Unilateral Muscle Weakness Research Articles

Patterns of asymmetry and energy cost generated from predictive simulations of hemiparetic gait

Hemiparesis, defined as unilateral muscle weakness, often occurs in people post-stroke or people with cerebral palsy, however it is difficult to understand how this hemiparesis affects movement patterns as it often presents alongside a variety of other neuromuscular impairments. Predictive musculoskeletal modeling presents an opportunity to investigate how impairments affect gait performance assuming a particular cost function. Here, we use predictive simulation to quantify the spatiotemporal asymmetries and changes to metabolic cost that emerge when muscle strength is unilaterally reduced and how reducing spatiotemporal symmetry affects metabolic cost. We modified a 2-D musculoskeletal model by uniformly reducing the peak isometric muscle force unilaterally. We then solved optimal control simulations of walking across a range of speeds by minimizing the sum of the cubed muscle excitations. Lastly, we ran additional optimizations to test if reducing spatiotemporal asymmetry would result in an increase in metabolic cost. Our results showed that the magnitude and direction of effort-optimal spatiotemporal asymmetries depends on both the gait speed and level of weakness. Also, the optimal speed was 1.25 m/s for the symmetrical and 20% weakness models but slower (1.00 m/s) for the 40% and 60% weakness models, suggesting that hemiparesis can account for a portion of the slower gait speed seen in people with hemiparesis. Modifying the cost function to minimize spatiotemporal asymmetry resulted in small increases (~4%) in metabolic cost. Overall, our results indicate that spatiotemporal asymmetry may be optimal for people with hemiparesis. Additionally, the effect of speed and the level of weakness on spatiotemporal asymmetry may help explain the well-known heterogenous distribution of spatiotemporal asymmetries observed in the clinic. Future work could extend our results by testing the effects of other neuromuscular impairments on optimal gait strategies, and therefore build a more comprehensive understanding of the gait patterns observed in clinical populations.

Hirayama Disease Diagnosed after COVID-19 mRNA Vaccination in an Adolescent Patient: A Case Report

Hirayama disease is characterized by initially progressive muscular weakness and wasting of the distal upper limbs in young people. It has a male predominance, and its progression spontaneously arrests within several years. Here, we report the case of a 15-year-old girl with findings of Hirayama disease on spinal magnetic resonance imaging (MRI) after she visited the hospital with unilateral muscle weakness that occurred after coronavirus disease 2019 mRNA vaccination. She was asymptomatic for 3 weeks after vaccination; however, starting the night before hospitalization, her right limb began to lose strength. MRI demonstrated typical Hirayama disease findings.

Gluteus Maximus Muscle Activation Characteristics During a Chair-Rise in Adults With Chronic Stroke.

A successful chair-rise is an important indicator of functional independence post-stroke. Lower extremity electromyographic analyses provide a basis for muscle activation from which clinical intervention protocols may be derived. Gluteus maximus activation during the chair-rise has not been thoroughly researched in the chronic stroke population. This study investigated the magnitude and onset of gluteus maximus activation during the chair-rise comparing adults post-stroke with healthy controls. In this cross-sectional study, adults with chronic stroke (n = 12) and healthy controls (n = 12) completed 4 natural-speed chair-rise trials. Magnitude and onset of bilateral gluteus maximus activation were measured during the movement with secondary comparative data from biceps femoris and vastus lateralis muscles. Kinetic and kinematic measurements were used to quantify chair-rise phases and movement cycle duration. Significant decreases in paretic ( P = 0.002), and nonparetic ( P = 0.001) gluteus maximus magnitudes were noted post-stroke compared with ipsilateral extremities of healthy adults. Significant gluteus maximus onset delays were noted in paretic extremities compared with nonparetic extremities post-stroke ( P = 0.009) that were not apparent in comparative muscles. Similar onset times were noted when comparing the paretic extremity post-stroke to the ipsilateral extremity of healthy controls ( P = 0.714) despite prolonged movement cycle durations in those with chronic stroke ( P = 0.001). No onset delays were evident in the biceps femoris ( P = 0.72) or vastus lateralis ( P = 0.338) muscles. Despite apparent unilateral muscle weakness post-stroke, bilateral decreases in gluteus maximus activation magnitudes and compounding onset deficits of the paretic extremity were observed during chair-rising. Further research is needed to determine whether interventions maximizing bilateral activation magnitudes and improving temporal activation congruency during chair-rising will carry over to functional gainsVideo Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A387 ).

