Loss of function in the spinal accessory nerve, which may cause weakness in shoulder and neck muscles.
Because the ratings turn entirely on motor function of the sternomastoid and trapezius muscles, medical records and physical examination findings that document how those muscles perform are central. A neurological examination noting the degree of weakness, atrophy, or absence of movement in those muscles would reflect the difference between complete and incomplete paralysis. Electromyography or nerve conduction studies can provide objective evidence of the extent of nerve damage and whether any regeneration has occurred. Records showing the level or location of the nerve lesion also speak to the degree of impairment. Statements from you or people who know you describing difficulty turning your head, shrugging your shoulder, or lifting your arm above your head because of trapezius weakness can help show how the functional loss affects your work and daily activities. If both sides are involved, documentation of each side separately helps VA apply the correct rating to each.
Conditions that are often caused or made worse by this one. If you have any of these, they may be claimable as secondary service connection.
