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Nerve root morphological and functional changes after degenerative cervical myelopathy surgery: preliminary study using ultrasound and electrophysiology


Study design

A prospective observational study.


To depict morphological and functional changes in the cervical nerve roots before and after spinal cord decompression surgery for degenerative cervical myelopathy (DCM).


A general hospital in Japan.


Thirteen DCM patients who underwent posterior spinal cord decompression surgery, laminoplasty or laminectomy, were included in this study. The neural foramen shown on MRI and the cross-sectional area (CSA) of the nerve roots on ultrasound were used to evaluate the C5 and C6 nerve roots. The compound muscle action potentials (CMAPs) of deltoid and biceps muscle were also recorded.


All patients showed sensorimotor functional improvement without the postoperative C5 palsy after surgery. Foraminal stenosis and preoperative CSA of the nerve root: C4/5 foramen and C5 nerve root, C5/6 foramen and C6 nerve root, had no significant correlation (P = 0.53 and 0.08). CSA of the C5 nerve root displayed no significant change before and after surgery (P = 0.2), however, that of the C6 nerve root reduced significantly after surgery (P = 0.038). The amplitude of the deltoid and biceps CMAPs displayed no significant change before and after surgery (P = 0.05 and 0.05).


The C6 nerve root CSA change was observed after spinal cord decompression surgery with functional recovery. However, deltoid and biceps CMAPs amplitude showed no significant change. Independent CSA changes on ultrasound might be useful when conducting a functional evaluation of the postoperative nerve root.


The Grant of Japan Orthopaedics and Traumatology Research Foundation No. 395.

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Fig. 1: Patient no. 5: MRI, nerve root US and CMAPs.

Data archiving

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.


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This study was supported by the Grant of Japan Orthopaedics and Traumatology Research Foundation No. 395.

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Authors and Affiliations



NT was responsible for designing the study protocols, conducting the research, analysing data, interpreting results, and writing the paper. QH, YY, HM, and TS were involved in recruiting patients and editing the paper.

Corresponding author

Correspondence to Toshihiro Sano.

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The authors declare no competing interests.


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Tadokoro, N., Hashimoto, K., Yanagawa, Y. et al. Nerve root morphological and functional changes after degenerative cervical myelopathy surgery: preliminary study using ultrasound and electrophysiology. Spinal Cord 60, 301–305 (2022).

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