Chapter 45- Condensed

Chapter 45: Sensory Functioning — Condensed Study Guide

Core concept

Sensory perception is the conscious process of selecting, organizing, and interpreting sensory information.

Sensory reception = receiving sensory data.
Sensory perception = interpreting what that data means.

Main senses:

  • Visual = sight

  • Auditory = hearing

  • Olfactory = smell

  • Gustatory = taste

  • Tactile = touch

  • Kinesthesia = awareness of body position/movement

  • Proprioception = subconscious awareness of body/limb position

  • Visceral sense = awareness of internal organs

  • Stereognosis = identifying object size, shape, solidity, and texture by touch


1. Four conditions required for sensation

A sensory experience requires:

  1. Stimulus

  2. Receptor/sense organ

  3. Nerve impulse transmission to the brain

  4. Brain interpretation

Memorize

Stimulus → receptor → transmission → interpretation


2. Reticular Activating System (RAS)

The RAS regulates arousal and filters sensory input before it reaches the cerebral cortex.

Sensoristasis = optimal level of arousal/stimulation.

  • Too little stimulation → sensory deprivation

  • Too much stimulation → sensory overload


3. Sensory Deprivation vs. Sensory Overload


Sensory Deprivation

Sensory Overload

Definition

Too little, monotonous, unpatterned, or meaningless stimulation

More stimulation than the brain can meaningfully process

Common risks

Isolation, bed rest, sensory deficits, institutionalization, CNS depression

ICU, pain, invasive devices, illness, bright lights, noise, frequent procedures

Common effects

Drowsiness, poor concentration, irritability, hallucinations

Anxiety, agitation, confusion, difficulty concentrating

Nursing goal

Increase meaningful stimulation

Reduce/organize stimulation

Sensory deprivation signs

  • Excessive yawning/drowsiness

  • Increased sleeping

  • Poor attention

  • Difficulty concentrating

  • Reduced problem solving

  • Irritability

  • Panic/depression

  • Illusions/hallucinations

Deprivation interventions

Provide meaningful:

  • Conversation/social interaction

  • Music, TV, reading

  • Clocks/calendars/photos

  • Pleasant foods/aromas

  • Touch, ROM, grooming

  • Familiar objects

  • Orientation and self-care activities

Sensory overload causes

Internal: pain, IVs, tubes, catheters, discomfort, worry
External: lights, alarms, noise, strangers, frequent touch, procedures, unfamiliar environment

Overload interventions

  • Create predictable routines

  • Explain procedures simply

  • Reduce noise/visitors/calls

  • Speak calmly and move slowly

  • Control pain

  • Identify and remove distressing stimuli

  • Avoid reducing stimulation so much that deprivation develops

Important trap

The symptoms can overlap. If adding stimulation makes a patient worse, consider sensory overload instead of deprivation.


4. Sensory Deficit

Sensory deficit = impaired or absent functioning of one or more senses.

May be:

  • Temporary or permanent

  • Sudden or gradual

  • Congenital or acquired

Nursing focus:

  • Safety

  • Compensation

  • Self-care

  • Coping

  • Appropriate assistive devices


5. Sensory Processing Disorder

Difficulty in how the brain receives, organizes, interprets, or uses sensory information.

Patterns include:

  • Overresponsivity

  • Underresponsivity

  • Sensory craving

  • Sensory discrimination disorder

  • Postural disorder

  • Dyspraxia

May interfere with:

  • Attention

  • Learning

  • Listening

  • Interaction

  • Purposeful movement


6. Factors Affecting Sensory Stimulation

Sensory needs vary with:

  • Development

  • Culture

  • Personality/lifestyle

  • Stress

  • Illness

  • Medications

Development

  • Infants require appropriate stimulation for sensory development.

  • Fragile neonates may need reduced light/visual/vestibular stimulation.

  • Children benefit from play.

  • Aging and chronic illness may reduce sensory function.

Culture

The patient determines what touch, noise, symbols, and stimulation are meaningful or acceptable.

Stress

  • Low stress → may seek stimulation

  • High stress → may need reduced stimulation


7. Medication Effects

Medications can alter sensory perception.

