Assessing Sensation - Part 2 PDF

Assessing Abilities and Capacities: Sensation Part 2 OT 211 Dr. Qussai Obiedat  PERIPHERAL NERVE INJURY Patterns of sensory loss following peripheral nerve injury vary with the nerve or nerves involved. Damage to a si...

Assessing Abilities and Capacities: Sensation Part 2 OT 211 Dr. Qussai Obiedat  PERIPHERAL NERVE INJURY Patterns of sensory loss following peripheral nerve injury vary with the nerve or nerves involved. Damage to a single nerve root as it exits the spinal cord affects sensation on one side of the body within a single dermatome. Damage to a peripheral nerve distal to the brachial plexus affects sensation within the appropriate peripheral nerve distribution. EX: In carpal tunnel syndrome, compression of the median nerve at the wrist produces sensory symptoms in the thumb, index, middle, and half of the ring finger on the affected side with the greatest changes in two-point discrimination being found in the middle finger. 2  COMPRESSION OF PERIPHERAL NERVES Furthermore, compression of peripheral nerves in the upper limb can be characterized by the following: 1. Pathology is observed primarily at anatomical locations where compression is more likely 2. Pathology may involve one or several specific nerves and locations within the course of the nerves 3. Pathology has a smaller or larger extension along the nerve versus being limited to a small focal point 4. Pathology is likely to spread and extend over time and involve several and/or larger nerve segments. 3  SEVERITY OF THE SENSORY LOSS The severity of the sensory loss can vary widely. A complete transection of a peripheral nerve results in a total loss of tactile sensation within the region, especially loss of two-point discrimination and cutaneous pain sensibility. A mild nerve compression, such as in early stages of CTS, produces a slightly elevated threshold for sensing light touch or vibration. As the compression persists or increases in severity: Further loss of sensation will occur The threshold of light touch and vibration sensation will be further elevated The patient will begin to report symptoms such as frequently dropping items from the hand. Eventually, if the compression is not relieved, numbness and loss of protective sensation will develop, and furthermore, prolonged loss of peripheral sensation results in cortical reorganization of the body part, further disrupting sensory interpretation. 4  RECOVERY AFTER PNI Recovery of sensation following release of a nerve from compression is very likely if the compression is brief and mild. Significant recovery following prolonged compression is common, but sensory perception does not always reach normal levels. Recovery of sensation following total transection of a nerve is possible only with surgical intervention and adequate regrowth of neurons. The prognosis of sensory recovery for the transected peripheral nerve appears most correlated with length of graft and length of time before grafting. 5  RECOVERY AFTER PNI Sensation of temperature and pain generally (but not always) recovers first, followed by touch sensation Regrowth of pain fibers averages 1.08 mm per day Regrowth of touch fibers averages 0.78 mm per day Moving touch recovers before light touch. Accurate touch localization recovers last. 6  RECOVERY AFTER PNI The pattern of sensory loss occurring as a result of peripheral polyneuropathies, which are associated with chronic conditions such as DM & AIDS, is: Typically, bilateral and symmetrical Usually beginning in the feet and hands (glove-and-stocking distribution) and spreading proximally. Paresthesia and pain may accompany peripheral neuropathy. Because of the chronic conditions associated with peripheral neuropathy, full recovery of sensation is generally not expected. 7  GUIDELINES FOR PLANNING ASSESSMENTS FOR PATIENTS WITH PNI The purpose of evaluation in clients with peripheral polyneuropathy is to establish the impact of disease on protective sensation, so choose an assessment of protective sensation. The desired outcome of sensory evaluation in clients with involvement of a single peripheral nerve is an accurate map of both the body area and severity of sensory loss. Evaluation of nerve compression and subsequent recovery requires measures that are highly sensitive to show small changes in sensory function. 8  GUIDELINES FOR PLANNING ASSESSMENTS FOR PATIENTS WITH PNI Because functional tests of sensation requiring object or texture identification are completed with the thumb, index, and middle fingers, these assessments provide information about the functioning of the C6, C7, and C8 nerve roots and the median nerve. In documenting recovery of peripheral nerve function, keep in mind the recovery sequence of pain → moving touch → light touch → touch localization. 