Potential Mechanism for Some Postoperative C5 Palsies: An Anatomical Study

Area of Science:

• Neurosurgery
• Anatomy
• Biomechanics

Background:

• Postoperative C5 nerve palsy is a known complication of cervical spine surgery.
• Inferior shoulder depression is frequently used to improve surgical visualization.

Purpose of the Study:

• To investigate whether shoulder depression can lead to C5 nerve traction and injury.
• To understand the anatomical basis of C5 nerve palsy in the context of surgical positioning.

Main Methods:

• Dissection of the spinal cord and cervical nerve roots (C4-T1) in 10 human cadavers.
• Application of various shoulder positions (elevation, retraction, protraction, depression) and head movements.
• Direct observation and measurement of nerve rootlet displacement and tension.

Main Results:

• Shoulder depression caused the greatest displacement of nervous tissue, particularly at the intradural C5 nerve rootlet level.
• Maximal shoulder depression resulted in C5-C7 rootlet tension and ipsilateral spinal cord movement.
• The C5 nerve root exhibited the farthest displacement, with potential contact with the dura.

Conclusions:

• Shoulder depression during cervical spine surgery can induce significant tension and displacement of C5 nerve rootlets.
• This mechanism may explain the occurrence of postoperative C5 palsy.
• Caution is advised when using shoulder depression in cervical spine procedures.