102 m a s s a g e & b o d y w o r k j u l y / a u g u s t 2 0 1 6
technique
MYOSKELETAL ALIGNMENT TECHNIQUES
Double Crush
Nerve Damage
Addressing Neurogenic
Thoracic Outlet Syndrome
By Erik Dalton, PhD
The term double crush syndrome (DCS) was coined
by Harvard University plastic surgeons Albert Upton
and Alan McComas, who wrote, "Neural function
is impaired when compressed axons at one site
cause the nerve to become especially susceptible
to damage at another site" (Image 1). Their double
crush research began after observing that many carpal,
cubital, and radial tunnel patients also complained of
unilateral shoulder, chest, and upper back pain.
1
While the
DCS mechanism is not completely understood, it likely
involves nerve sensitization and neuroplastic changes in
the pain-modulating systems of the brain and spinal cord.
Neural compression of the brachial plexus is suitably called
neurogenic thoracic outlet syndrome (NTOS). These clients present
with a variety of symptoms, including painless atrophy of intrinsic
hand muscles and nighttime paresthesia. Athletes may have diffi culty
grasping a racquet or ball, and some report pain. However, I've
found that rather than being a main pain event, NTOS is more of an
enhancer of symptoms at a distal site, such as the carpal tunnel. Put
simply, the brain pays more attention to double crush nerve insults
and is more likely to respond with pain or spasm.
Although most clinicians feel that NTOS is an underestimated
cause of DCS, assessment is often diffi cult due to vague, fl uctuating
symptoms. Instead of chasing the pain, I've achieved superior
outcomes by palpating and releasing all fi brous connective tissue sites
that may be kinking, stretching, or infl aming the brachial plexus.
In the January/February 2016 ("An Alternate Approach to Tennis
Elbow," page 102) and May/June 2016 ("Carpal Tunnel Syndrome
Revisited," page 102) issues of Massage & Bodywork, I addressed carpal
and radial tunnel compression sites. Now, we'll palpate and release
NTOS contractures at the interscalene triangle, costoclavicular
canal, and retropectoralis minor spaces (Image 2).
INTERSCALENE IMPINGEMENT
Nerve fi bers originating at the spinal cord travel from the neck,
through the thoracic outlet, and into the hand, providing sensation
and movement during daily tasks. Certain postures or sleeping
positions may increase tension and pressure on entrapped nerves.
Further complicating the nerve's journey through the thoracic
outlet, researcher David B. Roos, MD, FACS, discovered irregular
fi brous bands that increased brachial plexus stiffness and decreased
movement.
2
Roos classifi ed 10 types of contractures that can stiffen
the already unforgiving boundaries of the thoracic outlet container.
Despite all the neural roadblocks, it has been my experience that
many DCS clients respond well to massage, movement, and any
type of cognitive training that lowers the brain's threat level during
Double crush syndrome.
1
2
Interscalene,
costoclavicular,
and retropectoralis
compression sites.
Carpal tunnel
compression
Neurogenic
thoracic outlet
syndrome
injury
subclavius
pectoralis
minor
scalenes
