Neurological System

1
Neurological System Mental Status Assessment

• Week 11

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Nervous System - 2 Parts

• Central Nervous System
• Brain
• Spinal cord
• Peripheral Nervous System
• 12 pairs of cranial nerves
• 31 pairs of spinal nerves their branches
• Sensory motor neurons as well as autonomic
  nervous system.

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Cerebral Cortex

• Outer layer of nerve cell bodies, looks like grey
  matter - lacks myelin
• Centre of higher brain functions thought,
  memory, reasoning, sensation voluntary movement
• Divided into halves hemispheres Left
  hemisphere dominant for 95 of people (including
  left handed people).

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Hemispheres Divided into 4 Lobes

• Frontal personality, behaviour, emotions,
  intellectual function
• Parietal - primary centre for sensation
• Occipital Primary visual receptor centre
• Temporal Primary auditory reception centre.

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Cerebral Cortex (23-1)
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2
1
3
5
6
7
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Figure 23-2. p. 663.
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Hypothalamus Control

• Temperature
• Heart rate
• Blood pressure control
• Sleep centre
• Anterior posterior pituitary gland regulator
• Coordinator of autonomic NS activity emotional
  status.

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Sensory Pathways

• Receptors all over body
• Monitors conscious sensation, internal organ
  functions, body position, initiate motor reflexes
• Travels through afferent fibres of PNS
• Takes 1 of 2 paths to sensory cortex map
• Spinothalamic tract pain, temperature crude
  or light touch
• Posterior (Dorsal) columns proprioception,
  vibration finely localized touch.

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Major Sensory Pathways (23-4)
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Motor Pathways - Corticospinal or Pyramidal Tract

• Originate motor cortex, travel to brain stem,
  cross over, proceed down to synapse with lower
  motor neuron in spinal cord
• Mediate voluntary movement, particularly very
  skilled, discrete purposeful movements
• Higher, newer motor system
• Mapped in motor cortex in human looking pattern
  called somatotopic organization.

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Extrapyramidal Tracts

• All motor nerve fibres originating in motor
  cortex, basal ganglia, brain stem spinal cord
  that are outside pyramidal tract
• Lower, older motor system
• Maintain muscle tone control automatic body
  movements like walking.

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Major Motor Pathways
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• Upper Motor Neurons
• All descending motor fibres from cerebral cortex
  to lower motor neurons
• Contained within CNS
• E.g. diseases CVA, Cerebral Palsy, MS
• Lower Motor Neurons
• Located mostly in peripheral nervous system
• Cell body in anterior grey matter of spinal cord
  but nerve extends out to muscle
• E.g. diseases spinal cord lesions,
  poliomyelitis and amyotrophic lateral sclerosis.

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Peripheral Nervous System

• Peripheral nervous system is composed of cranial
  nerves spinal nerves
• Peripheral nerves carry input to the CNS via
  their sensory afferent fibres deliver output
  from the CNS via the efferent fibres
• Reflex Arc
• Basic defence mechanism of nervous system  
• Involuntary operating below LOC control
  permits quick reaction to potentially painful or
  damaging situations
• Helps body maintain balance appropriate muscle
  tone.

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Four Types of Reflexes

• Deep tendon reflexes e.g. knee jerk
• Superficial e.g. corneal reflex
• Visceral e.g. pupillary response to light and
  accomodation
• Pathologic abnormal e.g. Babinskis.

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Figure 23-5. p. 666.
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Reflex Arc

• http//www.coursewareobjects.com/objects/hao/anim/
  21-001ap.htm

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Deep Tendon Reflex 5 Components

• An intact sensory nerve (afferent)
• A functional synapse in the cord
• An intact motor nerve fibre (efferent)
• The neuromuscular junction
• A competent muscle.

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Figure 23-6. p. 667.
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Table 23-1 Cranial Nerves
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Trick to Remember Cranial Nerves Names
Oh, oh, oh to touch and feel a grassy valley and
hillside.

• Oh - Olfactory
• Oh - Optic
• Oh - Oculomotor
• To - Trochlear
• Touch - Trigeminal
• And - Abducens

• Feel - Facial
• A - Acoustic
• Grassy - Glossopharyngeal
• Valley - Vagus
• And - Spinal Accessory
• Hillside - Hypoglossal.

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Figure 23-7. p. 668.
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Useful Dermatomes Landmarks

• Thumb, middle finger 5th finger are each in the
  dermatomes of C6, C7 C8
• Nipple is at level of T4
• Umbilicus is at level of T10
• Groin is in region of L1.

