SENSORY FUNCTION, TESTING STRETCH OR DEEP TENDON REFLEXES

Sensory Function

>>Sensation is tested by evaluating the patient’s ability to perceive a light touch, superficial pain (pin-prick), differences in temperature, vibration, position sense and motion. If any abnormality is found, it is important to identify the area of deficit clearly and find the point where the abnormal sensation becomes normal again. This point is referred to as a sensory level.

>>Touch the patient in various areas with cotton (light touch) and with the tip of a pin (pin-prick)

>>Typically begin with the face and move down the body, noting any asymmetry between the right and left sides.


Sensory Function: Stereognosis
-Test the person’s ability to recognize objects by feeling their forms, sizes and weights.
-With eyes closed, placed a familiar object (paper clip, key, coin, cotton ball, or pencil) in the person’s hand and ask the person to identify it.
-Normally, a person will explore it with the fingers and correctly name it.
-Testing the left hand assesses right parietal lobe functioning.
-Astereognosis – inability to identify object correctly. Occurs in sensory cortex lesions e.g. stroke

Sensory Function: Graphestesia

-The ability to “read” a number by having it traced on the skin.
-With the person’s eyes closed, use a blunt instrument to trace a single digit number or a letter on the palm.
-Ask the person to tell you what it is.
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Inability to distinguish number occurs with lesions of the sensory cortex

Testing Stretch or deep Tendon reflexes

-Evaluation of deep tendon reflexes (DTRs) reveals the intactness of the spinal reflex arc at specific spinal levels as well as the normal override on the reflex of the higher cortical levels.
-DTRs are usually tested by tapping on a tendon with fingers or a reflex hammer. This causes a stretching of certain muscles and results in contraction. When damage occurs to higher centers (upper motor neurons), the spinal reflex arc is uninhibited and the DTRs are hyperactive.

Grading Scale – Reflex (4 Point Scale)-Reflexes are graded on a scale of 0 to 4.

-4+ Very brisk, hyperactive with clonus, indicative of disease
-3+ Brisker than average, may indicate disease
-2+ Average, normal-1+ Diminished, low normal
-0 No response

Definition of terms:

Clonus – is a set of short jerking contractions of the same muscle, is a repeated reflex muscular movements. A hyperactive reflex with sustained clonus (lasting as long as the stretch is held) occurs with upper motor neuron disease.
Hyperreflexia – is the exaggerated reflex seen when the monosynaptic reflex arc is released from the influence of higher cortical levels. This occurs with upper motor neuron lesions. e.g. stroke
Hyporeflexia – which is the absence of a reflex, is a lower motor neuron problem. It occurs with interruption of sensory afferents or destruction of motor efferents and anterior horn cells e.g. spinal cord injury

Dermatomes
-A circumscribed skin area that is supplied mainly from one spinal cord segment through a particular spinal nerve.
-The dermatomes overlap, which is a form of biologic insurance. That is, if one nerve is severed, most of the sensations can be transmitted by one above and the one below.

Dermatomes Landmarks
-The thumb, middle finger and fifth finger are each in the dermatomes of C6, C7 and C8.
-The nipple is at the level of T4.
-The umbilicus is at the level of T10.
-The groin is in the region of L1.

Biceps Reflex (C5 to C6)

-Support the person’s

forearm on yours; this position relaxes, as well as partially flexes, the person’s arm.
-Place your thumb

on the biceps tendon and strike a blow on your thumb.
-You can feel as well as see the normal response, which is contraction of the biceps muscle and flexion of the forearm.

Triceps reflex (C7 to C8)


-Tell the person to let the arm “just go dead” as you suspend it by holding the upper arm. Strike the triceps tendon directly just above the elbow.
-The normal response is extension of the forearm.
-Alternately, hold the person’s wrist across the chest to flex the arm at the elbow, and tap the tendon.

Brachioradialis reflex (C5 to C6)


-Hold the person’s thumbs to suspend the forearms in relaxation.
-Strike the forearm directly, about 2 to 3 cm above the radial styloid process.
-The normal response is flexion and supination of the forearm.

Quadriceps reflex “Knee jerk” (L2 to L4)


-Let the lower legs dangle freely the knee and stretch the tendons.
-Strike the tendon directly just below the patella.
-Extension of the lower leg is the expected response.
-For the person in the supine position, use your own arm as a lever to support the weight of one leg against the other leg.
-This maneuver also flexes the knee.

Achilles reflex “Ankle jerk” (L5 to S2)

-Position the person with the kn

ee flexed and the hip externally rotated.
-Hold the foot in dorsiflexio

n, and strike the Achilles tendon directly.
-Feel the normal response as the foot plantar flexes against your hand.
-For the person in the supine position, flex one knee and support that lower leg against the other leg so that it falls “open.”
-Dorsiflex the foot and tap the tendon.

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