Chapter 55 Assessment of Nervous System - LAHC

1

Assessment of Nervous System

Chapter 55

Copyright © 2017, Elsevier Inc. All Rights Reserved.

Structures and Func6ons of Nervous System

•  Central nervous system (CNS) – Brain – Spinal cord – Cranial nerves I and III

•  Peripheral nervous system (PNS) – Cranial nerves III to XII – Spinal nerves – Autonomic nervous system (ANS)



•  Neurons – Primary func6onal unit – Characterized by

•  Excitability •  Conduc6vity •  Influence


2




•  Neurons – Axon func6on

•  Carries nerve impulses

– Myelin sheath • White, lipid protein substance •  Insulator for the conduc6on of impulses •  Myelinated or unmyelinated



•  Glial cells – Provide support, nourishment, and protec6on to neurons

– Cons6tute almost half of the brain and spinal cord mass

•  Microglia •  Macroglia


3


•  Microglia – Protect the neurons – Specialized macrophages capable of phagocytosis – Mobile within the brain – Mul6ply when the brain is damaged



•  Macroglia – Astrocytes – Oligodendrocytes – Ependymal cells



•  Astrocytes – Found primarily in gray maMer – Provide structural support to neurons – Form the blood-‐brain barrier with endothelium of the blood vessels

– Play a role in synap6c transmission – Act as phagocytes when brain is injured – Contribute to forma6on of scar 6ssue (gliosis)


4


•  Oligodendrocytes – Found primarily in white maMer – Produce the myelin sheath

•  Ependymal cells – Line the brain ventricles – Aid in secre6on of CSF



•  Neuroglia – Mito6c – Can replicate – Replace destroyed neurons – Comprise most primary CNS tumors



•  Nerve regenera6on (repair) – AMempt to grow back – PNS more successful than CNS

•  Recent evidence indicates astrocytes proliferate aSer certain CNS injuries – Historically we considered neurons nonmito6c


5


•  Nerve impulse – Ac6on poten6al – Synapse – NeurotransmiMers – Myelin increases speed of conduc6on

•  Nodes of Ranvier •  Saltatory conduc6on



•  Synapse –  Junc6on between two neurons

•  Presynap6c terminal •  Synap6c cleS •  Receptor site on postsynap6c cell


Impulse Genera6on Between Neurons


Impulse generation between neurons. Synapse shown with neurotransmitters and receptors.

6


•  NeurotransmiMers – Chemicals that affect transmission of impulses across the synap6c cleS

•  Excitatory neurotransmiMers –  Epinephrine, norepinephrine, glutamate

•  Inhibitory neurotransmiMers –  Serotonin, GABA, dopamine





•  Spinal cord – Gray maMer

•  Centrally located •  Contains cell bodies of various neurons

– White maMer •  Surrounds gray maMer •  Contains axons of ascending sensory and descending motor fibers

•  Sounded by myelin sheath


7


•  Spinal pathways (tracts) – Named for point of origin and des6na6on

•  Ascending tracts –  Carry sensory informa6on to higher levels of CNS

»  Spinocerebellar tract »  Spinothalamic tract

•  Descending tracts –  Carry impulses responsible for muscle movement –  Pyramidal tract

»  Cor6cobulbar tract »  Cor6cospinal tract





•  Lower and upper motor neurons – UMNs

•  Originate in cerebral cortex and project downward •  Influence skeletal muscle tone (spas6city)

– LMNs •  Final common pathway through which descending motor tracts influence skeletal muscle


8


•  Brain – Cerebrum

•  Basal ganglia –  Ini6a6on, execu6on, and comple6on of voluntary movements –  Learning –  Emo6onal response –  Automa6c movements associated with skeletal muscle ac6vity




•  Thalamus – Major relay center for sensory input from the body, face, re6na, cochlear, and taste receptors

–  Connect cerebellum and basal ganglia to frontal cortex

•  Limbic system –  Concerned with emo6on, aggression, feeding behavior, and sexual response




•  Hypothalamus –  Directly influences the release from and transport of hormones from the anterior pituitary gland

–  Sa6ety center and appe6te –  Body temperature – Water balance –  Circadian rhythm –  Expression of emo6on


9




•  Brain – Brainstem

•  Midbrain, pons, medulla •  Ascending and descending fibers •  Cranial nerves III – XII •  Re6cular forma6on •  Vital and other centers



•  Brain – Cerebellum

•  Coordinates •  Receives •  Influences


10


•  Brain – Ventricles – Cerebrospinal fluid (CSF)

•  Subarachnoid space in brain, brainstem, spinal cord •  Cushions, fluid shiSs, carries nutrients



•  Peripheral Nervous System (PNS) – Spinal nerves – Cranial nerves – Ganglia – Por6ons of autonomic nervous system (ANS)




11


Dermatomes




Cranial nerves


•  Autonomic nervous system (ANS) – Preganglionic cell bodies of SNS in spinal segments T1-‐L2

– Preganglionic cell bodies of PSNS in brainstem and sacral spinal segments S2-‐S4

– Opposing func6ons


12






•  Blood‑brain barrier – Protects from harmful agents – Lipid-‐soluble agents enter easily – Water-‐soluble agents enter slowly


13



Meninges


•  Skull – 8 cranial bones and 14 facial bones – Foramen magnum

•  Only major space for the expansion of brain contents when increased intracranial pressure occurs




14

Gerontologic Considera6ons Effects of Aging on Nervous System

•  CNS – Loss of neurons – Enlargement of ventricles – ↓ Brain weight, cerebral blood flow, CSF

