Quick Reference: Chapter 3: The Peripheral Nervous System

Most impairment ratings for conditions affecting the cervical spine are relatively straightforward and can be addressed using the first three categories of the Injury Model in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). This real-life case study illustrates how higher impairment categories are applied, including combining categories; the importance of rating the patient's condition based on the injury (as opposed to treatment outcome); and how apportionment is handled in different jurisdictions. Mr Smith, a 64-year-old high school principal, presented with numbness and burning pain from the chest to the feet, unsteadiness of gait, and difficulty maintaining an erection. Symptoms reportedly began two years earlier when he tripped and fell down a flight of stairs at work, striking his face. An MRI scan revealed marked spinal stenosis and cervical cord compression at C3 due to a combination of posterior C3-4 disc protrusion and osteophyte formation. Via an anterior approach, the orthopedic surgeon performed a C4 corpectomy, C3-4 and C4-5 discectomies, and then inserted a tricortical iliac bone graft between C3 and C5. Mr Smith improved postoperatively but still complained of numbness from upper chest to feet, mild unsteadiness of gait, and difficulty maintaining an erection. Evaluators can use the Injury Model, recalling that surgery to treat an impairment does not modify the original impairment, and in the jurisdiction in which Mr Smith was rated, if a claimant was asymptomatic before a work injury, the entire impairment is attributed thereto.