9  EVALUATION TECHNIQUES There are numerous methods of testing sensation. Some are intended to evaluate a specific type of sensory receptor Vibration awareness using a tuning fork. Some are intended to evaluate the use of sensation in skills that support occupational functioning Use of the hand to identify objects by touch in the test of stereognosis. Some are designed to detect very small changes in sensory perception Touch threshold test using monofilaments (fine nylon strands). 10  EVALUATION TECHNIQUES The locognosia test: can be used after peripheral nerve injuries to determine touch localization. The test uses a grid superimposed on the hand or map of the hand divided into zones. The patient or subject is asked to identify the zone in which a stimulus such as an aesthesiometer is perceived. 11  PRINCIPLES OF SENSORY TESTING These principles are to optimize the reliability of the testing results. The purpose of these principles is to eliminate nontactile cues and to ensure that the responses from the patient accurately reflect actual sensation. Because many of the tests require subjective reports from the patient, results can be either deliberately or unconsciously manipulated by the patient to make the deficit appear better or worse. 12  PRINCIPLES OF SENSORY TESTING 1. Choose an environment with minimal distractions. 2. Ensure that the patient is comfortable and relaxed. 3. Ensure that the patient can understand and produce spoken language. If the patient cannot, modify testing procedures to ensure reliable communication. 4. Determine areas of the body to be tested. 5. Stabilize the limb or body part being tested. 13  PRINCIPLES OF SENSORY TESTING 6. Note any differences in skin thickness, calluses, and so on. Expect sensation to be decreased in these areas. 7. State the instructions for the test. 8. Demonstrate the test stimulus on an area of skin with intact sensation while the patient observes. 9. Ensure that the patient understands the instructions by eliciting the correct response to the demonstration. 10. Occlude the patient’s vision for administration of the test. Place a screen or a file folder between the patient’s face and area being tested, blindfold the patient, or ask the patient to close his or her eyes. 14  PRINCIPLES OF SENSORY TESTING 11. Apply stimuli at irregular intervals or insert catch trials in which no stimulus is given. 12. Avoid giving inadvertent cues, such as auditory cues or facial expressions, during stimulus application. 13. Carefully observe the correctness, confidence, and promptness of the responses. 14. Observe the patient for any discomfort relating to the stimuli that may signal hypersensitivity (exaggerated or unpleasant sensation). 15. Ensure that the therapist who does the initial testing does any reassessment. 15  SENSORY TESTS Therapists must consider the various qualities of the types of sensory tests as they choose and administer them. Threshold tests determine the smallest stimuli that can be noticed by the patient. They are the most sensitive and have numeric results that can easily be compared over time. Two-point discrimination measures innervation density in the fingers and is quite sensitive to change. Touch localization evaluates not only sensation but also whether that sensation is accurately perceived. Touch, temperature, vibration, and pain awareness are simple to administer but are not very sensitive to change. Tests of kinesthetic and proprioceptive sensations are less commonly used and are not very sensitive to change but are believed to be related to the specific type of sensory feedback required for coordinated movement. 16  SENSORY TESTS The Moberg Pick-Up Test and stereognosis test are more functional but require combined motor and sensory function in the hand. Both the DASH (Disabilities of the Arm, Shoulder, and Hand) and Quick DASH Outcome Measures are questionnaires designed to look at changes in motor and sensory function of the upper extremity. The HASTe (Hand Active Sensation Test) is a functional tool designed to assess the haptic perception of people who have sustained a stroke 17  SPECIAL CONSIDERATIONS Sensory tests are usually administered with the patient rested and in a comfortable, supported position Exceptions to this principle occur in the case of patients with peripheral nerve compression. Provocative testing, which determines whether increases in symptoms occur as a result of additional stress or compression on the peripheral nerve, is used. Increased sensory loss in the median nerve distribution with the wrist in flexion implicates compression of that nerve in the carpal tunnel area. Elbow flexion is the stress position for suspected cubital tunnel syndrome, which is compression of the ulnar nerve in the elbow area. Manual pressure over the nerve can be combined with the provocative position to further increase stress on the nerve. 