Health Assessment of Head & Neck Health Assessment of Eyes, Ears
Assessment of the Eyes
The eye and the ear are sensory structures that connect us with the environment. They allow us to perceive our surroundings through sight and sound. Disorders of the eye and the ear can range from minor annoyances to life-threatening problems. Most problems do not result in acute illness; however, they may be associated with more serious neurological conditions such as brain tumor, stroke, or head injury.
No matter what the cause, visual and hearing problems can have a major impact on physiological functioning as well as psychological and social well-being. Early detection reduces the likelihood of problems related to social interaction.
Determining whether a patient has adequate vision and hearing is crucial before assessing mental status or providing instructions.The eyes and the ears are common sites of injury; they also exhibit structural variations as a result of age, cultural background, and genetic influences. Although, for the sake of clarity, the eyes and the ears are covered separately here, they are usually examined along with the head and neck because of their location.
A thorough assessment of the eyes and the ears includes vision and hearing screenings and examination of the external and internal structures.The assessment provides not only specific data about the eyes and the ears but also vital information on the health status of other systems.
Before you begin your assessment, an understanding of the anatomy and physiology of the eyes and the ears is essential.You need to be able to identify normal structures before you can identify abnormal findings, accurately perform the assessment, and correctly interpret your findings.This chapter covers assessment of the eyes first and then assessment of the ears.
Anatomy and Physiology Review: The Eye
The primary function of the eye is vision, including central and peripheral vision, near and distance vision, and differentiation of colors.To accomplish these tasks, the external and internal structures of the eye work together to receive and transmit images to the occipital lobe of the brain for interpretation.Visual difficulties can result from disease or injury to any of the structures involved in the visual pathway.
Structures and Functions of the Eye. The eye consists of internal and external structures that support or protect it.
How We See. The ability to see objects in the environment depends on light waves that reflect off images. Natural lighting produces gradations of shading that help to determine an object’s shape and position in the environment.The light rays pass through the cornea, anterior chamber, pupil, lens, and posterior chamber to the back of the eye (retina).The pupil,which is actually created by the aperture of a muscular layer of tissue called the iris,dilates or constricts to allow more or less light onto the retina.The lens, an elastic biconvex disc, bends the light waves entering the eye by either flattening or increasing the lens curvature.The precise functioning of the pupil and iris together allows a clear image to focus on the retina.
Several conditions result from variations in how or where the light rays entering the eye converge and focus. People with myopia (nearsightedness) need to hold objects close to the eye to see them clearly. In the myopic eye, the globe is elongated, causing light rays to focus in front of the retina.When the globe is shorter thaormal, light rays focus at a point beyond the retina,producing a condition called hyperopia (farsightedness). People with hyperopia must move close objects farther away to see them clearly. Astigmatism is an irregular curvature of the lens or cornea that causes light rays to scatter, blurring images on the retina (Fig. 12.6).
The retina is rich in sensory neurons, which are necessary for reception and transmission of accurate images. The retina contains specialized nerve cells called rods, which are sensitive to dim light, and cone cells, which are sensitive to bright light and color. From the rods and cones of the retina, the visual image is transmitted to the optic disc,where the nerve fibers of the retina converge to enter the optic nerve.
Nerve fibers from the optic disc join to form the optic nerve.The neural impulses are then transmitted by the optic nerve to the optic track and optic radiations, where they are interpreted by the visual cortex. Nerve fibers from the nasal portion of each eye cross over to the opposite side of the brain at the optic chiasm. Fibers from the temporal portion of the retina of each eye do not cross over before being received by the visual cortex in the occipital lobe of the brain
The Cardiovascular System. The optic fundus is the only area in the body where blood vessels can be directly observed without using invasive techniques.Use of an ophthalmoscope provides direct visualization of the optic disc, where the vessels that supply the retina emerge.Changes in the optic disc, blood vessels, macula, and general background of the retina can reveal systemic problems with circulation as a result of chronic hypertension (HTN) or diabetes. Or they can reveal localized circulatory problems that occur with glaucoma, increased intracranial pressure, and other neurological problems.
The Musculoskeletal System. Movement of the eyes in a parallel or conjugate manner is made possible by the coordinated movement of the extraocular muscles. Each of the six extraocular muscles is responsible for rotating the eyes in a specific direction and maintaining the eyes’ conjugate movement. Each extraocular muscle is innervated by a specific cranial nerve (CN). The superior rectus, inferior rectus, medial rectus, and inferior oblique muscles are innervated by CN III.Damage to CN III can therefore result in limited range of movement in the upward, downward, nasal, and upper diagonal fields of vision.The remaining extraocular muscles, the lateral rectus and superior oblique, provide movement of the eye in the temporal lateral and nasal inferior direction, respectively. Damage to the nerves that innervate the lateral rectus muscle (CN VI) and the superior oblique muscle (CN IV) can result in limited eye movement in the corresponding directions.
Movement of the eyelid is controlled by another set of muscles, the orbicularis oculi and the levator palpebrae.The orbicularis oculi encircles the eyelids and is innervated by CN VII.Damage to the orbicularis oculi muscle or the part of the cranial nerve that innervates it results in an inability to close the eyelid completely.The ability to raise or open the eyelid depends on an intact CN III,which innervates the levator palpebrae muscle.
