Keywords
Arthrogryposis - Upper limb - Nerve transfer - Brachial plexus
Introduction
Arthrogryposis multiplex congenita (AMC) is a well known clinical entity of unknown,
certainly multifactorial etiology [[1],[2]]. Akinetic, neuro- and/or myopathic forms are described and associations with syndromes
like the whistling face syndrome (Freeman- Sheldon) are particular clinical entities.
AMC is characterized by a variable functional impairment of upper and/or lower limbs
due to muscular hypotrophy and imbalance and joint ankylosis since birth. The treatment
is orthopaedic and surgical according to the severity. In upper limb impairment, some
authors claim an early surgical correction by joint releases and muscle transfers,
to reanimate essential motor functions like the elbow flexion [[2]]. Little is known about the underlying pathophysiology and eventual peripheral or
central nerve damages [[1]]. There is generally no spasticity in the affected limbs.
We present two clinical observations allowing insights in nerve variations and a possible
strategy for an early functional improvement. Further studies and observations should
strengthen the hypothesis of treatable proximal motor nerve alterations in some cases
of upper limb AMC.
Case presentations
Girl patient 1 was born as the first child of a mother with a known uterus malformation
(septum) by caesarian section. Immediately after birth, hypotrophy of the partially
paralyzed left upper limb was observed. Due to the lack of active shoulder and elbow
movements in a medially rotated arm, the diagnosis of severe upper obstetric brachial
plexus palsy was hypothesized and the child was presented at our consultation.
As the palsy was severe and did not show any clinical improvement at three months,
a surgical exploration of the left brachial plexus was performed when she was aged
four months ([Figure 1]) under the hypothesis of a possible intrauterine malposition of the child (a very
rare condition discussed in obstetric palsy).
Figure 1 Patient 1 preoperatively. Left upper limb palsy, medial rotation position and hypotrophy.
The brachial plexus showed to be hypoplastic, with thin roots and trunks ([Figure 2a and b]). There were no anterior – posterior divisions at the trunk level; the lower and
middle trunk could not be individualized and the suprascapular nerve was absent. On
intraoperative direct electrical stimulation, the upper trunk gave some answers in
the deltoid muscle, but no biceps activity could be identified. The lower trunk stimulation
showed some finger flexion activity. No further reconstruction was performed at this
age and the child was followed for over eight years, confirming finally a typical
unilateral upper limb development consistent with AMC.
Figure 2 Patient 1 intraoperative view of the brachial plexus. Root and trunk hypoplasia
Boy patient 2 was born with typical AMC affecting all four limbs. No active elbow
flexion was present at 15 months and we decided together with the parents to explore
the right upper arm to verify the presence of the biceps muscle and to try to functionally
reanimate the elbow flexors by a fascicular ulnar nerve transfer [[3]], targeting the motor branch of the hypotrophied biceps brachii muscle ([Figure 3]).
Figure 3 Patient 2 intraoperative (Oberlin transfer).
Exploration was performed when he was 21 months old using an anterior approach of
the upper arm, showing a good muscle bulk corresponding to the biceps brachii muscle
and the presence of a rather thin musculocutaneous nerve, silent on direct electrical
stimulation. We identified the motor branch directed to the biceps brachii muscle
and performed a typical nerve transfer according to the technique described by Oberlin
[[3]], using motor fascicles out of the median nerve to target the biceps motor branch
([Figure 3a] and [Figure 3b]). Six months postoperatively, the boy started to show active elbow flexion ([Additional file 1]: Video ten months postoperatively), an active movement pattern never shown before.
The recovery is actually continuing 20 months after the nerve transfer.
Discussion
These two cases illustrate that upper limb AMC may be associated with brachial plexus
root hypoplasia, like seen in traumatic partial root avulsions. All five roots in
patient 1 were thin and did only partially and weakly respond to direct electrical
stimulation. This pattern has been observed in children suffering from severe upper
obstetric brachial plexus palsy after a breech delivery with proven partial or total
root avulsions. True hypoplastic malformations or congenital abnormalities of the
brachial plexus are not described in the literature; but are reported by surgeons
with longlasting experience: Gilbert described 3 cases of brachial plexus malformation
out of 1000 operated children [[4]].
In our clinic, after these first two cases with specific upper limb involvement, presence
of a good muscle mass with absent or poor motor innervation has since been verified
in three other children ([Figure 4]). Only in the here presented patient 2, the muscle mass was sufficient to expect
a functional reinnervation through a fascicular motor nerve transfer. So far, the
postoperative evolution shows an increase in active elbow flexion, hopefully ending
up with a strength M3-M4 rendering a secondary muscle transfer of the latissimus dorsi
or pectoralis muscle unnecessary.
Figure 4 Other child: no functional biceps mass present.
Selective motor nerve transfers thus might be helpful in these children, if enough
muscle mass is present at the shoulder or arm level and if dispensable motor nerve
donors are available, without compromising the existing and sometimes weaker than
normal motor functions. Obviously, the challenge in patient 2 was to avoid downgrading
the overall good hand function, which did not appear on global hand function assessment
postoperatively.
Conclusion
Nerve transfers prior to muscle transfers could change the prognosis and functional
outcome in selected AMC children, as morphologically developed target muscles even
with poor motor innervation could be salvaged and functionally upgraded. Muscle transfer
options still remain possible, even at an early moment.
Consent
Written informed consent was obtained from the patients’ parents for publication of
both case reports and any accompanying images and videos. A copy of the written consent
for each case report is available for review by the editorial office.
Competing interest
The author declares he has no competing interests.
Additional file
Video. Patient 2 right upper limb function after surgery.
Cite this article as: Bahm: Arguments for a neuroorthopaedic strategy in upper limb arthrogryposis. Journal of Brachial Plexus and Peripheral Nerve Injury 2013 8:9.
