Surface Mapping of Motor Points in Biceps Brachii Muscle

OBJECTIVE: To localize the site of motor points within human biceps brachii muscles through surface mapping using electrophysiological method. 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. RESULTS: 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). CONCLUSION: 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.

Surface Mapping of Motor Points in Biceps Brachii Muscle

OBJECTIVE: To localize the site of motor points within human biceps brachii muscles through surface mapping using electrophysiological method. 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. RESULTS: 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). CONCLUSION: 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.

Surface Mapping of Masseter for Botulinum Toxin Injection

Generally, many Asian women tend to dislike the square jaw, as they believe it makes the face look wider, giving a stubborn and strong impression. Contouring of the mandible is therefore a relatively common aesthetic procedure among Asians. These days, the use of botulinum toxin for contouring of the lower face offer simple alternative to surgery. Motor point, which is the site over a muscle where its contraction may be elicited by a minimal intensity short duration electrical stimulus, is the optimal injection point of botulinum toxin. Study was undertaken to identify the location of motor point of the masseter muscle and the skin surface landmark. First, the thickest point of the masseter muscle was inspected through palpation and inspection by 3 different individual plastic surgeons and then compound muscle action potentials(CMAPs) of masseter muscle in 15 health volunteers were recorded using EMG. For the localization of the measured points, line between lateral canthus to the mandibular angle was used. Location of motor points were mapped to skin surface from lateral canthus in a percentage of the distance along the landmark line and in distance in millimeters. The clinical injection point was located at 71.69 percentile and 7.3mm of the landmark line. The motor point test was located at 72.54 percentile and 7.1mm of the landmark line. The depth of motor point was 16mm. There was no statistically significant difference between the clinical injection point and the motor point. We conclude that surface mapping of motor point of the masseter muscle would increase accessibility and accuracy in botulinum toxin injection for contouring of the lower face.

Myocardial Infarction: Comparison of 12-Lead Electrocardiographic Criteria with 80-Lead Body Surface Mapping

PURPOSE: Right ventricular (RV) infarction is associated with increased morbidity and mortality in patients with acute inferior wall myocardial infarction (MI). A 12-lead electrocardiogram (ECG) has a poor tendency to identify RV involvement. Our objective was to evaluate the diagnostic accuracy of 80-lead body surface mapping (BSM) for RV infarction and to compare diagnostic accuracy of 12-lead ECG criteria and 80-lead BSM for RV infarction in patients with acute inferior wall MI. METHODS: Between September 2002 and January 2003, 96 patients visited to our emergency center with AMI. All standard initial 12-lead ECG and 80-lead BSM were examined and compared with angiographic and echocardiographic findings. RESULTS: Thirty-one patients were confirmed as inferior wall MI. With the use of exclusion criteria, sixteen patients included in this study. RV infarction accompanied in 5 patients of these 16 patients. BSM showed a high sensitivity (60%), specificity (82%), high positive and negative predictive values (60%, and 82%, respectively), and high diagnostic accuracy (75%) in diagnosing RV infarction in patients with acute inferior wall MI. BSM showed increase in the sensitivity for RV infarction from 40% to 60% when compared with the 12-lead ECG. CONCLUSION: The 80-lead BSM is a more useful test in diagnosing RV infarction in patients with acute inferior wall

Surface Mapping of Motor Points of Gastrocnemius and Soleus Muscles

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.