Background: Habituation of the nociception-specific blink reflex (nBR)
was found to be reduced interictally in migraine patients. This reduction may
be due to inherited susceptibility that is involved in migraine, as determining
a critical threshold, and also it may be responsible for interictal nervous
system dysfunction. Objective: To
search for an abnormal habituation pattern of the nBR in healthy asymptomatic
subjects who have a first degree relative affected by migraine, and to compare
them with healthy volunteers and migraine patients. Methods: The study was done on 25 patients suffering from migraine
without aura (MO), 25 subjects having at
least one first degree relative who suffers from migraine (HV-F), and 27
subjects without family history of migraine (HV). We elicited the nBR by
stimulating the right supraorbital region with a custom-built electrode.
Habituation was measured as the percentage area-under-the-curve decrease in 10
consecutive blocks of five averaged rectified responses. Results: The nBR habituation
was clearly reduced in MO and HV-F compared to HV. Percentage area under the
curve decreased between the 1st and the 10th block by 54.08 % in HV, 23.71 % in
MO (P = 0.001) and 27.42 % in HV-F (P = 0.049). A positive intra-individual
correlation was found between attack frequency and habituation in MO (r =
0.621; P = 0.010). Migraine patients have interictally a deficient habituation
of the nBR which is inversely related to attack frequency. Habituation
deficit was more evident in asymptomatic
individuals with a family history of migraine. Conclusion: Deficient nBR habituation could thus be a trait marker for
the genetic predisposition to migraine. A longitudinal follow-up study may be
needed for healthy subjects at high risk to compare the genotypes. [Egypt J Neurol Psychiat
Neurosurg. 2012; 49(1): 27-32]
Key Words: Migraine, habituation, blink reflex.
Correspondence to Aktham I. Alemam, Department of Neurology, Minoufiya University, Egypt.
Tel: +20109084905 E-mail:
e_aktham@yahoo.com