Upon completion of this chapter, the learner should be able to:
Distinguish between normal and abnormal sensory functions.
Describe the mechanisms of common pathologies related to sensory impairment.
Recognize common signs and symptoms of sensory impairment.
Formulate functional patient-centered goals based on results of an examination.
Design an appropriate plan of care for sensory impairments.
Choose sensory interventions using current research and evidence-based practice.
Introduction to Sensory Impairment
Imagine a warm summer day, and you are sitting on your front porch, quietly rocking in a wicker chair with your bare feet. You feel the breeze blow across you while you sip on a glass of iced tea. Out of nowhere, a tiny mouse runs across your feet, causing you to leap out of your seat and spill the icy tea all over yourself. Without having to think about it, your sensory system works instantly and automatically to take in, process, organize, and plan a response to the myriad sensory events that just took place. In an instant, sensory receptors in your joints, skin, and head alerted the central nervous system to process and respond to the numerous temperature, touch, movement, and pressure stimuli.
The human body possesses numerous sensory systems that function both independently and in conjunction with each other. The mechanisms determining how they work are different, yet they all share the overall goal of helping the person be aware of and react to internal (body) and external (environment) stimulations in a functional and purposeful manner. The sensory systems can be categorized as somatosensory (tactile and proprioceptive), vestibular, and other special senses such as vision, hearing, taste, and smell. Impairments in tactile, proprioceptive, and vestibular systems are the sensory dysfunctions covered in this chapter. The reader is also referred to Chapters 7 and 29 for additional information on vestibular, visual, olfactory, taste, and auditory impairments.
According to the Guide to Physical Therapist Practice (Guide), sensory integrity is the accuracy of cortical sensory processing, to include proprioception, vibration sense, stereognosis, and cutaneous sense (American Physical Therapy Association [APTA], 2015b). Sensory processing is defined by the Guide as the ability to integrate movement-related information that is derived from the environment (APTA, 2015b). It involves taking in, processing, organizing, and planning a motor response to sensory stimuli. In normal, healthy individuals, this response is an automatic, efficient, and effective occurrence. Perhaps an overlooked, taken for granted event, it occurs continually throughout the day for every person. When disease or injury does not permit the sensory system to function smoothly, automatically, completely, or efficiently, however, it suddenly gains our attention.
THINK ABOUT IT 27.1
How might movement-related symptoms present differently in an individual depending on whether the dysfunction is in the afferent input, the processing/organizing of sensory information, or the motor response?