Complications of Local Anesthesia

Introduction: Local anesthetic complications can be divided into two areas. There are local complications and systemic complications. Local complications are the result of the mechanics of the injection or the properties of the anesthetic drug on the local environment. Systemic complications are those general complications occurring as a result of the drug used or a local problem that can lead to systemic sequela.

Required reading: Handbook of Local Anesthesia, Fourth Edition, Stanley F. Malamed, Mosby Publishing Company. Chapters, 17 and 18. Pages 246-286. Chapter 20. Pages 303-310.  

I. Local complications 

A. Needle Breakage

1. Causes- needle size, smaller more likely, prior bending of needle unexpected patient movement, defective needles

2. Problems, if retrievable, if not retrievable easily

3. Prevention - larger gauge for deep penetrating injections, longer needles, do not insert to hub, do not bend needle, do not redirect needle when in deep tissue.

4. Management - calm, no panic, inform patient, no movement patient, keep mouth open. Use hemostat to retrieve if possible. If not visible refer to competent surgeon. If superficial and easily identified surgeon removes. May have to leave in if deep or difficult to find. However it is better to have it removed if possible. Possible litigation highly likely. 

B.  Pain on Injection

1. Causes - Careless injection technique, dull needle, rapid injection, barbed needles. 

2. Problems - anxiety increase, unexpected movement and its sequela.

3. Prevention - proper injection technique, sharp needles, topical, sterile LA soln., slow injection, room temperature anesthetic soln.

4. Management - prevention is management.

C. Burning on Injection

1. Causes - ph LA Soln, rapid injection, contamination cartridge, rapid injections, warmed soln.

2. Problem - none if due to ph, (usually), if due to contamination tissue damage, trismus, edema, parasthesia.

3 Prevention - prevention, slow injection, (ideal, 1ml/min, recommended not more than 1.8ml/min)

4. Management - specific problems that arise are managed.

D.  Persistent Anesthesia or Parasthesia - Anesthesia lasts for longer than expected. Some patients are hyperreactors, longer anesthesia. However some anesthesia lasts week, months, years. Longer lasting increases problems. Parasthesia, anesthesia may not be preventable. Parasthesia results in many malpractice suits.

1. Causes - alcohol contamination LA, solutions. Sterilizing solution contamination LA. Trauma to nerve with needle. Inserting a needle into a foramen increases risk of nerve trauma. Hemorrhage in and around neural sheath secondary to trauma.  

2. Problem - patient can injure anesthetized area. Bite, burn, chemical injury. Lingual nerve damage effect taste. Can get hyperesthesia or dysesthesia. Prilocaine apparently involved in paresthesia more often than other LA agents.

3. Prevention - observe protocol for handling and care of LA cartridges. Parasthesia can still occur.

4. Management - most parasthesias resolve in about 8 weeks without treatment. Sever damage may lead to permanent anesthesia, rare. Most paresthesia is minimal. In general dentistry most parasthesias involve tongue. Reassure patient, you speak directly to patient. Explain paresthesia to patient and usual course. Examine patient. Chart location and depth. Record incident on record. Some waiting indicated. Sensory deficit of three months get consultation with oral and maxillofacial surgeon and or neurologist. Avoid dental injections in same area of injury to nerve. Steroids may be indicated at time of or shortly after injury. If you are aware of the nerve injury at the time of surgery steroids also may be indicated.

E.  Trismus - Prolonged spasm of the jaw muscles. Restriction of opening. Can be used to indicate any limitation of movement. Can be chronic and difficult to manage.

1. Cause - Most common cause from dental injections is the trauma to blood vessels or muscles in the infratemporal fossa. Contaminated cartridges, with alcohol or sterilizing solution cause tissue damage. Intramuscular injections LA. Hemorrhage in area. Infection post injection.     Multiple injections in same area. Barbed needles. Barbed needles. Large amounts of LA solution in same area.

2. Problems - limitation usually minor and transient. Can become sever and chronic. Can require extensive therapy and or surgery. 

3. Prevention - sharp needles, care of cartridges, aseptic technique, atraumatic injection, know anatomy, avoid multiple injections same area, use minimum effective volume.

