The digiti quinti sign in hemiplegic migraine: An fMRI study

Background and Purpose The digiti quinti sign (DQS) consists of a wider angle between the fourth and fifth fingers (ANG) indicative of subtle hemiparesis that has been found interictally in hemiplegic migraine (HM), suggesting a permanent subtle motor dysfunction. The aim of this study was to find a possible cortical origin for the DQS using blood oxygen level dependent (BOLD) functional (f) MRI. Methods Eight HM patients and 13 controls entered the cross-sectional study. We examined hand dominance, performed handgrip tests with dynamometry, documented the DQS graphically in two consecutive sessions, and used BOLD-fMRI during a motor task specifically designed to measure the evoked activation in the motor cortex (M1). The brain activation at the symptomatic side was compared with the contralateral hemisphere and with both correspondent hemispheres in controls. Results Subjects had a normal neurological examination, except for DQS in all HM patients. The activation amplitude (beta values) and the cluster extension (mm(3)) of the activation area in M1 was smaller at the affected side. Besides, the cluster extension correlated negatively with the disease time span. The ANG was wider bilaterally in patients and the fMRI signals were reduced in the patient's group. Conclusion The DQS, a relevant clinical finding in HM, indicates a disrupted cortical activation.

Automated summary

This study demonstrated the presence of Digiti quinti sign (DQS) in hemiplegic migraine patients, indicating a permanent subtle motor dysfunction and disrupted cortical activation. The activation amplitude and cluster extension in M1 were lower in the affected side of patients compared to controls.