Combined measurement of nerve root blood flow and electrophysiological values: intraoperative straight-leg-raising test for lumbar disc herniation.
METHODS
A total of 15 patients with lumbar disc herniation at the L5-S1 disc level who underwent microendoscopic discectomy were examined. The nerve root blood flow and electrophysiological values were measured during an intraoperative straight-leg-raising (SLR) test.


OBJECTIVE
To investigate the relationships between nerve root blood flow changes and the electrophysiological values during an intraoperative SLR test.


BACKGROUND
It is unknown how the electrophysiological values are affected by nerve root blood flow changes during an SLR test.


METHODS
We measured S1 nerve root blood flow and electrophysiologically evaluated the nerve root using the compound muscle action potentials (CMAPs) from the gastrocnemius muscle after S1 nerve root stimulation during an intraoperative SLR test. Subsequently, we analyzed the relationships between the nerve root blood flow changes and the electrophysiological values.


RESULTS
Before discectomy, there were sharp decreases in the nerve root blood flow after 1 and 3 minutes of the SLR test (P < 0.001), and the amplitudes of the CMAPs deteriorated significantly (P < 0.001). Significant correlations were found between the decrease ratio for the nerve root blood flow during the SLR test and the deterioration ratio for the amplitude of the CMAPs. After discectomy, the blood flow increased significantly (P = 0.001). When the SLR test was performed again, the blood flow showed no significant decreases. The average amplitudes of the CMAPs were significantly ameliorated (P < 0.01). When the SLR test was performed again, no significant differences were found for the average amplitudes after 1 and 3 minutes of the test.


CONCLUSIONS
Significant correlations were found between the decrease ratio for the nerve root blood flow and the deterioration ratio for the amplitude of the CMAPs. The present results demonstrate that temporary ischemic changes in the nerve root cause transient conduction disturbances.
Takamori
Yoshihiro
Y
Department of Orthopaedic Surgery, Fukuoka University, Fukuoka, Japan. davi_1003@yahoo.co.jp
Arimizu
Jun
J
Izaki
Teruaki
T
Naito
Masatoshi
M
Kobayashi
Tatsuki
T
D000328:Adult; D001783:Blood Flow Velocity; D017586:Diskectomy / Q000009:adverse effects / Q000379:methods*; D004724:Endoscopy / Q000009:adverse effects; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D007564:Japan; D017078:Laser-Doppler Flowmetry; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D018482:Muscle, Skeletal / Q000294:innervation*; D056888:Patient Positioning; D011237:Predictive Value of Tests; D011930:Reaction Time; D012039:Regional Blood Flow; D012585:Sciatica / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D013126:Spinal Nerve Roots / Q000098:blood supply*; D013997:Time Factors; D055815:Young Adult