Assessing Sensation: Part 1 PDF

Assessing Abilities and Capacities: Sensation Part 1 OT 211 Dr. Qussai Obiedat  INTRODUCTION The AOTA defines sensory-perceptual skills as: Actions or behaviors a client uses to locate, identify, and resp...

Assessing Abilities and Capacities: Sensation Part 1 OT 211 Dr. Qussai Obiedat  INTRODUCTION The AOTA defines sensory-perceptual skills as: Actions or behaviors a client uses to locate, identify, and respond to sensations, interpret, organize, and remember sensory events via sensations that include: Visual Auditory Proprioceptive Tactile Olfactory Gustatory Vestibular sensations 2  INTRODUCTION In this lecture, tactile, thermal, and proprioceptive sensations will be discussed. Methods of evaluating these senses will be described. The tactile sense throughout the body is necessary for competent occupational functioning. Tactile sensation is especially important in the hands. After birth, an infant is bombarded with tactile sensations that are different from those in utero. In a few weeks, the infant learns to interpret a multitude of tactile stimuli This developed capacity supports further development of abilities and skills as the infant uses touch to grasp an object, bring two hands together at midline, and reach out to stroke a parent’s face. 3  ROLE OF SENSATION IN OCCUPATIONAL FUNCTIONING Ian Waterman Case: Acquired a rare neurological illness at 19 years of age that resulted in the loss of all sensation of touch in his body from the neck down. He had no awareness of the positions of his arms, legs, or body. Muscle movement were not affected. Any attempt at movement was wildly uncontrolled. Ian’s initial attempt at standing up resulted in him falling He was unable to feed himself, get dressed, or do any functional activity requiring control of movement. 4  ROLE OF SENSATION IN OCCUPATIONAL FUNCTIONING Although a loss of sensation without any motor loss is unusual, it exemplifies the close connection between the motor and sensory systems. With sensory loss in the hand, fine motor coordination is impaired, and manipulative ability is decreased. The amount of force needed to maintain grasp on an object also depends on sensory feedback. Usually, we use force that is just sufficient to overcome the pull of gravity, taking into account the amount of friction afforded by the surface texture. Without adequate tactile sensation, the force used to grip an object is either lower or higher than the force needed This results in objects slipping from grasp, delicate objects being crushed by excessive grip force, or muscles developing fatigue from overactivity. 5  ROLE OF SENSATION IN OCCUPATIONAL FUNCTIONING Some activities require sensory feedback because they are totally dependent on the sense of touch: Determining the temperature of a bowl taken from the microwave. Tactile sensations let us know whether the food is warm and whether the bowl is too hot to carry to the table. Haptic perception, active touch, helps to determine the three-dimensional characteristics of objects: Finding coins or other objects in a pocket Fastening a necklace Closing a back zipper Therefore, we rely entirely on sensory feedback 6  PURPOSES OF SENSORY EVALUATION Assess the type and extent of sensory loss Evaluate and document sensory recovery Assist in diagnosis Determine impairment and functional limitation Provide direction for occupational therapy intervention Determine time to begin sensory re-education Determine need for education to prevent injury during occupational functioning Determine need for desensitization 7  NEUROPHYSIOLOGICAL FOUNDATIONS OF TACTILE SENSATION Receptors for tactile sensation are present within skin, muscles, and joints. Each tactile receptor is usually specialized for a single type of sensory stimulation such as touch, temperature, or pain. Types of Sensation: Constant touch or pressure Moving touch or vibration Proprioception and kinesthesia Pain (pinprick) Pain (chronic) Temperature 8  NEUROPHYSIOLOGICAL FOUNDATIONS OF TACTILE SENSATION Each sensory neuron and its distal and proximal terminations can be considered a sensory unit. Each sensory unit serves an area of skin that encompasses its defined receptive field. A stimulus anywhere in the field may evoke a response, but stimuli applied to the center of the receptive field produce sensations more easily. The center of a receptive field has a lower threshold than the periphery. Adjacent receptive fields overlap; therefore, a single stimulus evokes a profile of responses from overlapping sensory units. 9  NEUROPHYSIOLOGICAL FOUNDATIONS OF TACTILE SENSATION The variation in the number of sensory units in a given area of skin is called innervation density. Face, hand, and fingers have high innervation densities. Areas with high innervation density are highly sensitive and have a proportionately large representation area within the somatosensory area of the cortex, the postcentral gyrus of the parietal lobe. Sensation is a complex process: Tactile stimuli of sufficient strength elicit responses from both constant and moving touch receptors and perhaps also from the pain receptors. Extremes of hot and cold stimuli activate the pain receptors rather than the temperature receptors. Perception of joint motion ( kinesthesia ) and joint position ( proprioception ) appear to be a result of information from multiple kinds of receptors. 10 BODY PARTS SENSORY REPRESENTATION IN THE POSTCENTRAL GYRUS 11  SOMATOSENSORY DEFICIT PATTERNS Any interruption along the ascending sensory pathway or in the sensory areas of the cortex can lead to a decrease or loss of sensation. The extent and severity of the sensory deficit can generally be predicted in accordance with the mechanism and location of the lesion or injury. Patterns of sensory impairment are directly related to the involved neuroanatomical structures, which could be anywhere in the central or peripheral nervous system. Somatosensory and perceptual impairments contribute to poor motor control and may have an impact on participation in rehabilitation. 