Gerald S. Fine, D.D.S.
Oral and Maxillofacial Surgery
Last week, I received a telephone call from a dentist who's patient had lingual paresthesia following the administration of local anesthesia. Although adverse effects of local anesthesia are uncommon, they can occur. Complications of local anesthesia are reviewed along with guidelines for their prevention and management.
Paresthesia -- Irreversible paresthesia occurs for every 785,000 local anesthetic injected. Most paresthesias resolve within 8 weeks. Possible causes include intraneural hematomas, direct needle trauma and contamination with alcohol or sterilizing solution. It has a high incidence with prilocaine. If paresthesia occurs, tell the patient it is likely to resolve over time, record the signs and symptoms in the chart and maintain patient contact. If symptoms do not resolve after 2 months refer the patient to an oral and maxillofacial surgeon.
Trismus -- Needle insertion through a muscle or bleeding into a muscle may cause spasm. Trismus symptoms may appear within 1 to 6 days of injection. If there is no improvement within 2-3 days, consider treating the patient for infection. Instruct the patient with trismus to apply hot moist towels for 20 minutes every hour, use analgesics as necessary.
Hematoma -- Hematoma, which may result if a needle nicks a blood vessel, presents as bruising which last 7-14 days. Apply direct pressure to stop bleeding in a newly formed hematoma. Discharge the patient after the bleeding has stopped and direct him or her to apply ice (not heat) for the first 6 hours and to use analgesics as needed.
Injection Pain -- Patients may experience pain if the needle passes through a muscle or tendon, or if local anesthesia is administered too quickly. To prevent injection pain, store anesthetic solutions at room temperature, inject slowly, and do not store cartridges in disinfecting solution.
Facial Nerve Paralysis -- Facial nerve paralysis can occur if local anesthesia is administered into the parotid gland. Reassure the patient that the paralysis is transient.
Broken Needle -- To avoid needle breakage, do not insert a needle up to its hub in tissue. Use long needles when injecting up to a depth of 18mm or more. If breakage occurs, remain calm and keep the patient's mouth open. Remove the needle fragment with a hemostat if visible. If the needle can not be seen, refer the patient to an experienced oral and maxillofacial surgeon.
Infection -- Infection, which is an extremely rare complication of local anesthesia injections, presents as pain and trismus. If pain and trismus persist for 3 days and worsens, treat with appropriate antibiotics. To prevent infection, use sterile disposable needles, avoid injecting through an infected area into an uncontaminated space, and apply a topical antiseptic before injecting into a severely immunocompromised patient.
By following the precautions described here, one can reduce the complications associated with local anesthesia.
Gerald S. Fine, D.D.S.
Practice limited to oral & maxillofacial surgery