Sphenopalatine ganglion block for orofacial complex regional pain syndrome with sympathetically maintained pain: a case report.

OBJECTIVE: Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by disproportionate pain intensity and duration relative to the initiating event. Its occurrence in the orofacial region is extremely rare and often misdiagnosed as odontogenic, sinus, or temporomandibular pain. CASE PRESENTATION: This report describes a 41-year-old man presenting with persistent left midfacial pain following an episode of sinusitis. The pain, refractory to multiple medical and surgical interventions, was ultimately diagnosed as sympathetically maintained orofacial pain with CRPS features, based on clinical features and quantitative sudomotor axon reflex testing. The patient was treated with a series of transnasal sphenopalatine ganglion blocks. Progressive and sustained pain reduction was achieved, with pain scores decreasing from 8-9/10 to 1-2/10 after six sessions. The patient remained in remission for over 4 years, maintained on intermittent intranasal lidocaine spray without systemic medications. CLINICAL SIGNIFICANCE: This case highlights the importance of recognizing CRPS as a potential cause of persistent orofacial pain and demonstrates the effectiveness of sphenopalatine ganglion block as a minimally invasive, safe, and repeatable treatment modality. General dental practitioners are often the first to encounter such atypical pain presentations and play a key role in early recognition, referral, and collaborative management alongside orofacial pain specialists, who are trained in providing interventional therapies such as sphenopalatine ganglion block.