Constriction and relaxation of the muscular tissue of the iris and ciliary body allows visual adaptation.In a darkened environment,contraction of the smooth muscle of the iris causes the aperture of the iris or pupil to dilate.As a result,more light enters the retina and night vision is enhanced. In brightly lighted environments, the retina does not need to receive additional light; as a result, the pupil is constricted.
The ciliary body, located posterior to the outer edge of the iris, alters the shape of the lens and allows the eye to adjust to near or far objects, an occurrence referred to as accommodation. Constriction of the ciliary body results in flattening of the normal convex shape of the lens. Flattening of the lens facilitates the eye’s ability to focus on objects in the distance. Relaxation of the ciliary body allows the lens to assume its normal convex shape and facilitates focusing oear objects.Both the iris and the ciliary body can be affected by damage to CN III, resulting in pupil dilatation (mydriasis) and loss of accommodation.
The Neurological System. The ability to see images depends on an intact visual pathway.From the time when an image is received on the retina to the time when it is interpreted by the visual cortex, the neurological system plays a key role. Damage to the retina can result in diminished visual acuity or diminished color and night vision.Damage to the optic nerve, a source of retinal nervous tissue, can result in similar visual changes. Damage to specific points along the optic track or to the visual cortex can produce deficits in corresponding visual fields
Increased intracranial pressure from intracranial tumors, head injuries, or severe intracranial hemorrhage may impinge on CN II (optic), CN III, CN IV, or CN VI, causing specific eye changes.The optic nerve innervates the retina and is surrounded by a meningeal sheath that is continuous with the meninges of the brain.When intracranial pressure increases, the pressure is transmitted from the brain to the optic disc,where swelling occurs.
Pressure on a specific part of the optic nerve tract can produce visual loss (hemianopia) on the ipsilateral (same side) or contralateral (opposite side) visual field, depending on the location of the injury or lesion.
Developmental, Cultural, and Ethnic Variations
Infants. Several variations may be noted in the eyes of infants.The shape, slope, spacing, and color of the eyes should be noted. Normal shape is oval. Slope is determined by drawing an imaginary line through the inner canthus to the occiput. Except in people of Asian descent, the slope line transects the outer canthus.Measurement of the distance between various structures of the eye can be plotted on a growth chart.Normal spacing measurements are plotted between the 10th and the 90th percentiles.
Infants usually open their eyes when held upright, permitting inspection of the iris,pupil,and sclera.The color of the iris after birth is normally blue-gray in light-skinned infants and brown in darker-skinned infants. Permanent eye color is usually established by 9 months of age.White specks in the iris called Brushfield spots can be a normal variant or a sign of Down syndrome. Edema of the eyelids and irritation of the conjunctiva may be caused by birth trauma or silver nitrate prophylaxis.The sclera is very thin at birth, so it may have a slightly blue undertone.
A gross assessment of visual acuity is made by testing for pupillary light reflexes and also by noting the infant’s behavior.The pupils should normally constrict to light. After 3 weeks, if no pupillary light reflex is present, blindness is indicated. However, the presence of pupillary reaction alone does not confirm an infant’s ability to see. A blink reflex in response to bright light and observing the infant for ability to follow objects or light with the eyes confirm that some degree of vision is intact. By 2 to 4 weeks, an infant should be able to fixate on an object and,by 1 month, to fixate and follow an object.An infant’s visual acuity is usually about 20/200;20/20 vision is usually achieved by school age.
During the first 1 to 2 months, infants’ eye movements are often disconjugate (not working in unison), making screening for strabismus difficult. Persistence of disconjugate eye movements after this time may indicate strabismus and warrants referral to a specialist. In infants, the fundoscopic examination is difficult but still important.The internal structures of the eye should be examined regularly during the first few years of life.One of the first things to note is the presence of a red reflex,which is a normal finding.Absence of a red reflex may indicate congenital cataracts or retinal detachment. The general background in infants is typically paler than that in adults because the blood vessels to the area are not fully developed. The macula is also not fully developed until about 1 year of age.
Toddlers. Visual acuity in toddlers is determined by the Allen test, which uses picture cards of seven common objects. The child should successfully identify three of the seven objects at a distance of
The corneal light reflex can provide an initial, rapid screening test for strabismus that can be followed by additional measures as the child grows. Untreated strabismus can lead to permanent visual damage. Eventually, the brain suppresses information from the affected eye, and visual acuity in that eye deteriorates.
Preschool Children. Between the ages 3 and 5, the Snellen E chart,which uses various sizes of Es facing in different directions, can usually be used to determine visual acuity.Normal visual acuity for a 3-year-old is approximately 20/40 or better. By the time the child is 4 years old, visual acuity should be about 20/30 or better.
School-Age Children. By the time a child is about 5 to 6 years old, normal visual acuity approximates that of the adult—20/20 in both eyes. You should continue using the Snellen E chart until the child has acquired reading skills and can easily verbalize the letters seen on the Snellen chart. Some degree of myopia (nearsightedness) often occurs during adolescence. Children should be screened for defects in color perception (colorblindness) between 4 and 8 years of age. Though many forms of color blindness exist, most cases involve inherited recessive X-linked traits in males that affect the ability to distinguish red and green.
