Neurology System Reflexes

Reflex Arch Spinal nerves have sensory (Afferent) & motor (Efferent) portions Spinal nerves have sensory (Afferent) & motor (Efferent) portions Control DTRs & superficial reflexes Control DTRs & superficial reflexes Simple reflex arch needs a sensory & motor neuron Simple reflex arch needs a sensory & motor neuron Ex. Of normal reflex arch = knee- jerk/patellar reflex Ex. Of normal reflex arch = knee- jerk/patellar reflex

Reflex Arch Reflexes= basic defense mechanisms of the nervous system Reflexes= basic defense mechanisms of the nervous system –Involuntary –Unconscious –Allow quick reaction to painful/damaging situations –Maintain balance –Appropriate muscle tone

Four Types of Reflexes 1. Deep tendon Patellar or knee jerkPatellar or knee jerk 2. Superficial CornealCorneal abdominalabdominal 3. Visceral Pupillary reflex to light and accommodationPupillary reflex to light and accommodation 4. Pathologic BabinskiBabinski Extensor plantar reflexExtensor plantar reflex

Deep Tendon Response Briskly tap the tendon of a partially stretched muscle Briskly tap the tendon of a partially stretched muscle For the reflex to fire, all components of the reflex arch must be intact For the reflex to fire, all components of the reflex arch must be intact –Sensory nerve fibers –Spinal cord synapse –Motor nerve fibers –Neuromuscular junction –Muscle fibers

Deep Tendon Response Tapping the tendon activates special sensory fibers in the partially stretched muscle, triggering a sensory impulse that travels to the spinal cord via peripheral nerve Tapping the tendon activates special sensory fibers in the partially stretched muscle, triggering a sensory impulse that travels to the spinal cord via peripheral nerve the stimulated sensory fiber synapses directly with the anterior horn cell innervating the same muscle. the stimulated sensory fiber synapses directly with the anterior horn cell innervating the same muscle.

Deep Tendon Response When the impulse crosses the neuromuscular junction, the muscle suddenly contracts, completing the reflex arch. When the impulse crosses the neuromuscular junction, the muscle suddenly contracts, completing the reflex arch.

Deep Tendon Response Each deep tendon reflex involves specific spinal segments Each deep tendon reflex involves specific spinal segments Abnormal reflex help locate an a pathologic lesion Abnormal reflex help locate an a pathologic lesion

The Plantar Response Normally flexion of toes Normally flexion of toes Dorsiflexion of the big toe & fanning of the other toes = Babinski Response Dorsiflexion of the big toe & fanning of the other toes = Babinski Response –Indicative of CNS lesion in corticospinal tract –Babinski may also be seen in unconscious states due to drug or alcohol intoxication or postictal period

Grading Reflex Response Compare Right and Left Sides Compare Right and Left Sides Graded on a 4 point scale Graded on a 4 point scale –4+ very brisk,hyperactive with clonus –3+ brisker than average –2+ average, normal –1+ diminished, low normal –0 No response

4 point scale Subjective Subjective No standard exists No standard exists Wide range of normal Wide range of normal Advise to assess DTRs only as part of the complete neurologic exam Advise to assess DTRs only as part of the complete neurologic exam

Abnormal Findings Clonus Clonus –Short jerking contractions of the same muscle Hyperreflexia Hyperreflexia –Exaggerated reflex –Monosynaptic reflex arch from higher cortical levels –Brain attack

Hyporeflexia Hyporeflexia –Absence of reflex –Lower motor neuron problem –Spinal cord injury

Reinforcement Reflex response fails Reflex response fails –Vary position –Increase the strength Reinforcement Technique Reinforcement Technique –Relaxes muscles –Enhances response –Isometric exercise in muscle group away from the one being tested

sample multiple choice sample multiple choice During a neurologic examination, the tendon reflex fails to appear. Before striking the tendon again, the examiner might use the technique of: During a neurologic examination, the tendon reflex fails to appear. Before striking the tendon again, the examiner might use the technique of:

