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By Kathleen Doheny
HealthDay Reporter
MONDAY, Jan. 31 (HealthDayNews) -- For years, damaged discs in the lower
back or spinal nerve problems have taken the blame as the most common cause of
sciatica, a painful condition in which the sciatic nerve in the back of the leg
is pinched and pain radiates down the leg.

But a new study suggests the cause of sciatica pain may actually be
piriformis syndrome, a condition in which a muscle in the buttocks called the
piriformis compresses or irritates the sciatic nerve.

The study appears in the February issue of the Journal of Neurosurgery:
Spine.

The findings may help many patients finally get relief from their pain, said
study author Dr. Aaron Filler, a neurosurgeon at Cedars-Sinai Institute of
Spinal Disorders in Los Angeles. "Doctors often recommend spinal fusion surgery
for spinal problems [associated with sciatica]," he said, "when the real
problem is piriformis syndrome."

In the study, Filler and his colleagues evaluated 239 patients whose
symptoms of sciatica had not improved after diagnosis or treatment for a damaged
disc. They performed the usual X-rays and MRI scans, and found seven of the
patients had torn disc-related conditions that could be treated successfully with
spine surgery.

The other 232 patients underwent MR neurography, a new technique that
generates detailed images of nerves. The researchers report that 69 percent had
piriformis syndrome, while the other 31 percent had some other nerve, joint or
muscle condition.

To treat piriformis syndrome, Filler's team injected a long-acting
anesthetic into the spine, muscle or nerve areas. About 85 percent of the patients got
some relief from the injections, which helps relax muscle spasm. However,
relief was not long-lasting and 62 patients needed surgery to correct the
syndrome. Of those, 82 percent had a good or excellent result during the six-year
follow-up.

The findings may help legions of Americans suffering from sciatica, Filler
said. "More than 1.5 million Americans have experienced sciatica severe enough
to be sent for lumbar MRI scanning each year," Filler said. "About 300,000
lumbar disc surgeries are done each year for sciatica. Of those, about one-third
fail."

In some cases, those surgeries may fail because disc damage is not the
underlying problem, Filler said. Instead, the real culprit could be other
conditions, such as piriformis syndrome.

The nerve scan used in the study is relatively new, Filler said, being first
used in humans in 1993. His group reported on the first groups of patients
who underwent the technique in 1996. "Since 1996, we have imaged several
thousand patients," he said. The technique is available now at major universities and
hospitals, Filler said, and is expected to become more widespread in the next
year or so.

While the study provides new clues to sciatica, experts say its results need
to be duplicated. When patients complain of sciatica, "we typically focus on
spinal nerves," explained Dr. Scott M. Fishman, president-elect of the
American Academy of Pain Medicine.

"This study helps clarify that pain that radiates down the back of the leg
is often of sciatic origin," Fishman said, and doctors should consider the
possibility that the pain may be due to entrapment of the sciatic nerve by the
piriformis muscle.

"Piriformis syndrome is pooh-poohed [as a diagnosis] by orthopedic surgeons
and neurosurgeons," added Dr. Peter Slabaugh, a spokesman for the American
Academy of Orthopaedic Surgeons. But the new findings, he said, "might have some
merit," although he said more studies with similar results are crucial before
firm recommendations can be made.

Those with sciatica should also know that the pain typically comes and goes,
Slabaugh said. Unless symptoms are very severe, waiting three months after
the pain starts before undergoing serious treatments such as surgery is usually
sound advice, he added.

If the pain doesn't subside after three months, patients would be wise to
then consider imaging studies of the spine and nerves, he added.

More information

To learn more about piriformis syndrome, visit the National Institute of
Neurological Disorders and Stroke.



Sources: HealthDay