Older Adults. Many changes in the structure and function of the eye occur with aging. Both central and peripheral visual acuity may be diminished with advanced age. Changes iear vision occur around the fourth and fifth decades, often resulting in decreased ability to focus clearly oear objects (presbyopia).The adult may compensate for these changes by holding near objects farther away.
External structures of the eye also undergo significant changes with advanced age. Tissues of the eyelids lose elasticity and fatty deposits, causing the eyes to appear sunken. The lower eyelid may sag away from the globe. The latter condition, called ectropion, is significant because the punctum,which drains the tears, is no longer in contact with the globe, resulting in constant tearing.The laxity that develops in the eyelids may also lead to an inward turning of the eyelids, referred to as entropion.With entropion, the punctum also may not be able to drain tears. In addition, the eyelashes may rub the conjunctiva and cornea, causing pain and injury to the cornea. Older adults also may experience dry eyes because of a decrease in tear production.
Changes in the internal structures of the eye are also common with aging.The lens becomes more opaque and yellowish, obscuring the transfer of light rays to the retina. This clouding of the lens is referred to as senile cataract. Arcus senilis, a white opaque ring around the edge of the cornea resulting from fat deposits, is a common benign finding. The older adult’s pupil size at rest is generally smaller than that of younger adults. Pupillary reaction to light and accommodation slow because of decreased ability to constrict and relax.The general background is paler, and the blood vessels of the eye may show signs of the same atherosclerotic processes that are occurring elsewhere throughout the body.Visual fields may be less thaormal. Other visual changes that occur with aging reflect degeneration of the rods and cones. Color vision may be less vivid as a result of degeneration of the cones, and night vision may be impaired because of degeneration of the rods.
Several eye diseases also occur more commonly in older adults. Macular degeneration and glaucoma, the two leading causes of blindness in older adults, show a significant increase with aging.
People of Different Cultures and Ethnic Groups. Differences in physical characteristics of the eye and differences in the risk of certain eye diseases are found in various ethnic groups.People of Asian origin typically have an epicanthal fold at the medial canthus,giving the eyes an almond-shaped appearance. The outer canthus also may slant in an upward direction. In African Americans and others with normally dark skin, brown-pigmented spots on the sclera, referred to as muddy sclera, are common. In dark-skinned people, the color of the optic disc is also typically darker orange, and the retinal background is darker red than in fair-skinned people.An African American person’s sclera also may have a blue-gray appearance or a yellowish cast at the peripheral margins. The incidence and severity of glaucoma is greater in African Americans than in people of other races. Cataracts also occur with greater frequency in people living in sunny climates.
Performing the Eye Assessment. Assessment of the eye includes taking a thorough health history and performing a physical examination. Data obtained are combined and analyzed to determine the patient’s existing health status and to identify potential health risks and disorders of the eye.
Health History. The health history addresses the patient’s personal and family history of eye diseases and diseases that affect the eye. A comprehensive health history also allows the nurse to identify areas of the physical examination that require more or less depth. The health history will include biographical data, current health status,past health history, family history, a review of systems, a psychosocial profile, and a detailed eye history. If time is an issue and you are unable to perform a complete health history,perform a focused eye history.
Biographical Data. First, review the patient’s medical records, intake surveys, and other sources of data to identify her or his age, occupation, gender, and ethnic background. This information will help you decide what questions to ask and how to interpret subsequent history and examination findings. For example, the way you measure visual acuity and interpret the findings differs greatly with the patient’s age. The patient’s occupation can be a source of environmental risk for eye injury.Gender may be a factor in certain disorders such as colorblindness,which is more common in males. Knowledge of the patient’s race or ethnic group is useful when interpreting many physical examination findings.
Current Health Status. Begin by asking about the person’s chief complaint, asking him or her to describe the problem in his or her own words.Use the PQRST format to probe further about any symptoms reported. If the person has an eye problem, focus your questions on the eye symptoms prioritized later.
Symptom Analysis.
Vision Loss. Vision loss refers to the inability to see the shape, size, position,or color of objects. Vision loss may be complete, resulting in the inability to perceive light from dark,or incomplete, causing the person to see objects with varying degrees of detail.
Eye Pain. Eye pain is a subjective sensation of discomfort in the eye that may be caused by trauma, irritation, infection,or neurological conditions.
Double Vision. Double vision (diplopia) refers to seeing two overlapping images because of the inability of the eyes to focus on an object and to move in a conjugate manner.Double vision can be caused by a variety of conditions, including diseases of the cerebellum, cranial nerves, and extraocular muscles.
Eye Tearing. Tears are normally produced by the lacrimal gland, located along the upper outer orbit of the eye, and are distributed over the eye by blinking.Tearing is a discharge of clear,watery fluid as a result of the inability of the tears to drain through the punctum and into the nasolacrimal duct.Tearing occurs in a variety of conditions such as infections; irritation;and exposure to chemicals, irritants,or allergens.
Dry Eyes. Dry eyes occur when there is insufficient lubrication of the eye and the bulbar and palpebral conjunctiva become less moist. It often results in a subjective sensation of irritation, a gritty sensation or discomfort, especially during blinking.Dryness occurs from trauma to the eye surface or facial trigeminal nerve paralysis, in certain systemic diseases, or after taking certain medications.
Eye Drainage. Drainage from the eyes is abnormal and is commonly associated with eye infections or allergies.
