Inferring the spinal nerve root segments responsible for innervation of the lower limb muscles by use of magnetic stimulation
10.3760/cma.j.issn.0254-1424.2024.10.010
- VernacularTitle:采用磁刺激确定下肢肌肉脊神经支配节段的临床研究
- Author:
Xiuli ZHANG
1
;
Zongyao WU
;
Weiwei DENG
;
Siyu DONG
;
Xiaoran TANG
;
Xianli ZHOU
;
Lijuan XIE
;
Hongliang LIU
Author Information
1. 陆军军医大学附属第一医院康复医学科，重庆 400038
- Keywords:
Magnetic stimulation;
Nerve roots;
Electrophysiology
- From:
Chinese Journal of Physical Medicine and Rehabilitation
2024;46(10):916-922
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the locations of the lumbosacral nerve roots by use of the magnetic stimulation.Methods:Thirty healthy subjects were studied. The projections of the right L 2 to S 1 intervertebral foramina on their body surfaces were determined manually with ultrasound assistance. Magnetic stimulation was applied to different nerve root segments to induce compound muscle action potentials (CMAP) in the vastus medialis, tibialis anterior, and gastrocnemius muscles of the lower limbs. The changes in latency, amplitude, and motor threshold were observed. Results:Magnetic stimulation on the L 2-L 3 segment resulted in a significant direct excitation of the vastus medialis. That on the L 5-S 1 segment evoked a significant direct excitatory effect on the tibialis anterior and gastrocnemius, with a motor threshold below 40%, an amplitude exceeding 1mV, and many effective responses. However, during the magnetic stimulation on the L 4 segment, the amplitude of the vastus medialis was above 1mV, with no significant differences in the number of effective responses among the muscle groups. Moreover, there was a stepwise change in the latency of effective muscle responses to magnetic stimulation at different segments. The CMAP latencies of 12+ ms for the tibialis anterior and 13+ ms for the gastrocnemius indicated activation of the L 5 and L 4 nerve roots, respectively, while those of 6+ ms, 7+ ms, and 8+ ms for the vastus medialis suggested activation of the L 4, L 3, and L 2 nerve roots, respectively. Conclusions:Based on the responses (CMAP latency, amplitude and motor threshold) of the vastus medialis, tibialis anterior and gastrocnemius to magnetic stimulation at different L 2 to S 1 segments, the spinal nerve root segments responsible for innervation can be inferred.
