title: Measurement of motor nerve conduction velocity of the sciatic nerve in patients with piriformis syndrome: a magnetic stimulation study.
abstract: OBJECTIVE
  To assess the motor nerve conduction of the sciatic nerve by a magnetic stimulation method in patients with piriformis syndrome.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  An electrodiagnostic laboratory in a university hospital.
  
  
  METHODS
  Twenty-three patients with piriformis syndrome and 15 healthy persons for control.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Motor nerve conduction velocity (MNCV) of the sciatic nerve was measured at the gluteal segment by magnetic stimulation proximally at L5 and S1 roots and distally at sciatic nerve at gluteal fold and recording at the corresponding muscles. Diagnostic sensitivities were measured in the magnetic stimulation method and the conventional nerve conduction, long latency reflex, and needle electromyography studies.
  
  
  RESULTS
  The mean MNCV of the sciatic nerve +/- standard deviation at the gluteal segment in L5 component was 55.4+/-7.8 m/s in patients with piriformis syndrome, which was slower than the mean value of 68.1+/-10.3 m/s obtained in healthy controls (P=.014). The MNCV of the sciatic nerve in S1 component showed no significant difference between the patients and controls (P=.062). A negative relation was found between the disease duration and the MNCV values of sciatic nerves in patients with piriformis syndrome (r=-.68, P<.01). The diagnostic sensitivity by magnetic stimulation is .467.
  
  
  CONCLUSIONS
  Magnetic nerve stimulation provides a painless, noninvasive, and objective method for evaluation of sciatic nerve function in patients with piriformis syndrome.
authors.affiliation: Department of Physical Medicine and Rehabilitation, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan. cwchang@ha.mc.ntu.edu.tw
authors.forename: Chein-Wei
authors.initials: CW
authors.lastname: Chang
authors.forename: Shie-Fu
authors.initials: SF
authors.lastname: Shieh
authors.forename: Chih-Ming
authors.initials: CM
authors.lastname: Li
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Wu
authors.forename: Kai-Fong
authors.initials: KF
authors.lastname: Chang
mesh_terms: D000368:Aged; D002081:Buttocks / Q000294:innervation; D003943:Diagnostic Techniques, Neurological; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D011446:Prospective Studies; D012584:Sciatic Nerve / Q000503:physiopathology*; D020426:Sciatic Neuropathy / Q000175:diagnosis* / Q000503:physiopathology; D013577:Syndrome