Ultrasound of the brachial plexus in obstetric brachial plexus injury. Feasibility study in healthy neonates

Ultrasound of the brachial plexus in obstetric brachial plexus injury:
feasibility study in healthy neonates.

Background
The incidence of obstetric brachial plexus injury (OBPI) is 1.6 to 2.9 /1000
neonates. It is the most common peripheral nerve injury in children.
Studies on the long term outcome of OBPI vary between studies, but a large
population study showed that approximately 25% of all children with OBPI suffer
from reduction in arm function because of paresis of upper arm, fore arm or
hand muscles, contractures and growth disorders of the affected arm.
In case of severe nerve damage without signs of improvement in the first month,
especially of the biceps brachii muscle, surgical intervention is indicated. It
is difficult to estimate early which children are going to need surgery, as
both reversible nerve damage (neuropraxis and axonotmesis) as well as
irreversible nerve damage (neurotmesis, root avulsion) show the smae clinical
picture in the first weeks. Electrophysiological studies did show significant
differences between children with an unfavourable outcome compared to those
with a good outcome, but it was impossible to determine a cut-off point with
high enough predictive values to be used in clincial practice. Currently,
referral to a neurosurgical expertise centre (LUMC in Leiden, Atrium MC in
Heerlen and VU in Amsterdam) is done at 3 months of age, with surgical
intervention around 6 months of age.
Early intervention, when indicated, would be desirable, as the brain has its
highest plasticity in the first months of life. Therefore, it would plausible
the early surgical intervention would improve functional outcome. However,
there are no clinical or electrophysiological parameters yet to determine the
long term outcome reliably before the age of 3 months.

With improvement of ultrasound technology it has become possible to visualize
the aspect and continuity of peripheral nerves with high resolution. As
ultrasound can be used bedside and without sedation even in the very young, it
is a very useful diagnostic tool in children. Nerve ultrasound is currently
primarily used in the diagnosis of compression neuropathies, such as carpal
tunnel syndrome, but new applications are evolving rapidly. Recent studies have
showed that also the brachial plexus can be visualized with ultrasound. This
technique is used for ultrasound guided regional anesthesia. Studies on the use
of this technique in traumatic brachial plexus injury are limited to one study
in which was showed that root avulsion could be predicted right in 9 out of 12
patients, in 2 patients nerve damage was underestimated. This would indicate
that the predictive value of nerve ultrasound in brachial plexus injury is
higher than MRI or CT.

The aim of this study is to visualize the cervical roots and brachial plexus in
neonates reliably and reproducable.

Inclusion criteria:
20 Neonates with a gestational age of at least 32 weeks. Inclusion occurs in
the first week of life.

Exclusion criteria:
- Symptoms or signs suspect for a neurological disoder (brain haemorrhage or
infarction, periferal nerve damage, neuromuscular disorder)
- Fracture of clavicula or humerus
- Family history of peripheral neuropathy

Measurements setting
The measurements will be performed at the maternity ward or neonatology
department.

Equipment:
Ultrasound images will be made with a Philips IU22 ultrasound device with a
linear broadband 7-15 MHz probe with a small footprint ("hockeystick probe").

Measurements (bilaterally):
1. Nerve roots: C4 to T1 nerve roots will be visualized longitudinally to
evaluate continuity with the spinal cord and aspect of the nerves and
surrounding tissue.
2. Brachial plexus: The brachial plexus will be visualized transverse at 3
levels: cervical, supraclavicular and infraclavicula. Continuity, aspect of the
nerve and surrounding tissue, visibility of internal structures, and
cross-sectional area will be evaluated.
3. Peripheral nerves: Transverse images of the medial nerve at the wrist and
ulnar nerve just ditally from the elbow will be made to evaluate the diameter,
cross sectional area and visibility of internal structures.
4. Muscle ultrasound of C4 to T1 innervated muscles (measurement of muscle echo
intensity and muscle thickness):
a. Infraspinatus (C4-C6)
b. Deltoid (C5-C6)
c. Biceps brachii (C5-C6)
d. Triceps (C6-C8)
e. Extensor digitorum communis (C6-C8)
f. Flexor digitorum superficialis (C7-C8)
g. Adductor digitorum brevis (C8-T1)

The final protocol will be determined based on the first 5 measurements. The
feasibility study will be performed in 20 neonates.

There are no risks or burden associated with participation in this study