Page 73 - Read Online

Page 2 of 12 Mitchell et al. Plast Aesthet Res 2023;10:35 https://dx.doi.org/10.20517/2347-9264.2023.14

Despite our understanding of the epidemiology and presentation of these injuries, the workup can vary
significantly. This is seen primarily in the utilization of diagnostic imaging and electromyographic studies.
94% of surgeons surveyed obtained pre-operative advanced imaging. 80% routinely requested CT
myelography, 55% a brachial plexus MRI, and 41% obtained both studies pre-operatively. Furthermore,
electrodiagnostic studies were only acquired by approximately seven out of ten surgeons .
[2]
An MRI of the brachial plexus has the benefit of identifying signal changes both at the site of nerve injury as
well as a possible lesion distally. A CT myelogram, on the other hand, has the specific benefit of delineating
a nerve root avulsion vs. rupture. Plexus surgeons should be aware of this as a nerve rupture separates the
distal trunk from a healthy nerve root that can be grafted. In contrast, an avulsion injury requires extra-
plexal intervention.

Another inconsistency exists in the timing of surgical intervention. A survey completed by Belzberg et al.
among experienced brachial plexus surgeons revealed an average recommended time for surgery of 2.4
[2]
[3-5]
months . However, literature recommendations between 2 weeks up to 6 months have been reported .
Similarly, the time point after which surgeons recommend against nerve transfer/grafting ranges from six
months up to one year, citing concerns over endplate viability, muscle atrophy and joint contractures [2-4,6,7] .

One area of agreement is the priority of restoring elbow flexion and shoulder stability/abduction during the
initial intervention. These two functions are imperative in restoring the ability to self-feed and in
reestablishing rudimentary self-care. However, after this, there appear to be mixed preferences among
surgeons for restoration of elbow extension, finger flexion, wrist motion, and hand sensation. Restoration
techniques rely heavily on whether a C5 nerve root persists in a graftable state following acute PBPI. The
frequency of a graftable C5 nerve root varies in the literature from 15% to 88%. With such a high incidence,
most surgeons recommend brachial plexus exploration with a CT myelogram to ascertain C5 nerve root
viability prior to finalizing the reconstructive plan . Although less frequent, the same applies to the
[6,7]
presence of a graftable C6 nerve root and below.

In the case of complete plexus injuries, practical nerve transfer options must come from outside of the
plexus itself. This can include the spinal accessory nerve (SAN), the phrenic nerve (PN), the contralateral
cervical seventh nerve root (CC7), intercostal nerves (ICN), and/or the hypoglossal nerve in a variety of
donor-recipient combinations. Additional reconstructive options include tendon transfers, arthrodesis, and
free functional muscle transfers (FFMT). Given the complexity of this clinical topic, the heterogeneity of
PBPI, and the many permutations of treatment options that are available, multiple reasonable strategies may
be employed in the treatment of PBPI. The following review is not meant to be exhaustive or prescriptive,
but rather to describe three reasonable options that may provide a framework for surgeons who care for
these challenging injuries.

TREATMENT METHODOLOGIES
Method 1: extra-plexal nerve transfers
The most referenced method for PBPI intervention involves nerve transfers from outside the injured
brachial plexus, termed “extra-plexal transfers”. According to recent polls of experienced brachial plexus
surgeons, the SAN was the most utilized donor nerve, incorporated by 68% of surgeons during PBPI
reconstruction, with the suprascapular nerve (SSN) being the most common recipient. The next most
common donor was the intercostal nerves. Most often, these were transferred to the musculocutaneous
nerve (MCN) and the median nerve. We will describe each of these techniques in further detail based on the
function they aim to restore.