Complications of local anesthesia 1 Pain on Injection

Complications of local anesthesia

1. Pain on Injection • Causes: • Careless injection technique • A needle can become dull from multiple injections. • Rapid deposition of the local anesthetic solution may cause tissue damage. • Unintentionally pricking an anatomical structure, e. g. a tendon or muscle, the periosteum, a nerve or blood vessel. • Prevention: • Management: • No management is necessary

2. Burning on Injection • Causes: • The p. H of the solution being deposited into the soft tissues. The p. H of “plain” local anesthetics is approximately 6. 5, whereas solutions that contain a vasopressor are considerably more acidic (around 3. 5). • Rapid injection of local anesthetic • Contamination of local anesthetic cartridges. • Overheated solution • Prevention: • Management: • No treatment is indicated

3. Failure to obtain anesthesia or insufficient anesthesia. • Causes: v Operator-dependent • Selection of local anesthetic agent • Improper injection technique: – Wrong technique – Not waiting long enough for anesthesia to act. • Intravascular administration. v Patient-dependent • Anatomical: – Anatomical variations – Accessory innervations

• Pathological: – Presence of infection: – Presence of trismus. • Psychological: – Fear and anxiety. – Uncooperative patient, inadequate opening of the mouth, movement by the patient • Prevention: • Management: • Repeat the injection. • Consider giving additional injections. • Consider anesthetizing additional nerves.

4. Needle Breakage • Causes: • if the needle is bent to before the entrance into the area to be injected. • Unexpected movements of the patient. • Changing the direction of the needle inside the tissue. • Forceful contact with bone due to aggressive insertion of the needle • Needle inserted to its hub inside the tissue increase the potential of breakage. • Prevention:

• Management

5. Prolonged Anesthesia or Paresthesia • Causes: • Trauma to any nerve may lead to paresthesia. • Injection of a local anesthetic solution contaminated by alcohol or sterilizing solution near a nerve. • Hemorrhage into or around the neural sheath. • Prevention: • Management: • Be reassuring. • Observation every 2 months for as long as the sensory deficit persists. • Surgery.

6. Facial Nerve Paralysis • Cause: • introduction of local anesthetic into the capsule of the parotid gland. • Directing the needle posteriorly, or over inserting during a Vazirani-Akinosi nerve block, may place the • Prevention: • Management: • Reassure the patient. • Contact lenses should be removed. • An eye patch should be applied to the affected eye.

• The primary problem associated with transient facial nerve paralysis is cosmetic. • A secondary problem is that the patient is unable to voluntarily close one eye.

7. Trismus • Causes: • Trauma to muscles or blood vessels in the infratemporal fossa. • Local anesthetic solutions into which alcohol or sterilizing solutions have diffused produce irritation of tissues • Hemorrhage leading to muscle dysfunction as the blood is slowly resorbed (over approximately 2 weeks). • Low-grade infection. • Excessive volumes of local anesthetic solution. • Prevention:

• Management: • Heat therapy. • Use analgesic as Aspirin. Also prescribe muscle relaxation. • physiotherapy. Chewing gum (sugarless, of course!). (In virtually all cases of trismus related to intraoral injections that are managed as described, patients report improvement within 48 to 72 hours). • If pain and dysfunction continue unabated beyond 48 hours, consider the possibility of infection. Antibiotics should be added to the treatment regimen described and continued for 7 full days.

8. Soft Tissue Injury • Cause: • The primary reason is the fact that soft tissue anesthesia lasts significantly longer than does pulpal anesthesia.

• Prevention: • A local anesthetic of appropriate duration should be selected. • A cotton roll can be placed between the lips and the teeth. • Warn the patient and the guardian against eating, drinking hot fluids, and biting on the lips or tongue. • Management: • • Analgesics for pain. Antibiotics. Warm saline rinses to aid in decreasing any swelling. Use any lubricant to cover a lip lesion and minimize irritation.

9. Hematoma • Cause: • result from arterial or venous puncture commonly after a posterior superior alveolar (visible extraorally) or inferior alveolar nerve block (visible intraorally). • Prevention: • Knowledge of the normal anatomy • Minimize the number of needle penetrations into tissue. • “Hematoma is not always preventable. Whenever a needle is inserted into tissue, the risk of inadvertent puncturing of a blood vessel is present”.

• Management: • Immediate • When swelling becomes evident, direct pressure should be applied to the site of bleeding for no less than 2 minutes, this effectively stops the bleeding. • Subsequent • Advise the patient about possible trismus. • Ice may be applied to the region immediately. • Do not apply heat to the area for at least 4 to 6 hours after the incident. Heat may be applied to the region beginning the next day • Time is the most important element in managing a hematoma. With or without treatment, a hematoma will be present for 7 to 14 days.

10. Infection • Causes: • The major cause is contamination of a needle before injection if the needle touches mucous membrane in the oral cavity. • Improper technique in the handling of local anesthetic equipment. • Injecting local anesthetic solution into an area of infection. • Prevention:

• Management: • The patient usually reports post injection pain and dysfunction 1 or more days after dental care. • Immediate treatment consists of those procedures used to manage trismus. – Trismus produced by factors other than infection normally responds with resolution or improvement within several days. • If signs and symptoms of trismus do not begin to respond to conservative therapy within 3 days, the possibility of a low-grade infection should be entertained and the patient started on a 7 - to 10 -day course of antibiotics.

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