Kazuto Akaboshi

Functional assessment of patients with spinal cord injury: measured by the motor score and the Functional Independence Measure

There is some information about the Functional Independence Measure (FIM) score of patients with spinal cord injury (SCI), but there are a few publications dealing with the relationship between the FIM score and the motor score of the American Spinal Injury Association (ASIA). We have studied the relationship of all FIM items with the motor score, and reviewed the disability of patients with spinal cord injury in greater detail. The purpose of this study was to describe the characteristics of impairment and disability in patients with SCI, using the FIM and motor score of the ASIA. The subjects were 100 inpatients with SCI (Frankel A, B). Neurological level, days from the onset, and the FIM were examined. In addition to these items, the ASIA motor scores were calculated for 22 tétraplégie patients. We investigated the relationships among these various respects. We also examined the changes of the physical items of the FIM score (physical FIM) over time for 18 patients. The mean FIM scores of those with tetraplegia with C4, C5, C6, C7, C8 lesions, and those with paraplegia with above T5 levels, and those below T6 were 35, 61, 82, 90, 116, 114 and 114 respectively. The FIM score reached the plateau in approximately 10 months, 6 months and 3 months post-injury, in tetraplegia, paraplegia above T5 and that below T6 respectively. The FIM scores in C6 patients were widely distributed from 56 to 104. On the other hand, the ASIA motor score could subdivide C6 patients and related well to the FIM score. The mean FIM scores for each neurological level were similar to those previously reported, thus they appeared to be plateau scores. With regard to the motor score, we feel that it could reflect the disability of the patients better than considering the neurological levels alone. Also considering the changes in the physical FIM score over time within a year from the onset of the injury, there were differences in the ADL improvement patterns among patients with different neurological levels. It appears that timing of the highest physical FIM improvement for each neurological level can exist. Thus it is important not to delay the start of the rehabilitation of patients with spinal cord injury in proper time.

Motor unit firing behavior in slow and fast contractions of the first dorsal interosseous muscle of healthy men

The motor unit recruitment threshold and firing rate were evaluated during slow and fast contraction of the first dorsal interosseous (FDI) muscle by healthy young men. Using a special quadrifilar electrode myoelectric activity was recorded during voluntary isometric contraction. Motor unit action potentials (MUAPs) were decomposed into individual MUAP trains by the electromyography (EMG) signal decomposition technique. Recruitment thresholds of the motor units decreased with the increase in the speed of contraction, and there was no recruitment reversal despite the increase. In terms of rate coding, the firing rates of the motor units increased as the speed of contraction increased; however, a high threshold motor unit always had a lower firing rate than a low threshold motor unit regardless of the contraction speed. At all contraction speeds, recruitment and rate coding may act through the same mechanism. If excitation of the motoneuron pool occurs rather than excitation of an individual motoneuron, a low threshold motor unit is easier to recruit and fire repetitively than a high threshold one. The motor unit firing behavior during fast contraction basically may be the same as during slow contraction.

Macro-EMG and motor unit recruitment threshold: differences between the young and the aged

The relationship between macro-EMG (electromyography) and motor unit recruitment threshold was studied in the first dorsal interosseous (FDI) muscle of normal young and aged subjects. During voluntary isometric contraction, motor unit action potentials (MUAP) were collected by a special quadrifilar electrode and decomposed to each MUAP train (MUAPT) using an EMG signal decomposition technique. Macro-EMG was obtained from the electrode shaft, then triggered and averaged for each MUAPT. A positive linear correlation was observed in both the young and aged subjects. However, the correlation coefficients were significantly lower in the aged individuals than in the young individuals.