  • Narcotics/sedatives → decrease sensory awareness

  • Antipsychotics → may alter processing

  • Ototoxic drugs mentioned:

    • Furosemide

    • Some chemotherapies

    • Aspirin

Always review medications when a new sensory problem appears.


8. Age-Related Vision Changes

Presbyopia

Age-related loss of lens elasticity causing difficulty with:

  • Near vision

  • Fine print

  • Light adaptation

Cataracts

  • Lens clouding

  • Painless

  • Progressive vision loss

Macular degeneration

  • Central vision loss

  • Associated with drusen deposits

  • Risk factors include smoking and excessive sunlight

Glaucoma

May cause:

  • Peripheral vision loss

  • Glare intolerance

  • Reduced contrast

  • Poor dark adaptation

  • Possible blindness

Diabetic retinopathy

Retinal damage from diabetes.

Hypertensive retinopathy

Retinal damage from poorly controlled hypertension.

Temporal arteritis — EMERGENCY

Possible:

  • Temporal headache

  • Scalp tenderness

  • Jaw claudication

  • Sudden vision loss

Detached retina — EMERGENCY

Classic description:

“Curtain coming down across vision.”


9. Age-Related Hearing Changes

Presbycusis

Age-related sensorineural hearing loss.

Features:

  • Gradual

  • Progressive

  • Bilateral

  • High-frequency sounds affected first

  • Background noise worsens hearing

Conductive hearing loss

Problem with outer/middle ear.

Causes:

  • Cerumen

  • Foreign body

  • Ruptured eardrum

  • Otitis media

  • Otosclerosis

Sensorineural hearing loss

Problem with:

  • Inner ear

  • Cochlea

  • CN VIII

Possible causes:

  • Heredity

  • Noise

  • Infection

  • Trauma

  • Tumor

  • Ototoxic drugs

  • Ménière disease

Central auditory processing disorder

Hearing may be intact, but the brain cannot properly process the sound.

Ménière disease

  • Fluctuating hearing loss

  • Dizziness

  • Tinnitus


10. Smell and Taste

Key terms

Term

Meaning

Anosmia

No smell

Hyposmia

Decreased smell

Dysosmia

Altered smell

Normosmia

Normal smell

Ageusia

No taste

Hypogeusia

Decreased taste

Dysgeusia

Altered/distorted taste

Normogeusia

Normal taste

Aging may decrease:

  • Smell sensitivity

  • Ability to detect sweet tastes

Taste may also change because of:

  • Medications

  • Disease

  • Tobacco

  • Reduced smell


11. Peripheral Sensation

With aging:

  • Touch may decrease slightly

  • Two-point discrimination decreases

  • Vibration sense decreases

  • Pain sensation remains, but reaction may be slower

Peripheral neuropathy

May be related to:

  • Circulatory problems

  • B6 deficiency

  • B12 deficiency

  • Folate deficiency

Diabetic neuropathy

Can cause loss of foot sensation → unnoticed injury/infection.

Priority: careful foot care.

Phantom limb pain

Pain perceived in an amputated limb.

Acute sensory loss

May occur with:

  • Stroke

  • Nerve entrapment

  • Compartment syndrome

Sudden numbness, tingling, sensory loss, or loss of function needs prompt evaluation.


12. Nursing Assessment Framework

Assess:

Stimulation → Reception → Transmission → Perception → Reaction

Also assess:

  • Baseline sensory function

  • Environment

  • Corrective devices

  • Self-care ability

  • Behavioral changes

Family may notice changes before the patient does.


13. Focused Assessment by Sense

Vision

Look for:

  • Squinting

  • Eye rubbing

  • Bumping into objects

  • Reading difficulty

  • Central/peripheral vision changes

Hearing

Look for:

  • Asking others to repeat

  • Lip reading

  • Blank/inappropriate responses

  • Difficulty locating sound

  • Tinnitus

Taste

Assess:

  • Sweet

  • Sour

  • Bitter

  • Salty

  • Umami

  • Metallic/strange taste

  • Oral hygiene/dentures

Smell

Assess ability to identify familiar odors.

