To localize the site of motor points within human biceps brachii muscles through surface mapping using electrophysiological method.
We recorded the compound muscle action potentials of each lattice of the biceps brachii in 40 healthy subjects. Standardized reference lines were made as the following: 1) a horizontal reference line (elbow crease) and 2) a vertical reference line connecting coracoid process and mid-point of the horizontal reference line. The Compound muscle action potentials were mapped in reference to the standardized reference lines. The locations of motor points were mapped to the skin surface, in the ratio to the length of the vertical and the half of the horizontal reference lines.
The motor point of the short head of biceps was located at 69.0±4.9% distal and 19.1±9.5% medial to the mid-point of horizontal reference line. The location of the motor point of the long head of the biceps was 67.3±4.3% distal and 21.4±8.7% lateral. The motor point of the short head of the biceps was located more medially and distally in the male subjects compared to that in the female (p<0.05).
This study showed electrophysiological motor points of the biceps brachii muscles through surface mapping. This data might improve the clinical efficacy and the feasibility of motor point targeting, when injecting botulinum neurotoxin in biceps brachii.
Citations
Objective: To identify the relationship between the location of motor points of gastrocnemius and soleus and the skin surface landmarks.
Method: Compound muscle action potentials (CMAPs) of each lattice of gastrocnemius and soleus in 11 healthy subjects were recorded. Standardized reference lines were made as follows: 1) a horizontal reference line (popliteal crease) and 2) a vertical reference line drawn between mid-points of the horizontal reference line and inter-malleolus connection line. The CMAPs were mapped horizontally and vertically 1cm width to the standardized reference lines. Location of motor points was mapped to the skin surface in the ratio of length of the vertical and horizontal reference lines.
Results: The motor point of medial head of gastrocnemius was located at 41.0⁑6.1% distal and 54.6⁑19.2% medial to the mid-point of horizontal reference line. The location of the motor point of the lateral head of gastrocnemius was 35.7⁑5.2% distal and 48.5⁑15.1% lateral, respectively. In the soleus, the motor point was at 68.6⁑8.0% distal and 10.5⁑9.0% lateral, respectively.
Conclusion: The motor point of the lateral head of gastrocnemius was located more proximally relative to medial head, and the motor point of soleus was located at slightly lateral side of the vertical reference line. The author concluded that mapping of motor points of the gastro-soleus muscles would increase accessibility in performing phenol motor point block or botulinum toxin injection for management of spasticity or abnormal tonicity of the ankle.
Objective: To investigate the clinical usefulness of the motor cortex mapping using transcranial magnetic stimulation (TMS) in stroke patients.
Method: Five stroke patients were studied. A piece of cloth which marked at 1 cm interval was fixed on the patient's head. Motor cortex mapping for abductor pollicis brevis muscles (APB) was performed with a butterfly coil or with a round coil if motor cortex mapping was impossible.
Results: Ipsilateral motor pathways were discovered from the unaffected motor cortex to the affected APB in patient 1. This patient showed delayed latency and low amplitude of ipsilateral motor evoked potentials (MEP) that seems to be evoked from the descending motor pathway rather than the corticospinal tract. In patient 2 and 3, contralateral motor pathways traveled from the affected hemisphere to the affected APB. The short latency and high amplitude of MEPs seems to be attributed to the corticospinal tract. In patient 4, no MEP was evoked by any hemisphere or magnetic stimulator. We believe that the affected APB had no motor pathway, and it correlated well with the poor motor function of her hand. In patient 5, contralateral pathways from the affected hemisphere to the affected APB were present. In this patient, the parameters of the motor cortex map such as the amplitude of MEP, the number of MEP evoked site, and the excitatory threshold were improved after 2 months, which correlated well with clinical improvement.
Conclusion: Motor cortex mapping using TMS is clinically useful for the evaluation of the characteristics of motor pathways and the change of motor cortex excitability in stroke patients.
The aim of this study is to investigate the mechanism of motor recovery using both functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS) in a patient with hemorrhagic contusion on the right basal ganglia area. Functional MRI showed that the left primary sensorimotor cortex and the supplementary motor area were activated when the right fingers performed the flexion-extension exercise. On the other hand, the bilateral primary sensorimotor cortex and the left premotor area were activated with the excerise of left hand. Brain mapping for both abductor pollicis brevis muscles (APB) using TMS revealed that ipsilateral motor evoked potentials (MEPs) were obtained at left APB. Ipsilateral MEPs of left APB showed delayed latency and lower amplitude compared to that of right APB when stimulated at the left motor cortex. We concluded that ipsilateral motor pathway from undamaged motor cortex seems to contribute to the motor recovery in this patient and combining TMS with fMRI may provide a powerful tool for investigating the mechanism of motor recovery.
Objective: To investigate the characteristics of the motor cortex map for abductor pollicis brevis muscle (APB) using transcranial magnetic stimulation (TMS) in normal subjects.
Method: Ten adults without neurological disorder were studied. A piece of cloth which marked at 1 cm interval was fixed on the head of the subject. The motor cortex mapping for APB was done with butterfly magnetic stimulator, and then with round magnetic stimulator.
Results: The average optimal scalp position for left APB was located on lateral 6.2 cm, anterior 0.1 cm from Cz and that for right APB was located on lateral 6.0 cm, anterior 0.1 cm from Cz when stimulated with butterfly magnetic stimulator. The differences between hemispheres were less than 1 cm in the location of optimal scalp position and less than 10% in excitatory threshold (ET) irrespective of magnetic stimulator. The ipsilateral motor evoked potential (MEP) was not evoked in all subjects. The ET when stimulated with butterfly magnetic stimulator was higher to that when stimulated with round magnetic stimulator.
Conclusion: We conclude that TMS using butterfly and round magnetic stimulator is useful for the motor cortex mapping.
Objective: To increase the accuracy and consistency in determining the level of radiculopathy by a needle electromyography (EMG) of multifidus muscle.
Method: We performed the EMGs on 29 patients with a low back pain to investigate an evidence of radiculopathy. All patients had the herniated nucleus pulposus (HNP) by a myelography, CT or MRI. The exclusion criteria were the patients with a scoliosis, spondylolisthesis or history of back surgery. We examined 5 points (P 1∼5) of the lumbosacral paraspinal muscles according to the paraspinal mapping by Haig et al and scored from 0∼4 according to the degree of abnormalities. The scores according to the points were correlated with the segments of radiculopathy and the levels of HNP.
Result: The maximal mean scores were 1.80⁑0.83 at P2 and 2.00⁑1.41 at P3 in a lumbar (L) 3, 4 radiculopathy, 2.00⁑0.56 at P5 in a L5 radiculopathy, and 2.13⁑0.64 at P4 and 2.63⁑0.51 at P5 in a S1 radiculopathy. The sensitivity/specificity was high at P2, P3 in a L3, 4 radiculopathy, at P4 in a L5 radiculopathy, at P5 in a S1 radiculopathy.
Conclusion: The results suggest that the localization of lumbosacral radiculopathy by a needle EMG of multifidus muscles provides an easy accessibility, better accuracy and consistency to determine the level of radiculopathy.
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