Eye Appearance Changes. Changes in the appearance of the external eye, such as in the iris, anterior chamber, and sclera, can signal a variety of problems, including trauma, infection, and systemic disorders.
Blurred Vision. Blurred vision refers to an object’s shape and detail being indistinct and fuzzy. It can occur for near objects as well as for distant ones.
Past Health History. This section of the health history focuses on gathering relevant information about the patient’s past eye health and any injuries, diseases, or medications that could affect the eyes.The following are specific areas related to the eye that should be explored.
Physical Assessment. During the physical examination, you will assess the functions and structures of the body, including a focused examination of the eye.You will use the information obtained in the health history to guide you and help determine what body structures and functions should be focused upon. After you have explored the patient’s key health history information and determined what aspects should be explored, begin the physical examination.The purpose of the physical examination is to identify normal, age-appropriate structures and functions of the eye as well as potential and actual health problems.
Approach. To assess the eye, use the techniques of inspection and palpation. Begin by testing visual acuity and performing other assessments that can be completed while you stand at a distance from the patient. For visual acuity, test and record the findings for each eye separately and then together. Standard abbreviations for recording findings are OD for the right eye, OS for the left eye, and OU for both eyes.
Performing a General Survey. Before performing the eye assessment,perform a general survey, noting the patient’s overall appearance. Observe nutritional status,emotional status,and body habitus,noting changes that would relate to the eyes.Then inspect for use of corrective lenses,noticeable visual deficits, and gross eye abnormalities such as ptosis, exophthalmos, edema, and redness. Also take vital signs.A temperature elevation may indicate an infection and give the eyes a glazed appearance. High BP should alert you to look for vascular changes when performing the fundoscopic examination.
Performing a Head-to-Toe Physical Assessment. Now examine the patient for more specific signs of diseases affecting other organ systems that might have an impact on the eyes and vision.
Performing Physical Assessment of the Eye. A comprehensive physical examination of the eye involves assessing the functions, such as vision (distant, near, color, and peripheral), eye muscle functioning, and pupil reflexes, as well as inspecting the external and internal eye structures.The sequence for testing visual acuity progresses from testing done at a distance, such as the visual acuity examination, to observations made at close range, such as the ophthalmic examination. Proceeding in this sequence allows the patient to become comfortable with the nurse before examination at close range is performed. It also allows the nurse to establish the patient’s degree of visual functioning, which establishes a baseline for conducting the remainder of the examination. The ophthalmic examination often requires administration of mydriatic or pupil-dilating eye drops.
Visual Acuity Testing. Visual acuity testing involves determining distant, near, peripheral, and color vision. The Snellen eye chart is used to test distant vision in adults and children of school age.The patient stands
Have the person cover the opposite eye and repeat the procedure. After testing each eye individually, test both eyes simultaneously and record the fractioext to the smallest line read.A pocket vision screener may also be used. The letters are scaled down and simulate the Snellen chart,but the card is held only
Near vision is tested using Jaeger cards, in which lines of text are repeated in progressively smaller fonts. Test each eye separately by having the patient cover one eye and read the smallest line of text while holding the card at a distance of
Color vision is tested using Ishihara’s embedded colors test, which consists of a series of cards displaying colored dots that contain an embedded colored figure or number. The patient is asked to identify the figure in each card.An alternative measure is to point to one of the red or green colored bars on the Snellen eye chart and ask the patient what color she or he sees
Peripheral vision in each eye is measured on two planes—horizontal and vertical—and in four directions—superior, inferior,medial (nasal), and lateral (temporal), using the confrontation test. The patient and nurse stand face to face, about 1 to 11⁄2 feet apart.Ask the patient to fix his or her gaze straight ahead and cover one eye at a time, using his or her hand or an opaque cover.Then wiggle your fingers or bring a pen or other small object from the periphery to the center of the visual field.Tell the patient to say “now” as soon as your hand or the object enters his or her peripheral vision.
Repeat this procedure in each of the four visual fields, moving in a clockwise direction. Be sure to start testing from positions that are outside the normal peripheral vision range; then slowly move your hand or the object into each of the four peripheral fields.
Assessment of the Extraocular Muscles. To perform the corneal light reflex test, instruct the patient to fix her or his gaze straight ahead. Shine a penlight at the bridge of the nose and note where the light reflects on the cornea of each eye. Using the face of a clock as a guide, determine if the light reflex appears at the same clock position in each eye.The corneal light reflex test determines if the eyes are being maintained in a conjugate position.
The cover/uncover test helps determine if there is a weakness in the eye muscles of one or both eyes that can result in disconjugate eye movement.To perform the test, have the patient fix his or her gaze straight ahead. Stand in front of the patient, cover one of his or her eyes with a piece of paper, and observe the uncovered eye for movement indicating re-fixation of the gaze.Remove the cover and observe the previously covered eye for movement indicating re-fixation of the gaze.Repeat the procedure for the other eye.The gaze should remain steady in each eye throughout the test.
