Chronic Facial Pain and Blood Serotonin: A Pilot Study

Abstract

Objective: To study whole blood serotonin levels in patients with chronic mid-facial segmental pain and to compare with normal matched controls. Peripheral blood serotonin is stored almost exclusively in platelets, which reflect intra-neuronal serotonin. In chronic facial pain, low intraneuronal serotonin may cause dysfunction of descending serotonergic inhibition of nociceptive pathways. Method: Thirty patients with chronic tension-type facial pain according to International Headache Society criteria and 30 matched controls were studied. Patients were symptomatic for at least 3 months, had normal nasoendoscopy, and had normal CT sinuses/brain. Other causes of pain, such as facial migraine, trigeminal neuralgia, or TMJ dysfunction, were excluded. Results: Patients with chronic facial pain tended to have normal peripheral blood serotonin levels. There was no significant difference in serotonin levels between patients and controls. Conclusion: This study does not provide evidence of serotonergic dysfunction in chronic tension-type facial pain. Dysfunction of other inhibitory descending pathways, such as noradrenergic pathways, may play a significant role in the development of chronic tension-type facial pain.