18  STANDARDIZED SENSORY TESTING Sensory Test: Touch threshold Test Instrument: Semmes-Weinstein monofilaments Stimulus and Response: S: Begin testing with filament marked 2.83 Hold filament perpendicular to skin, apply to skin until filament bends. Apply in 1.5 seconds, and remove in 1.5 seconds. Repeat three times at each testing site, using thicker filaments if the patient does not perceive thin ones (except for filaments marked 4.08, which are applied one time to each site). R: Patient says, “yes” upon feeling the stimulus. Scoring and Expected Results: Score involves recording the number of the filament or the actual force of the thinnest filament detected at least once in three trials. Normal touch threshold for adults: filament 2.83 (force, 0.08 g) (Sole of the foot, 3.61 (force, 0.21 g)). 19  STANDARDIZED SENSORY TESTING Sensory Test: Static two-point discrimination Test Instrument: Disk-Criminator OR aesthesiometer Stimulus and Response: S: Begin with a 5-mm separation of points. Lightly (just to the point of blanching) apply one or two points (randomly sequenced) in a transverse or longitudinal orientation on the hand Hold for at least 3 seconds or until patient responds. Gradually adjust distance of separation to find least distance that patient can correctly perceive two points. R: Patient responds by saying, “one,” “two,” or “I can’t tell.” Scoring and Expected Results: Score is smallest distance at which perception of one or two points is better than chance. Norms: 3–5 mm in fingertips ages 18–70 years; 5–6 mm in fingertips ages 70 and above; 5–9 mm for middle and proximal phalanges in adults age 18–60 years; 0–12 mm middle and proximal phalanges of those age 60 years and older 20  STANDARDIZED SENSORY TESTING Sensory Test: Moving two-point discrimination Test Instrument: Disk-Criminator OR aesthesiometer Stimulus and Response: S: Beginning with a 5- to 8-mm distance, Move one or two points randomly from proximal to distal on the distal phalanx with points side by side and parallel to the long axis of the finger. Use just enough pressure for the patient to appreciate the stimulus. Gradually adjust distance of separation to find least distance that patient can correctly perceive. R: Patient responds by saying, “one,” “two,” or “I can’t tell.” Scoring and Expected Results: Score is smallest distance at which perception of one or two points is better than chance. When the patient’s responses become hesitant or inaccurate, require 2 of 3, 4 of 7, or 7 of 10 correct responses. Norms: 2–4 mm for ages 4–60 years; 4–6 mm for ages 60 years and older. 21  STANDARDIZED SENSORY TESTING Sensory Test: Touch localization Test Instrument: Semmes-Weinstein monofilament number 4.17, pen, or pencil eraser Stimulus and Response: S: Apply touch to patient’s skin with vision occluded. R: Patient remembers location of stimulus. With vision no longer occluded, patient uses index finger or marking pen to point to spot just touched. Scoring and Expected Results: Score is the measured distance in millimeter between location of the stimulus and location of the response. Normal response is approximately 3–4 mm in digit tips, 7–10 mm in palm of hand, 15–18 mm in forearm. 22  STANDARDIZED SENSORY TESTING Sensory Test: Touch localization or locognosia Test Instrument: Semmes-Weinstein monofilament number 6.65 or black filament on WEST, grid superimposed on the hand or a drawn map of the hand divided into zones. Stimulus and Response: S: While vision is occluded, apply touch to patient’s skin on palmar side of tips of fingers for 2 seconds followed by an interval of 3 seconds before next stimulus. Test the unaffected hand first. Each zone is stimulated twice. R: Patient identifies the location of the stimulus by calling out the corresponding number on the map. Scoring and Expected Results: A score of 2 points is given for each zone identified correctly. When localization is correct orientation but in an adjacent finger or correct finger but adjacent zone, a score of 1 is given. When zone cannot be identified, but correct digit is perceived, a score of 1 is also given. Anything worse or nonresponse is scored 0. Maximum score is 56 points for the area of the median nerve and 24 points for the area of the ulnar nerve. 