Neurology SystemNeurology System

ReflexesReflexes

Reflex ArchReflex Arch

• Spinal nerves have sensory (Afferent) & Spinal nerves have sensory (Afferent) & motor (Efferent) portionsmotor (Efferent) portions

• Control DTRs & superficial reflexesControl DTRs & superficial reflexes

• Simple reflex arch needs a sensory & Simple reflex arch needs a sensory & motor neuronmotor neuron

• Ex. Of normal reflex arch = knee-Ex. Of normal reflex arch = knee-jerk/patellar reflexjerk/patellar reflex

Reflex ArchReflex Arch

• Reflexes= basic defense mechanisms of Reflexes= basic defense mechanisms of the nervous systemthe nervous system– InvoluntaryInvoluntary– UnconsciousUnconscious– Allow quick reaction to painful/damaging Allow quick reaction to painful/damaging

situations situations – Maintain balanceMaintain balance– Appropriate muscle tone Appropriate muscle tone

Four Types of ReflexesFour Types of Reflexes

1.1. Deep tendonDeep tendon• Patellar or knee jerkPatellar or knee jerk

2.2. SuperficialSuperficial• Corneal Corneal • abdominal abdominal

3.3. VisceralVisceral• Pupillary reflex to light and accommodationPupillary reflex to light and accommodation

4.4. PathologicPathologic• BabinskiBabinski• Extensor plantar reflexExtensor plantar reflex

Deep Tendon ResponseDeep Tendon Response

• Briskly tap the tendon of a partially stretched Briskly tap the tendon of a partially stretched musclemuscle

• For the reflex to fire, all components of the For the reflex to fire, all components of the reflex arch must be intactreflex arch must be intact– Sensory nerve fibersSensory nerve fibers– Spinal cord synapseSpinal cord synapse– Motor nerve fibersMotor nerve fibers– Neuromuscular junctionNeuromuscular junction– Muscle fibers Muscle fibers

Deep Tendon ResponseDeep Tendon Response

• Tapping the tendon activates special Tapping the tendon activates special sensory fibers in the partially stretched sensory fibers in the partially stretched muscle, triggering a sensory impulse that muscle, triggering a sensory impulse that travels to the spinal cord via peripheral travels to the spinal cord via peripheral nervenerve

• the stimulated sensory fiber synapses the stimulated sensory fiber synapses directly with the anterior horn cell directly with the anterior horn cell innervating the same muscle. innervating the same muscle.

Deep Tendon ResponseDeep Tendon Response

• When the impulse crosses the When the impulse crosses the neuromuscular junction, the muscle neuromuscular junction, the muscle suddenly contracts, completing the reflex suddenly contracts, completing the reflex arch.arch.

Deep Tendon ResponseDeep Tendon Response

• Each deep tendon reflex involves specific Each deep tendon reflex involves specific spinal segmentsspinal segments

• Abnormal reflex help locate an a Abnormal reflex help locate an a pathologic lesion pathologic lesion

The Plantar ResponseThe Plantar Response

• Normally flexion of toesNormally flexion of toes

• Dorsiflexion of the big toe & fanning of the Dorsiflexion of the big toe & fanning of the other toes = other toes = Babinski ResponseBabinski Response– Indicative of CNS lesion in corticospinal tractIndicative of CNS lesion in corticospinal tract– Babinski may also be seen in unconscious Babinski may also be seen in unconscious

states due to drug or alcohol intoxication or states due to drug or alcohol intoxication or postictal periodpostictal period

Grading Reflex ResponseGrading Reflex Response

• Compare Right and Left SidesCompare Right and Left Sides

• Graded on a 4 point scaleGraded on a 4 point scale– 4+ very brisk,hyperactive with clonus4+ very brisk,hyperactive with clonus– 3+ brisker than average3+ brisker than average– 2+ average, normal2+ average, normal– 1+ diminished, low normal1+ diminished, low normal– 0 No response0 No response

4 point scale4 point scale

• SubjectiveSubjective

• No standard existsNo standard exists

• Wide range of normalWide range of normal

• Advise to assess DTRs only as part of the Advise to assess DTRs only as part of the complete neurologic exam complete neurologic exam

Abnormal FindingsAbnormal Findings

• ClonusClonus– Short jerking contractions of the same muscleShort jerking contractions of the same muscle

• HyperreflexiaHyperreflexia– Exaggerated reflexExaggerated reflex– Monosynaptic reflex arch from higher cortical Monosynaptic reflex arch from higher cortical

levelslevels– Brain attackBrain attack

• HyporeflexiaHyporeflexia– Absence of reflexAbsence of reflex– Lower motor neuron problemLower motor neuron problem– Spinal cord injurySpinal cord injury

ReinforcementReinforcement

• Reflex response failsReflex response fails– Vary positionVary position– Increase the strengthIncrease the strength

