We investigated the predictive value of intra-operative
neurophysiological investigations in obstetric brachial plexus injuries.
Between January 2005 and June 2011 a total of 32 infants of 206
referred to our unit underwent exploration of the plexus, including
neurolysis. The findings from intra-operative electromyography,
sensory evoked potentials across the lesion and gross muscular response
to stimulation were evaluated. A total of 22 infants underwent neurolysis
alone and ten had microsurgical reconstruction. Of the former, one
was lost to follow-up, one had glenoplasty and three had subsequent
nerve reconstructions. Of the remaining 17 infants with neurolysis,
13 (76%) achieved a modified Mallet score >
13 at a mean age of
3.5 years (0.75 to 6.25). Subluxation or dislocation of the shoulder
is a major confounding factor. The positive predictive value and
sensitivity of the intra-operative EMG for C5 were 100% and 85.7%,
respectively, in infants without concurrent shoulder pathology.
The positive and negative predictive values, sensitivity and specificity
of the three investigations combined were 77%, 100%, 100% and 57%, respectively. In all, 20 infants underwent neurolysis alone for C6 and three
had reconstruction. All of the former and one of the latter achieved
biceps function of Raimondi grade 5. The positive and negative predictive
values, sensitivity and specificity of electromyography for C6 were
65%, 71%, 87% and 42%, respectively. Our method is effective in evaluating the prognosis of C5 lesion.
Neurolysis is preferred for C6 lesions. Cite this article:
We retrospectively studied the possibility that direct trauma to the biceps muscle might be the cause of poor elbow flexion and supination in 18 consecutive children with birth lesions of the brachial plexus who had delayed or impaired biceps recovery despite neurophysiological evidence of reinnervation. All had good shoulder and hand function at three months of age. Eight recovered a strong biceps after six months, but nine required a pectoralis minor to biceps transfer to augment elbow flexion and supination. One had a delayed but good recovery of the biceps after microsurgical reconstruction of the plexus. All had a clinical ‘pseudotumour’ in the biceps muscle, which was biopsied during pectoralis minor transfer in two patients and showed rupture and degeneration of muscle fibres with a fibro-fatty infiltrate, suggesting previous muscle trauma. Direct muscle trauma is an uncommon but important cause of delayed or impaired biceps recovery after brachial plexus birth injuries. Surgery to reinnervate the biceps muscle will not work if substantial muscle damage is present when a suitable muscle transfer should be considered.
Whereas a general trend in the management of obstetric brachial plexus injuries has been nerve reconstruction in patients without spontaneous recovery of biceps function by three to six months of age, many recent studies suggest this may be unnecessary. In this study, the severity of glenohumeral dysplasia and shoulder function and strength in two groups of matched patients with a C5-6 lesion at a mean age of seven years (2.7 to 13.3) were investigated. One group (23 patients) underwent nerve reconstruction and secondary operations, and the other (52 patients) underwent only secondary operations for similar initial clinical presentations. In the patients with nerve reconstruction shoulder function did not improve and they developed more severe shoulder deformities (posterior subluxation, glenoid version and scapular elevation) and required a mean of 2.4 times as many operations as patients without nerve reconstruction. This study suggests that less invasive management, addressing the muscle and bone complications, is a more effective approach. Nerve reconstruction should be reserved for those less common cases where the C5 and C6 nerve roots will not recover.