A. Two-point discrimination B. Reinforcement C. vibration D. graphesthesia

Complete Neurologic Exam Mental Status Mental Status Cranial Nerves II - XII Cranial Nerves II - XII Motor System – muscle size, strength, tone, gait, and balance, RAMs Motor System – muscle size, strength, tone, gait, and balance, RAMs Sensory System – superficial pain, light touch and vibration, position sense, stereognosis, graphesthesia, 2 point discrimination Sensory System – superficial pain, light touch and vibration, position sense, stereognosis, graphesthesia, 2 point discrimination Reflexes – DTRs, biceps, triceps, brachioradialis, patellar, Achilles Reflexes – DTRs, biceps, triceps, brachioradialis, patellar, Achilles –Superficial – abdomonal, Plantar

Neurologic Screening Exam Mental Status Mental Status Cranial Nerves Cranial Nerves –II Optic –III, IV, VI Extraocular muscles –V Trigeminal –VII Facial Mobility Motor Function- gait & balance, Knee flexion (hop or shallow knee bend) Motor Function- gait & balance, Knee flexion (hop or shallow knee bend)

Screening Sensory function – superficial pain & light touch (arms & legs) Sensory function – superficial pain & light touch (arms & legs) –Vibration – arms & legs Reflexes Reflexes –Biceps –Triceps –Patellar –Achilles

Neurologic Recheck In house patients with head trauma or neurologic deficit due to systemic disease process must be monitored closely for change in status or signs of  ICP. Use this shortened form of the neurologic exam: In house patients with head trauma or neurologic deficit due to systemic disease process must be monitored closely for change in status or signs of  ICP. Use this shortened form of the neurologic exam:LOC Motor function Pupillary Response Pupillary Response Vital Signs

LOC A change in the level of consciousness is the single most imp. Factor in this exam. It is the earliest sign. Check arousal, awareness, orientation – person, place & time. A change in the level of consciousness is the single most imp. Factor in this exam. It is the earliest sign. Check arousal, awareness, orientation – person, place & time. A person is fully alert when his eyes open at your approach or spontaneously, orientated x3, follows verbal commands appropriately. If not fully alert increase the amt. Of stimulus used as follows: name called, light touch on arm, vigorous shake of shoulder, pain (Nail bed, sternal rub) A person is fully alert when his eyes open at your approach or spontaneously, orientated x3, follows verbal commands appropriately. If not fully alert increase the amt. Of stimulus used as follows: name called, light touch on arm, vigorous shake of shoulder, pain (Nail bed, sternal rub)

Motor Function Check voluntary movement with commands (raise right arm, squeeze fingers) Check voluntary movement with commands (raise right arm, squeeze fingers) If spontaneous movement occurs in reaction to noxious stimuli = Localizing, documented as a purposeful movement If spontaneous movement occurs in reaction to noxious stimuli = Localizing, documented as a purposeful movement

Pupillary Response Size, shape, and symmetry of both pupils Size, shape, and symmetry of both pupils In a brain injured person – a sudden, unilateral, dilated and nonreactive pupil is ominous. When  ICP pushes the brain stem down (uncal herniation) it put pressure on Cranial nerve III (runs parallel to brain stem) causing pupil dilatation In a brain injured person – a sudden, unilateral, dilated and nonreactive pupil is ominous. When  ICP pushes the brain stem down (uncal herniation) it put pressure on Cranial nerve III (runs parallel to brain stem) causing pupil dilatation

Vital Signs TPR & B/P prn TPR & B/P prn Note pulse & B/P are notoriously unreliable parameters of CNS deficit. Changes are late consequences of  ICP Note pulse & B/P are notoriously unreliable parameters of CNS deficit. Changes are late consequences of  ICP –Cushing Reflex = sudden  B/P with widening pulse pressure ; pulse  slow & bounding

Glascow Coma Scale Objective tool that defines LOC by assigning it a numeric value. Scale divided into 3 areas; Objective tool that defines LOC by assigning it a numeric value. Scale divided into 3 areas; –Eye opening –Verbal response –Motor response Alert, normal person scores 15 Alert, normal person scores 15 Score of 7 or < reflects coma Score of 7 or < reflects coma