assessment of neurologic function_2012

7/29/2019 Assessment of Neurologic Function_2012

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ASSESSMENT OF

NEUROLOGIC FUNCTION


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LEARNING OBJECTIVES

1. Describe the structure and functions of the central andperipheral nervous systems

2. Differentiate between pathologic changes that affect motorcontrol and those that affect sensory pathways.

3. Compare the functions of the sympathetic and parasympatheticnervous systems

4. Describe the significance of physical assessment to thediagnosis of neurologic dysfunction.

5. Describe changes in neurologic function associated with agingand their impact on neurologic assessment findings.

6. Describe diagnostic tests used for assessment of suspectedneurologic disorders and the related nursing implications.


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GLOSSARY

Agnosia loss of ability to recognize objects through aparticular sensory may be visual, auditory, tactile

Ataxia Inability to coordinate muscle movements,resulting in difficulty in walking, talking, and performing

self-care activities. Autonomic Nervous system division of the nervous

system that regulates the involuntary body functions

Axon portion of the neuron that conducts impulses

away from the cell body. Babinski reflex (sign) a reflex action of the toes,indicative of abnormalities in the motor control pathwaysleading from the cerebral cortex.


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Clonus abnormal movement marked by alternating contraction andrelaxation of a muscle occurring succession.

Delirium transient loss of intellectual function, usually due tosystemic problems.

Dendrite portion of the neuron that conducts impulses toward the

cell body. Flaccidity displaying lack of muscle tone; limp, floppy

Parasympathetic Nervous system division of the autonomicnervous system active primarily during non-stressful conditions,controlling mostly visceral functions.

Photophobia- inability to tolerate light

Position (postural) sense awareness of position of parts of thebody without looking at them; also referred to as proprioception.

Reflex an automatic response to stimuli

Rigidity increase in muscle tone at rest characterized by increasedresistance to passive stretch


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Romberg Test test for cerebellar dysfunction requiringthe patient to stand with feet together, eyes closed andarms extended; inability to maintain the position, witheither significant stagger or sway, is a positive test.

Spasticity sustained increase in tension of a musclewhen it is passively lengthened or stretch.

Sympathetic nervous system division of the autonomicnervous system with predominantly excitatory response;the fight-or-flight system

Vertigo an illusion of movement, usually rotation


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Anatomic and Physiologic

Overview

Nervous system

2 major parts:

a. Nervous systemb. Peripheral nervous system

Function: control motor, sensory, autonomic,cognitive, behavioral activities.


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The brain itself contains more than 100

billion cells that link the motor and sensory

pathways, monitor the bodys processes,

respond to the internal and externalenvironment, maintain homeostasis, and

direct all psychological, biologic and

physical activity through complex chemicaland electrical messages.


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CELLS OF THE NERVOUS

SYSTEM

Neuron- functional unit of the brain

Composed of dendrites, a cell body and axon.

Dendrites are branch-type structures for

receiving electrochemical messages.

Axon is a long projection that carries electrical

impulses away from the cell body.

*some neurons have a myelinated sheath thatincreases the speed of conduction*


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NEUROTRANSMITTERS

Communicate messages from one neuron

to another or from a neuron to a specific

target tissue.

*stored in synaptic vesicles*

As an electrical action potential propagated

along the axon reaches the nerve terminal,

it is released into the synapse.


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Diffuses or is transported across the

synapse, binding to receptors in the

postsynaptic cell membrane.

It potentiates, terminates, or modulates a

specific action, can either excite or inhibit

activity of the target cell.


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MAJOR NEUROTRANSMITTERSNEUROTRANSMITTER SOURCE ACTION

1. Acetylcholine (major

transmitter of the PNS)

Many areas of the brain, ANS Usually excitatory; PNS effects

sometimes inhibitory (stimulation

of heart by vagal nerve)

2. Serotonin Brain stem, hypothalamus, dorsal

horn of the spinal cord

Inhibitory, helps control mood

and sleep, inhibits pain pathways

3. Dopamine Substantia nigra and basalganglia Usually inhibits, affects behavior( attention, emotions) and fine

movement

4.Norepinephrine (major

transmitter of the SNS)

Brain stem, hypothalamus,

postganglionic neurons of the

SNS

Usually excitatory; affects mood

and overall activity

5. Gamma-aminobutyric acid

(GABA)

Spinal cord, cerebellum, basal

ganglia, some cortical areas

Inhibitory

6. Enkephalin, Endorphin Nerve terminals in the spine,

brain stem, thalamus and

hypothalamus, pituitary gland

Excitatory; pleasurable

sensation, inhibits pain

transmission.


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Neurologic disorder due to an imbalance

in neurotransmitter

Ex. Parkinsons disease develops from

decreased of dopamine

Myasthenia Gravis Acetylcholine binding

in muscle cells is impaired


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Evaluating diagnostic tests detect abnormal

levels of neurotransmitter

POSITRON EMISSION TOMOGRAPHY (PET)

can detect dopamine, serotonin, andacetylcholine.

SINGLE PHOTON EMISSION COMPUTED

TOMOGRAPHY (SPECT) can detect

changes in some neurotransmitter such as

dopamine in Parkinsons disease


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CENTRAL NERVOUS

SYSTEM


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THE BRAIN

Accounts approx. 2% of the total bodyweight (average young adult)

Weighs approx: 1400 g (average adult)

1200 g (elderly persons)Divided into three major areas:

1. Cerebrum

2. Brain stem3. Cerebellum


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Cerebrum

Composed of two hemispheres:

thalamus;hypothalamus and the basal

ganglia


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Brain stem

Includes the midbrain, pons and medulla


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Cerebellum

Located under the cerebrum and behind

the brain stem


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CEREBRUM


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Gyri the outside surface of thehemispheres which has wrinkledappearance as a result of many folded

layers or convolutions. Sulcus or Fissures which serves as an

anatomic division.

Great longitudinal fissures separates thecerebrum into the right and lefthemispheres


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Corpus Callosum joined two

hemispheres at the lower portion of the

fissures.

Cerebral Cortex the external or outer

portion of the hemispheres which is made

up of gray matter approx 2 to 5 mm in

depth. Contains billions of neuron cellbodies giving it a gray appearance.


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White matter makes up the innermost

layer and is composed of myelinated

nerve fibers and neuroglia cells that form

tracts or pathways connecting variousparts of the brain with one another.


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CEREBRAL HEMISPHERES

(divided into pairs of lobes)


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FRONTAL

Largest lobe

Located in front of the brain

Major functions:

Concentration, abstract thought, information

storage or memory and motor function.

Contains brocas area left hemisphere and is

critical for motor control of speech. Responsible for a persons affect, judgment,

personality, and inhibitions.


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PARIETAL

Predominantly sensory lobe

Posterior to the frontal lobe

Analyzes sensory information Relays the interpretation of this

information to other cortical areas

Essential to a persons awareness of bodyposition in space, size and shape

discrimination, and right-left orientation


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TEMPORAL

Located inferior to the frontal and parietal

Contains auditory receptive areas

Plays a role in memory of sound andunderstanding of language and music


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OCCIPITAL

Located posterior to the parietal lobe

Responsible for visual interpretation and

memory


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Corpus Callosum

Connects the two hemispheres of the

brain


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