Anesthesia · patient case question
Which complication of an inferior alveolar nerve block injection is LEAST likely to occur?
Patient case: Third molar surgery and post-operative pain
Patient: Male, 18 years old
Chief complaint: “My bottom left tooth is really irritated.”
History: Healthy. No medications, no allergies.
Findings: Pericoronitis surrounding tooth #17. Referral planned to an oral and maxillofacial surgeon. Tooth #32 is also to be removed at the same visit.
Show answer and explanation
Correct answer: B. Infection
- A. Haematoma occurs when the needle lacerates a vessel in the pterygomandibular space — the inferior alveolar vessels or the pterygoid venous plexus — and is a well-recognised sequela.
- B. CORRECT. INFECTION after an inferior alveolar nerve block is rare. It requires either a contaminated needle or passage of the needle through an infected field into deep tissue, and with single-use sterile needles and appropriate injection sites both are uncommon. It is not among the routinely-listed complications.
- C. Ecchymosis is the visible bruising that follows a haematoma as blood tracks through tissue planes. It is common enough that patients should be warned about it.
- D. Trismus is one of the commonest complications, arising from needle trauma or haemorrhage into the medial pterygoid muscle, or from an irritant solution. It presents as progressively limited opening over the days following the injection.
Note: Other recognised IANB complications: transient facial nerve palsy from depositing into the parotid when the needle passes too far posteriorly, and paraesthesia, which is more frequent with 4 percent solutions such as articaine and prilocaine.