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Autonomic Nervous System

• PNS composed of cranial nerves spinal nerves
• Can be somatic innervate skeletal voluntary
  muscle, or, autonomic innervate smooth muscle,
  cardiac muscle glands
• Autonomic system mediates unconscious activity
• 2 parts to the autonomic nervous system
  sympathetic parasympathetic
• Sympathetic fight or flight
• Parasympathetic homeostasis (opposite to fight
  or flight).

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Dev. Considerations infants/children

• Motor activity controlled by spinal cord
  medulla
• Directed primarily by primitive reflexes
• As cerebral cortex develops in 1st year, it
  inhibits reflexes they disappear at predictable
  times
• Very little cortical control, neurons not yet
  myelinated myelin needed to conduct most
  impulses
• Process follows cephalocaudal proximodistal
  order
• Occurs in increasingly complex coordinated
  manner 
• Sensation also rudimentary at birth as
  myelinization develops infant is able to localize
  stimulus more precisely make more accurate
  motor responses.

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Dev. Considerations Aging Adults

• General atrophy - steady loss neurons in brain
  spinal cord affects areas innervated by those
  after age 65
• General loss muscle bulk ? muscle tone in face,
  neck around spine ? muscle strength, fine
  coordination agility loss of vibratory sense
  at ankle, ?/absent Achilles reflex loss of
  position sense at big toe pupillary miosis,
  irregular pupil shape, ? pupillary reflexes
• ? velocity of nerve conduction ? delay at
  synapse, making reaction time slower
• Touch, pain sensation, taste smell may be ?  
• Progressive ? in cerebral blood flow O2
  consumption.

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Subjective Data Collection

• Headache
• Head injury
• Dizziness/vertigo
• Seizures
• Tremors
• Weakness

• Incoordination
• Numbness or tingling
• Difficulty swallowing
• Difficulty speaking
• Significant past history
• Environmental/occupational hazards.

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Objective Data Collection

• Screening neurological exam on seemingly well
  clts - no significant subjective findings from
  history
• Complete neurological exam on persons with
  neurological concerns or show signs of deficit
• Neurologic recheck person with demonstrated
  neurologic deficits who require periodic
  assessments
• Integrate neurological examination with exam of
  each part of body e.g. test cranial nerves
  while assessing head neck.

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Sequence of Objective Exam

• Mental Status
• Cranial nerves
• Motor system
• Sensory system
• Reflexes.

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Cranial Nerve Assessments

• I Olfactory nerve smell
• Test if report loss of smell, had head trauma,
  with abnormal mental status or when suspect
  intracranial lesion
• Each nostril should identify odour may ? with
  aging
• Occlude each test with non-noxious smells
  coffee, toothpaste, orange, vanilla, soap,
  peppermint
• II Optic nerve vision
• visual acuity/visual fields, opthalmoscopic exam
  chpt 14
• III, IV, VI Occulomotor, Trochlear, Abducens
  Extra ocular eye movements
•  Check pupil size, regularity, equality, direct
  consensual light reaction accommodation
• Check extraocular movements by cardinal positions
  of gaze
• Assess for nystagmus carefully chpt.14.

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Cranial Nerve Assessments

• V Trigeminal Nerve mastication, sensation of
  face, corneal reflex
• Test motor component Assess muscles of
  mastication - palpate temporal masseter muscles
  as person clenches teeth, try to separate jaws by
  pushing down on chin normally you cannot.
• Test sensory function eyes closed test light
  touch sensation touch cotton wisp to forehead,
  cheeks chin
• Corneal reflex omit unless clt has abnormal
  facial sensation or movement remove contact
  lenses bring wisp of cotton in from the side
  lightly touch cornea not conjuctiva person
  should blink bilaterally tests sensory afferent
  neuron of cranial nerve V and motor efferent in
  cranial nerve VII.

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FIGURE 23-8.   Assess the Muscles of Mastication
by Palpating the Temporal and Masseter Muscles
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FIGURE 23-9.   With the Person's Eyes Closed,
Test Light Touch Sensation by Touching a Cotton
Wisp to these Designated Areas on Person's Face
Forehead, Cheeks, and Chin.
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FIGURE 23-10.   With the Person Looking Forward,
Bring a Wisp of Cotton in from the Side (to
Minimize Defensive Blinking) and Lightly Touch
the CorneaNot the Conjunctiva.
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Cranial Nerve Assessments

• VII Facial Nerve facial muscle movement,
  taste
• Motor Assessment Note mobility facial symmetry
  as clt smiles, frowns, closes eyes tightly, lifts
  eyebrows, shows teeth puffs cheeks
• Do not test taste routinely only if suspect
  facial nerve injury ask person to identify
  taste of sugar, salt lemon juice
• VIII Acoustic nerve hearing acuity
• Test hearing in normal conversation, whispered
  voice test, Weber Rinne chpt. 15.

