Non-painful sensory phenomena after spinal cord injury

Non-painful sensory phenomena or "phantom" sensations are common after spinal cord injury. However, the physiological mechanisms responsible for these sensations are poorly understood. The aim of this study, therefore, was to document in a prospective fashion the time course, prevalence, and features of non-painful sensory phenomena after spinal cord injury, and to determine whether there was a relation between the presence of these sensations and completeness, level of injury, and type of spinal cord injury.

Patients admitted to an acute spinal injuries unit were interviewed after admission and at several time points over a 2 year period to determine the presence and characteristics of non-painful sensations. Sensations were divided into simple and complex, with complex referring to sensations that incorporated a sensation of volume, length, posture, or movement.

The present study showed that the large majority (90%) of patients experience either type of sensation and most complex sensations (60%) are first experienced within 24 hours after the injury. Complex sensations were more common in those patients who had complete spinal cord injuries. The presence of either type of sensation did not seem to be related to the level of injury or the type of injury (cord syndrome). A relatively small proportion (22%) of patients reported that the postural sensations were related to their position at the time of injury and sensations were more commonly related to a familiar, comfortable, or often used position before the spinal cord injury.

Complex sensations such as postural illusions seem to be due to functional changes in the CNS that may occur almost immediately after spinal cord injury. These sensations may be related to a strong sensory memory "imprint" that has been established before injury.