16 - Loss of somatic sensation

Summary

Evidence of behavioral recovery of somatic sensations following peripheral and central nervous system lesions challenges therapists to not only understand the nature and extent of the change, but the conditions under which the recovery can be maximized and the mechanisms underlying. This challenge requires input from basic sciences and rehabilitation fields. Integration of these fields will provide direction for the development and testing of scientific-based interventions designed to maximize recovery by driving and shaping neural reorganization.

The focus of this chapter will be on loss of somatic sensations, treatments currently available to address this problem, and the potential application of theories of perceptual learning and neural plasticity. More detail will be given to therapies following central nervous system (CNS) lesions, with particular reference to stroke. Comparisons will also be made in relation to loss following peripheral nervous system (PNS) lesions.

Nature of impairment and functional implications of loss

Definition and processing within the somatosensory system

Somatosensory function is the ability to interpret bodily sensation (Puce, 2003). Sensory systems are organized to receive, process and transmit information obtained from the periphery to the cerebral cortex. Within the somatosensory system submodalities of touch, proprioception, temperature sense, pain and itch are identified. (Gardner and Martin, 2000). Detailed description of the system involved in sensory processing is provided in seminal texts such as Kandel, Schwartz and Jessell (Gardner and Martin, 2000). Further, neuroimaging studies are complementing and extending information gained from animal and lesion studies in humans (Schnitzler et al., 2000).