No study has previously analyzed pressure pain sensitivity of nerve trunks in migraine. This study aimed to examine the differences in mechanical pain sensitivity over specific nerves between patients with unilateral migraine and healthy controls.
Blinded investigators assessed pressure pain thresholds (PPT) over the supra-orbital nerves (V1) and peripheral nerve trunks of both upper extremities (median, radial, and ulnar nerves) in 20 patients with strictly unilateral migraine and 20 healthy matched controls. Pain intensity after palpation over both supra-orbital nerves was also assessed. A pressure algometer was used to quantify PPT, whereas a 10-point numerical pain rate scale was used to evaluate pain to palpation over the supra-orbital nerve.
The analysis of covariance revealed that pain to palpation over the supra-orbital nerve was significantly higher (P<0.001) on the symptomatic side (mean: 3.4, SD: 1.5) as compared with the nonsymptomatic side (mean: 0.5, SD: 1.2) in patients with migraine and both the dominant (mean: 0.2, SD: 0.4) and nondominant (mean: 0.3, SD: 0.5) sides in healthy controls. PPT assessed over the supra-orbital nerve on the symptomatic side (mean: 1.05, SD: 0.2 kg/cm2) was significantly lower (P<0.05) than PPT measurements on the nonsymptomatic side (mean: 1.35, SD: 0.3 kg/cm2) and either the dominant (mean: 1.9, SD: 0.2 kg/cm2) or nondominant (mean: 1.9, SD: 0.3 kg/cm2) sides in controls (P<0.001). Finally, PPT assessed over the median, ulnar, and radial nerves were significantly lower in patients with migraine as compared with controls (P<0.001), without side-to-side differences (P>0.6).
In patients with unilateral migraine, we found increased mechano-sensitivity of the supra-orbital nerve on the symptomatic side of the head. Outside the head, the same patients showed increased mechano-sensitivity of the main peripheral nerves of both upper limbs, without asymmetries. Such diffuse hypersensitivity of the peripheral nerves lends further evidence to the presence of a state of hyperexcitability of the central nervous system in patients with unilateral migraine.
*Department of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation of Universidad Rey Juan Carlos
†Esthesiology Laboratory of Universidad Rey Juan Carlos
§Departments of Neurology of Fundación Hospital Alcorcón and Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain
‡Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
Reprints: César Fernández-de-las-Peñas, PT, PhD, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avenida de Atenas s/n, 28922 Alcorcón, Madrid, Spain (e-mail: email@example.com).
Received for publication January 7, 2008; revised February 24, 2008; accepted November 3, 2008