Clinical Features of Idiopathic Parotid Pain Triggered by the First Bite in Japanese Patients with Type 2 Diabetes: A Case Study of Nine Patients

OBJECTIVE: First bite syndrome, characterized by pain in the parotid region after the first bite of each meal, predominantly develops in patients who have had head and neck surgery. Idiopathic parotid pain (IPP) that mimics first bite syndrome may present in patients without a history of surgery or evidence of an underlying tumor, but its clinical features are unclear. This study characterized the clinical characteristics of IPP in patients with diabetes. STUDY DESIGN: A retrospective case review involving the clinical findings and pain characteristics of nine patients with IPP and diabetes who presented to our department between 2013 and 2016. RESULTS: All the patients were men diagnosed with type 2 diabetes (median age, 43 years). IPP developed unilaterally in seven patients and bilaterally in two. The median intensity of the first bite pain was 8 on a numerical rating scale of 0–10. The trigger factor was gustatory stimuli, and the trigger area was the posterior section of the tongue. Postprandial pain occurred within 1–10 min after meals in six patients. CONCLUSIONS: IPP may be considered a separate disorder, in which the pain characteristics are similar to those of first bite syndrome but the clinical features and pathophysiology are different.