Accidental injection of anesthetic into the infraorbital artery causing facial blanching.

Infraorbital artery facial blanching from injection of anesthetic into an artery is an uncommon adverse event but it does happen to every dentist at some point. Since delivering local anesthesia in the maxillofacial region is a routine part of a dental practice most dentists will see this from time to time. While techniques like the infraorbital nerve block and inferior alveolar nerve block are generally safe and effective, complications do arise. For instance, if the anesthetic is inadvertently injected into an artery the blood flow to that area will be temporarily compromised. When that happens the most visible and alarming sign will be facial blanching.

What is the infraorbital artery?

The infraorbital artery is a branch of the maxillary artery that travels through the infraorbital canal alongside the infraorbital nerve. It emerges at the infraorbital foramen to supply the lower eyelid, upper lip, and side of the nose. Given its proximity to the infraorbital nerve, it lies within the region commonly targeted during an infraorbital nerve block. The most common way that the blanching of the face occurs is actually from an inferior alveolar nerve block that hits the maxillary artery.

What happens when we inject local anesthetic into the infraorbital artery?

An inadvertent intra-arterial injection can lead to several immediate side effects:

Ocular Complications: Because the infraorbital artery communicates with branches supplying the orbit, intra-arterial injection may lead to visual disturbances, transient blindness, or ophthalmoplegia.
Facial Blanching: Vasoconstrictors like epinephrine may cause temporary blanching of the skin in the distribution of the infraorbital artery. The blanching will be a pale or white looking.
Pain or Pressure: Patients may experience sharp pain or a sensation of pressure radiating toward the eye or temple. They will often describe it as burning or shock like.
Hematoma Formation: If the dentist punctures the artery, a hematoma may develop under the eye or cheek area.

Other than the hematoma, which will cause bruising, the rest of the side effects should be very short lived. Most of the time these side effects are gone before the dental visit is over or whenever the anesthetic wears off.

Infraorbital Artery Facial Blanching of upper lip, nose, and under the eyelid. — Notice the patient’s upper lip, side of their nose and all the skin under the eye. These areas are all supplied by the infraorbital artery. This was mostly gone in 5 minutes. The patient felt an immediate burning sensation during an IAN block.

Prevention of the infraorbital artery facial blanching and other complications

To minimize the risk of injecting dental anesthetic into the infraorbital artery:

Use Aspiration: Always aspirate before injecting. If blood appears in the syringe, reposition the needle.
Inject Slowly: Deliver the anesthetic solution gradually to reduce pressure and monitor for adverse reactions.
Avoid Force: Never inject against resistance; this may indicate you’re within a blood vessel or dense tissue.

What to do if an intra-arterial injection occurs

Stop the injection immediately if symptoms arise. Typically the issue arises so quickly that there will not be time to react. However, if you see signs of an artery injection just stop.
Apply cold compresses if swelling or a hematoma forms.
Reassure the patient. Any pain, visual issues, or facial blanching or typically very short lasting.

Infraorbital artery facial blanching and the post op patient care

While rare, accidental injection into the infraorbital artery or maxillary artery during a nerve block can cause complications. Dentists must remain vigilant with proper aspiration techniques, anatomical knowledge, and slow injection protocols. Reassuring patients that this is a temporary issue is key, unless there is a hematoma which will cause a bruise.