Sunday, February 12, 2012

Spinal Accessary Nerve Injury

Updated 3/2017--all links removed as many no longer active. 

This injury will never result in an individual qualifying for SSI disability.  Not even when it occurs on the side of  your dominant hand.  That doesn’t mean it isn’t a serious problem and can result in significant shoulder dysfunction and pain.  It simply means it will never “meet” an SSI disability listing and will not result in more than a one-arm light RFC (residual functional capacity) rating. 
The spinal accessary nerve  supplies the sternocleidomastoid (SCM) and trapezius muscles.  So when the nerve is injured your ability to rotate, tilt, flex your head may be impaired (SCM).  Your ability to elevate your shoulder and draw your head back so the face is upward may also be impaired (trapezius muscle involvement).  The shoulder may exhibit a winged scapula which may be more apparent or exaggerated on arm abduction.
Causes of SAN injury include iatrogenic, traumatic, and neurologic. 
Most iatrogenic SAN injury occur following diagnostic lymph node biopsies of the posterior triangle of the neck. Injury rates from these procedures are reportedly 3-8%.   Functional neck dissections are another source of iatrogenic SAN injury.
As with other nerve injuries, if the injury is a transection and is recognized it can be repaired.  This may be done immediately or within 3 to 6 months after the injury. 
If it is uncertain if this nerve was indeed cut or is a closed injury (ie trauma), then close follow-up with serial electrical tests helps determine if surgery will be required. Physical therapy is the mainstay of treatment regardless of whether surgery is indicated. It improves range of motion and encourages a return of strength once contraction occurs.
Nerve regeneration can take 3-12 months, during which time physical therapy is performed. Patients with a spinal accessory nerve injury older than 1-2 years may not be a candidate for nerve surgery.  So the sooner the injury is recognized and diagnosed, the better. Options for these patients may include tendon/muscle transfer techniques to stabilize the scapula and reduce pain.

1.  Cranial Nerve XI: The Spinal Accessory Nerve – Clinical Methods
2.  Accessory Nerve Injury; Rohan Ramchandra Walvekar, MD, et al; eMedicine, July 20, 2010
3.  Spinal Accessory Nerve Injury; NYU Medical Center


Elaine Schattner, MD said...

This diagram, and your explanation of how the nerve works, is detailed and instructive, Ramona. Thanks!

Rocky Hudson said...

It's amazing how you explaining these terms to the patients, it's understandable and very helpful, thanks for sharing.