pn 141 neurosensory nursing care

PN 141 Neurosensory Nursing Care

Day 1 Objectives• List major sense organs and their anatomical

position• List the parts of the eye and the function of each

part• List the three divisions of the ear and discuss

the function of each• Discuss age related changes of the sensory

system and the differences of assessment findings

• Discuss the purpose, significant results of, and nursing responsibilities related to diagnostic testing of the visual and auditory systems

Overview

• The sensory system:– gathers information from receptors throughout

the body– delivers it to the brain for interpretation.

• The five major senses are: taste, touch, smell, sight, and hearing.– The sense of balance is linked with hearing

because the sensors are located within the ear.

Special and General Senses

General Senses:PressureTemperaturePainTouchPosition

Can experience alteration in any of these senses.

Sensory System

Sensory System

• Sense of position (proprioception)• Proprioceptors = any sensory nerve

ending • Respond to stimuli originating from

within the body re: movement and spatial perception

• Work in conjunction with the inner ear

Sensory System

• Taste

– Taste buds are receptor for 4 basic sensations:• Sweet

• Sour

• Salty

• Bitter

– See tongue map

Special senses that respond to chemicals. (A) Organs of taste (gustation) and smell (olfaction). (B) A taste map of the tongue.

Sensory System

• Smell – olfactory receptors– Located in the roof of the mouth or the upper

part of the nasal cavity– Memory for certain smells is long-standing– Olfactory cells cannot be regenerated

How does it work?

• Sensory system detects environmental change

• Environmental change initiates nerve impulse (stimulus)

• Stimulus interpreted by cerebral cortex (brain) --.

• Sensation experienced

Sensory System

SENSORY DEFICIT

• A change in the perception of sensory stimuli, can affect all five senses.

• Sensory deprivation–state of reduced sensory input from internal or external environment.

• Sensory overload–state of excessive and sustained multi-sensory stimulation.

Classifying Sensory Receptors

• Classified according to the type of stimulus to which they respond:– Chemoreceptors (chemicals – taste, smell)– Photorecptors (light)– Thermoreceptors (temperature)– Mechanorecptors (pressure– Proprioreceptors (position)

The Eye and Vision

The Eye and Vision

• The adult eye is approx. 1”

• Eye protection structures• Eye cavity bones

• Frontal• Zygomatic• Ethmoid• Sphenoid• Lacrimal

The Eye and Vision

• Accessory structures that function as protective devices:• Eyelids• Eyelashes and eyebrow• Lacrimal glands (produce tears-salt, mucous,

and bacteriocidal enzyme called lysozyme)• Conjunctiva (mucous membrane)

The Eye and Vision

• Lacrimal Apparatus– Manufactures and drains tears

• To keep the eyeball moist• To sweep away debris

Figure 13-1

Lacrimal apparatus.

(From Thibodeau, G.A., Patton, K.T. [2003]. Anatomy and physiology. [5th ed.]. St. Louis: Mosby.)

The eye. Note the three tunics, the refractive parts of the eye (cornea, aqueous humor, lens, vitreous body), and other

structures involved in vision.

Overview of Anatomy and Physiology

• Structures of the eyeball

• Sclera (white): connective tissue, thick, fibrous– Gives shape, protects inner eye structures

• Cornea: central anterior portion of the sclera– Covers the iris; allows light rays to enter the

inner portion of the eye

Overview Anatomy and Physiology

– Structures of the eyeball cont.• Choroid: Thin dark brown membrane that lines

most of the internal area of sclera– Vascular– Supplies nutrients to the retina

• Ciliary body: intrinsic muscular ring; holds lens in place; changes shape for near and distant vision


– Structures of the eyeball cont.• Iris:

– The colored portion of the eye– Lies between the cornea and lens– regulates the amount of light entering through

the pupil

• Pupil: circular, central opening of the Iris


• Retina:

Received images of external objects transmits impulses through the optic nerve the brain

–Contains Rods and Cones: receptor cells of the body


– Rods:Function in dim light – contain receptors for night

vision and peripheral vision• Provide blurred images

– Cones: Function in bright light• Responsible for day vision• Color sensitive (red, green, blue cones)• Provide sharp images


– Structures of the eyeball cont.• Conjunctiva: thin mucous membrane that lines

the inner aspect of eyelids and anterior surface of the eyeball edge of the cornea

Eyeball has three separate coats (tunics)• Sclera • Choroid• Retina

Chambers of the eye:Anterior: Crystalline Lens

Aqueous Humor



– Crystalline Lens: transparent, colorlessFunction: focus light rays so that they form a

perfect image on the retina• Held in place behind the pupil by suspensory

ligaments

– Aqueous Humor: clear watery fluid• Constantly formed, drained, and replaced to

maintain normal intraocular pressure• Also helps to maintain eyeball shape, keep the

retina attached, and refract light


• Posterior Chamber: filled with:– Vitreous Humor:

• transparent jellylike substance• Gives shape • Keeps the retina attached

Refracts light• Fluid/jellylike substance not continually replaced

Pathway of Light Rays and Refraction

• Transparent parts of the eye:– Cornea– Aqueous Humor– Pupil– Crystalline Lens– Vitreous body– Rods/Cones

• The transparent parts change the direction of light rays as they enter the eye.

