The Electrophysiology Study Of Trunk Muscles In Stroke

Objective: Hemiparesis caused by upper motor lesions is known to be more detrimental to distal than proximal body musculature. This "proximal to distal" gradient of impairment is explained by the fact that motor neurons innervating axial and proximal limb muscles receive both ipsilateral and contralateral descending inputs, whereas peripheral muscles are supplied by motor neurons, of which the supraspinal input is mainly contralateral. But in the rehabilitation course of hemiparesis, the disfunction of trunk muscles is also seen. There some reports that the flexion-extension function of trunk muscles decrease. Some believe that the imbalance of paretic side and non-paretic side caused by the enhanced activity of trunk muscles contributes to the decrease. While some one have the contrary result. About rotatory function, there is no relative reports except Japanese scholar' study using cybex to analyse the rotatory function. This paper uses surface EMG to collect data of flexion- extension muscles and rotatory muscles, and to study the presentation of lumber,thoracic erector spinae and rectus abdominis in trunk flexion-extension and the presentation of internal oblique,external oblique,latissimus dorsi,mass pectoris,lumber erector spinae,thoracic erector spinae in rotatory. To depict the change of trunk muscles and to clarify the clinical sense is the main purpose of this study. Subjects and methods: 18 strokes and 7 normals are involved in this study. Before test, all the patients accept MAS. According to MAS, the patients are divided into two groups: hemiplegia: sitting balance is beween II and IV degree and walking ability is below III degree. Hemiparesis: sitting balance is beyond V (including V) and walking ability is beyond V (including V). We choose 7 normals as controls. We use DNI-200P EMG machine and Ag-Agcl surface electrodes. Deal with the skin carefully when place electrodes and collect the EMG signals of bilateral lumber erector spinae,thoracic erector spinae,rectus abdominis,internal oblique,external oblique,latissimus dorsi,mass pectoris. The subjects are fixed on the chair without backrest. They are required to carry out five kinds of actions: (1) from relaxed sitting to upsitting. (2) to upsitting to forward 45degree. (3) to upsitting to backward 30 degree. (4) to upsitting to left rotatory 45degree.(5) to upsitting to right rotatory 45degree. At the end of each action, the EMG signals are collected three times every 2 seconds. We calculate the mean voltage value as the main data. Use SPSS 11.0 to analyse the data. Use independent t test to analyse the difference within the groups and use one way ANAVO to analyse the difference between groups. The significance is P <0.05, bilateral tested. Results: The curve of erector spinae of normals have apparent peak which occurs at forward/rest, while the curve of hemiplegia have not apparent peak no matter of paretic side and non-paretic side. There is significant difference between groups. The hemiplegia have less activity than hemiparesis and normals. When compared with normals, the rectus abdominis of hemiplegia have no apparent peak and tuough which occurs at backward/rest and forward/backward in normals. The significant difference between groups can also be seen. The hemiplegia have less activity than hemiparesis and normals. While the hemiparesis have the exactly the same activity when compared with normals. When compared with normals, the activity of internal oblique and latissimus dorsi decreases no matter when hemiplegia turn to the non-paretic side and non-paretic side. The activity of external oblique,mass pectoris have no significant difference when compared with normals. The normals have more activity of left erector spinae than of right erector spinae no matter when turn to left and turn to right. While the hemiplegia and hemiparesis have no such appearance. Hemiparesis have the same presentation of internal oblique,latissimus dorsi,external oblique,mass pectoris when compared with normals.