Further testing of the extraocular muscles is done by testing for symmetrical (conjugate) rotation of the eyes, symmetrical movement of the upper eyelid, and nystagmus in the six cardinal fields of gaze test.The six cardinal fields of gaze tests the cranial nerves III, IV, and VI and the extraocular muscle.To perform this test, stand in front of the patient and instruct her or him to look straight ahead and follow your finger as you move slowly through the six cardinal fields.The patient should hold her or his head still and move only her or his eyes. Observe for smooth, symmetrical movement of the eyes and eyelids
Assessment of the External Structures. The next phase of the eye examination involves inspection and palpation of external eye structures. Careful inspection and palpation can reveal a variety of eye disorders as well as systemic disorders that affect the eye.
Testing the pupils to determine reaction to light is important for evaluating neurological function. Increased intracranial pressure from a head injury, tumor, or stroke may manifest in specific pupillary changes. Other conditions such as hypoxia or brain death or the use of certain medications can also affect the papillary light reflex.
To test pupillary reflex, observe for direct (same side) and consensual (opposite side) response to a focused beam of light. Darken the room if possible.Then, using a penlight, flashlight, or ophthalmoscope light, shine the light onto one eye as you observe whether the pupil constricts (referred to as a direct response).Repeat the procedure and note whether the other eye exhibits a consensual response or constriction to light. Repeat the test for the opposite eye.
Inspection of the anterior chamber of the eye can reveal a variety of conditions including infection, trauma, and risk for glaucoma.The shadow test is useful in identifying a shallow anterior chamber, which is commonly seen in glaucoma.To inspect the anterior chamber using this test, have the patient look straight ahead. Hold your penlight at the temporal side of one eye at a 90-degree angle across the anterior chamber.Without moving the penlight, shine the light across the limbus of the eye, toward the nose. A crescent-shaped shadow on the nasal side of the iris indicates a shallow anterior chamber.
The first thing you should see with the ophthalmoscope is a red reflex over the pupil area,which is the reflection of light off the retina. Note the color and clarity of the red reflex. Now gradually move closer to the patient while holding the red reflex in sight.When you are approximately
Note the size of the physiological cup compared with the size of the optic disc (cup-to-disc ratio).The cup should be half the size of the disc or less.The cup is normally lighter or white in color. Follow the vessels as they leave the optic disc.Note the size of the arteries compared with the veins (AV ratio).Arteries will appear smaller and brighter red than veins and will have a light streak reflecting off them. Also note constriction of the vessels and whether or not any nicking is noted when vessels cross. Inspect the general background for color and lesions. Color should be a uniform yellow-orange-red color,depending on individual skin tone.The lighter the skin tone, the lighter the background.After inspecting the optic disc,vessels,and general background, examine the macula.The macula is a circular area of slightly darker pigmentation located about two disc diameters (DD) temporally from the optic disc. It is the site of central vision and the source of one of the most common causes of blindness,macular degeneration.
The macula is difficult to see, especially through undilated pupils.To see it,have the patient look directly into the ophthalmoscope light.This places the macula into direct view.
SUMMARY
■ The eyes are complex sensory organs that provide specialized functions crucial to neurosensory development in infancy; to the development of psychosocial,motor,and cognitive skills in childhood;and to the maintenance of those skills in adulthood.
■ A thorough health history provides direction for the physical examination, including exploration of factors that may be related to eye health.
■ A comprehensive history and physical examination enable early detection and treatment of sight problems.
■ Information from both the history and the physical examination is then analyzed to determine appropriate nursing diagnoses.
Assessment of the Ears
The eye and the ear are sensory structures that connect us with the environment. They allow us to perceive our surroundings through sight and sound. Disorders of the eye and the ear can range from minor annoyances to life-threatening problems. Most problems do not result in acute illness; however, they may be associated with more serious neurological conditions such as brain tumor, stroke, or head injury.
No matter what the cause, visual and hearing problems can have a major impact on physiological functioning as well as psychological and social well-being. Early detection reduces the likelihood of problems related to social interaction.
Determining whether a patient has adequate vision and hearing is crucial before assessing mental status or providing instructions.The eyes and the ears are common sites of injury; they also exhibit structural variations as a result of age, cultural background, and genetic influences. Although, for the sake of clarity, the eyes and the ears are covered separately here, they are usually examined along with the head and neck because of their location.
A thorough assessment of the eyes and the ears includes vision and hearing screenings and examination of the external and internal structures.The assessment provides not only specific data about the eyes and the ears but also vital information on the health status of other systems.
Before you begin your assessment, an understanding of the anatomy and physiology of the eyes and the ears is essential.You need to be able to identify normal structures before you can identify abnormal findings, accurately perform the assessment, and correctly interpret your findings.This chapter covers assessment of the eyes first and then assessment of the ears.
Anatomy and Physiology Review: The Ear
The main functions of the ears are hearing and equilibrium. Hearing requires an intact and unobstructed external canal, middle and inner ear, vestibulocochlear nerve (CN VIII), and temporal lobe (Figs. 12.14 and 12.15). Sound waves move through the external, middle, and inner ear,where they stimulate the vestibulocochlear nerve and transmit the impulses to the temporal lobe for interpretation. Maintaining normal equilibrium requires proper functioning of the structures in the inner ear.
