Paraplegia: causes, features, classification, and rehabilitation

Damage to the spinal cord can result in a loss of active control of muscles and muscle groups controlled by nerves that must pass through the site of spinal cord injury.

Depending on the location of the damage, the muscles of the arms, the respiratory muscles, the muscles of the abdomen and back, and the muscles of the legs may be affected. Depending on the severity of the paralysis, the loss of motor function can extend to complete immobility of the affected extremities (arms, legs).

In addition, sensitivity may be impaired due to the spinal cord damage. On the one hand, this means that the sensitivity of the skin to touch may be reduced or eliminated, and on the other hand, pain stimuli from internal organs (for example, in the case of appendicitis) may not be perceived by the affected person.

As a further functional group, the vegetative functions can be affected. Here, too, the specific pattern of damage depends essentially on the location of the site of damage in the spinal cord. In the foreground of the so-called vegetative dysfunctions are disturbances of the bladder function with urine retention or incontinence. Bowel function is also affected and the patient loses control over bowel movements. Other important vegetative functions are the control of blood pressure, e.g. through loss of tonic function of the vessels (vegetative circulatory dysfunction) in the legs and the loss of temperature regulation through corresponding sweating.

Paraplegia cannot be equated with wheelchair dependence. Despite significant deficits in other areas, spinal cord damage can leave so much muscle function intact that the affected person can still walk. These people also need to be given the option of paraplegia-specific treatment in one of the specialist centres for paraplegics in order to avoid long-term damage and complications.

Paraplegia is described according to the height (with regard to the localization of the damage in the spinal cord) and its severity. For height localization, the division of the spinal cord into segments is used, which are oriented to the segments of the spinal column and the respective nerve exit points of the so-called spinal nerves. There are eight neurological segments in the cervical spine, twelve in the thoracic spine, five in the lumbar spine and four in the sacral region. For the description of paraplegia, the last completely intact spinal cord segment is specified.

In addition to motor function, the level of paralysis is determined by the "sensitive level". It refers to the last intact dermatome. A dermatome is an area of skin that represents the supply area of a specific spinal nerve. The dermatomes shown in the figure differ in terms of their spinal nerve supply and thus always refer to a specific spinal cord segment. Their examination is suitable for assessing the lesion level in spinal cord damage. The dermatomes are examined by means of cold stimulation, touch or pinprick stimulation. These three qualities of sensation may well lead to different results in the affected dermatomes, which would suggest incomplete spinal cord damage. Paraplegia does not lead to a restriction of cognitive functions, since only the functions below the level of the lesion are affected.

In addition, the paralysis is described as complete (no function below the spinal cord damage) or incomplete (remaining residual function below the spinal cord damage). Since the sensitivity to touch at the anus corresponds to the "deepest" segments, it is required for the diagnosis of complete paraplegia that the loss of sensitivity to touch around the sphincter is demonstrated. Beyond the rather rough classification of paraplegia into complete and incomplete, several classifications are in use internationally. They were first given by Hans Fraenkel (Stoke Mandeville, England). Later they were adopted by the American Spinal Cord Association (ASIA) and are used in publications as the ASIA classification, with the AIS as the ASIA impairment score:

• ASIA A: No muscle function and no sensitivity below the level of spinal cord damage.
• ASIA B: No muscle function below the spinal cord damage, limited sensibility available
• ASIA C: Low non-relevant muscle function below the paralysis site, sensitivity (partially) present.
• ASIA D: Functionally relevant muscle functions present below the spinal cord injury site (partially preserved sensibility below the spinal cord injury).
• ASIA E: Fully preserved or restored functions below the spinal cord lesion.

Since the description of function by the AIS score is rather coarse, the ASIA has proposed a more differentiated assessment using the function score, which has since been renamed the "International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI)". It describes the functions of Kenn muscles and the sensitivity in the dermatomes with a point system. The determined point values are added up and result in a score value. In addition to the pure description of function, other function scores (for example: SCIM - Spinal Cord Independence Measure) are used to describe the functional deficits of paraplegics in everyday life. This consists of 19 items and questions the areas of activities of daily living, incontinence and coordination. The score varies from 0 to a maximum of 100 points.