Article

Treatment decisions in obstetric brachial plexus lesions are often based on
clinical paralysis of elbow flexion at 3 months of age, when electromyography
(EMG) is misleading because motor unit potentials (MUPs) occur in clinically
paralytic muscles. We investigated whether EMG at 1 week or 1 month identifies
infants with flexion paralysis at 3 months, allowing early referral. METHOD:
Forty-eight infants (27 females, 21 males) were prospectively studied. The
presence or absence of flexion paralysis at around 1 week (median 9 d; range
5-17d), 1 month (median 31 d; range 24-53 d), and 3 months of age (median 87 d;
range 77-106 d) was noted for clinical (shoulder external rotation, elbow
flexion, extension, and supination) and EMG parameters (denervation activity,
MUPs and polyphasic MUPs in the deltoid, biceps, and triceps muscles). RESULTS:
At 1 month, the absence of biceps MUPs had a sensitivity of 95% for later flexion
paralysis, and absence of deltoid MUPs had a sensitivity of 100% for flexion
paralysis; the false-positive rates for the same findings were 21% and 33%
respectively. EMG at 3 months was highly misleading as MUPs were seen in 19 of 20
clinically paralytic biceps muscles. INTERPRETATION: EMG at 1 month can identify
severe cases of flexion paralysis for early referral EMG of the biceps at 3
months is highly misleading; the discrepancy between the EMG and clinical testing
may be due to abnormal axonal branching and aberrant central motor control.
CI - (c) The Authors. Developmental Medicine & Child Neurology (c) 2012 Mac Keith
Press.

Langue : ANGLAIS