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Reflex sympathetic dystrophy (RSD) is a syndrome of abnormally intense
pain associated with hand and upper extremity injury, trauma or surgery.
Loss of function and autonomic nervous system dysfunction are associated with the pain.
The term RSD has numerous other synonyms in the medical literature making
this disease difficult to research and understand.
More recently, the term Complex Regional Pain Syndrome (CRPS) has been
proposed to encompass the term RSD. RSD
is now considered a subset of CRPS. These pages will follow this new
terminology.
Complex
Regional Pain Syndrome is divided into two types (although there may be a
type
3, this category is controversial)
-
Type
I RSD – pain and
loss of function associated with autonomic dysfunction and dystrophic changes
not secondary to a discrete nerve injury.
-
Type
2 Causalgia –
pain and loss of function with autonomic dysfunction and dystrophic changes
secondary to a discrete nerve lesion. Treatment for causalgia is
directed toward the discrete nerve lesion.
RSD
can be the result of only a minor trauma to an extremity, a major trauma, or it can
be post-surgical.
Fortunately,
RSD is rare after surgery. Although the degree to which it appears varies
between affected individuals, when RSD does strike, it can be extremely
disabling.
Definitions
-
Pain - a complex reaction
consisting of a physiological and emotional response to a noxious stimulus.
A
warning mechanism designed to protect the body.
-
Analgesia - loss of
sensation of pain as a result of an interruption in the nervous pathway
producing pain.
-
Causalgia – pain associated with autonomic dysfunction as a result of a
discrete peripheral nerve injury.
-
Dystrophic changes – stiffness, swelling, hair color and skin changes
associated autonomic dysfunction.
-
Hyperalgesia – increased pain
sensitivity
Anatomical
Considerations
In
order to comprehend RSD some basic anatomy should be understood.
The autonomic nervous system is a part of the nervous system involved in
controlling involuntary structures and functions, such as the intestines, blood
pressure and breathing. The
autonomic nervous system has been found to be divided into two parts:
It is the sympathetic nervous system that is involved in the disease RSD.
The sympathetic nervous system prepares the body for the “fight or
flight” reaction. It accelerates
heart rate, constricts blood vessels, and distributes blood to the brain,
heart and muscle. RSD is thought to be
a result of excitation of
peripheral nerve elements with an abnormal and severe sympathetic response resulting in the pain
and signs and symptoms of RSD.
Diagnosis
of RSD
A spectrum of findings may be present
to a variable degree and include severe pain and hyperesthesia, changes in skin and hair on the affected
extremity and a cool or warm extremity compared to the opposite side.
There may also be abnormal stiffness, abnormal sweating, edema and
hypersensitivity to minor stimulation. But, for RSD to be diagnosed,
three criteria must be met
-
diffuse pain
-
loss of function
-
sympathetic dysfunction
To
aid in the diagnosis of RSD, some further investigation may be helpful.
Nerve blocks can be performed to help in the diagnosis of sympathetic
dysfunction, and can be used in the treatment of RSD. Sympathetic
nerve blockade should relieve symptoms since the
disease process has been attributed to the sympathetic nervous system.
Radiography may reveal osteopenia. Three-phase technetium 99m bone scan
has been shown to be positive in the third phase with
diffuse periarticular uptake in many patients with RSD.
Treatment
of RSD
RSD
can be managed with aggressive physical therapy, sympathetic blockade using local anesthetic
injection and
pharmacologic intervention. Numerous pharmacologic treatments have been described
including:
A
pain management consultation is usually obtained for patients with RSD so that
sympathetic blockade and pharmacotherapy are performed in conjunction with an
anesthesiologist qualified in pain management.
Surgery
on the affected extremity is avoided.
It may only exacerbate symptoms and should be considered carefully.
Even more rarely
surgical treatment with sympathectomy is performed.
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