The loss of motor unit and it's influencing factors in patients with middle cerebral artery infarction / 中国神经精神疾病杂志

Objective To investigate the loss of motor unit and it's influencing factors in the lower motor neurons after middle cerebral artery infarction. Method Forty patients with first onset and unilateral middle cerebral artery infarction were divided into cortical-basal ganglia(26)and basal ganglia(14)groups and 10 healthy controls were served as control group.All included patients were scored by National Institute of Health stroke scale(NIHSS),modified Rankin scale (mRS), Fugl-Meyer Assessment (FMA) at 48 hours of admission. Nerve conduction study on the limb and motor unit number estimation (MUNE) on abductor pollicis brevis were performed at 2-4 weeks after onset, and the data of single motor action potential (SMUAP) were collected. SPSS 20.0 software was used to statistical analysis. Result The MUNE on were significantly lower and the amplitude and area of SMUAP were significantly increased in ipsilateral than contralateral sides (cortical-basal ganglia group:95.85±26.82 vs. 143.65±38.86, P<0.001; basal ganglia group: 126.71± 44.13 vs. 157.36±56.72, P=0.001). The affected MUNE was significantly decreased in the cortex-basal ganglia than in basal ganglia groups (95.85±26.82 vs.161.40±48.90,P=0.027). The MUNE was negatively correlated with NIHSS score (r=-0.362,P=0.022)and mRS score(r=-0.339,P=0.032).NIHSS score(β=-1.603,P=0.032,95%CI:-3.064~-0.142)and mRS score(OR=2.885,P=0.025,95%CI:1.139~7.158)on admission could predict the loss of MUNE on the affected side. Conclusion This study reveals the loss of motor unit and the compensation of remained motor unit on the affected side after middle cerebral artery infarction,NIHSS score and mRS score on admission may predict the loss of MUNE after stroke.

Motor-Unit Number Estimation Is Sensitive in Detecting Motor Nerve Involvement in Patients with Carpal Tunnel Syndrome

BACKGROUND AND PURPOSE: We compared the motor-unit number estimation (MUNE) findings in patients who presented with signs and/or findings associated with carpal tunnel syndrome (CTS) and healthy controls, with the aim of determining if motor-unit loss occurs during the clinically silent period and if there is a correlation between clinical and MUNE findings in CTS patients. METHODS: The study investigated 60 hands of 35 patients with clinical CTS and 60 hands of 34 healthy controls. Routine median and ulnar nerve conduction studies and MUNE analysis according to the multipoint stimulation method were performed. RESULTS: The most common electrophysiological abnormality was reduced conduction velocity in the median sensory nerve (100% of the hands). The MUNE value was significantly lower for the patient group than for the control group (p=0.0001). ROC analysis showed that a MUNE value of 121 was the optimal cutoff for differentiating between patients and controls, with a sensitivity of 63.3% and a specificity of 68.3%. MUNE values were lower in patients with complaints of numbness, pain, and weakness in the median nerve territory (p<0.05, for all comparisons), and lower in patients with hypoesthesia than in patients with normal neurological findings (p=0.023). CONCLUSIONS: The MUNE technique is sensitive in detecting motor nerve involvement in CTS patients who present with sensorial findings, and it may be useful in detecting the loss of motor units during the early stages of CTS. Larger-scale prospective clinical trials assessing the effect of early intervention on the outcome of these patients would help in confirming the possible benefit of detecting subclinical motor-unit loss in CTS.

The detection of motor nerve injury by MUNE in an animal model of diabetes / 天津医药

Objective To investigate motor nerve function status in rats with diabetes mellitus by motor unit number estimation (MUNE), and discuss it′s early diagnostic value in diabetic peripheral neuropathy (DPN). Methods Diabetic rat model (DM group) was induced by streptozotocin. The MUNE of gastrocnemius muscle and motor nerve conduction (MCV, CMAP) of the sciatic nerve were measured at the 4th, 8th and 12th week after onset of hyperglycemia in the DM group and the control group (normal SD rats). The ultrastructure of sciatic nerve was observed by electron microscope. Results At the 4th week, MUNE of gastrocnemius muscle was significantly decreased in DM group compared to that of the control group (275.88 ± 87.87 vs 369.71 ± 75.64,P<0.05). There were no significant differences in MCV and CMAP of sciatic nerve be?tween two groups. The electron microscopy observation showed that most nerve fibers were normal;a small amount of axonal atrophy, and myelin lamellar structure was separated in DM group. At the 8th week, compared with the control group, MUNE were reduced in gastrocnemius muscle in DM group (357.49±72.68 vs 221.26±92.41, P<0.01). There were no significant dif?ferences in MCV and CMAP of the sciatic nerve between DM group and control group. The electron microscope observation showed that part of nerve fibers were normal, the myelin focal plate layer was loose and separated, axonal atrophy, the axonal membrane and myelin sheath inner layer was separated with big gap. At the 12th week, MUNE of gastrocnemius muscle (127.87±19.80 vs 366.85±51.25), sciatic nerve MCV [(35.06±4.43) m/s vs (50.47±6.07) m/s] and CMAP [(2.91±1.37) mV vs (5.98±2.14) mV] were significantly decreased in DM group than those of control group (P<0.01). The electron microscopy observation showed severely damaged myelin flex and axonal squeeze. Conclusion MUNE is much earlier in detecting ear?ly motor nerve dysfunction in DM than conventional motor nerve conduction test.