Overview A&P

• Intrinsic Eye Muscles– Within the eye– Form the Iris and Ciliary muscle

• Extrinsic Eye Muscles: 6

Extrinsic muscles of the eye. The medial rectus is not shown.

Nerve Supply to the Eye

• Optic Nerve (Cranial Nerve II)– Transmits impulses from the retina

thalamus of the brain directed to the occipital cortex

Visual Pathway

• Steps to vision:– Light refracts (bends)– Muscles of the Iris adjust the pupil– Ciliary muscle adjusts the lens (accommodation)– Extrinsic eye muscles produce convergence– Light stimulates retinal receptor cells (rods and

cones)– Optic nerve transmits impulses to brain– Occipital lobe cortex interprets the impulses

Nursing Implications,Considerations

and Responsibilities

Age-Related Changes in the Eye

• Skin around the eye becomes wrinkled and loose

• Eyelids usually have some excess tissue; not important unless it interferes with vision

• The amount of fat around the eye decreases, permitting the eyeball to sink deeper into the orbit

• Tear secretion diminishes; cornea less sensitive

• Grayish ring may be around the outer margin of the iris

Age-Related Changes in the Eye

• Pupil: smaller and responds more slowly to light; need for brighter light

• Presbyopia: ability to focus is impaired for “near” objects

• Crystalline Lens:– hardens, becomes too large for the eye

muscles loss of accommodation (need for bi- and trifocal lens)

– Loses some transparency opaque; glare becomes a problem

Health History

• History of present illness – Record changes in vision– If pain, inquire about location and nature– Sensitivity to light (photophobia) – Discharge from the eyes– Complaints that the eyes feel dry and

irritated • Past medical history

– Diabetes, neurologic disorders, thyroid disease, hypertension

Health History

• Family history – Any eye diseases as well as a history of

arteriosclerosis, diabetes, and thyroid disease

• Functional assessment – Patient’s occupation, roles, usual activities

Sensory ASSESSMENT

Focuses specifically on the client’s

ability to:• Hear• See• Taste• Smell• Touch

Physical Examination

• Inspect the external eye, assess response of the pupil to light, and evaluate gross visual acuity

• If abnormalities suspected, inform physician or advise patient to seek medical evaluation

• Acuity commonly tested with Snellen chart

Diagnostic Tests and Procedures

• Ophthalmoscopic examination – examines the underlying structure of the eye

(Mydriatic drops dilate pupil)

• Refractometry – optometry/opthalmascopy asks patients to indicate “clear” or blurred vision with each lens

• Tonometry – measures intraocular pressure


• Visual fields – e.g. Tangent Screening– Evaluates the central and peripheral fields– (handout)

• Fluorescein angiography – Examines microvascular structures; assesses

patency of lacrimal system; assesses for corneal abrasion


• Corneal staining – looking for abrasion/infection

• Slit Lamp Exam – examines conjunctiva, lens, vitreous humor, iris, cornea

• Imaging procedures– CT, ultrasonography, radioisotope scanning, or MRI

Laboratory and Diagnostic Examinations

• Diagnostic eye tests– Snellen test (visual acuity)– Color vision – Ishihara test– Ophthalmoscopy– Tonometry– Amsler grid test (dx./monitor macular

problems)– Schirmer’s tear test (measures tear volume)

• Table 13-2. pp. 608, 609 AHN

Figure 51-5

Figure 51-6

Tonometry

Ishihara Chart

Amsler Grid

The Ear

The ear. Structures in the outer, middle, and inner divisions are shown.

The Ear

• The Sense organ for Hearing and Equilibrium

• Includes:– Outer Ear– Middle Ear– Inner Ear


• External/Outer ear• Auricle or Pinna

– Directs sound waves into the ear

• External auditory canal– Ceruminous (wax) glands– Channels sound waves middle ear

• Tympanic membrane (Ear drum)– Vibrates as sound waves enter ear


• Middle ear• 3 small bones or “ossicles” joined in such a way

that they amplify sound waves:– Malleus – shaped like a hammer

– Incus – shaped like an anvil

– Stapes – shaped like a stirrup of a saddle


• Middle Ear cont.

