Conditions: weakness of the eyelid(s)
(zygomatic branch of the facial nerve neuropathy)
What is the zygomatic branch of the facial nerve?
The zygomatic branch, one of the branches of the facial nerve, controls the muscle that closes the eyelids, the orbicularis oculi muscle. If this nerve is dysfunctional, the speed of a blink, the completeness of eye closure, and the resting position of the eyelids are affected. The branching pattern of the facial nerve is unique in each individual, as demonstrated in the following images.
why is the zygomatic branch affected by surgery?
The zygomatic branch of the facial nerve can be affected by surgery due to its anatomical location and proximity to surgical procedures performed in the face. During surgical interventions such as facelifts, facial trauma repairs, or tumor resections, there is a risk that the this branch is stretched or cut. The function of this nerve may be partially or completely dysfunctional afterwards, and the effect may be temporary or permanent. Careful surgical technique and a thorough understanding of the complex facial nerve branches are very helpful in minimizing the potential for postoperative dysfunction of the facial nerve and its branches.
What are the symptoms of zygomatic branch neuropathy?
Zygomatic branch neuropathy, which can mean partial or complete loss of function of this nerve branch, can cause dysfunction in the muscle that it controls, the orbicularis oculi muscle, which closes the eyelid on that side. The blink may be slow and eyelid closure may be incomplete, thus interfering with the protective tear film mechanism of the eye. The cornea, which is the clear tissue at the front of the eye, needs frequent moisturization to remain healthy. Corneal exposure (dryness) may be mild or it may be severe enough to threaten vision. Corneal exposure can also be uncomfortable, can stimulate excessive tearing, but without an effective blink, the tears may spill over onto the cheek rather than draining down the lacrimal duct to the nose, as they normally would.
What precautions may be undertaken with zygomatic branch neuropathy?
Preventing corneal exposure and, in particular, preventing permanent visual impairment is the key element of care with zygomatic branch neuropathy. There are several different techniques to protect the eye in this situation, including the following :
Intentionally extending the time of a blink—allowing additional time for the upper eyelid to cover the cornea.
Use of artificial tears or ointments. Water-based artificial tears do not cause blurry vision, but require frequent application. Petroleum based ointments last longer but can cause blurry vision, and are therefore best used before sleeping.
Taping the eyelid closed. This technique involves first placing tape on the upper eyelid and then pulling the eyelid closed before attaching the lower portion of the tape to the lower eyelid and cheek.
Applying an eye pad over the eye. I do not recommend this technique because an open eyelid can allow the eye pad to make a contact abrasion on the surface of the cornea.
Use of a humidity chamber over the eye. A device that delivers a water vapor mist to the eye may be used, typically in a hospital setting, to keep the eye moisturized. This is typically a short-term solution until an easier but effective longer term solution is undertaken.
Suturing the eyelid closed. This procedure, called a tarsorrhaphy, is a temporary measure. A tarsorraphy stitch may be left in place for up to several months and can be a simple and fairly hassle free way to protect the eye in this situation.
Placement of a platinum or gold weight in the upper eyelid. This short surgical procedure implants a weight into the upper eyelid to facilitate more rapid and more complete closure of the eyelid. This is often a good long-term solution.
Tightening of the lower eyelid. The tarsal strip procedure and its variants address ectropion, in which the lower eyelid sags away from the eyeball. This fairly simple procedure snugs the lower eyelid back to the eyeball and may be undertaken alone or in conjunction with an upper eyelid weight placement.
HOw is zygomatic branch neuropathy from surgery prevented?
While the course of an individual’s facial nerve branches, including the zygomatic branch, nerve is unique, surgeons know the anatomy and make every effort to avoid any injury to the nerve during dissection. Despite all efforts, sometimes injury to the facial nerve or its branches is unavoidable.
How much will zygomatic branch neuropathy bother someone?
The degree of bother to an individual from weakness of the zygomatic branch can vary, but depends mainly on what measures are needed to protect the eye. If, for example, the weakness is relatively minor, then occasional use of artificial tears may be all that is needed. If complete zygomatic branch paralysis is present, a more involved regimen of care can impose greater nuisance to the affected individual. Prolonged dryness of the cornea can cause the significant problem of visual loss in the affected eye.
Does zygomatic branch neuropathy improve over time?
When the zygomatic branch of the facial nerve is partially functional after an injury, it has a chance of regaining strength over time, though it may take up to a year. If this nerve branch is completely paralyzed (non-functional) after the injury, the nerve may or may not regain activity. Generally speaking, recovery may continue to take place over one year from the initial injury, so the full extent of recovery is not known until that time.