Pain evoked by distension of the uterine cervix in women with dysmenorrhea: evidence for central sensitization.
OBJECTIVE
To study sensitization in women with dysmenorrhea using a standardized experimental model. Women with dysmenorrhea experience intense visceral pain during menstruation. The dysmenorrhea pain mechanisms are not known but sensitization may play a role.


METHODS
Prospective experimental study.


METHODS
Ten women with dysmenorrhea and 10 control women having uterine cervical distensions in the mid-follicular period (days 6-10).


METHODS
University clinic.


METHODS
Cervical distension was delivered as three phasic stimuli with 1 min between distensions and as a prolonged (1 min) distension.


METHODS
Sensory intensity rated on a continuous visual analog scale.


RESULTS
Distension-induced pain was described as dull and aching and referred to the pelvis, lower back and lower abdomen. Larger evoked referred pain areas were present in women with dysmenorrhea compared with control women (p < 0.05). The pain threshold to the first stimulus was significantly higher in patients than controls (p < 0.04), but decreased significantly with repeated distensions (p < 0.01). For the prolonged distension the pain rating increased significantly (p < 0.008) in women with dysmenorrhea, but decreased (p < 0.02) in control women.


CONCLUSIONS
Pain sensitization (temporal summation, i.e. increase in pain during prolonged stimulation, and facilitation of referred pain areas as an indicator of central nervous system changes) is present in women with dysmenorrhea. The study provided new information on a poorly understood yet widespread condition and a basis for clinical studies to develop a biomarker tests for objective assessment of dysmenorrhea.
Center for Sensory-Motor Interactions (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Aalborg, Denmark.
Lars
L
Arendt-Nielsen
Hans
H
Madsen
John
J
Jarrell
Hans
H
Gregersen
Asbjørn M
AM
Drewes
D000328:Adult; D016022:Case-Control Studies; D059333:Central Nervous System Sensitization; D002584:Cervix Uteri / Q000503:physiopathology*; D004412:Dysmenorrhea / Q000503:physiopathology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D010147:Pain Measurement; D017288:Pain Threshold; D053591:Referred Pain; D010812:Physical Stimulation; D011446:Prospective Studies
Cervix; dilatation; dysmenorrhea; experimental pain; hyperalgesia