Understanding Sounds and Sound Waves. Hearing occurs by air conduction and bone conduction of sound waves. Sound waves are characterized by differences in pitch and loudness. Frequency, the number of sound waves per second, determines the pitch of the sound. Intensity or loudness is determined by the size of the sound waves. Sound waves can be classified on a continuum from high pitched to low pitched—for example, the high-pitched sounds of a whistle blowing or the screech of chalk on a chalkboard or the low-pitched sounds of a deep drum, thunder, or an explosion. The highness or lowness of pitch is a function of frequency or how fast or slow a sound wave vibrates.The frequency of a sound wave is measured in waves per second or Hertz (Hz). Low-frequency sound waves are interpreted by the brain as low-pitched sounds,and higher frequency waves are interpreted as high-pitched sounds.
The loudness of a sound wave is measured in a scale of units called decibels (dB). The structures of the inner ear are especially sensitive to loudness.Although we tolerate conversation,which is typically around 60 dB,exposure to excessive or repeated noise above 80 dB such as traffic or machinery noise or exposure to rock music concerts at 120 dB or more can cause damage to the hearing structures and result in permanent hearing loss.
How We Hear. Air conduction is the primary mechanism of hearing; it involves carrying sound waves through the external auditory canal to the tympanic membrane (TM).There, the sound vibrations cause the TM and the malleus (hammer), incus (anvil), and stapes (stirrup) bones to move, thus transmitting the vibrations to the inner ear structures.
Bone conduction provides an additional pathway whereby sound waves vibrate the skull bones and transmit the vibrations to the inner ear structures.Both air and bone conduction use a common final pathway involving transmission of the vibrations to the inner ear structures, then on to the cranial nerve and the temporal lobe
The Musculoskeletal System. Normal hearing involves proper functioning of certain skeletal structures.Hearing by air conduction involves the transmission of sound waves that vibrate the TM,which in turn transfers the vibrations to the three auditory ossicles. First, the malleus,which is in direct contact with the TM, receives the vibrations.The malleus then transfers the vibrations to the incus and then to the stapes,which transmits them directly to the oval window in the inner ear.
Hearing by bone conduction is much less precise and is dominant only when hearing by air conduction is not possible because of obstruction or perforation of the TM, fluid behind the membrane, or otosclerosis of the auditory ossicles.Nevertheless,hearing by bone conduction also relies on an intact skeletal structure, the temporal bone, to transmit vibrations to the inner ear.Cooperation between the neurological and the skeletal systems is necessary to provide precise and accurate hearing.
The Neurological System. The primary functions of the ears, hearing and equilibrium, rely strongly on an intact and functioning neurological system.Whether hearing occurs solely by air conduction or bone conduction, the sound waves must eventually travel to the inner ear,where they are picked up by the organ of Corti, the sensory organ for hearing.Hair cells in the organ of Corti bend and mediate the vibrations into electrical impulses that are conducted to the vestibulocochlear nerve (CN VIII).The process of picking up sound waves, transmitting them,converting them to electrical impulses, and transmitting them to the brain represents only the first of three levels of auditory functioning.
The second level involves the interaction of both ears and the brainstem in determining the location of the sound in space.When a sound is heard, the vestibulocochlear nerve from each ear sends electrical impulses to each side of the brainstem.The brainstem pinpoints the origin of the sound by evaluating factors such as head position, intensity, and timing of the information received from each ear.
The cortex of the brain, specifically the temporal lobe, is involved in the third level of auditory function, interpretation of the sound.Once sound waves have been converted to electrical impulses, they are received in the temporal lobe,where they are identified on the basis of past experience. Impulses are then sent to motor areas of the brain so that an appropriate response to the sound can be made.This level of response allows us to differentiate a telephone ring from a doorbell and take the actioeeded to either pick up the phone or answer the door.
As for maintaining equilibrium, the vestibule of the inner ear plays a crucial role.The vestibule is involved in sensing and perceiving how the body is moving in space.The vestibule also orients the body to maintain a vertical position, stabilizes the position of the head, and helps to maintain the center of gravity.
Disorders of equilibrium can result from two primary causes.The first is chronic loss of vestibular information caused by CN VIII and vestibular hair cell degeneration related to aging or neurotoxicity.The second is distortion of information produced by disruption of the fluid dynamics in the labyrinth of the inner ear. With chronic degeneration, problems with balance are more constant and the person can adapt to them to some degree if the terrain remains constant. However, persons with disorders involving disruption or distortion tend to have symptoms more intermittently and unpredictably, thus preventing the person from adapting as readily. In addition,movement of the head may trigger the vestibular receptors to signal the brain that the head and body are moving when in fact they are not.
Developmental, Cultural, and Ethnic Variations.
Infants and Children. The structures needed for hearing are predominantly developed in utero during the first trimester. During this time, damage to the structures from genetic, congenital, and infectious processes can cause hearing problems.
Assessment of the ear is especially important in infancy. Observing the appearance of the external ear and noting behaviors that indicate intact hearing are important ways to screen for potential problems that can cause developmental delays or indicate genetic conditions.Abnormalities in the structure and positioning of the ears are more common in infants who have a hearing deficit. Low-set ears, ears that are positioned at greater than a 15-degree angle, and malformed ears are often associated with genetic disorders and developmental delays.
