Self-Inflicted Lingual Trauma Following Inferior Alveolar Nerve Block in Dogs: A Multicenter Case Series

Introduction:
Locoregional anaesthesia techniques (LA) have become integral part in managing pain associated with dental interventions. Inferior alveolar nerve (IAN) is one of the branch of the mandibular division of the trigeminal nerve (CN V). Blocks of the IAN (IANb) are generally effective, but their success hinges on precise technique, anatomical knowledge, and appropriate anaesthetic volume. Incorrect landmark identification, volume related complication (VRC) and mechanical complication (haematoma, tissue swelling, local nerve damage) have been reported sporadically (1-3). Data on incidence, management and outcome of IANb related complications in clinical practice remain limited (4,5). In this retrospective, descriptive, multicentric study we present a pattern of complications occurred after IANb.

Material and Methods:
Data were collected retrospectively from the digital archives of 7 institutions over the course of 4 years period (2019-2022).
Age, breed, weight, sex, drug, dose, approach and location of IANb were registered (Table A). LA used were selected based on surgeon preference, procedure and desired length of postoperative analgesia. IANb was performed using either intra or extraoral approach by 7 different operators. Volume administered followed standard protocols from established reference (6). Location of the lingual trauma and mitigating interventions were recorded. Lesions were scored as mild, moderate and severe subjectively and categorically. Follow up was present for all except one case.

Results:
13 dogs reported complication postoperatively. Mean patient age was 5.5 years, and mean body weight was 20.6 kg. Procedures performed included extraction, root canal treatment, mandibulectomy, and gingivectomy.
2/13 (15%) dogs received combination of Bupivacaine 0.5% and Lidocaine 2%. 9/13 (69.2%) dogs received bupivacaine as a sole agent, 2/13 (15%) dogs received combination of bupivacaine 0.5% and buprenorphine.
IANb was performed bilaterally in all dog except one.
Of the 13 dogs with reported lingual auto-inflicted self trauma, 8 received intraoral IANb and 5 IANb via extraoral approach. The self-trauma occurred in a variable time after the extubation. Duration of chewing episodes was limited in all apart for 1 dog where it lasted for 3 days post-procedure. Mitigation strategies for lingual self-trauma included: sedation or re-anaesthesia and suturing, muzzling, titrated analgesia and antibiotic treatment. Follow-up data was available for all except 2 dogs. Most dogs reported complete healing of the lingual lesions within 3 months and normal eating behaviour.

Discussion:
Current recommendation for LA dosing is typically linked to body weight. This series describes a pattern of complications across multiple practices. It cannot establish causality (retrospective, uncontrolled, subjective scoring) therefore it does not allow calculation of complication incidence/risk after IANb.

Conclusion:
In this study we describe lingual auto-inflicted self-trauma as complication following IANb. Our results suggest that, albeit rare, is a possible event, mostly noticed in the immediate recovery. Breed, operator, or procedure are likely to play a role, while correct technique and volume are paramount as suggested by the previous literature (4,5). Interventions to mitigate the trauma are effective and prognosis is generally good.

Reference
1- “Globe penetration in a cat following maxillary nerve block for dental surgery” R.Perry et al. J Feline Med Surg. 2014; 17(1):66-72

2- “Regional anaesthesia and analgesia for oral and dental procedure”. J.Rochette Vet Clin North Am Small Anim Pract 2005; 35: 1041-1058

3-“Severe cardiovascular depression in a cat following a mandibular nerve block with bupivacaine” F. Aprea et al. Vet Anaesth Analg 2011; 38: 614-618.
4-“Tongue lacerations in a geriatric dog after bilateral inferior alveolar nerve blocks with bupivacaine” A Y K Chau Veterinary Case Report 2017, 5(3):
5- “A Retrospective Study of the Incidence and Management of Complications Associated with Regional Nerve Blocks in Equine Dental Patients” R B Tunner; A E Hubbell JVD 2019, vol 36 (1)
6- BSVA Manual of canine and feline dentistry and oral surgery 4TH edition. A M Reiter and M Gracis. Chapter 6, pag 133.