Chronic Facial Pain and Blood Serotonin: A Pilot Study

OBJECTIVE: The purpose of this pilot study was to establish the validity of an improved facial electromyogram (EMG) method for the measurement of facial pain expression.BACKGROUND: Darwin defined pain in connection with fear as a simultaneous occurrence of eye staring, brow contraction and teeth chattering. Prkachin was the first to use the video-based Facial Action Coding System to measure facial expressions while using four different types of pain triggers, identifying a group of facial muscles around the eyes.METHOD: The activity of nine facial muscles in 10 healthy male subjects was analyzed. Pain was induced through a laser system with a randomized sequence of different intensities. Muscle activity was measured with a new, highly sensitive and selective facial EMG.RESULTS: The results indicate two groups of muscles as key for pain expression. These results are in concordance with Darwin's definition. As in Prkachin's findings, one muscle group is assembled around the orbicularis oculi muscle, initiating eye staring. The second group consists of the mentalis and depressor anguli oris muscles, which trigger mouth movements.CONCLUSIONS: The results demonstrate the validity of the facial EMG method for measuring facial pain expression. Further studies with psychometric measurements, a larger sample size and a female test group should be conducted.

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Atypical facial pain: A double-blind placebo-controlled crossover pilot study of subcutaneous sumatriptan.

European Neuropsychopharmacology ◽

10.1016/s0924-977x(96)00385-9 ◽

1997 ◽

Vol 7 (2) ◽

pp. 83-88 ◽

Cited By ~ 26

Author(s):

S.D Harrison ◽

S.A Balawi ◽

C Feinmann ◽

M Harris

Keyword(s):

Pilot Study ◽

Facial Pain ◽

Atypical Facial Pain ◽

Double Blind ◽

Double Blind Placebo ◽

Subcutaneous Sumatriptan

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Serial blood serotonin levels in a randomized controlled trial comparing the efficacy of low-dose amitriptyline, amitriptyline with pindolol and surrogate placebo in patients with chronic tension-type facial pain

Rhinology Journal ◽

10.4193/rhino13.019 ◽

2013 ◽

Vol 51 (3) ◽

pp. 236-242

Author(s):

A.M. Agius ◽

N.S. Jones ◽

R. Muscat

Keyword(s):

Whole Blood ◽

Facial Pain ◽

Serotonin Receptor ◽

Low Dose ◽

Controlled Trial ◽

Tension Headache ◽

Control Group ◽

Blood Serotonin ◽

Before And After ◽

Group A

Background: Patients often present with chronic facial pain despite normal nasal endoscopy and sinus computerized tomography. Such pain has increasingly been recognized as being of neurological origin with one of the commonest underlying causes being mid-facial segmental tension-type pain (MFP) which is a version of tension headache in the face. Descending serotonergic neuronal projections are known to modulate pain and intra-platelet serotonin levels are an accepted model reflecting central intra-neuronal serotonin. Objectives: 1.To determine whether low-dose amitriptyline significantly changes whole blood serotonin compared to a surrogate placebo in patients with chronic MFP 2. To determine whether the addition of pindolol, a beta blocker with serotonin receptor blocking properties further alters blood serotonin. Methodology: Sixty-two patients were randomized to three treatment groups a) amitriptyline , b) amitriptyline with pindolol, and c) loratadine as surrogate placebo. Whole blood serotonin was taken before and after 8 weeks of treatment. Serotonin was also measured in 40 age-matched healthy controls. Results: There was a significant reduction in blood serotonin levels in the amitriptyline with pindolol group. A non-significant reduction was seen in the amitriptyline group, with no change in serotonin levels in the surrogate placebo group. A comparison of change in serotonin with change in pain frequency and intensity scores is presented. Women in the control group had significantly higher serotonin levels than men. Women with tension-type facial pain who failed to respond to treatment had significantly lower blood serotonin than women in the control group. Conclusion: When linked to the clinical response this study provides evidence that the serotonergic system is involved in the modulation of chronic MFP. Serotonin levels are sex-dependent and related to treatment response.

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