Deformation Characteristics of Hand Movement During Grasping / 医用生物力学

Objective Based on the multi-camera digital image correlation (DIC) method, the dynamic deformation characteristics of human hand during grasping were studied. Methods A continuous four-camera DIC system was established to measure surface strain of the skin on the back of the hand during grasping process, and then through the connection between skin, joints, bones and muscles, the regular pattern of muscle deformation could be known indirectly. Results Four grasping postures (medium cylinder, lateral pinch, index finger extension, power sphere) were measured. It was found that the increases of strain magnitude were different at different positions on back surface of the hand under different grasping postures, and the maximum principal strains were between 0.1 and 0.3. The movement characteristics for each muscle group of the hand under different grasping postures were obtained through analysis. Conclusions This method has the characteristics of non-contact, full field, intuitive results, which provides a new way for in vivo measurement of dynamic deformation during grasping.

Reversed Hand Movement during Sleep in Patients with Obstructive Sleep Apnea

OBJECTIVE: Previous findings suggest that hand movement laterality is reversed during sleep. The present study aimed to verify this phenomenon and evaluate whether the extent of reversal is correlated with the severity of sleep apnea. METHODS: A total of 184 participants (mean age: 44.5±13.0 years; 81.5% males) wore actigraphs on both hands during sleep, and nocturnal polysomnography was simultaneously performed. RESULTS: Actigraphic indices of hand movement were significantly higher for the left hand than those for the right hand (p < 0.001), including total activity score, mean activity score, mean score in active periods and fragmentation index. Additionally, calculated differences between the fragmentation index for the left versus right hands were significantly correlated with the apnea-hypopnea index (AHI, r=0.149, p=0.032). The AHI was not significantly correlated with differences in hand movement between both hands movement assessed by total activity score (r=0.004, p=0.957), mean activity score (r=0.011, p=0.876), mean score in active periods (r=-0.080, p=0.255). CONCLUSION: More severe symptoms of obstructive sleep apnea was associated with larger degree of hand movement reversal at night. This result support the theory that homeostatic deactivation occurs in the dominant hemisphere during sleep.

Lateralization in the hand motor cortex during rehabilitation after acute cerebral infarction / 中华物理医学与康复杂志

Objective To observe any change in the laterality index (LI) in the active volume of the hand motor cortex during rehabilitation after acute cerebral infarction and to analyze the mechanisms involved in the rehabilitation of motor function.Methods Sixteen patients with acute cerebral infarcts were administered standard but individualized rehabilitation training.Blood oxygenation-dependent functional magnetic resonance imaging (BOLD-fMRI) was used to evaluate the active volume of their hand sensorimotor cortex (SMC) and the LI,at admission and after 14 days of rehabilitation.The Fugl-Meyer motor assessment for the hand (FMA) was used to evaluate hand function.Ten healthy volunteers were recruited as a control group and subjected to a single BOLD-fMRI examination to confirm the location and the volume of the active area when performing the same rehabilitation exercises.Results The baseline LI of affected hand SMC activation was significantly smaller than that of the unaffected hand [(0.010 ±0.808) versus (0.789 ± 0.157)],but no significant difference was observed between the affected and the unaffected hands after treatment.Rehabilitation therapy significantly increased the SMC LI of affected hand activation when compared with the baseline,but no such effect was observed with the unaffected hand.In 12 patients with dysfunction of the right hand as evaluated by the FMA,the baseline LI of the affected hand was smaller than that of the unaffected hand and that of the healthy volunteers.Conclusion Rehabilitation after acute infarction can promote functional recovery.The LI of the affected hand reflects cerebral plasticity during rehabilitation after acute cerebral infarction.

