Correlation of the Motor Evoked Potentials Amplitude and Hand Function of the Affected Side in Stroke.

, Son, Soo Youn; , Park, Sung Hee; , Seo, Jeong Hwan; , Ko, Myoung Hwan

Original Article

Journal of the Korean Academy of Rehabilitation Medicine 2011;35(1):34-41.

Son, Soo Youn , Park, Sung Hee , Seo, Jeong Hwan , Ko, Myoung Hwan

¹Department of Physical Medicine and Rehabilitation, Chonbuk National University Medical School, Jeonju 561-712, Korea.
²Research Institute of Clinical Medicine, Chonbuk National University Hospital, Jeonju 561-712, Korea. mhko@jbnu.ac.kr

Abstract

Objective
To investigate the correlation between the motor evoked potentials (MEPs) amplitude of 1^st dorsal interosseus in affected limbs and affected hand function after stroke. MethodWe enrolled 109 patients with acute and subacute 1^st attack stroke. Transcranial magnetic stimulation (TMS) was applied to the motor cortex and MEP was recorded at the 1^st dorsal interossei (DI) muscle. MEP parameters were latency of the affected side, latency ratio (latency of affected side/latency of unaffected side), amplitude of affected side and amplitude ratio (amplitude of affected side/latency of unaffected side). Hand function tests (HFT) including hand power measures and a nine hole peg test (NHPT) were conducted and the ratios of the value of the affected hand to unaffected hand were used for the analysis. The Korean version of the modified Barthel index (K-MBI) and the manual muscle test (MMT) of finger flexion were also evaluated. Correlation between MEP parameters and the clinical variables such as HFT, K-MBI and MMT grades were analyzed.
Results
While MEPs in the affected 1^st DI were recorded in fifty six patients, MEPs were not recorded in forty nine patients. The responsiveness of MEPs was significantly correlated with the HFT, K-MBI and MMT grades. The amplitude ratio had the most significant correlation with the HFT and MMT grade in this MEP study. Also, the amplitude ratio had more significant correlations with the K-MBI score compared with other MEP parameters. Conclusion We concluded that the amplitude ratio may be a useful MEPs parameter for indicating hand function.

Key Words: Motor evoked potential, Amplitude, Hand function, Stroke