Variability of plantar response in normal population

ABSTRACT

Background: There is lack of normality data in the literature on the plantar response. Objective: To determine the variability of plantar response in normal population and factors that might contribute to the variability. Methods: We conducted a study of plantar response in healthy subjects aged 19-21 in two phases. First phase was plantar examination with hard strike. Subjects with big toe extension in the fi rst phase were re-examined with light and hard strike in the second phase. Results: 100 subjects recruited in fi rst phase, 19 subjects in second phase. Out of 600 attempts (3 attempts for each foot) with hard strike, responses of the big toe were fl exion (48.3%), extension (11.3%), no movement (39.8%); other toes were fl exion (55.0%), extension (13.0%), no movement (32.0%); ankle was dorsifl exion (30.8%), no movement (59.3%); knee were fl exion (15.7%), no movement (84.3%); hip were fl exion (15.2%), no movement (84.8%). Of those with big toe extension, signifi cantly less had persistent big toe extension with light strike. More (41%) among those with extensor big toe has withdrawal response (with fl exion of the hip and knee) as compared to those with fl exor big toe (18.5%, p<0.05). Interfoot asymmetry was seen in 27% (kappa 0.54). Plantar responses of sequential strikes were mostly consistent, with only 3.5% inter-attempt variability. Conclusion: Plantar response with extensor great toe is seen in about 10% of normal adults, less with lighter strike. Withdrawal response can be a partial explanation to the big toe extensor response in normal adults.