Spinal
cord injury reduces or eliminates skin sensation in dermatomes below
the injury site. Because people cannot feel or move, they may sit or
lie for long times on certain parts of their body. Pressure impedes
blood flow in the skin. Due to muscle atrophy, the normal tissue
padding that cushions the butt may be reduced. Absence of sensation,
loss of muscle padding, and long periods of pressure can lead to skin
breakdown and development of pressure sores or decubiti. Decubiti are
potentially life threatening but preventable.
Spinal cord
injury impairs skin blood flow responses. Normally, skin responds to
pressure, mechanical stimulation, or inflammation with increased blood
flow. Loss of this response not only adds to the vulnerability of the
skin to pressure sores but reduces the ability of the skin to repair
decubiti. Thus, great care must be taken to prevent decubiti by
shifting sitting positions and frequent turning. Special seats that
distribute the pressure are used in wheelchairs to prevent sacral
decubiti. Vulnerable areas such as the heels must be padded. If a
decubitus develops, all pressure must be removed or the decubitus can
progress to loss of skin and tissues to the point of exposing bone. The
sores must be kept clean or they can become infected. Plastic surgery
may be necessary to repair the decubitus.
Spinal cord injury
also paralyzes sweating in dermatomes below the injury level. People
with spinal cord injury must be very careful to maintain their body
temperatures. In contrast to loss of sweating below the injury site,
many people with spinal cord injury may have abnormal increases of
sweating above the injury site, often in their upper torso and face.
This is a form of autonomic hyperexcitability or spasticity. It is not
unusual for people to sweat profusely on one side of the face and not
the other. Such abnormal sweating responses may develop early or late
after injury.
Spinal cord injury disables vascular responses
that maintain blood pressure when a person sits or stands up. Blood
vessels in the guts and legs normally constrict when a person stands
up, to keep blood from pooling. When people with spinal cord injury sit
up for the first time after injury, their blood pressure may drop
sharply. Such postural hypotension may prevent a person from sitting or
standing during the first weeks after spinal cord injury. The vascular
responses recover over time but people must be be tilted gradually into
the vertical position over the several weeks after spinal cord injury.
Loss of vascular responses in the legs leads to a tendency for fluid to
accumulate in the legs when people sit for long times. Such dependent
edema can be prevented to some extent with stockings.
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