Relationship between shoulder muscle strength and functional independence measure (FIM) score among C6 tetraplegics

The degree of disability varies widely among C6 tetraplegic patients in comparison with that at other neurological levels. Shoulder muscle strength is thought to be one factor that affects functional outcome. The aim of this study was to examine the relationship between shoulder muscle strength and the Functional Independence Measure (FIM) motor score among 14 complete C6 tetraplegic patients. The FIM motor score and American Spinal Injury Association (ASIA) motor score of these patients were assessed upon discharge. We evaluated muscle strength of bilateral scapular abduction and upward rotation, shoulder vertical adduction and shoulder extension by manual muscle testing (MMT). The total shoulder strength score was calculated from the summation of those six MMT scores. The relationships among ASIA motor score, total shoulder strength score and FIM motor score were analyzed. The total shoulder strength score was significantly correlated with the FIM motor score and the score of the transfer item in the FIM. In the transfer item of the FIM, the total shoulder strength score showed a statistically significant difference between the Independent and Dependent Group. Shoulder muscle strength appears to be an important factor in the functional abilities of those with C6 complete tetraplegia. Functional variation depends on the strength of shoulder muscles, especially among C6 tetraplegics.

Development of a new measure to assess trunk impairment after stroke (trunk impairment scale): its psychometric properties.

Fujiwara T, Liu M, Tsuji T, Sonoda S, Mizuno K, Akaboshi K, Hase K, Masakado Y, Chino N: Development of a new measure to assess trunk impairment after stroke (Trunk Impairment Scale): Its psychometric properties. Am J Phys Med Rehabil 2004;83:681–688. Objective:The purpose of this study was to investigate reliability, validity, internal structure, and responsiveness of our newly developed Trunk Impairment Scale (TIS) for patients with stroke. Design:A total of 73 patients with stroke participated in this prospective study. Interrater reliability (weighted kappa statistics), content validity (principal component analysis), concurrent validity (Spearmans rank correlation with the Trunk Control Test), predictive validity (prediction of discharge FIM™ scores), and responsiveness (standardized response mean values) were examined. Internal consistency and item difficulties were analyzed with Rasch analysis. Results:The weighted kappa of each TIS item ranged from 0.66 to 1.0. Principal component analysis revealed that the TIS measured a domain similar to the Stroke Impairment Assessment Set trunk items but different from the Stroke Impairment Assessment Set motor and visuospatial items. The TIS correlated with the Trunk Control Test (r = 0.91). To predict discharge FIM motor scores, addition of the TIS as one of the predictors to age, time from onset, and admission FIM score increased the adjusted R2 from 0.66 to 0.75. With Rasch analysis, the misfit was acceptable, except for the abdominal muscle strength item. The difficulty patterns were similar at admission and discharge, except for the abdominal muscle strength item. The responsiveness of the TIS was satisfactory and comparable with that of the Trunk Control Test (standardized response mean values, 0.94 and 1.06). Conclusions:Our newly developed TIS is reliable, valid, and responsive for use in stroke outcome research.

Quantitative EMG and motor unit recruitment threshold using a concentric needle with quadrifilar electrode.

According to Hennemans size principle, small motor units are recruited before large ones. We used the electromyographic (EMG) signal decomposition technique to determine the quantitative relationships between five motor unit action potential (MUAP) parameters (amplitude, duration, area, thickness, and size index) and the recruitment threshold of the motor units recruited up to 50% of the maximum voluntary contraction in the first dorsal interosseous, biceps brachii, rectus femoris, and tibialis anterior muscles of 5 healthy young men. In each muscle, the amplitude, duration, area, and size index had significant, positive high correlations with the motor unit recruitment thresholds. We conclude that the size principle applies to recordings made with concentric needle EMG electrodes under special recording conditions, and therefore that more importance should be attached to the patients contraction force during EMG examinations in order to evaluate MUAPs for electrodiagnostic purposes.