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FIGURE 23-11/12.   Note Mobility and Facial
Symmetry as the Person Smiles, Frowns, Closes
Eyes Tightly, Lifts Eyebrows, Shows Teeth, and
Puffs Cheeks.
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Cranial Nerves Assessments

• IX X Glossopharyngeal Vagus nerves
• Motor Depress tongue with blade, note pharyngeal
  movement as person says ahhhh or yawns uvula
  soft palate should rise in midline, tonsillar
  pillars should move medially
• Touch posterior pharyngeal wall with blade note
  gag reflex
• Voice sounds should be smooth not strained
• Sensory IX mediates taste on posterior 1/3 of
  tongue but too difficult to test
•  XI Spinal Accessory nerve sternomastoid
  trapezius muscle strength
• Ask person to turn head against resistance, shrug
  shoulders against resistance. 

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FIGURE 23-13.   Check Equal Strength by Asking
the Person to Rotate the Head Forcibly Against
Resistance
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FIGURE 23-14.   Ask the Person to Shrug the
Shoulders Against Resistance
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Cranial Nerves Assessment

• XII Hypoglossal nerve tongue
• Inspect tongue watch for wasting or tremors,
  should thrust midline as person protrudes
• Ask person to say light, tight, dynamite note
  lingual speech is clear distinct.

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Motor System Assessment

• Muscles size, symmetry, strength, tone,
  involuntary movements
• Cerebellar Function balance coordination
  tests gait, tandem walking, Romberg test, hop
  in place, rapid alternating movements, thumb to
  each finger, finger to finger test, finger to
  nose test, heel to shin tests.

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Assessing Muscle Tone (23-15)
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Tandem Walking (23-16)
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Romberg Test (23-17/18)
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Rapid Alternating Movements (23-19/20)
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Finger-to-Nose Test (23-21)
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Heel to Shin Test (23-22)
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Sensory System Assessment

• Test superficial pain, light touch vibration in
  few distal locations for clt with no suspected
  deficit
• Complete testing needed for clt with neurological
  symptoms test all sensory modalities cover
  most dermatomes of body
• Compare sensations on symmetric parts of body
  map out any sensation changes
• Spinothalamic tract pain, temperature, light
  touch
• Posterior column vibration, position, fine
  touch (tactile discrimination stereognosis,
  graphesthesia, 2-point discrimination,
  extinction, point location.

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Testing Pain Sensation (23-23)
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Testing Light Touch (23-24)
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Assessing Vibration Sensation (23-25)
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Kinesthesia (23-26)
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Stereognosis (23-27)
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Graphesthesia (23-28)
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Deep Tendon Reflexes

• Reveals intactness of reflex arc test equality
  R L
• Use 4-point scale
• 4 Very brisk, hyperactive with clonus,
  indicative of dis.
• 3 brisker than average, may indicate disease
• 2 average, normal
• 1 diminished, low normal
• no response
• Ask person to relax muscles (Reinforcement)
  test
• Biceps (C5 to C6)
• Triceps (C7 to C8)
• Brachioradialis (C5 to C6)
• Quadriceps knee jerk (L2 to L4)
• Achilles or Ankle (L5 to S2)
• Test for clonus especially if reflexes are
  hyperactive.

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Reinforcement (23-29)
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Testing Biceps Reflex (23-30)
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Testing Triceps Reflex (23-31)
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Testing Brachioradialis Reflex (23-32)C5-C6
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Testing Quadriceps Reflex (23-33)L2-L4
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Testing Achilles Reflex (23-35/36)
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Testing for Clonus (23-37)
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Superficial Reflexes

• Receptors in skin rather than muscles
• Abdominal reflexes Upper (T8 to T10), lower
  (T10 to T12)
• Cremasteric reflex (L1 to L2)
• Plantar reflex (L4 to S2).

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Testing for Abdominal Cremasteric Reflex
(23-38)
Upper T8-T10 Lower T10-T12
L1-L2
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Testing Plantar Reflex (23-39)L4-S2
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Developmental Considerations Aging

• Slower response to requests
• Senile tremors occasionally occur
• Gait may be slower more deliberate
• RAM may be more difficult
• gt 65 loss of sensation of vibration at ankle
  malleolus usually accompanied by loss of ankle
  jerk reflex
• Lose position sense of big toe
• Tactile sensation may be impaired
• DTR less brisk
• Superficial abdominal reflexes my be absent.

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Neurological Recheck

• Level of consciousness
• Motor function
• Pupillary response
• Vital signs.

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Checking Grasps (23-53)
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Checking for Palmar Drift (23-54)
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Checking Strength of Lower Extremities (23-55/56)
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Assessing Pupillary Response (23-57)
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Decorticate Decerebrate Rigidity (Table 23-10,
p. 717)