4. Management - Pain and trismus usually occurs 1-6 days post injection. See patient. Rx. Analgesics, heat, warm rinses and muscle relaxants if indicated. Initiate physical therapy. Opening and closing. Use of tongue blades to stretch. Gum chewing. Antibiotics if indicated. If severe and no response within 2-3 days no antibiotics, and 5days with antibiotics refer to oral and maxillofacial surgeon. Severe dysfunction can require surgery.

 F.  Hematoma

1. Causes - puncture artery or vein.
2. Problem - Swelling, discoloration, bruise, trismus, pain and infection rare
3. Prevention - Knowledge of the anatomy. Certain blocks more likely. PSA most. Inf. Alveolar, mental. Modify technique for smaller adults. Reduce number of punctures. Do not probe with needle.

4. Management - direct pressure immediate. Two minutes. Inf. Alveolar against medial portion mandible. Infra orbital, skin over foramen. PSA side of face. Ice to face. Intraoral pressure at site of injection. Usually can be large hematoma. Record hematoma=s in patients chart. Inform patient of sequeli. No heat four to six hours post injection. Can use ice or cold rinses. Usually resolves 7-10 days. 

G.  Infection 

1. Causes - Needle contamination. Usually not from local flora. Usually from improper handling of the injection set up. Injecting through a an infected area to non infected

2. Problem - Low-grade infection in deeper tissue. Trismus possible. Must recognize infection.

3. Prevention - Disposable needles. Handle cartridges well. Store well. Do not contaminate cartridge solution. Cap needle. Do not touch to non sterile surface. Wipe diaphragm with sterile disposable alcohol let dry.

4. Management - Difficult to diagnose. Trismus may be sign. Treat trismus. No response in three days then place on antibiotic. Use penicillin or appropriate antibiotic if allergic to penicillin for at least seven days. Record progress and if no response refer to Oral and Maxillofacial surgeon or other specialist if indicated.

H.  Edema - Swelling of the tissue. Sign of other disorder.

1. Causes -Trauma, infection, allergy and hemorrhage.

2. Problem - swelling usually not a problem. Some pain discomfort. Angioneurotic edema may be life threatening. Can compromise airway.

3. Prevention - handling injection equipment. Atraumatic injection. Complete medical evaluation patient.

 

4. Management - traumatic may be small and self-resolving. Bleeding requires pressure, ice. Infection usually requires antibiotics or other treatment. Allergy induced edema can be life threatening. Airway may be compromised. If unconscious provide basic life support, call 911, secure airway if possible. Epinephrine, Corticosteroid, Antihistamine, possible cricothyrotomy. Later evaluate cause. 

I.  Sloughing of Tissue

1. Causes - Epithelial Desquamation, sterile abscess.

2. Problem - Pain

3. Prevention - Use topical anesthetic as directed. Do not use high concentration vasoconstrictor. 

4. Management - Symptomatic for pain. Systemic analgesics, topical orabase.

J. Soft Tissue Injury - Self inflicted injury.

1. Causes - self inflicted, children, mentally or physically disabled. Soft tissue anesthesia.

2. Problem - swelling, pain. Infection rare.

3. Prevention - Select LA for duration of procedure. Instruct parents or patient. Sticker warning on children.

4. Management - Analgesics, antibiotics,   lubricants of needed.

 k. Facial Nerve Paralysis - Paralysis of branches of the seventh nerve.

1. Causes - Infraorbital block, Maxillary canine infiltration, Inferior alveolar injection into parotid gland.
2. Problems – Pt. Anxiety, unable to close eye. Unilateral facial paralysis, (secondary to inferior alveolar in parotid gland.
3. Prevention – Know anatomy. With Inferior alveolar touch bone. If using Vazarani- Akinosi know landmarks, with gow gates know landmarks.

4. Management – Paralysis shows up quickly. Reassure patient. Explain. Eye patch. Instruct in eye care. Lubricate eye. Record incident. Stop procedure.

L. Post Anesthetic Intraoral Lesions – Usually several days after injections in area of injection.

1. Causes – recurrent aphthous ulcers or herpes simplex. Trauma needles, swab, and may activate latent forms.
2. Problem – pain, sensitivity
3. Prevention – not known. Can treat prodromel syndrome with antiviral agents. Usually runs its course.
4. Management – Reassure patient. Not bacterial. Will run course. Follow patient. Can occur again