Sensory Systems and Alterations – Key Vocabulary

Relationship Between Sensory Function & Wellness

• Intact senses = prerequisite for interaction with environment → supports safety, independence, emotional health, learning, & overall quality of life.
• Altered sensory input (deficit, deprivation, overload) → ↓ wellness, ↑ anxiety, depression, cognitive decline, risk for injury.

Core Components of Sensory Experience

• Reception
  • Stimulus activates receptor → impulse travels to spinal cord/brain.
• Perception
  • Conscious awareness, interpretation via past experiences, expectations, emotions.
• Reaction
  • Brain prioritizes, stores, or disregards stimuli; reacts only to most meaningful.

Human Senses (with specialty terms)

• Visual
• Auditory
• Tactile
• Olfactory
• Gustatory
• Kinesthetic (proprioception)
• Stereognosis → ability to recognize object placed in hand with eyes closed.

Categories of Sensory Alterations

• Sensory Deficit: loss/impairment of reception or perception (e.g., cataract, neuropathy).
• Sensory Deprivation: inadequate quality/quantity of stimulation → cognitive (disorientation), affective (boredom, anxiety), perceptual (hallucinations) changes.
• Sensory Overload: excessive, unfiltered stimuli → fatigue, irritability, anxiety, disorientation; common in ICU.​

Common Examples of Alterations

• Sight: Presbyopia, glaucoma, cataracts, macular degeneration.
• Hearing: Presbycusis, cerumen impaction, Ménière’s, otosclerosis.
• Touch: ↓ temp & pressure sensitivity.
• Smell: ↓ appetite; unsafe detection of smoke/spoiled food.
• Taste: Xerostomia → ↓ appetite/nutrition.
• Kinesthetic: gait imbalance, unilateral neglect post-stroke.

Factors Influencing Sensory Function

• Age (physiologic degeneration)
• Meaningful stimuli (family, hobbies)
• Amount of stimuli (ICU vs. rural home)
• Social interaction (isolation vs. engaging community)
• Environment/occupation (loud factory, bright OR)
• Culture (sickle-cell retinopathy higher in African ancestry, etc.)

Age-Related Sensory Changes

• Visual: presbyopia, astigmatism, ↓ night/depth vision.
• Hearing: ↓ acuity, speech discrimination, high-pitch loss.
• Taste/Smell: ↓ receptors → bland food, safety risk.
• Proprioception: ↓ balance & coordination.

Patient-Centered Care Implications

• Invite open dialogue about senses.
• Know community resources (audiology, low-vision, interpreters).
• Screen early; encourage routine exams.
• Determine patient’s preferred communication mode; back up with written instructions.

Critical Thinking Skills for Nurses

• Combine pathophysiology knowledge + assessment findings + therapeutic communication.
• Use to Assess → Plan → Implement → Evaluate safe, effective care.

Typical Nursing Diagnoses for Sensory Issues

• Risk for Injury / Falls
• Bathing Self-Care Deficit
• Social Isolation
• Impaired Verbal Communication
• Impaired Physical Mobility

Nursing Process: Comprehensive Assessment

• Patients may hide deficits; explore history, lifestyle impact, culture, mental status.
• Physical exam of each sense (e.g., Snellen chart, whisper test, sharp/dull discrimination).
• Medication review: ototoxic (aminoglycosides), CNS depressants alter perception.

Environmental & Safety Assessment

• Vision ↓ ⇒ good lighting, remove clutter, clear path to bathroom.
• Proprioceptive loss ⇒ items within reach, grab bars.
• Reduced sensation ⇒ label hot/cold faucets.

Communication Strategies

• Aphasia: allow time, short clear statements, picture boards.
• Artificial airway: picture cards, pad & pencil, rest breaks.
• Hearing impaired: face patient, quiet room, normal tone, talk toward stronger ear, write key info, no chewing/gum.

Acute-Care Interventions

• Orient to room, keep layout consistent, explain equipment noises.
• Enable self-care: ROM, positioning assistance.
• Involve family.

Safety Techniques

• Sighted-guide ambulation: nurse one step ahead, describe environment, place hand on chair before sitting.
• Discharge prep: large-print labels, phone amplifiers, smoke detectors, date-check food.

Visual System Anatomy

• External: eyebrows, lids, lashes, conjunctiva, sclera (white, vascular).
• Internal: iris, pupil, lens (accommodation), ciliary body (aqueous humor), choroid, retina.
• Retina: rods (dim), cones (color), fovea/macula (sharp vision), forms optic nerve.
• Refractive media: cornea, aqueous humor, lens, vitreous.
• Extraocular muscles: 6 cardinal gazes.

Refractive Errors

• Myopia (near-sighted), hyperopia (far-sighted), astigmatism (irregular cornea), presbyopia (loss of accommodation with age).

Age-Related Ocular Changes

• Dry eyes, yellow sclera, floaters, cataracts, ↓ acuity.

Visual Assessment Highlights

• Subjective: last exam, trauma, meds, ADLs.
• Objective: acuity, fields, PERRLA, ocular alignment, ptosis, nystagmus, fundoscopic exam.

Conjunctivitis (Pink Eye)

• Bacterial: contagious, self-limited, hand hygiene.
• Viral: mild → palliative Tx.
• Chlamydial: major global blindness cause; assess for co-STD.
• Allergic: artificial tears, antihistamine/steroid drops.

Corneal Disorders

• Penetrating vs. lamellar injuries.
• Corneal ulcer ⇒ urgent; risk blindness.
• Transplant indicated for scarring, keratoconus.

