Sensation and Perception (Exam 3, Disorders)

General: Inner hair cell damage

Can also cause a large effect Results in loss of sensitivity Loss of frequencies corresponding with optimal frequency of the cell

Meniere's disease

1 in 500 Meniere's disease is a disorder of the inner ear that causes episodes in which you feel as if you're spinning (vertigo), and you have fluctuating hearing loss with a progressive, ultimately permanent loss of hearing, ringing in the ear (tinnitus), and sometimes a feeling of fullness or pressure in your ear. In most cases, Meniere's disease affects only one ear. One popular theory that hasn't been proved is that Meniere's disease appears to be the result of the abnormal amount of fluid (endolymph) in the inner ear. Factors that affect the fluid, which might contribute to Meniere's disease, include: Improper fluid drainage, perhaps because of a blockage or anatomic abnormality Abnormal immune response Allergies Viral infection Genetic predisposition Head trauma Migraines No cure Some treatments include battling motion sickness, nausea. Diuretics help to reduce fluid retention. Low sodium diet

Ototoxicity

From notes: Drugs can predispose damage. (Saturated fat causes rigid basal membrane, predisposes them to breaking). Inner ear is very sensitive to drugs because we made our vestibular and inner ear sensitive to drugs as a way of getting rid of toxic exposures. If you're motion sick, you want to throw up because your body thinks you've eaten something bad. Sensitive to toxins, including: Aspirin, antibiotics, alcohol, quinine, cistaplatin, loop diuretics, carboplatin, gentamicin. They increase your vulnerability to loud noises From online: Drug or chemical-related damage to the inner ear, resulting in damage to the organs responsible for hearing and balance. Can lead to temporary or permanent hearing loss, and/or loss of balance. Ototoxic substances include several therapeutic medicines (e.g. aminoglycoside antibiotics, some anti-cancer agents, loop diuretics, anti-malarial drugs and aspirin), and other environmental substances (e.g. mercury, lead and arsenic). Symptoms: Tinnitus Hearing loss Dizziness Incoordination Oscillating or bouncing vision (nystagmus)

General: Outer hair cells damage

Larger affect on the response of the auditory nerve fibers Most common cause of hearing loss Results in loss of sensitivity (inability to hear quiet sounds) and loss of sharp frequency tuning Basilar membrane resembles a dead cochlea Harder to separate out sounds (hard to hear speech in a noisy environment) Loss of frequencies corresponding with optimal frequency of the cell

Sensorineural vs conduction hearing loss (Incidence!!!! LOOK UP!!!)

Sensorineural Hearing loss due to problems with the inner ear. Also known as nerve-related hearing loss Causes: Loud noise, trauma, virus/disease, presbycusis, malformation of structures, meniere's disease, tumors Treatments: Corticosteroids (reduce cell swelling), cochlear implants Conductive Due to problems with ear canal, ear drum or middle ear and ossicles. Causes: Wrong formation of structures, fluid in middle ear from a cold, ear infection (otitis media), poor eustachian tube function, benign tumors, impacted ear wax, otosclerosis (genetic), infection in ear canal Treatments: Surgery, hearing aid, antibiotics,

How can you tell the difference between conductive hearing loss and sensorineural?

Take a tuning fork to your jaw If you can her the sound, it is conductive hearing loss. The damage is not to your hair cells, you hear it through bone conduction despite the lack of air conduction. If you cannot hear the sound, there is a problem with the reception of the stimuli, so it is sensorineural hearing loss.

Benign paroxysmal positional vertigo

Treat with Epley's maneuver (shaking the head) Most common cause of vertigo Inside your ear is a tiny organ called the vestibular labyrinth. It includes three loop-shaped structures (semicircular canals) that contain fluid and fine, hair-like sensors that monitor the rotation of your head. Other structures (otolith organs) in your ear monitor movements of your head — up and down, right and left, back and forth — and your head's position related to gravity. These otolith organs contain crystals that make you sensitive to gravity. For a variety of reasons, these crystals can become dislodged. When they become dislodged, they can move into one of the semicircular canals — especially while you're lying down. This causes the semicircular canal to become sensitive to head position changes it would normally not respond to, which is what makes you feel dizzy.