Herpes Zoster–Induced Trunk Muscle Paresis Presenting With Abdominal Wall Pseudohernia, Scoliosis, and Gait Disturbance and Its Rehabilitation: A Case Report

Herpes zoster (HZ)-induced abdominal wall pseudohernia has been frequently reported, but there has been no report describing HZ-induced trunk muscle paresis leading to functional problems. We describe a 73-year-old man with T12 and L1 segmental paresis caused by HZ presenting with abdominal wall pseudohernia, scoliosis, and standing and gait disturbance who responded well to a systematic rehabilitation approach. He first noticed a right abdominal bulge in the 6th postherpetic week, which was gradually accompanied by right convex thoracolumbar scoliosis, pain, and standing and gait disturbance in the 12th week. Needle electromyography revealed abnormal spontaneous activities at rest in the right T12 myotomal muscles, and motor unit recruitment was markedly decreased. We arranged an outpatient rehabilitation program consisting of using a soft thoracolumbosacral orthosis for pain relief and trunk stability, muscle reeducation of the paretic abdominal muscles, strengthening of the disused trunk and extremity muscles, and gait exercise. Based on electromyographic findings, we instructed him in an effective method of muscle reeducation. After 4 months of rehabilitation, he showed marked improvement and became an outdoor ambulator. We suggest that electromyography is a useful tool to evaluate clinical status and devise an effective rehabilitation program in patients with HZ trunk paresis.

Tonic and kinetic motor units revisited: does motor unit firing behavior differentiate motor units?

OBJECTIVE We tried to differentiate motor unit into two distinct populations, tonic and kinetic, on the basis of the relationship between the mean inter-spike interval and its variability. METHODS During voluntary isometric contraction myoelectric activity was recorded with a special quadrifilar electrode from first dorsal interosseous, biceps brachii, soleus, and tibialis anterior muscle. Motor unit action potentials (MUAP) were decomposed into individual MUAP trains, by electromyography (EMG) signal decomposition. The variability in the instantaneous firing rate was assessed at two or more levels of contraction in each muscle. RESULTS We found each muscle tested had a homogeneous population. There were no tonic and kinetic motor units. But there were differences in the variability in the instantaneous firing rate in the 4 muscles tested. CONCLUSION Motor unit firing behavior in a muscle may be fitted for its function.

B-13. Educational lecture B-13. Fun of needle electromyography

I think that many physicians feel “needle electromyography is interesting?” But it is interesting if you can understand and boring if you can not. For that, it is important to know the meaning of electromyogram waveform. Since any of these waveforms is a potential originating from the muscle fibers, it is natural that the appearances are similar, and experts can not judge only by that “shape”. They judge based on the rhythm of the waveform and muscular strength. It is important to know the characteristics of the waveform, for example, whether the waveform originates from one muscle fiber, whether it is firing as a motor unit, or a potential arising from multiple muscle fibers not related to motor units. It is also important to know whether the potential is generated by voluntary muscle contraction, irrelevant to muscle contraction or induced by needle sticking. For example, there are fibrillation potentials, positive sharp waves, and myotonic discharges as potentials to be generated from one muscle fiber, and the motion unit potential and the fasciculation potential are potentials generated from the motion unit. In this presentation, we will briefly describe other potentials and clinical points.

87. A parameter of ‘Activity’ is useful for quantitative evaluation of interference pattern in needle electromyography

The aim of this study was to decide an adequate parameter to evaluate interference pattern in needle electromyography quantitatively. We usually evaluate interference pattern by semiquantitative evaluation to 4 from 1;‘4’ is the state that base line is full of motor unit, and‘1’ is only one or two motor units. In this study, we compared semiquantitative evaluation and four quantitative parameters: ‘Activity’, ‘Peak counting’, ‘Integral value’ and ‘Average amplitude’, and considered which parameter was useful. We defined Activity as a ratio more than the threshold of ±50 V. We examined 46 muscles, in which 25 muscles had neurogenic changes, of seven patients who was necessary to take needle electromyography. We used concentric needle electrode for examination. As a result, four parameters showed high correlation between semiquantitative evaluation. A correlation coefficient was highest in Activity: Activity 0.898; Peak counting 0.833; Integral value 0.624; Average amplitude 0.728. Activity was useful when we evaluated semiquantitative evaluation 4, Peak counting was useful in evaluation 1 or 2 more in detail. It is particularly useful in muscle of a neurogenic change.