Low Vision & Legal Blindness

• Low vision: BCVA 20/70–20/200.
• Blindness: BCVA \le 20/400 or field < 20^{\circ} best eye.
• Strategies: environmental organization, “clock method,” OT referral, Braille, service animals.

Age-Related Macular Degeneration (AMD)

• Dry (non-exudative): cell atrophy, slow.
• Wet (exudative): rapid, severe; VEGF-inhibitor injections slow loss.
• S/S: blurred/dark areas, central blind spots, distorted lines.

Glaucoma

• Optic nerve damage from ↑ intraocular pressure (IOP) due to aqueous humor congestion.
• Primary Open-Angle (POAG): gradual peripheral loss → “tunnel vision.”
• Primary Angle-Closure (PACG): sudden pain, halos, redness (ocular emergency; may be medication- or darkness-induced).
• Management: meds; not curative.

Cataracts

• Lens opacity from age (senile), trauma, congenital, steroids.
• S/S: blurred vision, color fade, glare.
• Surgery: phacoemulsification + IOL implant; pre-op dilating drops, post-op antibiotics/steroids, avoid pressure (bending, lifting), night patch.

Retinal Disorders

• Retinopathy: diabetic, hypertensive microvascular damage.
• Retinal detachment: flashes (photopsia), floaters, curtain; Tx laser photocoagulation, cryopexy, scleral buckle; post-op positioning & eye protection.

Ophthalmic Medication Administration

• Drops: hold 1\text{–}2\ \text{cm} above sac, gentle close, wait 5 min between.
• Ointment: inner→outer canthus thin line.
• Intraocular disk: place on sclera beneath lower lid.

Auditory System Anatomy

• External: auricle, canal.
• Middle: tympanic membrane, ossicles (malleus, incus, stapes), eustachian tube.
• Inner: cochlea (Organ of Corti – hearing) + vestibular apparatus (semicircular canals, vestibule – balance).

Types of Hearing Loss

• Conductive: blockage outer→middle (cerumen, TM perforation).
• Sensorineural: damage inner ear or CN VIII.
• Mixed: both.
• Central/Functional: cortical interpretation defect.

Auditory Assessment

• Whisper, Weber & Rinne tuning-fork (air vs. bone conduction).
• Subjective Hx: childhood infections, ototoxic meds (furosemide, gentamicin), surgeries.
• Objective cues: repeating, cupping ear, ↑ TV volume, social isolation.

External Ear Issues

• External Otitis (“swimmer’s ear”): pain on tragus movement, drainage → topical abx/steroids.
• Cerumen/foreign body: irrigation (pull auricle up/back) or removal by specialist; avoid pushing deeper.

Otitis Media Spectrum

• Acute (AOM): kids; red bulging TM, pain, fever → antibiotics, possible myringotomy.
• With Effusion: fluid after URI; fullness; resolves.
• Chronic: repeated infections → TM/ossicle damage; may need tympanoplasty/mastoidectomy.

Otosclerosis

• Autosomal dominant conductive loss in young adults; ↓ stapes mobility.
• Tx: fluoride, Vit D, calcium; hearing aids; stapedectomy.
• Post-op: cotton ball dressing, avoid ↑ inner-ear pressure (cough, sneeze).

Vestibular Disorders

• Dizziness (disorientation), vertigo (illusory motion), nystagmus.
• Ménière’s Disease
  • Endolymph imbalance → episodic vertigo, tinnitus, fluctuating sensorineural loss, “drop attacks.”
  • Acute: antihistamines, benzodiazepines, antiemetics in dark quiet room.
  • Between attacks: \le 2000\ \text{mg} Na diet, diuretics, meclizine.
  • Nursing: safety, slow movement, no bright/flashing lights, call for help.

Presbycusis (Age-Related Sensorineural Loss)

• Early tinnitus, difficult group conversation, TV loud.
• Progressive → speech deterioration, fatigue, withdrawal.

Communication & Teaching for Hearing Impairment

• Face patient, well-lit room, normal tone, no chewing, speak toward best ear, use gestures/written aids.
• Review question example: best approach = face patient & demonstrate ideas (ensures visual & contextual cues).

Integrated Ethical & Practical Considerations

• Early identification prevents irreversible damage (e.g., glaucoma screenings ≥40 yrs).
• Respect autonomy: engage patients in care plans & selection of assistive tech.
• Health disparities: certain cultural groups at ↑ risk (e.g., glaucoma in African ancestry) → tailor education & access.
• Safety and dignity: adapt environment (labels, lighting, call-bells) to reduce falls & promote independence.

Quick Reference Formulas & Numbers

• Legal blindness: \text{BCVA} \le 20/200 (best eye) or field < 20^{\circ}.
• Low-vision range: 20/70 \text{ – } 20/200.
• Low-sodium diet for Ménière’s: 2000\ \text{mg day}^{-1}.
• Ophthalmic drop spacing: 5\ \text{min} between meds.

Study-Guide Reminders & Mnemonics

• "ABC" of vision aging: Acuity ↓, Bright-light need ↑, Contrast sensitivity ↓.
• "CLOCK" method for meal trays: imagine plate as a clock face when describing item location.
• "SOAP" for hearing-aid check: Switch on, Occlusion clear, Aids inserted, Batteries working.
• "SAFETY" for vertigo episode: Stay seated, Avoid bright lights, Fluids IV, Evaluate meds, Teach slow moves, Your call light within reach.

Sample Clinical Judgment Questions

• ICU patient in pain = highest sensory-overload risk (alarms, procedures, pain stimulus).
• Elderly with unilateral hearing aid: nurse should face patient & use visuals (slide review answer 3).