Effectiveness of Nerve Blocks for the Management of Head and Neck Cancer Associated Neuropathic Pain Disorders; a Retrospective Study.

Introduction: A portion of patients with head and neck cancer (HNC)- associated pain may not experience relief in symptoms with non-invasive modalities. A nerve block is a procedure in which a local anaesthetic agent is injected along the nerve track to preferentially block sensory transmission. The literature on the effectiveness of nerve blocks in the management of HNC-related pain is limited. The purpose of this study was to determine the effectiveness of nerve blocks in the management of breakthrough HNC-associated trigeminal or cervical neuropathic pain disorders.

Materials and methods: A retrospective chart review of patients who underwent a nerve block or infiltration procedure in the regions of head and neck for the management of breakthrough HNC-associated trigeminal or cervical neuropathic pain disorders in the Orofacial Pain Medicine Clinic, Shaukat Khanum Memorial Cancer Hospital and Research Centre, between November 2018 and November 2019 was completed. Information regarding demographics, diagnosis and pain characteristics was extracted and reviewed. The Fisher's exact test and Mann-Whitney U-test were used for analysis between independent and dependent variables.

Results: A total of 27 participants were included in the investigation, of which 66.7% were male. The average pre-procedure pain score was 6.85±2.54. Following intervention, 81.5% of the participants experienced >75% relief in pain for longer than 48 hours. The mean immediate post-procedure pain score was 0.26±1.02 and the average duration of relief was 6.10±6.50 weeks. The significant effect of nerve blocks was found to be statistically associated with the concurrent use of amitriptyline (P = 0.017).

Conclusion: Nerve blocks, as an adjunctive therapy to pharmacologic treatment, can provide significant relief to patients with breakthrough HNC-associated trigeminal and cervical neuropathic pain disorders. However, the duration of relief experienced by the participants is inconsistent. The beneficial effect of nerve blocks appears to be more common in patients that were concurrently using amitriptyline.