12  CORTICAL INJURY Patients with brain lesions caused by stroke or acquired brain injury demonstrate sensory losses related to loss of functioning of specific neurons within the central nervous system. Perception of fine touch and proprioception are most affected, temperature sensation is affected less, and pain sensibility is affected least. Effects of stroke on sensation depend on specific disruption of blood supply. Occlusion of the middle cerebral artery (most common site) is often associated with contralateral impairment of all sensory modalities on the face, arm, and leg. Massive infarction in the distribution of the anterior and middle cerebral arteries may present with dense sensory deficits. Occlusion of the anterior cerebral artery tends to cause more loss of sensation in the contralateral leg than in the face and arm because of this artery’s supply to the medial aspect of the cerebral cortex. 13  CORTICAL INJURY Compared patients with left and right stroke and found that loss of proprioception and pain perception were more common following right stroke than left stroke. Patients with stroke also demonstrated decreased performance with visual deprivation. Lesions to the posterior thalamus tend to result in loss or impaired cold sensation and central pain response. Patterns of sensory loss following head trauma are less predictable because of the more diffuse areas of brain damage associated with this condition. 14  CORTICAL INJURY Partial recovery of sensation following cortical injury is attributed to: Decreased edema Improved vascular flow Cortical plasticity Relearning Recovery of pain and temperature perception usually precedes recovery of proprioception and light touch. 15  GUIDELINES FOR PLANNING ASSESSMENTS AFTER CORTICAL INJURIES Quickly screen those areas of the body where sensation is likely to be intact, followed by a more thorough evaluation only if a deficit is found during screening. Assess more thoroughly those areas most likely to be affected, usually the side contralateral to the injury. If tactile sensation and proprioception are intact, assessment of temperature and pain is not necessary, because these protective sensations will also be intact. For patients with mild cortical impairment, begin the sensory assessment with light touch and/or proprioception. If pain and temperature are absent, assessment of light touch and proprioception is not necessary because these sensations will also be absent. For patients with severe cortical impairment, begin with assessment of pain and temperature for greatest efficiency. During reassessment to document recovery, remember that pain and temperature sensation recover before light touch and proprioception. 16  SPINAL CORD INJURY Patients with complete lesions of the spinal cord demonstrate a total absence of sensation in the dermatomes below the level of the lesion. The level of the lesion determines the extent of the sensory loss. The greatest loss occurring in patients with lesions in the highest cervical regions of the spinal cord. Paresthesia: (tingling or pins and needles sensation) may occur in the dermatome associated with the level of the lesion 17  SPINAL CORD INJURY Incomplete spinal cord lesions result in sensory losses that are related to damage within specific spinal tracts. Damage to the anterior part of the spinal cord usually results in loss of pain and temperature sensation below the level of the lesion, whereas touch, vibration, and proprioception remain intact. Conversely, patients who have damaged the posterior portion of the spinal cord cannot feel light touch and vibration but can feel differences in temperature and painful stimuli. 18  BROWN-SEQUARD SYNDROME Damage to one side of the spinal cord. Patients display loss of touch, vibration, and proprioception on the side of the lesion. Loss of temperature and pain sensation on the side opposite the lesion. This occurs because of the differences in the pathways of the ascending sensory fibers Neurons carrying temperature and pain sensations cross to the opposite side of the spinal cord immediately after entering it Whereas neurons carrying touch sensations ascend to the medulla before crossing to the opposite side. 19  SPINAL CORD INJURY Damage to the central spinal cord often results in bilateral loss of pain and temperature sensation below the level of the lesion. Neurons cross to the opposite side through the central portion of the cord. Mild to moderate compression of the spinal cord may result in: Decreased or absent sensation in the single dermatome at the level of the compression Or could involve dermatomes below the compressed area. 20  RECOVERY AFTER SCI Any sensory recovery following traumatic spinal cord injury usually occurs within the first year The greatest recovery in the first 3–6 months Especially in incomplete injuries Recovery of sensation is thought to occur because of resolution of ischemia and edema within the spinal cord. 21 DERMATOMES 22  GUIDELINES FOR PLANNING ASSESSMENTS FOR PATIENTS WITH SCI Use a test with both pain and light touch stimuli (pinprick and cotton ball, respectively) to determine level of injury. Apply stimuli to key sensory points within each dermatome when assessing neurological level in a rostral to caudal direction. Test bilaterally because results may differ from side to side. Do complete testing of pinprick and light touch for patients with complete lesions where sacral sparing is absent to determine the zone of partial preservation. The zone of partial preservation provides more comprehensive information to the therapist regarding the intervention and education needed regarding sensory concerns after SCI. 23  GUIDELINES FOR PLANNING ASSESSMENTS FOR PATIENTS WITH SCI Test for multiple sensory modalities, including at least one pain or temperature assessment and at least one measure of touch, vibration, or proprioception in patients with incomplete or unknown lesions. To determine spinothalamic function, select a thermal threshold test. Medoc Thermal Sensory Analyzer Cool and warm pain thresholds and cold and heat pain thresholds To determine posterior column involvement, select a vibration threshold test (Bio-Thesiometer). Finally, to test both spinothalamic and posterior column function, the electrical threshold Quantitative Sensory Test (QST) may be used. QST is typically used in research settings rather than clinical therapy settings because of the cost of the instrument and the time required to administer the test. 24 25 26 Light touch testing using key sensory points for neurological classification of spinal cord injury: A. Light touch testing of T1 key sensory point using cotton swab B. Key sensory points of the arm 27 Thank You! 28