Numbness and Weakness Aren't Always Due to Stroke
Dec. 1, 1999 (Atlanta) -- People complaining of numbness and weakness in the
extremities -- the legs and arms -- often associate these symptoms with stroke
and seek emergency care. But frequently these symptoms are caused by nerve
compression injuries, according to an article in the October issue of the
journal IM: Internal Medicine. Neurologists say knowing which nerves are
commonly affected can help prevent expensive and unnecessary diagnostic
"Compression injuries occur when bones and ligaments [constrict] nerves
in the arms and legs," says Robert Schwendimann, MD. "In the upper
extremities, an injury to the medial nerve occurs most often at the wrist and
affects the hands. Of course, this is known as carpal tunnel syndrome. In the
lower extremities, injury to the peroneal nerve occurs most often at the knee
and affects the feet. This is commonly known as footdrop." Schwendimann is
the study author and assistant professor of neurology at Louisiana State
University Medical Center in Shreveport.
The peroneal nerve passes over the bony structure on the outside of the
knee. Affected individuals tend to have their affected foot pointing toward the
ground when they lift it up (hence the term "footdrop") and usually
lift that foot up higher when walking.
Schwendimann says there are many causes of nerve compression. "Carpal
tunnel syndrome is associated with repetitive activities and frequent use of
power tools. It's also more common in patients with diabetes and
hypothyroidism," he says. "Footdrop is associated with habitual leg
crossing, prolonged squatting, and bedrest. In either case, patients almost
always report weakness, numbness, tingling, and pain."
Other common nerve compression injuries are compression of nerves in the
forearm or more commonly at the elbow. The nerve compressed at the elbow -- the
ulnar nerve -- produces symptoms of tingling and numbness in the ring and
little fingers. Most people have experienced these symptoms after resting the
elbow on a table or desk for a while. Ulnar compression can also temporarily
lead to a weakened grip. But patient history alone is inconclusive.
"Electrodiagnostic studies help determine the extent of the injury so
that a plan of treatment can be developed, " Schwendimann tells WebMD.
Electrodiagnostic studies measure sensory and motor function by stimulating
affected nerves and muscles with electrical impulses. "The tests are
uncomfortable but certainly not excruciating," he says. "Kind of like
accidentally touching a spark plug wire." Physicians say these studies have
other important uses as well.
"Other neurological causes can be ruled out with electrodiagnostic
studies," Joseph Brundy, MD, a physiatrist and associate professor of
rehabilitation medicine at New York University School of Medicine, tells WebMD.
"And that's why they should always be ordered prior to surgery."
Physicians also say that conservative treatment should precede surgical
intervention for most compression injuries.