• Reinforcement TechniqueReinforcement Technique– Relaxes musclesRelaxes muscles– Enhances responseEnhances response– Isometric exercise in muscle group away from Isometric exercise in muscle group away from

the one being testedthe one being tested

sample multiple choicesample multiple choice

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

A.A. Two-point discriminationTwo-point discrimination

B.B. ReinforcementReinforcementC.C. vibrationvibration

D.D. graphesthesiagraphesthesia

Complete Neurologic ExamComplete Neurologic Exam

• Mental StatusMental Status• Cranial Nerves II - XIICranial Nerves II - XII• Motor System – muscle size, strength, tone, Motor System – muscle size, strength, tone,

gait, and balance, RAMsgait, and balance, RAMs• Sensory System – superficial pain, light touch Sensory System – superficial pain, light touch

and vibration, position sense, stereognosis, and vibration, position sense, stereognosis, graphesthesia, 2 point discriminationgraphesthesia, 2 point discrimination

• Reflexes – DTRs, biceps, triceps, brachioradialis, Reflexes – DTRs, biceps, triceps, brachioradialis, patellar, Achillespatellar, Achilles– Superficial – abdomonal , PlantarSuperficial – abdomonal , Plantar

Neurologic Screening ExamNeurologic Screening Exam

• Mental StatusMental Status• Cranial Nerves Cranial Nerves

– II OpticII Optic– III, IV, VI Extraocular musclesIII, IV, VI Extraocular muscles– V TrigeminalV Trigeminal– VII Facial MobilityVII Facial Mobility

• Motor Function- gait & balance, Knee Motor Function- gait & balance, Knee flexion (hop or shallow knee bend)flexion (hop or shallow knee bend)

ScreeningScreening

• Sensory function – superficial pain & light Sensory function – superficial pain & light touch (arms & legs)touch (arms & legs)– Vibration – arms & legsVibration – arms & legs

• ReflexesReflexes– BicepsBiceps– TricepsTriceps– PatellarPatellar– AchillesAchilles

Neurologic RecheckNeurologic Recheck

• In house patients with head trauma or In house patients with head trauma or neurologic deficit due to systemic disease neurologic deficit due to systemic disease process must be monitored closely for change in process must be monitored closely for change in status or signs of status or signs of ⇑⇑ ICP. Use this shortened form ICP. Use this shortened form of the neurologic exam:of the neurologic exam:

LOCLOCMotor functionMotor function

Pupillary ResponsePupillary ResponseVital SignsVital Signs

LOCLOC

• A change in the level of consciousness is the A change in the level of consciousness is the single most imp. Factor in this exam. It is the single most imp. Factor in this exam. It is the earliest sign. Check arousal, awareness, earliest sign. Check arousal, awareness, orientation – person, place & time. orientation – person, place & time.

• A person is fully alert when his eyes open at A person is fully alert when his eyes open at your approach or spontaneously, orientated x3, your approach or spontaneously, orientated x3, follows verbal commands appropriately. If not follows verbal commands appropriately. If not fully alert increase the amt. Of stimulus used as fully alert increase the amt. Of stimulus used as follows: name called, light touch on arm, follows: name called, light touch on arm, vigorous shake of shoulder, pain (Nail bed, vigorous shake of shoulder, pain (Nail bed, sternal rub)sternal rub)

Motor FunctionMotor Function

• Check voluntary movement with Check voluntary movement with commands (raise right arm, squeeze commands (raise right arm, squeeze fingers)fingers)

• If spontaneous movement occurs in If spontaneous movement occurs in reaction to noxious stimuli = Localizing, reaction to noxious stimuli = Localizing, documented as a purposeful movementdocumented as a purposeful movement

Pupillary ResponsePupillary Response

• Size, shape, and symmetry of both pupilsSize, shape, and symmetry of both pupils

• In a brain injured person – a sudden, In a brain injured person – a sudden, unilateral, dilated and nonreactive pupil is unilateral, dilated and nonreactive pupil is ominous. When ominous. When ⇑⇑ ICP pushes the brain ICP pushes the brain stem down (uncal herniation) it put stem down (uncal herniation) it put pressure on Cranial nerve III (runs parallel pressure on Cranial nerve III (runs parallel to brain stem) causing pupil dilatationto brain stem) causing pupil dilatation

Vital SignsVital Signs

• TPR & B/P prnTPR & B/P prn

• Note pulse & B/P are notoriously Note pulse & B/P are notoriously unreliable parameters of CNS deficit. unreliable parameters of CNS deficit. Changes are late consequences of Changes are late consequences of ⇑⇑ ICP ICP– Cushing Reflex = sudden Cushing Reflex = sudden ⇑⇑ B/P with widening B/P with widening

pulse pressure ; pulse pulse pressure ; pulse ⇓⇓ slow & bounding slow & bounding

Glascow Coma ScaleGlascow Coma Scale

• Objective tool that defines LOC by Objective tool that defines LOC by assigning it a numeric value. Scale divided assigning it a numeric value. Scale divided into 3 areas;into 3 areas;– Eye openingEye opening– Verbal response Verbal response – Motor responseMotor response

• Alert, normal person scores 15Alert, normal person scores 15• Score of 7 or Score of 7 or < reflects coma< reflects coma