Параліч Белла: літературна довідка та власний клінічний випадок

Bell's palsy is an acute peripheral paralysis of the facial nerve of unknown etiology. The facial nerve is the seventh cranial nerve. One part of the facial nerve is the motor fibers that innervate the facial muscles. The facial nerve emerges from the brain between the posterior edge of the pons and the medulla oblongata with two roots. The main motor nucleus is responsible for the voluntary control of facial muscles. There are central and peripheral paresis of the facial nerve. Central paresis occurs during а stroke. Peripheral paresis (unilateral muscle weakness of the entire half of the face) develops when the facial nerve is affected from the motor nucleus to the exit from the stylomastoid foramen. Among the various localizations of damage to the peripheral part of the facial nerve, the most common is Bell's palsy as a result of edema and compression of the nerve in the bone canal. Clinical symptoms of facial nerve neuropathy are characterized by acute paralysis or paresis of facial muscles: smoothed skin fold on the affected side of the face; swelling of the cheeks; an inability to close the eyelid, Bell's symptom; facial muscle weakness. The degree of damage is determined by the House Brackmann scale. Treatment with glucocorticosteroids, antiviral drugs, physiotherapy procedures. Purpose — to present a clinical case of a patient with Bell's palsy as an example of delayed diagnosis, treatment and, as a result, long-term restoration of the facial muscles functions. Clinical case. The boy after suffering from the flu, began to complain of acute ear pain, vomiting, lack of movement in the right half of the face, dizziness, insomnia. Asymmetry of the face, lack of movement of the right side of the face, inability to completely close the right eye, a symptom of sailing on the right, muscle weakness were revealed during examination. The general condition of the patient improved, facial expressions were restored, sleep was normalized after hormonal, metabolic therapy, physiotherapy procedures. Conclusions. The article describes a case of inflammation of the facial nerve or Bell's palsy in a teenager who developed on the background of the flu. Timely diagnosis and treatment of the above pathology is the key to a satisfactory prognosis for the restoration of facial expressions, prevention of negative consequences of the the disease. The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: facial nerve, Bell's palsy, flu, inflammation.

Learning to Collaborate From Simulation for Robot-Assisted Dressing

We investigated the application of haptic feedback control and deep reinforcement learning (DRL) to robot-assisted dressing. Our method uses DRL to simultaneously train human and robot control policies as separate neural networks using physics simulations. In addition, we modeled variations in human impairments relevant to dressing, including unilateral muscle weakness, involuntary arm motion, and limited range of motion. Our approach resulted in control policies that successfully collaborate in a variety of simulated dressing tasks involving a hospital gown and a T-shirt. In addition, our approach resulted in policies trained in simulation that enabled a real PR2 robot to dress the arm of a humanoid robot with a hospital gown. We found that training policies for specific impairments dramatically improved performance; that controller execution speed could be scaled after training to reduce the robot's speed without steep reductions in performance; that curriculum learning could be used to lower applied forces; and that multi-modal sensing, including a simulated capacitive sensor, improved performance.

Effect of Contralateral Strength Training on Muscle Weakness in People With Multiple Sclerosis: Proof-of-Concept Case Series.

The contralateral strength training (CST) effect is a transfer of muscle performance to the untrained limb following training of the contralateral side. The aim of this study was to explore, in individuals with multiple sclerosis (MS) presenting marked lower limb strength asymmetry, the effectiveness of CST on management of muscle weakness of the more-affected limb following training of the less-affected limb. A single-subject research design was used. Eight individuals with MS underwent 16 to 18 high-intensity training sessions of the less-affected ankle dorsiflexor muscles. The primary outcome measure of this single-system case series was maximal strength expressed as peak moment and maximal work. Secondary outcome measures were: Six-Minute-Walk Test, Timed "Up & Go" Test, 10-Meter Timed Walk Test, and Multiple Sclerosis Quality of Life-54 questionnaire. After the 6-week intervention, the contralateral more affected (untrained) limb showed a 22% to 24% increase in maximal strength. From pretest-posttest measurements, participants also performed significantly better on the clinical and functional secondary outcome measures. At the 12-week follow-up, the strength levels of the weaker untrained limb remained significantly superior to baseline levels in the majority (5 out of 8) of the outcome parameters. Considering the design used, the absence of a control group, and the sample size, these findings should be cautiously generalized and will need confirmation in a properly planned randomized controlled trial. The present proof-of-concept study shows, for the first time, the occurrence of the CST effect on muscle performance of ankle dorsiflexor muscles in people with MS. These preliminary findings reveal new potential implications for CST as a promising rehabilitation approach to those conditions where unilateral muscle weakness does not allow or makes difficult performing conventional strength training of the weaker limb.

