In the evaluation of spinal injuries, they are often classified as complete or incomplete injuries. Traditionally, a complete spinal cord injury meant that there was no motor or sensory function below the level of lesion. But at times these definitions are difficult to apply and can create confusion.
For example it is common to have zone of partial preservation in many spinal injuries which is an area of preserved partial sensation below the injury site but below which no significant motor and sensory function is present.
Where to put these patients?
American spinal injury association (ASIA) suggests that if the person does not do not have motor and sensory function in the anal and perineal region representing the lowest sacral cord (S4-S5), it should be classified as complete spinal injury. These segments represent the last spinal nerves of the cord and if the injury has occurred to the lowest segments, it is a complete injury.
This kind of complete definition on type of injury also helps in predicting recovery of function. ASIA recommends that both motor and sensory levels should be expressed on each side separately.
Whether this concept is really useful in clinical settings is still doubtful The absence of motor and sensory function below the injury site does not necessarily mean that there are no axons that cross the injury site. Many clinicians equate a “complete” spinal cord injury with the lack of axons crossing the injury site.
Animal and clinical data suggest that function below the injury site can recover even in complete injuries labeled models when the spinal cord is reperfused (in the case ischemia to the cord) or the compression of the cord is relieved.
Whether it is right to label a person as complete or incomplete has many answers. While it can give rough idea about the severity of the lesion but can also result in bias in therapy or negative psychological impact on the patient.