Motor neuron involvement in experimental lumbar nerve root compression: a light and electron microscopic study.
METHODS
The aim of this study is to investigate changes in lumbar motor neurons induced by mechanical nerve root compression using an in vivo model. This study is to investigate the changes of lumbar motor neuron induced by mechanical nerve root compression using in vivo model.


OBJECTIVE
The effect of axonal flow disturbance induced by nerve root compression was determined in lumbar motor neuron.


BACKGROUND
The lumbar motor neuron should not be overlooked when considering the mechanism of weakness, so it is important to understand the morphologic and functional changes that occur in motor neurons of the spinal cord as a result of nerve root compression. However, few studies have looked at changes of neurons within the caused by disturbance of axonal flow, the axon reaction, chromatolysis, and cell death as a result of mechanical compression of the ventral root.


METHODS
In mongrel dogs, the seventh lumbar nerve root was compressed for 1 week, or 3 weeks using a clip. Morphologic changes of the motor neurons secondary to the axon reaction were examined by light and electron microscopy.


RESULTS
Light and electron microscopy showed central chromatolysis of motor neurons in the lumbar cord from 1 week after the start of compression. After 3 weeks, some neurons undergoing apoptosis were seen in the ventral horn.


CONCLUSIONS
It is important to be aware that, in patients with nerve root compression due to lumbar disc herniation or lumbar canal stenosis, dysfunction is not confined to degeneration at the site of compression but also extends to the motor neurons within the lumbar cord as a result of the axon reaction. Patients with weakness of lower leg should therefore be fully informed of the fact that these symptoms will not resolve immediately after surgery.
Kobayashi
Shigeru
S
Department of Orthopedic Surgery and Rehabilitation Medicine, Fukui University School of Medicine, Fukui, Japan. kshigeru@fmsrsa.fukui-med.ac.jp
Uchida
Kenzo
K
Yayama
Takafumi
T
Takeno
Kenichi
K
Miyazaki
Tsuyoshi
T
Shimada
Seiichiro
S
Kubota
Masafumi
M
Nomura
Eiki
E
Meir
Adam
A
Baba
Hisatoshi
H
D000818:Animals; D000870:Anterior Horn Cells / Q000648:ultrastructure*; D017209:Apoptosis; D004195:Disease Models, Animal; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D008159:Lumbar Vertebrae; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D009046:Motor Neurons / Q000648:ultrastructure*; D009562:Nissl Bodies / Q000648:ultrastructure; D011843:Radiculopathy / Q000473:pathology* / Q000503:physiopathology; D012183:Retrograde Degeneration / Q000473:pathology; D013126:Spinal Nerve Roots / Q000601:surgery; D013997:Time Factors