Muscle Weakness in a Patient with History of Poliomyelitis: A Differential Diagnosis for Post-polio Syndrome (PPS) and Dermatomyositis

Dermatomyositis (DM) is an idiopathic inflammatory myopathy, characterized by inflammation of the proximal skeletal muscles and typical skin manifestations, which results in symmetric muscle weakness. A 43year-old man was presented with skin rash and left leg weakness, and he had a history of poliomyelitis. Initially, he was diagnosed as having post-polio syndrome (PPS) due to unilateral muscle weakness and a result of an the electromyography (EMG), which had shown patterns of PPS. After 4 months with conservative therapy for PPS, weakness of bilateral upper arms had developed and skin rashes on his entire body had aggravated and progressed. He was diagnosed as having dermatomyositis, based on elevated muscle enzyme levels, typical skin rashes, and typical EMG findings, which indicated muscle disease. When a patient with previous poliomyelitis has a newly developed muscle weakness or pain, we should consider various possible causes other than PPS.

Forces and moments in knee–ankle–foot orthoses while walking on irregular surfaces

Kinetic data provide important information about the mobility performance of individuals with lower limb impairments and their assistive devices; however, there is limited understanding of this in real-life environments. To evaluate the effect of real-life irregular surfaces on forces and moments in knee-ankle-foot orthoses. In this case series study, a load cell was used to measure the forces and moments at the knee joint of knee-ankle-foot orthoses of individuals with unilateral muscle weakness as a result of poliomyelitis while walking on different ground surfaces and at different speeds. Significantly higher shear forces and external peak knee flexion moments were found when walking on irregular surfaces. In individual cases, certain irregular ground conditions elicited large increases in peak flexion moments (>50%) when compared to walking on smooth level ground. Forces and moments were significantly higher at faster walking speeds. Higher external peak knee flexion moments during the stance phase suggest that greater demands for support and stability are placed on individuals and their assistive devices when negotiating real-life ground surfaces. Clinical relevance This study demonstrates that walking on irregular surfaces alters the loads placed on knee-ankle-foot orthoses and that the requirements for knee stabilization increase. This has important clinical implications on the design, prescription, and use of such devices given the structural and functional demands placed on them.

A late neurological complication following posterior correction surgery of severe cervical kyphosis.

Though a possible cause of late neurological deficits after posterior cervical reconstruction surgery was reported to be an iatrogenic foraminal stenosis caused not by implant malposition but probably by posterior shift of the lateral mass induced by tightening screws and plates, its clinical features and pathomechanisms remain unclear. The aim of this retrospective clinical review was to investigate the clinical features of these neurological complications and to analyze the pathomechanisms by reviewing pre- and post-operative imaging studies. Among 227 patients who underwent cervical stabilization using cervical pedicle screws (CPSs), six patients who underwent correction of cervical kyphosis showed postoperative late neurological complications without any malposition of CPS (ND group). The clinical courses of the patients with deficits were reviewed from the medical records. Radiographic assessment of the sagittal alignment was conducted using lateral radiographs. The diameter of the neural foramen was measured on preoperative CT images. These results were compared with the other 14 patients who underwent correction of cervical kyphosis without late postoperative neurological complications (non-ND group). The six patients in the ND group showed no deficits in the immediate postoperative periods, but unilateral muscle weakness of the deltoid and biceps brachii occurred at 2.8days postoperatively on average. Preoperative sagittal alignment of fusion area showed significant kyphosis in the ND group. The average of kyphosis correction in the ND was 17.6° per fused segment (range 9.7°-35.0°), and 4.5° (range 1.3°-10.0°) in the non-ND group. A statistically significant difference was observed in the degree of preoperative kyphosis and the correction angles at C4-5 between the two groups. The diameter of the C4-5 foramen on the side of deficits was significantly smaller than that of the opposite side in the ND group. Late postoperative neurological complications after correction of cervical kyphosis were highly associated with a large amount of kyphosis correction, which may lead foraminal stenosis and enhance posterior drift of the spinal cord. These factors may lead to both compression and traction of the nerves, which eventually cause late neurological deficits. To avoid such complications, excessive kyphosis correction should not be performed during posterior surgery to avoid significant posterior shift of the spinal cord and prophylactic foraminotomies are recommended if narrow neuroforamina were evident on preoperative CT images. Regardless of revision decompression or observation, the majority of this late neurological complication showed complete recovery over time.