Touch

Assess:

  • Light touch

  • Sharp/dull

  • Hot/cold

  • Object recognition

  • Numbness/tingling


14. Potential Effects of Sensory Problems

Sensory alterations may contribute to:

  • Confusion

  • Impaired cognition

  • Delirium risk

  • Disorientation

  • Anxiety

  • Ineffective coping

  • Communication problems

  • Impaired mobility

  • Skin injury

  • Sleep problems

  • Social isolation

  • Impaired self-care


15. Reduced Vision: Nursing Care

  • Identify yourself when entering

  • Announce your presence

  • Explain before touching

  • Speak normally

  • Keep call light accessible

  • Keep bed low

  • Orient to room layout and sounds

  • Keep pathways clear

  • Do not rearrange furniture

  • Walk slightly ahead and allow the patient to hold your arm

  • Tell the patient when you leave

Teaching

  • Protect eyes from UV rays

  • Avoid rubbing eyes

  • Avoid eyestrain

  • Keep glasses clean

  • Avoid nonprescription eye drops

  • Use caution with chemicals/aerosols

  • Seek care for persistent eye symptoms


16. Reduced Hearing: Nursing Care

  • Gain attention before speaking

  • Reduce background noise

  • Face the patient

  • Ensure good lighting

  • Keep mouth visible

  • Ensure hearing aid works

  • Use the better-hearing ear

  • Speak naturally and clearly

  • Use simple sentences

  • Do not cover your mouth or turn away

  • Write information if necessary

NCLEX point

Do not automatically shout. Use a natural, often lower tone.

Assistive devices may include:

  • Amplified phones

  • Closed captions

  • Flashing alarms

  • Flashing smoke detectors

  • Voice amplifiers


17. Communicating With a Confused Patient

  • Speak calmly, simply, directly

  • Allow time to respond

  • Reorient frequently

  • Use clocks/calendars

  • Use familiar objects

  • Encourage self-care

  • Focus on strengths

  • Explain care

  • Change environmental stimuli gradually

  • Reinforce reality


18. Communicating With an Unconscious Patient

The textbook states hearing is believed to be the last sense lost.

Therefore:

  • Assume the patient can hear

  • Speak normally

  • Explain care before touching

  • Be careful what is said nearby

  • Use appropriate touch

  • Keep noise low


19. Computer Eye Strain

Symptoms:

  • Eye fatigue

  • Dry eyes

  • Headache

  • Blurred vision

  • Red eyes

  • Eye twitching

  • Neck/shoulder discomfort

Prevention

  • Proper lighting

  • Reduce glare

  • Blink often

  • Take breaks

  • Adjust workstation

  • Obtain eye exams

20-20-20 Rule

Every 20 minutes, look 20 feet away for 20 seconds.


20. Expected Outcomes

The patient should be able to:

  • Function in a safe environment

  • Maintain appropriate arousal

  • Remain oriented

  • Respond appropriately to stimuli

  • Perform self-care

  • Use assistive devices

  • Feel safe and in control

  • Compensate for sensory deficits

  • Maintain meaningful stimulation without overload


NCLEX Must-Know Box

Reception = receives sensory data.
Perception = interprets sensory data.

RAS = regulates arousal and sensory input.

Sensoristasis = optimal stimulation.

Sensory deprivation = too little stimulation → ADD meaningful stimulation.

Sensory overload = too much stimulation → REDUCE/organize stimulation.

Hallucinations may occur with sensory deprivation.

Presbyopia = near-vision problem.

Presbycusis = high-frequency hearing loss.

Conductive = outer/middle ear.

Sensorineural = inner ear/cochlea/CN VIII.

“Curtain over vision” = detached retina = immediate evaluation.

Temporal headache + jaw claudication + sudden visual loss = temporal arteritis = emergency.

Visually impaired patient → announce yourself; do not rearrange room.

Hearing impaired patient → face them, reduce background noise, keep mouth visible.

Unconscious patient → assume hearing may remain intact.

Always assess whether confusion is caused by too much or too little stimulation before changing the environment.