Axon Count and Sympathetic Skin Responses in Lumbosacral Radiculopathy

BACKGROUND AND PURPOSE: Electrodiagnostic studies can be used to confirm the diagnosis of lumbosacral radiculopathies, but more sensitive diagnostic methods are often needed to measure the ensuing motor neuronal loss and sympathetic failure. METHODS: Twenty-six patients with lumbar radiculopathy and 30 controls were investigated using nerve conduction studies, motor unit number estimation (MUNE), testing of the sympathetic skin response (SSR), quantitative electromyography (QEMG), and magnetic resonance myelography (MRM). RESULTS: Using QEMG as the gold standard, the sensitivity and specificity of MUNE for the abductor hallucis longus muscle were 71.4% and 70%, respectively. While they were 75% and 68.8%, respectively, when used MRM as gold standard. The sensitivity and specificity of MUNE for the extensor digitorum brevis muscle were 100% and 84.1%, respectively, when the peroneal motor amplitude as the gold standard. The SSR latency was slightly longer in the patients than in the controls. CONCLUSIONS: MUNE is a simple and sensitive test for evaluating autonomic function and for diagnosing lumbosacral radiculopathy in patients. MUNE could be used routinely as a guide for the rehabilitation of patients with radiculopathies. SSR measurements may reveal subtle sympathetic abnormalities in patients with lumbosacral radiculopathy.

Motor Unit Number Estimation in Evaluating Disease Progression in Patients with Amyotrophic Lateral Sclerosis

We investigated the availability of motor unit number estimation (MUNE) as a quantitative method to assess the severity and clinical progression of amyotrophic lateral sclerosis (ALS). The 143 ALS patients were evaluated by statistical MUNE and the revised amyotrophic lateral sclerosis functional rating scale (ALSFRS-R). By using mean values of MUNE according to disease duration, regression equation between mean MUNE and disease duration was presented as a formula. The individual MUNE ratio was calculated by dividing individual MUNE value by mean MUNE value. All patients were classified into 2 groups (MUNE ratio or =1) according to the MUNE ratio. Comparison between the 2 groups revealed that the patients in MUNE ratio or =1 group were respectively assigned to rapid progression or slow progression. We recommended informative mean values of MUNE and best regression equation in ALS patients according to disease duration. These values allow us to evaluate the severity and rapidity of progression in ALS.

Estimation of Motor Unit Number According to Severity of Peripheral Nerve Injury in Rat

OBJECTIVE: To evaluate the changes of motor unit number estimation (MUNE) and the amplitude of compound muscle action potential (CMAP) according to severity of nerve injury in rat. METHOD: The sciatic nerve was compressed with two different severity (mild, severe) in 20 rats each. MUNE was performed in gastrocnemius of rat using the Poisson statistics. MUNE and amplitude of CMAP were compared according to severity of injury at two and four weeks after injury. RESULTS: The MUNE and amplitude of CMAP were significantly diminished at two and four weeks after nerve injury in severely injured rat. Both values were also diminished at two weeks after injury in mildly injured rat. The amplitude of CMAP was slightly increased at four weeks after mild injury despite of further decrement of MUNE. CONCLUSION: The MUNE and amplitude of CMAP changed differently according to severity of nerve injury in rat, which might represent different denervation and reinnervation process.

Motor Unit Number Estimation in Thenar Muscles of the Hemiplegic Patients

Motor unit number estimation(MUNE) was performed in the thenar muscles of 22 hemiplegic patients without a peripheral nerve lesion using the statistical method. The studies were done bilaterally in the affected and unaffected sides. The distal latency and conduction velocity of median nerve in the affected side were not different from those in the unaffected side. But the amplitude and area of the compound muscle action potential in the affected side were smaller than those in the unaffected side. Motor unit numbers in the affected side decreased than those of the unaffected side, especially in the first 6 months after the onset of hemiplegia. And the motor unit numbers in the affected side decreased as the muscle strength decreased. Single motor unit potential(SMUP) area in the affected side increased after 1 year from the onset of hemiplegia. The estimation of the number of motor units in the thenar muscles of hemiplegic patients could be an indicator for predicting recovery of the muscle power in hemiplegia.

Motor Unit Number Estimation of the Thenar Muscles

Thenar motor unit number estimation(MUNE) was performed in 49 normal subjects without known neuromuscular diseases using statistical method. The purposes of this study were to compare MUNE parameters between the dominant and non-dominant hands and to evaluate the changes according to age. Reproducibility was assessed in 20 subjects also. The results showed that thenar motor units number, maximum negative peak compound muscle action potential (CMAP) area and mean area of single motor unit potentials(SMUP) were not different between dominant and non-dominant sides, but maximum negative peak CMAP amplitude was larger in dominant than non-dominant side. With aging, the motor unit number, maximum negative peak CMAP amplitude and area decreased and the mean area of single motor unit potentials increased. There was a high reproducibility between the test and the retest values for motor unit number, maximum negative peak CMAP amplitude and area as well as mean area of single motor unit potentials. The statistical estimate of the motor unit number is a reliable method and easily available in clinical settings. The results of this study are expected to be used as a baseline data for the future.