A control study on functional magnetic resonance imaging brain map in health adult undergoing clenching and relaxing the fist / 中国医师进修杂志

Objective To observe the characteristic of the functional magnetic resonance imaging (fMRI) brain map in health adult undergoing clenching and relaxing the fist, for exploring the essence of the fMRI brain map in patients suffering from motor dysfunction by cerebrovascular accidents. Methods Twelve healthy volunteers had been chosen to partake the experience. Everyone had accomplished the following three actions separately: (1) Only clenching and relaxing the fist of left hand. (2) Only clenching and relaxing the fist of right hand. (3) Clenching and relaxing the fist of both hands at one time. The data had been analyzed statistically using analysis of functional neuroimages (AFNI) software. Results Under condition of F (6,1121), P = 0.005. Only clenching and relaxing the fist of left hand had gained the following brain functional area: right precentral gyms, left parietal,right superior temporal gyrus,right parietal, right parahippocampal gyrus, right superior frontal gyrus, right medial frontal gyrus, left precuneus, right superior parietal lobule, right middle frontal gyrus, left superior frontal gyrus. Only clenching and relaxing the fist of right hand had gained the following brain functional area: left precentral gyms, left postcentral gyrus right parietal, right medial frontal gyrus. Clenching and relaxing the fist of beth hands simultaneously had gained the following brain functional area: left precentral gyms,left postcentral gyrus, right precentral gyrus, right postcentral gyrus. Conclusions Hand movement (clenching and relaxing the fist) has its own specific brain activated areas. The brain areas activated by clenching and relaxing the fist of both hands simultaneously concentrate in the motor area of both cerebral hemisphere. The brain areas activated by clenching and relaxing the fist of single hand contain not only the motor area, but also the supplementary motor area. As compared with the right handedness, the brain areas activated by clenching and relaxing the fist of left hand is more widespread.

Hand Function and Diffusion Tensor Imaging according to Response of Evoked Potentials in Post-stroke Hemiplegic Patients

OBJECTIVE: To investigate the association between evoked potentials and fractional anisotropy (FA) ratio in posterior limb of the internal capsule and hand movement scale (HMS) in post-stroke hemiplegic patients. METHOD: Thirty-six post-stroke hemiplegic patients with a lesion in the internal capsule were included in this study. Diffusion tensor imaging (DTI) was performed with a 3.0 tesla MR at about 1 month after stroke. FA ratio was measured in posterior limb of the internal capsule of the patients. Motor evoked potential (MEP) was obtained by magnetic stimulation of the motor cortex and recorded from the abductor pollicis muscle. Somatosensory evoked potential (SSEP) was obtained by electrical stimulation of the median nerve at the wrist and recorded from the somatosensory cortex. Hand movement scale was obtained at about 1 month and 3 months after stroke. RESULTS: Hand movement scale at about 1 month and 3 months after stroke and FA ratio were reduced significantly in patients who showed no response on MEP. However, no significant differences were observed between the patients who showed SSEP response and those who did not. FA ratio and hand movement scale were highly correlated to each other. CONCLUSION: MEP and FA ratio can be helpful in assessing the hand function at about 1 month and 3 months in post-stroke hemiplegic patients.

Recovery of Hand Motor Function in Patients with Subcortical Hemorrhage

OBJECTIVE: The aim of this study was to find out the factors related to the recovery of hand motor function in patients with subcortical hemorrhage. METHOD: We investigated 21 patients with subcortical hemorrhage prospectively. We used their CT and/or MR imaging for the localization and estimation of the size of lesion. The Hand Movement Scale (HMS) was used for evaluation of the hand function. Proprioception, initial shoulder and hand recovery were also measured every month for at least 6 months during the follow up periods. RESULTS: There are 13 patients with putaminal hemorrhage and 8 patients with thalamic hemorrhage. There is no difference in general characteristics between the two groups. When recovery began within 4 weeks after onset, only thalamic hemorrhage patients showed significantly good recovery. Initial shoulder shrug, especially within 4 weeks after onset, could be one of the prognostic factors of good hand motor recovery. Putaminal hemorrhage patients, who had higher scores on the hand movement scale, showed early recovery of proprioceptive function. CONCLUSION: Among many other factors which can be involved in the recovery of hand function in patients with subcortical hemorrhage, the time of initial hand motor recovery, the time of initial shoulder shrug, and proprioceptive function were most important.