RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh sensory examination RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh

(Somatovisceral Sensory System) Somatosensory system (Somatovisceral Sensory System) - transmits sensations from receptor organs in the skin, muscles, joints and viscera to the brain.

* Two (2) main pathways: 1. Posterior (Dorsal) Column Lemniscal tract - fine touch, two-point discrimination, vibration and position sensations, fine pressure 2. Spinothalamic (Anterolateral) tract - pain and thermal sensations, crude touch, crude pressure, tickle and itch

1. tactile sensations – light touch, pressure, tactile OBJECTIVES: To be able to reasonably acquire the skill of testing the following general sensation: 1. tactile sensations – light touch, pressure, tactile localization and discrimination 2. joint position sense 3. recognition of size, shape, weight forms and textures of objects 4. vibration sense 5. pain sensations 6. temperature sense

REQUIREMENTS: Cotton wools Thin bristles Calipers, pins or disposable toothpicks Test tubes with warm and cold water Flat base tuning forks Different weights

TACTILE LOCALIZATION: 1. Ask the subject to close her eyes. 2. Touch different parts of the body with cotton wool. 3. Ask her to acknowledge whether she feels the touch and ask her to locate the exact area touched. 4. Note whether there is abnormality like hypoaesthesia or hyperaesthesia. * Hypoaesthesia – touch sensation is reduced. * Hyperaesthesia – sensations produced is either painful, irritating, or tingling.

Spinothalamic tract interruption - increase touch threshold - decrease in no. of touch spots in the skin - slight touch deficit - normal touch localization

Dorsal columns destroyed - vibration and proprioception sense are lost - increase touch threshold - no. of touch-sensitive areas in the skin - impaired localization of touch sensation

TWO-POINT DISCRIMINATION: 1. Ask the subject to close her eyes. 2. With the calipers wide apart, touch two areas of the back of the hand. 3. Ask the subject to say whether she feels two points of touch or a single point.

4. Now decrease the distance between two limbs of the caliper and measure in millimeter(mm) the minimum distance that can be recognized as two distinct points. * Two-point threshold – is the minimum distance at which two points of contact can be felt. – is impaired in: dorsal column and parietal cortical (somatosensory cortex) lesions 5. Determine two-point threshold in the following areas – palm of the hand, fingertip, leg and back of the neck.

RECOGNITION OF SIZE, SHAPE AND FORMS: 1. Ask the subject to close her eyes. 2. Place any common object like coins, keys, pen, etc. in her palm and ask her to identify the object without looking towards it.

* Stereognosis – ability to recognize objects. * Astereognosis – loss of recognition of – early sign of damage to cerebral cortex. – if without defect in touch and pressure sensation (Parietal lobe lesion posterior to postcentral gyrus)

RECOGNITION OF WEIGHT DISCRIMINATION: 1. Ask the subject to close her eyes and place her hand on the table. 2. Place different weighs in his hands. 3. Ask her to indicate if she could identify the variations in the weights placed on her hand.

Weight discrimination – the ability to assess the weight of an object. * An increase in intensity of stimuli is transmitted to the brain in the form of: a. an increase in the number of afferent fibers stimulated b. increased frequency of action potentials in these fibers … These two features are perceived as an indication of the strength of the stimulus.

VIBRATION SENSE: 1. Ask the subject to close her eyes. 2. Strike the tuning fork (128 – 250 cps) and place it successively over identical body areas on each side of the body. 3. Ask the subject to acknowledge whether she feels the vibration and whether it is of the same intensity on the two sides.

4. Proceed from the upper part of the body downwards – the clavicle, tip of the shoulder, elbow, wrist, dorsum of the hand, anterior chest wall, anterior superior iliac spine, patella, tibial tuberosity, lateral and medial malleoli and the base of the big toe. 5. Test if the subject can accurately identify when the vibration stops.

Vibration – a pattern of rhythmic pressure stimuli … receptors involved: touch receptors especially Pacinian corpuscles … pathway: dorsal column … degeneration occurs in: - poorly controlled diabetes - pernicious anemia - some vitamin deficiencies

JOINT POSITION SENSE: 1. Ask the subject to close her eyes. 2. Hold her finger or toe and make it up and down and ask her to recognize: a. movement of the joint by saying NOW b. direction of the fingers whether up or down.

PAIN SENSATION: * SUPERFICIAL … With the prick of a pin, elicit the sensation of pain on a willing partner.

* PRESSURE … Put pressure on deep structures such as muscles, tendoachilles or bones, superior orbital margin, etc and ask her whether she feels pain.

TEMPERATURE SENSE: 1. With two test-tubes containing warm and cold water, touch at different sites of the body of your subject. 2. Ask her to identify the temperature differences.