Infants and children are more prone to inner ear infections than are adults.One reason is that the Eustachian tube, which opens from the nasopharynx to the middle ear, is shorter,wider, and more horizontal than in adults, making migration of bacteria from the nasopharynx common. Infants also have greater amounts of lymphoidal tissue surrounding the lumen of the eustachian tube,which can occlude and trap bacteria.By school age, the external auditory canal has assumed a straighter,more adult configuration,which is less prone to infection
Young and Middle-Aged Adults. Hearing loss caused by excessive or chronic exposure to noise damages the cochlear structures of the inner ear that are involved in conduction of vibrations to CN VIII. Noise-induced hearing loss from exposure to loud music or machinery is the most common cause of hearing loss for the 20- to 40-year-old age group.
Older Adults. Hearing loss in older adults is extremely common and can be associated with sensorineural loss or conductive loss. Hearing loss associated with aging, referred to as presbycusis, occurs around the fifth decade and gradually progresses. Typically, presbycusis involves hearing loss for high-pitched sounds, such as consonants, and affects men more often than women.
Older adults are prone to stiffening of the cilia in the external canal. This impedes the transmission of sound waves to the TM and causes cerumen to accumulate more readily and obstruct the membrane. Excess accumulation of cerumen impairs hearing by air conduction and is one of the most common correctable causes of conductive hearing loss in older adults.
People of Different Cultures/Ethnic Groups. Several variations in ear structure and disorders of the ear are known to occur in certain ethnic groups.Otitis media, or middle ear infection, is a relatively common affliction in infants as a result of bottle feeding and exposure to second-hand smoke. However, the incidence and severity of otitis media for Native American,Hispanic,and Alaskan infants is higher than for infants in the general population.
The characteristics of cerumen, or ear wax, also vary with different ethnic groups. Cerumen can be of two types—dry, white, and flaky, as seen in the majority of Asians and Native Americans;or brown,wet,and sticky, as seen in the majority of blacks and whites.People living in highly industrialized communities are routinely exposed to sounds above 80 dB, such as traffic and occupational machinery, and are more prone to hearing loss. In the
Performing the Ear Assessment. Assessment of the ear involves obtaining a complete health history and performing a physical examination.As you perform the assessment, be alert for signs and symptoms of actual or potential problems in the various structures of the ear.
Health History. The health history identifies any related symptoms or risk factors and the presence of diseases involving the ear. It must also detect any other disorders that may affect the ear.Your history will include obtaining biographical data and asking questions about the patient’s current health,past health, and family and psychosocial history. It also includes a review of systems and an ear history. If your patient has severe hearing problems, you may have to communicate by writing or have a family member answer questions. If you don’t have time to perform a complete health history, make sure to perform at least a focused health history of the ears.
Biographical Data. Review the patient’s biographical data to identify age, occupation, gender, and ethnic background. Use these patient characteristics to guide the types of health history questions that you ask and facilitate your interpretation of subsequent history and examination findings. For example, the techniques used to examine an infant’s ear differ from those used to inspect an adult’s ear.The types of assessments you perform for hearing acuity also vary greatly with the patient’s age.Knowledge of the patient’s cultural and ethnic heritage can provide information on potential language barriers and can facilitate the evaluation of physical examination findings that vary with different groups.
Knowing the patient’s occupation can provide information about environmental risk for ear trauma and can help identify areas for health promotion education.
Current Health Status. First, ask the patient to describe the chief complaint in his or her own words. Next, use the PQRST format to investigate further about any symptoms reported. If your patient reports an ear problem, focus your questions on the ear symptoms presented in the following section.
Symptom Analysis.
Hearing Loss. Hearing loss is a diminished ability to perceive sounds. It may be a result of problems that affect transmission of sound waves to the middle ear (conductive loss) or problems involving interpreting the sound and converting it to neurological impulses (sensorineural loss). Hearing loss may be sudden or gradual, unilateral or bilateral, and may be limited to sounds of certain frequencies or pitches.
Vertigo. Vertigo is a subjective feeling of the body moving or swaying in space or of stationary objects moving or spinning in space.Vertigo most often results from a disturbance of structures involved with equilibrium and balance, which includes the inner ear and central nervous system.
Tinnitus. Tinnitus is a subjective perception of a high-pitched ringing or buzzing sound in one or both ears. It occurs in certain disorders of the external, middle, and inner ear.
Ear Drainage (Otorrhea). Drainage from the ear is abnormal. Purulent drainage indicates infection; drainage that is clear or contains cerebral spinal fluid or blood indicates trauma.
Earache (Otalgia). Ear pain, known as earache or otalgia, is a common symptom of ear disorders, particularly ear infections.
Past Health History. During this section of the health history interview, focus on gathering relevant information about the patient’s childhood illnesses and injuries,adult illness and injuries, and medication use as they relate to the ears.
Physical Assessment. The health history has provided you with clues that will help direct your physical examination.When examining patients who have severe hearing deficits, you may need to explain what you are doing by some other means,such as writing.
Approach. Physical assessment of the ear entails screening for hearing deficits and examining the external ear and TM.Keep in mind that ear problems may relate to other body systems, so assess for signs in every system. Examination of the ear involves inspection and palpation of the external ear and external auditory canal, followed by tests for hearing and equilibrium. Examination of the auditory canal and TM are done early in the examination to ensure that structures for hearing are intact and unobstructed before testing hearing acuity.
The examination is usually performed with the person in a sitting position. However,when performing the otoscopic examination on a young child, it is better if the child is supine with the head turned to the side being examined.A quiet environment is essential when performing the hearing screening tests.
