath the skin of the face and scalp. These muscles, primarily responsible for the vast array of human facial expressions, originate from the bones or fibrous structures of the skull and extend outwards to connect with the skin. While most skeletal muscles in the body are enveloped in thick fascia, facial muscles generally have a more delicate fascial covering, with the buccinator muscle being a...
01:26Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin
Directly acting muscle relaxants like dantrolene and botulinum toxin (BoNT) have distinct mechanisms and applications. Dantrolene, a hydantoin derivative, acts on the ryanodine receptor (RYR1) in skeletal muscle cells. RYR1 are calcium channels present at the sarcoplasmic reticulum membrane. In response to excitation, they release calcium ions from the sarcoplasmic reticulum to the cytosol. Calcium promotes actin-myosin-mediated contraction of muscles.
The binding of dantrolene to the RYR1...
The binding of dantrolene to the RYR1...
01:24Facial Feedback Hypothesis
Charles Darwin proposed that facial expressions are an evolutionary adaptation for communication. He argued that these expressions are not influenced by culture but are universal across species. For example, a snarling expression with exposed teeth signals a threat in many animals, including humans. Darwin also suggested that displaying an emotion can intensify the feeling. Smiling, for example, could enhance one's sense of happiness. This idea laid the foundation for understanding the role of...
01:31Skeletal Muscle Relaxants: Therapeutic Uses
Skeletal muscle relaxants are used to relax muscle tone and alleviate painful muscle contractions. However, the choice of skeletal muscle relaxants depends on the duration of the surgical procedure in order to minimize potential side effects. Skeletal muscle relaxants like neuromuscular blocking agents [NMBAs] are commonly employed as adjuvants alongside general anesthetics in clinical settings. NMBAs are also used to maintain controlled ventilation during surgery of the larynx or pharynx as...
01:20Myasthenia Gravis: Overview and Treatment
Myasthenia gravis is a neuromuscular transmission disorder characterized by weakness and increased fatigability of skeletal muscles. It is an autoimmune disease affecting approximately one in 2000 people, where antibodies against the α1 subunit of nicotinic acetylcholine receptors are produced.
These antibodies interfere with the function of the nicotinic receptors in three ways: by binding to the receptor and disrupting acetylcholine binding; by causing cross-linking of receptors which leads...
These antibodies interfere with the function of the nicotinic receptors in three ways: by binding to the receptor and disrupting acetylcholine binding; by causing cross-linking of receptors which leads...