Local Complications of Local Anaesthesia – Cause, Management, and Prevention of these Complications.

2.Injury to nerves
3.Injury to vessels
4.Trauma to muscles
5.Needle breakage
6.Intraglandular injections and their sequel


  • ‘Needle track’ infection – contaminated needle or injection. Through contaminated tissue
  • Contaminated solution-especially due to vials
  • Break of aseptic technique
  • Injecting LA into an area of infection by force or transfer bacteria into adjacent healthy tissue spreading infection.

2. Injury to nerves

  • Even 25-30 gauge can cause paraesthesia by mere touching of nerve (neuropraxia).
  • Hitting bone may ‘barb’ the tip & cause nerve damage on withdrawal (neurotmesis).
  • Paresthesia -persistent anesthesia (anesthesia well beyond the expected duration), or altered sensation (tingling or itching) well beyond the expected duration of anesthesia.
  • Hyperesthesia -increased sensitivity to noxious stimuli.
  • Dysesthesia – painful sensation to non=-noxious stimuli.


Neurovascular bundle can be traumatized by

  • the sharp needle-tip, movement of the needle tip.
  • extraneural or intraneural hemorrhage from trauma to the blood vessels.
  • neurotoxic effects of the local anesthetic solution.
  • Self-inflicted injury to oral tissues.
  • Rx – reassure the patient.
  • most cases resolve within eight weeks (Malamed1997).
  • Oral B-complex with B12 and B6.


  • Rapid injection insufficient time for diffusion pressure on nerve endings PAIN.
  • Improper temp/pH of a solution.
  • Contamination with sterilant/alcohol.

Failure to achieve profound anesthesia:

  • Improper technique – too low or too anterior
  • Insufficient volume
  • Local infection
  • Other neurological complications

Diffusion into orbit: ocular and extraocular symptoms

  • regional sixth nerve block-paralysis of extraocular muscles-temporary diplopia.
  • retrobulbar block (rare).
  • optic nerve block, which can result in temporary blindness (amaurosis).
  • Horner’s syndrome-like manifestations can occur, including enophthalmos, miosis, and palpebral ptosis.

3. Injury to vessels

  • Nick of vessels – hematoma
  • Arterial damage – rapidly expanding hematoma
  • Prevention:
  • – Knowledge of anatomy
    – Modify the tech. as dictated by patients anatomy
    – Minimize the no. of needle penetration into tissues
    – Never use a needle as a probe in the tissues

  • Management:
  • –Direct pressure-intra/extra oral
    –Usually self-limiting-observe over 48 hours
    –Injection Tranexamic acid iv
    –Arterial bleeds may require ligation

  • Epithelial desquamation:
  • –Prolonged use of topical anesthetics
    –High concentration of vasoconstrictors
    –Most common on palatal mucosa

  • Management
  • –Resolves in 7-10 days
    –Mild NSAIDS
    –Na bicarbonate, saline or Peridex mouth rinse

  • Maybe a sequel of paraesthesia

4.Trauma to muscles

  • Trismus – difficulty/inability to open the mouth
  • Various mechanisms:
  • –Direct injury of temporalis and medial pterygoid muscle fibers by needle
    –Intramuscular injection
    –Rapid rate on injection
    –Contaminated solution
    –Wrong temperature/pH of the solution

  • Prevention :
  • – Use a sharp, sterile, disposable needle
    – Proper handling of local anesthetic solution.
    – Not to contaminated needles
    – Practice atraumatic technique
    – Avoid repeat injection. And multiple injections.
    – Use minimum effective volumes of LA.

  • Management :
  • – Heat therapy ( after 2 days )
    – Warm saline rinses.
    – Analgesics, muscle relaxants.
    – If it does not improve within 48-72 hrs, – infection must be considered — treat with antibiotics.

5. Needle breakage

  • Causes :
  • – the weakening of dental needles by bending
    – Sudden unexpected movements of the patient
    – inserting needle up to the hub
    – Smaller gauge needles ( 30 gauge)
    – Defective manufacturing

  • Prevention :
  • – Use larger gauge needles
    – Do not insert the needle into the tissue till the hub
    – Do not redirect the needle once inserted into the tissue
    – Excessive lateral force on the needle

  • Management :
    – Ask the patient not to move or bite
    – If the fragment is visible, try to remove it with a hemostat
    – If the needle is not visible, do not proceed with incision or probing
    – It can be removed immediately. only if it is superficial and easily located through radiological and clinical

  • examination.

6 Intraglandular injection

  • IANB too posterior – injection within the parotid gland
  • Block of CN7-Transient Facial nerve palsy
  • Inability to blink/close eye
  • Feeling of facial paralysis
  • Rx-
  • –Reassure patient it is transient
    –protect the cornea

Leave a Reply

Your email address will not be published. Required fields are marked *

Finding us is as easy as

Typing in The Little Box Below

      Dental Services

      Orthodontic Treatment

      Dental Implants

      Root Canal Treatment   

      Dental Crowns            

      Dental Bridge