Are there differences between cephalic and extracephalic cutaneous allodynia in migraine patients?

Cutaneous allodynia (CA), pain in response to innocuous cutaneous stimuli, is recognized as a sign of central sensitization during migraine episodes. It is either restricted within the pain area on the ipsilateral head, or extends within and outside the head. Moreover, CA can be elicited in response to thermal (heat or cold) and/or mechanical stimuli. This raises the question as to whether cephalic and extracephalic CAs share the same properties. We assessed cephalic and extracephalic CAs in migraine episodic patients using a questionnaire completed at home during migraine attacks. A total of 67 episodic migraine patients (58 women, nine men; 40 +/- 13 years old) addressed all questions in the questionnaire. Forty-nine patients (73%) cited one or more allodynic symptoms during or immediately after the migraine attack. Almost all 49 patients reported cephalic CA, whereas 24 (49%) also reported extracephalic CA. Occurrence and extension of CA correlated (P = 0.005) with headache intensity. Modalities of cephalic and extracephalic CA were different (chi(2) = 12.03; P = 0.002), extracephalic CA being mostly thermal (75%) whereas cephalic CA was mostly mechanical (92%). This suggests that cephalic and extracephalic CAs involve different mechanisms.