Neuralgia-inducing cavitational osteonecrosis (NICO): A scoping review of a controversial concept in orofacial pain

Neuralgia-Inducing Cavitational Osteonecrosis (NICO) is a debated diagnostic entity proposed as a cause of chronic orofacial pain. Despite ongoing clinical use, systematic evaluations integrating historical foundations and methodological gaps remain limited.

A comprehensive search of PubMed/MEDLINE, Scopus, and Web of Science mapped NICO's development from 1979 to 2024. The search yielded 603 records; 41 studies were included after screening. Data extraction categorized studies by type, methodology, diagnostic criteria, and limitations. Methodological quality was assessed using Joanna Briggs Institute critical appraisal tools.

The 41 studies revealed recurrent methodological limitations: absence of control groups, non-standardized diagnostic criteria, limited histological evidence, and interpretive bias. Proposed mechanisms such as RANTES/CCL5 overexpression lack independent validation. Diagnostic tools remain unvalidated, and surgical interventions continue based on unclear criteria. Evidence consists predominantly of low to moderate quality retrospective case series, with no randomized controlled trials. Many patients diagnosed with NICO may be more appropriately classified as having persistent idiopathic facial pain or trigeminal neuropathic pain according to International Classification of Orofacial Pain criteria.

Current evidence is insufficient to support NICO as a distinct, validated clinical entity. The substantial physical and psychological risks of surgical intervention underscore the ethical imperative to base treatment decisions on validated evidence. Rigorous, prospective research with standardized diagnostic frameworks and appropriate controls is urgently needed. Clinicians should exercise caution, prioritizing evidence-based non-surgical management and avoiding irreversible surgical interventions without clear justification.