Three-dimensional topographic analysis of spinal accessory motoneurons under chronic mechanical compression: an experimental study in the mouse

Abstract

We investigated the effect of chronic mechanical compression of the cervical spinal cord on the number of spinal accessory motoneurons in 25 tiptoe-walking Yoshimura mice. The animals had calcified deposits in the atlantoaxial membrane at the C1-C2 vertebral level, compressing the spinal cord posterolaterally. Motoneurons of the spinal accessory nerve between C1 and C5 segments were labelled using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injected into the sternocleidomastoid muscles. The counted cells were processed into a three-dimensional computer display to analyse the cytoarchitectonic changes caused by external cord compression. The number of WGA-HRP-labelled spinal accessory motoneurons was significantly reduced on the affected side. The number of motoneurons in compromised C2 and C3 cord segments correlated linearly with the extent of mechanical compression, but no such relationship was present on the contralateral side. There was an increase in the number of WGA-HRP-labelled spinal accessory motoneurons in the medial cell pools of the anterior grey horn at a level most rostral to the compression, and in the ventrolateral cell pools at levels immediately rostral to the compression. Our findings suggest that the spinal accessory motoneurons translocate rostral to the area of external compression in order to avoid mechanical injury.

Plasticity of the spinal cord contributes to neurological improvement after treatment by cervical decompression

“…On the other hand, in a series of studies, Kameyama et al [18][19][20] reported that the transverse area of the cervical cord in cadavers of normal Japanese people was 51 to 59 mm 2 and demonstrated that a decrement in the area of the cervical cord by approximately two-thirds of the normal value by compressive lesions caused myelopathy and damage of the grey matter. Using a specific mouse model, we also demonstrated that reversible neuronal loss was possible when the transverse area of the murine cervical cord ranged from 50 to 70% of the control value [6,8]. However, in the present study, neurological recovery was noted even in patients with a transverse area of the cord of less than 40 mm 2 .…”

Cervical myeloradiculopathy with entrapment neuropathy: a study based on the double-crush concept

“…Therefore, a decision as to which lesion should be treated ®rst is an issue of great debate. In our recent experimental studies using wheat germ agglutininhorseradish peroxidase-labelling method, 17,18 we described improvement in the retrograde axonal transport that correlated with functioning spinal cord motoneurones (spinal accessory motoneurones). However, extensive mechanical compression of the cord and nerve roots may result in serious neuronal damage even in a case with normal retrograde axonal transport.…”

Prognostic Value of 18F-FDG PET in Monosegmental Stenosis and Myelopathy of the Cervical Spinal Cord

“…At that stage, the process is still reversible, as is supported by the good clinical outcome after surgical intervention. Chronic compression, however, leads to atrophy and necrosis of anterior gray horn cells and the loss of glucose-consuming neurons, resulting in decreased 18 F-FDG uptake in the spinal cord (29,30).…”