Visualizing and Evaluating Finger Movement Using Combined Acceleration and Contact-Force Sensors: A Proof-of-Concept Study

The 10-s grip and release is a method to evaluate hand dexterity. Current evaluations only visually determine the presence or absence of a disability, but experienced physicians may also make other diagnoses. In this study, we investigated a method for evaluating hand movement function by acquiring and analyzing fingertip data during a 10-s grip and release using a wearable sensor that can measure triaxial acceleration and strain. The subjects were two healthy females. The analysis was performed on the x-, y-, and z-axis data, and absolute acceleration and contact force of all fingertips. We calculated the variability of the data, the number of grip and release, the frequency response, and each finger’s correlation. Experiments with some grip-and-release patterns have resulted in different characteristics for each. It was suggested that this could be expressed in radar charts to intuitively know the state of grip and release. Contact-force data of each finger were found to be useful for understanding the characteristics of grip and release and improving the accuracy of calculating the number of times to grip and release. Frequency analysis suggests that knowing the periodicity of grip and release can detect unnatural grip and release and tremor states. The correlations between the fingers allow us to consider the finger’s grip-and-release characteristics, considering the hand’s anatomy. By taking these factors into account, it is thought that the 10-s grip-and-release test could give us a new value by objectively assessing the motor functions of the hands other than the number of times of grip and release.

Development and Evaluation of a New Assessment Tool for Myelopathy Hand Using Virtual Reality

Background: Impairment of hand function in myelopathy patients is commonly observed. However, no objective and effective method is widely accepted in clinical practice.Objective: To evaluate the validity, reliability and effectiveness of a new assessment tool, Myelopathy-hand Functional Evaluation System (MFES), in evaluating the hand function in the 10-s hand grip-and-release test (10s G-R test).Methods: MFES is mainly composed of a pair of wise-gloves and a computer with software. All included patients received optimal surgery treatment. The Japanese Orthopedic Association (JOA) scores were performed and the hand function was evaluated using MFES before operation, and 6 months after surgery. All patients were asked to perform the 10s G-R test and the hand movements were simulated and converted into waveforms by MFES. The waveform parameters were measured and analyzed. The validity and test-retest reliability were assessed.Results: The Bland-Altman showed significant agreement with a low bias and narrow limits of agreement. The test-retest reliability was high with a significant value (r=0.911). The JOA scores and the number of G-R cycles significantly in postoperative increased. Correspondingly, the waveforms of ulnar three fingers were significantly higher and narrower, along with the significantly declined average time per cycle in postoperative. The number of the first five-second segment (N1) was significantly higher than the second-five segment (N2) in postoperative, indicating the recovery of spinal cord function after surgery. The preoperative number of cycles was positively correlated with the improvement rates of JOA scores. And the increased number of cycles was significantly correlated with the improvement rates of JOA scores.Conclusion: MFES is a reliable and valid assessment tool for myelopathy hand, which can detect small changes of neurological function after decompression surgery.

Hand Dexterity Impairment in Patients with Cervical Myelopathy: A New Quantitative Assessment Using a Natural Prehension Movement

Cervical myelopathy (CM) caused by spinal cord compression can lead to reduced hand dexterity. However, except for the 10 sec grip-and-release test, there is no objective assessment system for hand dexterity in patients with CM. Therefore, we evaluated the hand dexterity impairment of patients with CM objectively by asking them to perform a natural prehension movement. Twenty-three patients with CM and 30 age-matched controls were asked to reach for and grasp a small object with their right thumb and index finger and to subsequently lift and hold it. To examine the effects of tactile afferents from the fingers, objects with surface materials of differing textures (silk, suede, and sandpaper) were used. All patients also underwent the Japanese Orthopedic Association (JOA) test. Preoperative patients showed significantly greater grip aperture during reach-to-grasp movements and weaker grip force than controls only while attempting to lift the most slippery object (silk). Patients, immediately after surgery, (n=15) tended to show improvements in the JOA score and in reaction time and movement time with respect to reaching movements. Multiple regression analysis demonstrated that some parameters of the prehension task could successfully predict subjective evaluations of dexterous hand movements based on JOA scores. These results suggest that quantitative assessments using prehension movements could be useful to objectively evaluate hand dexterity impairment in patients with CM.