Evaluation of habituation to visual evoked potentials using pattern reversal among migraine individuals - a cross-sectional study

Background Migraine is a multifaceted chronic disease with common ocular symptoms. Habituation is the decremental response on repeated stimulations. The literature review indicates controversial results regarding habituation in migraine individuals. The present study aimed to compare the habituation response using visual evoked potential (VEP) measures among migraine and control subjects. Methods This was a cross-sectional study performed among migraine individuals attending the Department of Medicine and Neurology, of the age group of 18-30 years at Sri Manakula Vinayagar Medical College and Hospital, Puducherry. Habituation was evaluated in the two groups, control (n = 40) and migraine (n = 40), using pattern reversal VEP. The recording was done for 15-min duration and divided into four blocks of 3.8 min each. The results were compared employing Student t-test, and p < 0.05 was considered to be statistically significant. Results Our study indicates that latency N75, N145, and P100 amplitude showed significant differences between the two groups. In the right eye, on comparing the first and fourth block P100 amplitude in the migraine group, a significant increase (p < 0.001) was observed in the fourth block. Similarly, in the left eye, the control group showed a significant decrease in the fourth block (p = 0.002), whereas the migraine group showed a significant increase (p < 0.001). Conclusions The present study concludes that migraine individuals report deficient habituation, evaluated using pattern reversal VEP.

Quantifying abnormal writing kinematics in writer's cramp using a novel software platform

BACKGROUND

Writer's cramp is a task-specific focal hand dystonia, which is diagnosed clinically. Quantification of defect in WC is done using clinical scales, while digitized platforms are lacking.

OBJECTIVE

To design and test a platform that can differentiate and quantify the abnormal kinematics of writing using a software interface and to validate it in adult-onset isolated writer's cramp (WC).

METHODS

A native platform was designed using Java and Wacom Intuos pro tablet and the data analyzed using a MATLAB-based platform called Large Data-Based Evaluation of Kinematics in Handwriting (LEKH). We standardized this new platform by comparing the handwriting between patients with WC and age, and gender and education-matched healthy controls, using standard tasks to assess the kinematics.

RESULTS

Comparison of the writing of right-handed WC patients (N = 21) and 39 healthy controls (N = 39) showed that patients differed from controls in the frequency of strokes (P < 0.001), number of inversions of velocity (P < 0.001), number of breaks (P = 0.02), air time and paper time (P < 0.001).

CONCLUSIONS

Using the LEKH platform, the kinematic profile of patients with WC could be differentiated from healthy controls. Studies in larger samples will be needed to derive statistical models that can differentiate the flexion and extension types of WC which can help in muscle selection and to quantify the effects of treatment.