– Mastoid Process – part of the temporal bone that projects downward immediately behind the external ear

– Contains the mastoid air cells and serves as a place for muscle attachment


• Middle Ear cont.– Eustachian tube – connects the middle ear

cavity with throat (pharynx)Allows pressure to equalize on both sides of

tympanic membrane– A valve that closes the tube can be forced open

by swallowing hard or yawning– Mucous membrane of the pharynx is

continuous through the eustachian tube into the middle ear cavity


• Inner ear– Labyrinth – a series of canals

• Has 3 separate areas containing sensory receptors

• Bony labyrinth—filled with perilymph fluid– Semicircular canals contain receptors for equilibrium– Vestibule also contains receptors for equilibrium– Cochlea contains organ of Corti which contains

receptors for hearing


• Inner Ear– Organ of Corti (the organ of hearing)– Ciliated receptor cells (hair cells)

• Respond to sound waves by stimulating the cochlear nerve (CN VIII) sends message to brain


• Inner Ear– Vestibule

• Deeper in the inner ear past the chochlea• The oval central portion of the boney labyrinth• Contain receptors that respond to gravity

Provide information on which way is up or down

The inner ear. The vestibule, semicircular canals, and cochlea are made of a bony shell (labyrinth) with an interior membranous labyrinth. Endolymph fills the membranous labyrinth and perilymph is around it in the bony labyrinth.

Figure 52-3

Sequence of Hearing

• Pinna (auricle)Directs sound waves into ear

• External auditory canal (meatus)Ceruminous glands

• Tympanic membrane• Vibrates as sound waves enter ear

• Middle ear cavity contains ossicles (small bones) that amplify sound waves and transmit sounds to inner ear

The Steps in Hearing

• Middle Ear cont.• The stapes transmits the vibrations to

the inner ear• Inner Ear

• Vibrations move the cilia on hair cells of the organ of Corti in the cochlear duct

• Nerve impulses are generated• Impulses travel brain

• Temporal lobe cortex interprets the impulses

The Steps in Hearing

Nursing Implications, Considerations and

Responsibilities

Age-Related Changes• Skin of the auricle may become dry and

wrinkled • Cerumen production declines; protective wax is

drier • Hairs in canal coarser/longer, especially in men• Eardrum thickens; bony joints in middle ear

degenerate• Degenerative changes: atrophy of the cochlea,

the cochlear nerve cells, and the organ of Corti

• Type of hearing loss associated with age: presbycusis

Health History

• History of present illness

– Changes in hearing acuity, pain, tinnitus, dizziness, vertigo, nausea, vomiting, and problems with balance

• Functional assessment – Exposure to excessively loud noise, such as

amplified music, firearms, or noisy machinery

– The use of any assistive hearing devices

Health History

• Past medical history – Acute or chronic problems – It should be noted whether female patients

have had rubella or have been immunized for the infection

– Medication history identifies drugs taken that might be ototoxic


• Observe how patient responds to a normal voice

• Note presence of a visible hearing aid

• Patient’s posture and balance while walking and sitting alert the examiner to possible inner ear problems


• External ear – Position of the auricles is significant– Auricles examined for shape, lesions,

nodules – Palpate auricles and mastoid process for

tenderness – Palpation in front of, below, and behind the

ear may locate enlarged lymph nodes


• External auditory canal – Inspect outer portion of the external auditory

canal for any obvious obstructions or drainage

– If drainage, the color, amount, and odor recorded

– Inspect the external canal and the tympanic membrane

Diagnostic Tests and Procedures• Nursing Responsibilities:

– Explaining procedure to the patient– What to expect– Safety measures

• Types:– Otoscopic examination– Audiometry - tests hearing acuity– Caloric test – Electronystagmography– Hearing acuity tests


• Tuning fork tests– Rinne’s test– Weber’s test

Both of the above tests are useful in determining conductive or sensorineural loss

• Other auditory tests

– Auditory evoked potential, auditory brainstem response, and electrocochleography

Laboratory and Diagnostic Examinations

• Diagnostic ear tests– Otoscopy– Tuning fork tests: Weber, Rinne– Autometric testing– Vestibular testing

• Romberg test – measures ability to perform specific tasks with eyes open/closed. Can they maintain balance?

• Past-point testing – measures ability or inability to place finger on selected part of body

Figure 13-13

Weber tuning fork test.

(From Seidel, H.M., Ball, J.W., Dains, J.E., Benedict, G.W. [2003]. Mosby’s guide to physical examination. [5th ed.]. St. Louis: Mosby.)

Figure 13-14

Rinne tuning fork test.

Figure 52-4

Figure 52-5

pn 141 neurosensory nursing care

Documents

sensory nerve

sensory receptorsclassified

visionthe eye

eye cornea

perception of sensory

inner eye structurescornea

multisensory stimulation

visionthe adult eye