Dec. 1, 1999 (Atlanta) -- People complaining of numbness and weakness in theextremities -- the legs and arms -- often associate these symptoms with strokeand seek emergency care. But frequently these symptoms are caused by nervecompression injuries, according to an article in the October issue of thejournal IM: Internal Medicine. Neurologists say knowing which nerves arecommonly affected can help prevent expensive and unnecessary diagnosticimaging.
"Compression injuries occur when bones and ligaments [constrict] nervesin the arms and legs," says Robert Schwendimann, MD. "In the upperextremities, an injury to the medial nerve occurs most often at the wrist andaffects the hands. Of course, this is known as carpal tunnel syndrome. In thelower extremities, injury to the peroneal nerve occurs most often at the kneeand affects the feet. This is commonly known as footdrop." Schwendimann isthe study author and assistant professor of neurology at Louisiana StateUniversity Medical Center in Shreveport.
The peroneal nerve passes over the bony structure on the outside of theknee. Affected individuals tend to have their affected foot pointing toward theground when they lift it up (hence the term "footdrop") and usuallylift that foot up higher when walking.
Schwendimann says there are many causes of nerve compression. "Carpaltunnel syndrome is associated with repetitive activities and frequent use ofpower tools. It's also more common in patients with diabetes andhypothyroidism," he says. "Footdrop is associated with habitual legcrossing, prolonged squatting, and bedrest. In either case, patients almostalways report weakness, numbness, tingling, and pain."
Other common nerve compression injuries are compression of nerves in theforearm or more commonly at the elbow. The nerve compressed at the elbow -- theulnar nerve -- produces symptoms of tingling and numbness in the ring andlittle fingers. Most people have experienced these symptoms after resting theelbow on a table or desk for a while. Ulnar compression can also temporarilylead to a weakened grip. But patient history alone is inconclusive.
"Electrodiagnostic studies help determine the extent of the injury sothat a plan of treatment can be developed, " Schwendimann tells WebMD.Electrodiagnostic studies measure sensory and motor function by stimulatingaffected nerves and muscles with electrical impulses. "The tests areuncomfortable but certainly not excruciating," he says. "Kind of likeaccidentally touching a spark plug wire." Physicians say these studies haveother important uses as well.
"Other neurological causes can be ruled out with electrodiagnosticstudies," Joseph Brundy, MD, a physiatrist and associate professor ofrehabilitation 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 surgicalintervention for most compression injuries.
"Generally, compression [injuries] can be managed effectively with acombination of activity modification, splints, nonsteroidal anti-inflammatorydrugs [NSAIDs], and steroid injections," says Brundy. But early surgicalintervention may be indicated in other cases.
"Only in the worst or most refractory cases would I refer the patient toa surgeon for surgical decompression," says Schwendimann. "[However,]... the results of this procedure are usually excellent."
"Compression [injuries] due to tumors or fractures should bedecompressed surgically," says Schwendimann. He also stresses thatneurological symptoms should not be ignored. "Numbness and weakness in theextremities are important markers of stroke, particularly when accompanied bychanges in speech or mentation. Anyone with these symptoms should seekemergency care."
- While numbness and weakness in the extremities can be a sign of stroke,they are also symptoms of nerve compression injuries.
- Compression occurs when bones and ligaments in the arms and leg constrictthe nerves, as in carpal tunnel syndrome or footdrop.
- Compression injuries can usually be managed with activity modification,splints, NSAIDs, and steroid injections, but in a few cases, surgery may benecessary.