Complications of Local Anesthesia: Paresthesia

Complications of Local Anesthesia

• Paresthesia is a transient or permanent condition caused by trauma to a nerve during injection, characterized by a sensation of an electric shock throughout the distribution of the involved nerve.

Causes of Paresthesia

• Trauma to any nerve during injection
• Injection of local anesthetic solution contaminated by a neurotoxic substance
• Hemorrhage and infection in close proximity to a nerve

Prevention of Paresthesia

• Strict adherence to injection protocol
• Proper care and handling of dental cartridges

Management of Paresthesia

• Most cases resolve within 8 weeks without treatment
• Reassure the patient that the condition is transient with strict follow-up
• If the damage to the nerve is severe, the paresthesia will be permanent

Needle Breakage

• Causes:
  • Weakening of the dental needle by bending it before insertion
  • Sudden unexpected movement of the patient
  • Smaller needles (e.g., gauge 30) are more likely to break than larger needles (e.g., gauge 25)
  • Re-use of the needle
  • Incorrect use of the needle (e.g., aggressive insertion, sudden change in direction, too deep penetration)
  • Defective needles in manufacture

Prevention of Needle Breakage

• Check the needles before using them
• Use appropriate needle size and type
• Handle needles carefully to avoid bending or damaging

Hematoma

• A localized mass of extravasated blood that may become clinically noticeable following injection
• Causes:
  • Penetration of the blood vessel with the needle during injection
• Prevention:
  • Learn anatomical landmarks and injection technique
  • Avoid relocating the needle to different sites inside the tissue
• Management:
  • Apply direct pressure if possible
  • Inform the patient and reevaluate the possibilities of continuing the treatment
  • Instruct the patient to avoid application of heat over the area
  • Prescribe analgesic and antibiotic if necessary

Infection

• Causes:
  • Contamination of the needle by touching the mucous membrane
  • Improper technique in handling the local anesthetic equipment
  • Injecting the solution into an area of infection
• Prevention:
  • Use sterile disposable needles
  • Proper handling of the needle to avoid its contact with non-sterile surfaces
  • Use cartridge only once and store it in its original container, covered at all times
• Management:
  • If an infection occurs, the patient will complain of pain and trismus
  • Immediate treatment consists of procedures used to manage trismus
  • Prescribe a course of antibiotic for 7 days

Systemic Complications of Local Anesthesia

Fainting (Vasovagal Attack)

• The most common systemic complication that occurs with local anesthesia
• Refers to a sudden transient loss of consciousness usually secondary to cerebral ischemia
• Causes:
  • Vasodilatation or an increase in peripheral vascular bed
  • Corresponding drop in blood pressure
• Management:
  • The first aid treatment should be started at once
  • Lower the head of the patient, elevate the legs, loosen tight belt and collar, and stimulate respiration
  • Spontaneous recovery is usual and it is often possible to complete the treatment at the same visit

Hypersensitivity or Allergy to Local Anesthesia

• More commonly seen with ester type agents than amide type
• Causes:
  • Local anesthetic agent
  • Vasoconstrictor
  • Additives like bisulfite used as a preservative
• Prevention:
  • Proper pre-anesthetic evaluation, which includes a proper personal history and past dental history
• Management:
  • Antihistamine injection
  • Epinephrine 0.5 ml of 1:1000 IM
  • Administer O2 if necessary
  • Substitution of the local anesthetic agent

Anaphylactic Shock

• A rare, life-threatening hypersensitivity reaction to an antigen
• Develops fast, causing death within a few minutes
• Characterized by:
  • Profound fall in the blood pressure
  • Dyspnea and respiratory embarrassment
  • Facial and laryngeal edema
  • Loss of consciousness
• Management:
  • If you suspect an anaphylactic reaction, immediately seek medical help
  • Epinephrine is the most important medication, given as intramuscular injection
  • Even if the patient responds to the epinephrine, it is vitally important to go to an emergency room immediately