Why Measure Lip Strength?
Inadequate lip strength may contribute to problems with deglutition, such as food containment during chewing. If lip weakness is severe, it also may interfere with the production of plosive speech sounds. Such weakness would probably be obvious, but being able to accurately "track" the degree of weakness would enable the clinician to determine whether the weakness is getting better or worse, and/or determine if training improves lip strength. Additionally, observing lip weakness in a patient may help identify abnormalities within the nervous system such as subtle cortical dysfunction, or disease processes gradually affecting the function of the facial nerve.
- Asymmetrical lip strength may reveal neurological problems of the brain or peripheral nerves.
- Food containment problems, as frequently seen in Traumatic Brain Injury (TBI) patients, can result from lip weakness.
Lip Strength Measurement
To measure lip strength, an IOPI bulb is placed inside the cheek just lateral to the corner of the mouth and the patient squeezes the IOPI bulb against the buccal surface of the teeth by pursing the lips as hard as possible. Although the bulb is not directly between the lips, it is valid because the pressure developed in the bulb depends upon the strength of the circumferential muscle complex that surrounds the mouth, in particular the obcularis oris. It is tension in these muscles that allows the lips to be compressed against one another.