Differential Response to Pregabalin in Coexisting Cervical Radiculopathy and Burning Mouth Syndrome: A Case Report

Background: Burning mouth syndrome (BMS) is a chronic oral pain disorder characterized by burning pain in the absence of visible mucosal lesions or identifiable laboratory abnormalities. Coexisting burning mouth syndrome and cervical radiculopathy may complicate interpretation of treatment response and suspected adverse drug reactions.

Case presentation: A 68-year-old woman with diabetes mellitus, hypertension, and hyperlipidemia presented with headache, dizziness, and occipital paresthesia. Cervical magnetic resonance imaging demonstrated multilevel degenerative changes with severe left foraminal stenosis at C3–4. Her cervical symptoms improved after pregabalin dose escalation from 50 mg to 75 mg twice daily. Approximately 7 weeks later, she developed burning tongue pain with metallic taste. Oral examination was normal, and laboratory studies were unremarkable. Pregabalin was discontinued because an adverse drug reaction was initially suspected; however, the tongue symptoms persisted for more than 5 months without improvement. Cervical epidural block completely relieved the headache and occipital paresthesia but did not change the tongue pain. Pregabalin was later reintroduced for recurrent cervical symptoms, resulting again in marked improvement of cervical symptoms without any change in the tongue pain. Repeated evaluations at tertiary hospitals found no structural or systemic cause.

Conclusion: This case suggests that temporal association alone is insufficient to establish drug causality. In patients with concurrent neuropathic pain syndromes, pregabalin may have markedly different effects on distinct pain generators, and persistent oral burning symptoms should prompt consideration of coexisting BMS rather than presumed medication toxicity alone.