Performing a General Survey. Before assessing the ear, perform a general survey. Note the person’s overall appearance, including nutritional status, body habitus, and emotional status.Also take vital signs—temperature elevations may indicate an infection.
Be especially alert for signs that suggest problems with the ear. Ask yourself these questions:
■ Is the person guarding her or his ear? If the patient is a child, is she or he tugging or rubbing the ear? These are signs of an ear infection.
■ Is the patient attentive and responding appropriately? Inappropriate responses or inattentiveness may result in hearing deficits.
■ Is the patient speaking loudly? People with hearing deficits tend to speak louder.
■ Do you notice any problems with the patient’s ability to maintain balance? Balance problems are associated with inner ear problems.
Performing a Head-to-Toe Physical Assessment. Now scan your patient from head to toe.Check for more specific signs of diseases that involve other organ systems and that might affect the ears.
Otoscopic Examination. The otoscope illuminates and magnifies the auditory canal and the TM. The auditory canal is assessed for color, lesions, and foreign objects. The TM is assessed for color, intactness, appropriateness of landmarks, and mobility of the drum. Select the largest and shortest speculum that will fit into the patient’s ear canal comfortably, and attach it to the head of the otoscope.Usually, a 4-,5-,or 6-mm, 1⁄2-inch speculum is appropriate for an adult ear canal.
Turn the otoscope light on.Have the patient tilt his or her head away from the side you are examining. Always look into the external canal before inserting the otoscope. Two insertion techniques may be used:
■ Technique #1: Hold the otoscope upside down like a pencil, with the magnifying lens facing the examiner. Pull the pinna of the ear up and back for adults and down for children under age 2. Brace your insertion hand on the patient’s head for stabilization. This technique is ideal for children, because if they move the head, your hand moves with it.
■ Technique #2: An alternative technique is to hold the otoscope handle upright and slowly and gently insert the scope along the axis of the external auditory canal (about 1⁄2 inch in an adult and 1⁄4 inch in a child). Be careful to enter only the outer third of the ear canal. With the scope inserted, put your eye up to the viewing lens. If you cannot visualize the TM, do not move the otoscope. Instead, apply more traction, pull on the ear, or carefully adjust the angle of the otoscope more toward the patient’s nose. Do not release the traction on the ear until the speculum of the otoscope has been removed from the ear. Remove the speculum in the same angle as it was inserted, and then release the traction to the pinna.
Hearing Tests. Examination of the ear includes conducting hearing tests for high-tone, low-tone, sensorineural, and conductive hearing loss. Typical tests include the following:
■ Watch tick test: This test determines the patient’s ability to hear high-pitched sounds and screen for hightone hearing loss.To do this test, have the patient obstruct one ear at a time by placing her or his index finger in the external canal.Using a ticking watch,hold it close to the unobstructed ear and slowly move it away until the patient says that she or he can hear the watch tick (usually about
■ Whisper test: This test assesses low-pitch or low-tone hearing loss.Again, have the patient obstruct one ear with the index finger. Then stand 1 to
■ Tuning-fork tests: These tests check for intact sensorineural and conductive hearing. The Weber test assesses lateralization of sound. Sound transmission with the Weber test is both through bone conduction (BC) and air conduction (AC). To perform the test, place a vibrating tuning fork firmly on top of your patient’s head or forehead.
Ask the patient if the vibration sounds the same in both ears or different. Normally, the vibration is heard equally in both ears. If the vibration is louder or more distinct in one ear than in the other, it has lateralized to that ear (positive lateralization). If there is conductive hearing loss, the sound lateralizes to the impaired ear; if there is sensorineural hearing loss, the sound lateralizes to the unaffected or good ear. Conductive hearing loss is usually caused by a problem with the external or middle ear, such as acute otitis media, perforated eardrum, or a blocked canal with cerumen. Sensorineural hearing loss is usually caused by a problem in the inner ear, such as acoustic nerve damage from ototoxic drugs.
Having a conductive loss in the lateralizing ear (e.g., as a result of accumulation of cerumen or a perforated eardrum) means that sound waves are not conducted effectively by AC to the inner ear. Thus, limited or no sound waves are received by AC. The only mechanism remaining for sound wave conduction in the lateralizing ear is by BC.But without competing AC, sound waves will be interpreted by the patient as sounding louder.To test this yourself, create a temporary conductive hearing loss by occluding the external auditory canal and placing the vibrating tuning fork as described. In a person with normal hearing, sound will lateralize to the obstructed ear because you have blocked any competing AC sounds from being transmitted.
With a sensorineural hearing loss, the sound lateralizes to the good ear. The ear with sensorineural deafness is unable to transmit sound waves by AC or BC to the acoustic nerve to the brain. Consequently, the sounds transmitted to the opposite ear will be interpreted as louder, or lateralizing.
The Weber test can detect lateralization, but it cannot differentiate the cause. So if lateralization occurs, you will need to perform the Rinne test to establish if the problem is caused by a conductive hearing loss.
The Rinne test is a timed tuning-fork test used to compare AC and BC. To perform this test, place a vibrating tuning fork on your patient’s mastoid process. When it is on the mastoid process, sound transmission is through BC to the inner ear. Ask the patient to tell you when he or she no longer hears the vibrations. Record the amount of time the patient heard the sound in seconds.When the sound is no longer heard, immediately place the vibrating fork about