Motion sickness

You get motion sickness when one part of your balance-sensing system (your inner ear , eyes, and sensory nerves) senses that your body is moving, but the other parts don't. For example, if you are in the cabin of a moving ship, your inner ear may sense the motion of waves, but your eyes don't see any movement. This conflict between the senses causes motion sickness. Motion sickness is caused by the mixed signals sent to the brain by the eyes and the inner ear (semicircular canals). If you cannot see the motion your body's feeling, or conversely, if you cannot feel the motion your eyes see, then it is likely that the brain will get mixed signals and the person will develop some aspect or symptom of motion sickness. Medical treatments: Scopolamine, which comes as a patch you put behind your ear. Medicines called antiemetics, which reduce nausea. Certain antihistamines, which may make you drowsy. Pregnant women more likely to get it

Presbycusis

Age related hearing loss, due to cumulative effects of noise exposure, drugs, age-related degeneration Loss is greater for high-pitched sounds Affects males more than females (historically exposed to more noisy environments) Tinnitus may also occur Causes: Sensorineural: inner ear or auditory nerve related Loss of hair cells (sensory receptors) Hearing aids, assistive listening devices (telephone amp)

Viral labrynthitis

Condition due to inflammation of the labyrinth in the inner ear Infection Symptoms: Vertigo: sensation that you and surroundings are moving, often vomit. Occurs because the damaged labyrinth sends conflicting signals to the brain compared to the normal ear. Hearing loss Nystagmus: shaking of eyes.

Otitis media

Conductive problem Inflammation of the middle ear Group of disorders Hearing loss, tinnitus, vertigo may occur. Also, otalgia (which is ear pain) From notes: There is air space where ossicles are. Fluid accumulates there when the eustachian tube is closed due to the swollen tympanic membrane. Fluid bulges from the ear drum. Kids are more at risk because of the squished shape of their head. There is a much more direct route from the eustachian tube to the air pocket around the ossicles. Causes: Disfunction of the eustachian tube, usually resulting from inflammation of mucous membranes or nasopharynx. Gas volume in the middle ear is trapped and parts are slowly absorbed into tissues surrounding. Negative pressure results in the middle ear. Fluid is sucked into the middle ear's cavity, tympanic cavity, causing effusion.

Tinnitus

Perception of noise or ringing in the ears. A common problem, tinnitus affects about 1 in 5 people. Tinnitus isn't a condition itself — it's a symptom of an underlying condition, such as age-related hearing loss, ear injury or a circulatory system disorder. Can be subjective (only heard by patient) or objective (audible to other people also) Causes: Outer Ear: Earwax blockage. Earwax protects your ear canal by trapping dirt and slowing the growth of bacteria. When too much earwax accumulates, it becomes too hard to wash away naturally, causing hearing loss or irritation of the eardrum, which can lead to tinnitus. Excessive ear wax, especially if the wax touches the ear drum, causing pressure and changing how the ear drum vibrates, can result in tinnitus. Middle Ear: Ear bone changes. Stiffening of the bones in your middle ear (otosclerosis) may affect your hearing and cause tinnitus. Muscle spasms of tensor tympani or stapedius. Inner Ear: A common cause of tinnitus is inner ear cell damage. Tiny, delicate hairs in your inner ear move in relation to the pressure of sound waves. This triggers ear cells to release an electrical signal through a nerve from your ear (auditory nerve) to your brain. Your brain interprets these signals as sound. If the hairs inside your inner ear are bent or broken, they can "leak" random electrical impulses to your brain, causing tinnitus. Warning sign for hearing loss. Meniere's disease Other: TMJ Head/neck injuries Tinnitus may also originate from lesions on or in the vicinity of the hearing portion of the brain. A special category is tinnitus that sounds like one's heartbeat or pulse, also known as pulsatile tinnitus. Infrequently, pulsatile tinnitus may signal the presence of cardiovascular disease or a vascular tumor in the head and neck or the ear.

Cochlear implants

Result of discovery that each pace on the basilar membrane is associated with a particular frequency used to create hearing in people with deafness caused by damage to the hair cells in the cochlea Hearing aids are ineffective when hair cells are damaged because the cells cannot convert the vibrations into electrical signals Consists of: Microphone (receives sounds signals) Sound processor (divides sound received into a number of frequency bands) Transmitter (sends signals to electrodes) Array of 22 electrodes (implanted along the length of the cochlea) Electrodes stimulate the cochlea at different places along its length, depending on the intensities of the frequencies in the stimuli received by microphone Stimulation activates auditory nerve fibers along cochlea, which sends signals to the brain