23  STANDARDIZED SENSORY TESTING Sensory Test: Vibration threshold Test Instrument: Vibrometer: biothesiometer, Vibratron II, automated tactile tester. Stimulus and Response: Protocols vary with instrument S: Generally, vibrating head is applied to area to be tested. Stimulus intensity is gradually increased or decreased R: Patient indicates when vibration is first felt or no longer felt Scoring and Expected Results: Scoring varies with instrument Norms usually provided by manufacturer 24  STANDARDIZED SENSORY TESTING Sensory Test: Modified Pick-Up Test Measures the interpretation of sensation in the distribution of the median nerve. Test Instrument: A small box and 12 standard metal objects: wing nut, screw, key, nail, large nut, nickel, dime, washer, safety pin, paper clip, small hex nut, and small square nut Stimulus and Response: Part 1: S: Tape small and ring digits to palm to prevent use. With patient using vision, have him or her pick up and place objects in a box as quickly as possible Time performance on two trials R: Patient picks up each object and deposits it in the box as quickly as Possible 25  STANDARDIZED SENSORY TESTING Stimulus and Response: Part 2: S: With patient’s vision occluded, place one object at a time between three-point pinch in random order and measure speed of response R: Patient manipulates object and names it as rapidly as possible Scoring and Expected Results: Part 1: Score is total time to pick up and place all 12 objects in the box for each of two trials Normal response: Trial 1: 10–19 seconds Trial 2: 9–16 seconds Part 2: Score is time to recognize each object on each of two trials (up to a maximum of 30 seconds) Normal response: 2 seconds per object 26  STANDARDIZED SENSORY TESTING Sensory Test: Erasmus MC Revised Nottingham Sensory Assessment Quantitative functional measure of sensation after stroke. Sensations assessed include light touch, pinprick, pressure, two-point discrimination, and proprioception. Test Instrument: A blindfold, cotton wool balls, neurotips, cocktail stick, aesthesiometer Stimulus and Response: S: Subjects are tested for light touch, pinprick, sharp-blunt discrimination, pressure, two-point discrimination, and proprioception. Areas tested are the face, trunk, shoulder, elbow, wrist, hand, hip, knee, ankle, and foot. Each stimulus is assessed three times on each area to the left and right sides in random order. For proprioception, the body part is moved by the researcher/therapist, and the subject is asked to replicate the position. R: Subjects indicate whether the stimulus is same as on unaffected side, different, or absent either by verbal response or movement of body. Scoring and Expected Results: All areas are scored based on 2 for normal response, 1 for impaired response, or 0 for absent response. For all categories, it is expected that the subject score “2 for normal response” for all areas 27  STANDARDIZED SENSORY TESTING Sensory Test: Hand Active Sensation Test (HASTe) Quantitative functional measure of haptic perception in the hand. Test Instrument: Objects of various weights and textures Stimulus and Response: S: To complete the HASTe, subjects use one hand to manually explore objects that vary by weight and texture by using a match-to-sample forced choice recognition task without visual assistance R: Subjects indicate their choice without identifying or describing the matching object property Scoring and Expected Results: 18 trials are completed; 9 test objects are matched twice, once to texture and once to weight. The total number of accurate matches (0–18) is recorded. 28  STANDARDIZED SENSORY TESTING Sensory Test: Quick DASH Self-report tool for people with musculoskeletal disorders of the upper extremities. Measures perceived abilities to do tasks requiring sensory feedback. Test Instrument: None Stimulus and Response: S: Survey of 11–19 items provided to patient to complete. R: Patient fills out items on the scale and grades ability on a scale of 1–5 (no difficulty to unable, respectively). Scoring and Expected Results: At least 10 of the 11 items must be completed for a score to be calculated. Assigned values for completed responses are summed and then averaged, producing the score. This score is then converted to a 100 scale by subtracting 1 from the average score and multiplying by 25. A higher score indicates greater disability. 29 Thank You! 30