Cervical Spondylotic Amyotrophy Treated by Anterior Decompression-Three Case Reports-

Cervical spondylotic amyotrophy (CSA) is a rare type of cervical spondylotic disorder. The surgical treatment of CSA is controversial. We treated three patients with the proximal type of CSA by anterior decompression. Three men (65, 61, and 58 years old) presented with CSA manifesting as unilateral muscle weakness and atrophy in the deltoid and biceps muscles without significant sensory deficit. Preoperative neuroradiological examinations revealed anterolateral spinal cord compression in one patient and ventral root compression in two patients at the C4-5 and C5-6 spaces. Magnetic resonance (MR) imaging showed no abnormal intramedullary signal intensity in any patient. Vertebrotomy deviated to the lesion side was performed to provide a better view of the laterally situated osteophytes. Anterior decompression was focused on the paramedial to lateral area, and further foraminotomy was performed according to the radiological findings. After decompression, intervertebral instrumentation was performed using titanium cervical cages. Two of the patients had good recovery of motor strength and one had moderate recovery despite persistent motor atrophy. Surgical intervention is effective in patients with CSA despite severe muscle atrophy unless MR imaging shows the presence of severe degenerative intramedullary lesion.

Changes in bone mineral content and density after stroke.

The purpose of this study was to determine whether there are differences in bone mineral content and density between paralyzed and nonparalyzed sides of patients who had sustained strokes associated with unilateral muscle weakness, to determine the relationship between duration of stroke and degree of demineralization and to compare the degree of demineralization in upper and lower limbs. The bone mineral content and density were measured by dual photon absorptiometry (high resolution scanning mode, Lunar DP4) in ambulant patients with a history of single completed strokes associated with unilateral weakness. The bone mineral content and density of each limb was determined by the region of interest analysis program. In the 30 patients included in this study, the bone mineral content and density were significantly less on the paralyzed than on the nonparalyzed side. The degree of demineralization was more pronounced in the upper than in the lower limbs. The mean percentage differences in bone mineral content and density between paralyzed and nonparalyzed arms were 13.8% (P < 0.00001) and 7.95% (P = 0.0003), respectively, and between paralyzed and nonparalyzed legs the differences were 4.5% (P = 0.0012) and 3.42% (P = 0.0028), respectively. A better correlation was noted between the time elapsed since the stroke and the degree of demineralization in the upper limbs (r = 0.75, P < 0.0001), than in the lower limbs (r = 0.60, P = 0.0004). In conclusion, patients who have strokes associated with muscle weakness are at an increased risk of developing osteoporosis on the paralyzed side and particularly in the upper limbs.

The influence of arthrogenous muscle inhibition on quadriceps rehabilitation of patients with early, unilateral osteoarthritic knees.

Reflex arthrogenous muscle inhibition (AMI) may cause muscle atrophy or impede effective rehabilitation of affected muscle groups. To investigate this, bilateral quadriceps AMI, isometric and isokinetic muscle strength were measured in 10 patients with unilateral osteoarthritic knees, before and after a course of routine physiotherapy. Before rehabilitation, quadriceps of all the diseased legs were inhibited (P < 0.05) and 40% weaker (P < 0.02) than the non-diseased legs. Following rehabilitation, AMI decreased (P < 0.01) in the diseased leg and strength increased at all test velocities (P < 0.05-0.005); however, strength deficits compared with the non-diseased leg remained. Subjective improvements in functional ability and confidence in the diseased leg were reported. Though AMI may be partially responsible for unilateral muscle weakness, it does not preclude strength gain in affected muscles. Possible physiological mechanisms which evoke AMI may also adversely affect muscle proprioception, implicating AMI as a possible cause of initiation or progression of degenerative joint disease.