P9 PAIN THRESHOLD IN PATIENTS WITH HAIR LOSS
Defrin R1, Lurie R2
1Department of Physical Therapy, Sackler Faculty of Medicine, Tel-Aviv University, Israel
2Pediatric Dermatology Hair Clinic, Schneider Children's Medical Center Petah Tivka, Israel

Introduction: Patients with hair loss may report of spontaneous pain sensation in their scalp or of pain evoked by brushing or by air blowing. This phenomenon is termed Trichodynia and its etiology is not well understood. We conducted a quantitative somatosensory testing in order to study possible association between hair loss and increased sensitivity to pain. Methods: The thresholds of touch (using Von Frey monofilaments) and of pressure pain (using pressure algometer) were measured in patients with hair loss and in healthy controls. The intensity of the reported pain was evaluated with a 0-10 visual analog scale (VAS). Results: Mean reported pain intensity was 5.5. Pain was located in scalp regions with hair loss- mostly in the upper frontal region and sides. In contrast, regions with no pain (mostly in the back of the scalp) did not exhibit hair loss. Pain threshold in regions of hair loss (mean of 112±51 kp) was significantly lower than pain threshold in regions without hair loss in the same patients (133±55, p<0.05). In addition, pain threshold in all regions of hair loss patients was significantly lower than that of parallel regions in healthy controls (174±76 and 229±94, respectively, p<0.001). The threshold for touch was not significantly different between regions with and without hair loss. Conclusions: The results suggest that nociceptors but not mechanoreceptors are sensitized in scalp regions exhibiting hair loss, namely that there is an association between hair loss and between regional changes in the pain system. The fact that pain threshold in all scalp regions of hair loss patients was lower than that of controls suggests a generalized hypersensitivity of nociceptors (hyperalgesia) in these patients.