Proprioceptive sensitivity to imposed finger deflections

Hand proprioception - the sense of the posture and movements of the wrist and digits - is critical to dexterous manual behavior and to stereognosis, the ability to sense the three-dimensional structure of objects held in the hand. To better understand this sensory modality and its role in hand function, we sought to characterize the acuity with which the postures and movements of finger joints are sensed. To this end, we measured the ability of human subjects to discriminate changes in posture and speed around the three joints of the index finger. In these experiments, we isolated the sensory component by imposing the postures on an otherwise still hand, to complement other studies, in which subjects made judgments on actively achieved postures. We found that subjects could reliably sense 12-16% changes in joint angle and 18-32% changes in joint speed. Furthermore, the acuity for posture and speed was comparable across the three joints of the finger. Finally, task performance was unaffected by the presence of a vibratory stimulus, calling into question the role of cutaneous cues in hand proprioception.

Objective Accuracy Indicators of the Single-Joint Arm Movements Simultaneous Reproduction with Closed Eyes and under Visual Control in Patients with Hemiparesis and Healthy Test Subjects (a New Method for Proprioceptive Sensitivity Objective Assessment)

Aim. We have developed a method for objective assessment of proprioceptive sensitivity (PS) based on determining the accuracy of reproduction with the eyes closed of the tested arm passive single-joint movements by active movements of the other arm during their execution. It was shown that healthy test subjects reproduce the passive movements with high accuracy, while post-stroke patients with hemiparesis reproduce a large proportion of paretic arm test movements with gross qualitative and quantitative errors. To make sure that the reproduction errors are associated with the state of PS but not with the cognitive factor or the functional state of the conditionally healthy arm, it was necessary to find out how accurately these patients are able to reproduce the test-movements under visual control. Materials and Methods. In 11 patients with a lesion in the right and in 9 patients in the left hemispheres of the brain and a control group of 23 healthy subjects, the accuracy of reproduction of the 5 elementary hand movements was studied: flexion-extension in the shoulder, elbow and wrist joints and abduction–adduction in the shoulder and wrist joints. The test person was subjected to a series of passive cyclic movements of the test hand during which he had to copy them with active movements of the other hand. The reproduction procedure for each test movement was performed first under visual control and then with the eyes closed. The angles in the test join and the same joint of the other arm were recorded. Qualitative and quantitative indicators were used to assess the degree of similarity of active and passive movements and to reveal the correspondence of copying accuracy to the previously developed conditional criterion of the norm (CCN) of PS in healthy test subjects. Results. It was shown that in healthy test subjects the accuracy of all movements copying in tests with closed eyes and 98% of movements in tests with opened eyes met the requirements of the CCN. In the group of patients in tests with eyes closed, copying only 61% of movements met this criterion. 20.4% of movements were reproduced with qualitative gross errors, 18.4% were copied qualitatively correctly but differed from CCN in quantitative indicators. In tests with visual tracking of passive movements, reproduction of 98% of movements was qualitatively correct and 83% of movements corresponded to CCN. Conclusions. The vast majority of single-articular movements of the paretic arm are copied by patients with unilateral brain damage under visual control qualitatively correctly and accurately (meeting the CCN). It means that in the course of the study of PS by the proposed method, they, as a rule, understand the motor task and can reproduce the tested movements with their conditionally healthy arm. From this it follows that the main cause of these movements impaired copying in tests with closed eyes is proprioceptive deficit.

Recent Ankle Injury, Sport Participation Level, and Tests of Proprioception

Objective: Assessing the effects of ankle injury and sport participation level on ankle proprioceptive sensitivity using a joint position reproduction (JPR) test and an inversion movement extent discrimination test. Design: Cross-sectional. Setting: Biomechanics lab. Participants: Forty-five student athletes ages 21–30 (mean = 24.8 y). Main Outcome Measures: Participants were tested for ankle inversion sensitivity using 2 devices; movement reproduction error was obtained from JPR in a non-weight-bearing (N-WB) state at 10° and 15° of inversion, and an ankle proprioceptive sensitivity score was obtained from the active movement extent discrimination apparatus (AMEDA), representing the ability to differentiate 5 inversion movement extents between 10.5° and 14.5°, with testing in both N-WB and weight-bearing (WB) states. Results: For the 34 athletes with no ankle injury in the previous 12 months, the sensitivity scores achieved on the AMEDA were significantly higher (P < .01) than those for the 11 athletes with ankle injury, and the injury effect was significantly greater in WB (P = .01). In JPR testing, the 2.96° error of reproduction for athletes with no recent ankle injury was not significantly different from the 3.36° error for those with ankle injury (P = .46). Correlation of current sport participation level with JPR showed less error for higher-level performers (r = .49, P = .001) but no significant relationship to WB or N-WB AMEDA scores (both P > .61). WB AMEDA scores were significantly higher for athletes who had competed at a higher level of sport competition when <18 years old (r = −.57, P < .001). Conclusions: Previous ankle sprains affected proprioceptive scores on the WB AMEDA and N-WB AMEDA tests, indicating the sensitivity of the AMEDA movement discrimination test to the effects of ankle injury. The correlation between JPR scores and current level of sport participation suggests the sensitivity of the JPR test to current ankle use.

CHARACTERISTICS OF BRAIN BIOELECTRICAL ACTIVITY DURING FEEDBACK TRAINING

Aim. The article deals with studying the effect of feedback training on the characteristics of brain bioelectrical activity. Materials and methods. 60 female non-athletes aged 18–20 years participated in the study. Sports training for improving the vestibular analyzer and proprioceptive sensitivity was conducted as well as feedback training with the data for ‘the projected center of mass position’ and ‘applied efforts’ parameters. EEG recording was conducted during the Romberg and Biryuk tests before and after the training course. Results. The specificity of the physiological mechanisms of various types of training, aimed at improving the vestibular analyzer and proprioceptive sensitivity, is reflected in the formation of special patterns of bioelectric activity of the cerebral cortex. Traditional training methods have the least effect on EEG characteristics, while biofeedback training is characterized by a more pronounced effect. Along with similar effects (the increased slow activity of theta and delta range, mainly in the frontal area of the cortex, and activation of high-frequency beta activity in the occipital leads), differences are also recorded. If training with the “projected center of mass position” parameter used as a BFB channel was accompanied by suppression of alpha-range activity, then training with the “applied efforts” parameter used as a BFB channel, on the contrary, increased the alpha activity in the occipital cortex. Conclusion. The parameters of bioelectrical activity of the cerebral cortex are informative when conducting biofeedback training and can be used to monitor its effectiveness and assess the physiological aspects.

Practical aspects of balance and vestibular rehabilitation after stroke

Balance and vestibular disorders are often detected in patients who have suffered a stroke. Instability may be caused by various reasons. In some cases, impairment of gait is caused by spastic paresis, in others by proprioceptive sensitivity and cerebellar disorders. Management of patients with balance disorders in the post-stroke period is composed of a detailed assessment of functional capabilities, the risk of falls and the cause of instability, as well as the adjustment of physical rehabilitation and drug therapy. The effective methods of physical rehabilitation include general exercises to strengthen stability and physical endurance, and special simulators with biological feedback. The drug therapy includes basic pharmacotherapy for the secondary prevention of stroke and symptomatic agents that can manage various disorders due to pathogenetic mechanisms of cerebral stroke (botulinum therapy, Vasobral).