•  PNS – ↓ Nerve conduc6on – ↓ Coordinated neuromuscular ac6vity

•  ↓ Memory •  ↓ Sensory/neuromuscular func6ons



•  Subjec6ve Data –  Important health informa6on

•  Characteris6cs of present illness –  Determine if an emergency exists – Mode of onset and course of illness

•  Birth history, TBI, stroke, degenera6ve disease •  Medica6ons •  Surgery or other treatments •  Growth and developmental history



•  Subjec6ve Data – Func6onal health paMerns

•  Health percep6on–health management paMern •  Nutri6onal-‐metabolic paMern •  Elimina6on paMern •  Ac6vity-‐exercise paMern •  Sleep‑rest paMern


15


•  Subjec6ve Data – Func6onal health paMerns

•  Cogni6ve‑perceptual paMern •  Self‑percep6on–self-‐concept paMern •  Role‑rela6onship paMern •  Sexuality‑reproduc6ve paMern •  Coping–stress tolerance paMern •  Value-‐belief paMern



•  Objec6ve Data – Physical examina6on

•  Mental status •  Cranial nerve func6on •  Motor func6on •  Sensory func6on •  Cerebellar func6on •  Reflexes



•  Mental Status – General appearance and behavior – Cogni6on – Mood and affect


16


•  Cranial Nerves – Olfactory (CN I) – sense of smell

•  Anosmia – loss of sense of smell

– Op6c nerve (CN II) •  Visual field •  Visual acuity

–  Hemianopsia – ½ of visual field is affected –  Quadrantanopsia – ¼ of visual field is affected –  Bitemporal hemianopsia – bilateral peripheral vision is affected

– Monocular vision Copyright © 2017, Elsevier Inc. All

Rights Reserved.




•  Cranial nerves – Oculomotor (CN III), trochlear IV, and abducens (CN VI) nerves

•  Extraocular movement •  Pupillary constric6on and accommoda6on

–  PERRL –  PERRLA

•  Eyelid drooping


17

Pupilometer



•  Motor Func6on – Strength

•  Push against resistance •  Pronator driS

–  Par6cularly sensi6ve when pa6ent has poten6al for vasospasm or increasing edema in one hemisphere of the cerebrum

–  Close eyes and hold out arms with palms up for 30 seconds



•  Motor Func6on – Tone

•  Hypotonia – flaccidity •  Hypertonia – spas6city •  Myoclonus – spasm of muscles •  Athetosis – slow, wri6ng, involuntary movement of extremi6es

•  Chorea – involuntary, purposeless, rapid mo6ons •  Dystonia – impairment of muscle tone


18


•  Motor Func6on – Balance and coordina6on

•  Posture , gait –  Risk for falling

•  Finger-‐to-‐nose; heel-‐to-‐shin tests – Symmetry



•  Sensory Func6on – Light touch

•  Ex6nc6on – when a s6mulus is perceived on only one side of the body when both sides of the body are touched symmetrically

– Pain – Temperature

•  Only assessed when response to deep pain is abnormal



•  Sensory Func6on – Vibra6on sense – Posi6on sense (propriocep6on)

•  Romberg test

– Cor6cal sensory func6ons •  Graphesthesia •  Stereognosis


19




•  Reflexes – Biceps – Triceps – Brachioradialis – Patellar – Achilles tendon


Diagnos6c Studies of Nervous System

•  Cerebrospinal fluid analysis – Lumbar puncture

•  Contraindica6ons •  Pre-‐procedure prepara6on •  Post-‐procedure monitoring


20



Normal images of the brain. A, Computed tomography scan. B, Magnetic resonance imaging.

(From Fuller G, Manford M: Neurology: an illustrated colour text, ed 3, New York, 2010, Churchill Livingstone)


•  PET scan •  Single-‐photon emission computed tomography (SPECT)

•  Myelogram


Positron emission tomography (PET) scan can be used to assist in the diagnosis of Alzheimer’s disease (AD). Radioactive fluorine is applied to glucose (fluorodeoxyglucose), and the yellow areas indicate metabolically active cells. A, A normal brain. B, Advanced AD is recognized by hypometabolism in many areas of the brain. (From Roberts GS: Neuropsychiatric disorders, London, 1993, Mosby-Wolfe)



Cerebral angiogram illustrating an arteriovenous malformation (arrow)

(From Chipps E, Clanin N, Campbell V: Neurologic disorders, St Louis, 1992, Mosby)

21


•  Electrographic Studies – Electroencephalography (EEG) – Electromyography (EMG) – Electroneurography (nerve conduc6on studies) – Evoked poten6als



•  Ultrasound – Caro6d artery duplex scan – Transcranial Doppler – Biopsies


The nurse is caring for a pa6ent who is admiMed aSer a head injury. When would the nurse obtain most of the data related to this pa6ent’s mental status? a.  During the nursing health history b.  While observing pa6ent behaviors c.  While asking specific problem-‐solving ques6ons d.  While reviewing answers on a wriMen mental

examina6on


Audience Response Ques5on

22

The nurse is caring for a pa6ent who has a spinothalamic tract lesion. Which assessment finding would the nurse expect? a.  Cranial nerve dysfunc6on b.  Decreased level of consciousness c.  Loss of peripheral sensi6vity to pain d.  Reduced extremity movement and strength


Audience Response Question

How should the nurse assess cranial nerves III, IV, and VI? a.  Check the pa6ent’s gag reflex. b.  Test the pa6ent’s eye movements. c.  Ask the pa6ent to smile and frown. d.  Have the pa6ent s6ck out his tongue.


Audience Response Question

Chapter 55 Assessment of Nervous System - LAHC

Documents

Transcript of Chapter 55 Assessment of Nervous System - LAHC