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.
To investigate the relationships between nerve root blood flow changes and the electrophysiological values during an intraoperative SLR test.
It is unknown how the electrophysiological values are affected by nerve root blood flow changes during an SLR test.
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.
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.
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.
The results of the present study demonstrate that temporary ischemic changes in the nerve root cause transient conduction disturbances. We therefore suggest that ischemia caused by mechanical nerve root compression is mainly related to the mechanisms underlying the neurologic deficits.
From the Department of Orthopaedic Surgery, Fukuoka University, Fukuoka, Japan.
Address correspondence and reprint requests to Yoshihiro Takamori, MD, Department of Orthopaedic Surgery, Fukuoka University, 7–45–1 Nanakuma, Jonan-ku, Fukuoka 814–0180, Japan; E-mail: firstname.lastname@example.org
Acknowledgment date: August 29, 2009. Revision date: October 26, 2009. Acceptance date: October 28, 2009.
The manuscript submitted does not contain information about medical device(s)/drug(s).
No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.