Ear, Nose, Throat | Conductive vs. Sensorineural Hearing Loss

Hi everyone, welcome back to the MedBullet Step 2 in 3 podcast. In today's episode, we cover the topic of conductive versus sensory neural hearing loss found under the ear, nose, and throat section. at medbullets.com. Let's begin with a clinical snapshot. A 30-year-old man presents with constant right ear pain and hearing loss for the last three months.

He also states that at times, he experiences ringing of the right ear. He was previously diagnosed with an ear infection that was treated with antibiotics. On physical exam, There is amorphous and white debris in the right middle ear. A tuning fork was placed on the mastoid process and subsequently by the external auditory canal. Bone conduction was louder than air conduction on the right ear.

When the tuning fork was placed in the middle of the patient's forehead, the tone was louder in the right ear. It is explained to the patient that a non-contrast computerized tomography scan of the temporal bone will be scheduled.

This is a case of conductive hearing loss secondary to a cholesteatoma. Let's continue with an introduction to conductive versus sensorineural hearing loss. In terms of the hearing loss basic principles, Remember that unilateral hearing loss can result from lesions affecting the external auditory canal, the middle ear, cochlea, cranial nerve 8, and the cochlear nuclei.

Bilateral hearing loss suggests a lesion after the auditory pathways enter the brainstem. This is because auditory information crosses bilaterally immediately after entering the brainstem. Hearing loss is generally divided into conductive hearing loss and sensorineural hearing loss. Conductive hearing loss is secondary to lesions affecting the external auditory canal in the middle ear.

Sensory neural hearing loss is secondary to lesions affecting the cochlea and cranial nerve 8. In terms of conductive hearing loss etiologies, these may include otitis externa, squamous cell carcinoma, osteoma, cerumen, otitis media, cholesteatoma, otosclerosis, or a tympanic membrane perforation. The etiologies for sensory neural hearing loss may include hereditary hearing loss, presbycusis, ototoxic drugs, Meniere disease, barotrauma, an acoustic neuroma, or multiple sclerosis.

Now let's discuss different physical exam maneuvers. In the whispered voice test, the examiner stands behind the patient at arm's length and one of the patient's ears are occluded. The examiner whispers a series of letters and numbers of which the patient must repeat. Normal findings are when a patient is able to repeat the whispered letters and numbers. It is pathologic if there is hearing impairment.

which should prompt further physical exam maneuvers such as the Weber and Rhine test. In the Rhine test, one compares air conduction to bone conduction. Air conduction is tested by placing the vibrating tuning fork by the outside of the ear. Bone conduction is tested by placing the tuning fork on the mastoid process. Normally, air conduction is more than bone conduction. In the Weber test,

The vibrating tuning fork is placed in the middle of the patient's forehead. The patient is subsequently asked to say which side is loudest. Normally, the sound should be equal in both ears. Abnormal findings depend on whether there is conductive hearing loss or sensory neural hearing loss. In conductive hearing loss, the tone is louder on the affected side.

This is because of compensatory mechanisms aimed at increasing the perceived volume of the affected side. In sensorineural hearing loss, the tone is decreased on the affected side. Other diagnostic studies include an audiogram. This is useful as a confirmatory diagnostic study in patients with hearing impairment that cannot be explained by obvious causes, such as cerumen impaction. Now let's discuss some more pathology. In conductive hearing loss,

the bone conduction is greater than air conduction. This is because bone conduction bypasses issues involving the external and middle ear. In sensorineural hearing loss, air conduction is greater than bone conduction bilaterally. just like in normal conditions, but there is decreased hearing in the affected ear. Now that we've discussed the major points relating to conductive versus sensory neural hearing loss, let's walk through some questions to apply what we've learned.

and get a sense of how the topic might be tested. For the first question, consider the following clinical scenario. A 68-year-old man is brought to his primary care physician by his daughter for abnormal behavior that has progressively worsened over the last year. His daughter says that the patient does not seem to understand what is being said to him by his daughter or his wife

He seems to be more responsive to questions from his son, and during family gatherings, the patient isolates himself. Lately, the patient has been sitting much closer to the television and does not notice people are around him. He is able to care for himself without assistance. He has a medical history of hypertension and hyperlipidemia and does not smoke or drink alcohol.

Neurological exam is notable for normal strength and sensation in the bilateral upper and lower extremities. Which of the following will most likely elucidate the diagnosis? Choice one, an audiogram. Choice two, a Montreal cognitive assessment. Choice three, MRI of the brain. Choice four, patient health questionnaire nine. Or choice five, urinalysis.

The best answer to this question is choice one, audiogram. This patient is presenting with presbycusis, which is difficulty hearing high-frequency voices such as the female voice and progressive social withdrawal. An audiogram helps to confirm the diagnosis. Presbycusis is a common cause of hearing loss in patients of older age. More than 50% of cases manifest before 75 years of age.

patients classically present with progressive and symmetric loss of high frequency hearing over the course of years. This high frequency hearing loss makes patients unable to understand what is being told to them. since high-frequency sounds contain consonant information in sentences. As a result, patients begin to withdraw during social events and have a difficult time hearing women more than men.

due to the inherently higher pitch in women's voices. Audiogram confirms the diagnosis, but a simple bedside test to perform is the whispered voice test. The examiner is at an arm's length behind the patient. One ear canal is occluded, and a short sequence of letters and numbers is whispered. The other ear is tested in the same way. Let's also discuss why the other choices are incorrect. Choice 1.

The Montreal Cognitive Assessment is a cognitive screening test to assess cognitive decline, such as in patients with Alzheimer's dementia. Alzheimer's dementia would present with forgetting upcoming events, mistakenly leaving the stove on, and getting lost in a familiar neighborhood. Choice 2. MRI of the brain is useful in identifying mass lesions, strokes, or enhancement along the leptomeninges that may suggest meningitis.

Besides hearing loss, the patient is otherwise neurologically intact. Given his age, his MRI may likely demonstrate generalized atrophy and chronic ischemic changes from his hypertension and hyperlipidemia. Patients would typically present with focal neurological deficits, such as weak limbs. Choice 3. Patient Health Questionnaire 9 is useful as a screening tool for depression and its severity.

The patient's social withdrawal is likely from his inability to understand what is being said to him. His ability to hear is further worsened with competing background noise in social gatherings. Patients with depression have a depressed mood and can have difficulty with sleep, interest, feelings of guilt, energy, concentration, appetite, psychomotor function, and suicidal ideation.

Choice 4. Urinalysis is useful in evaluating for urinary tract infections, which in the elderly can result in altered mental status. The patient is able to care for himself and a urinary tract infection would not explain his hearing difficulty. Patients may have dysuria and or foul-smelling urine along with altered mental status. Finally, a bullet summary.

Presbycusis presents with progressive and symmetric loss of high-frequency hearing, and it is confirmed with an audiogram. For the second question, consider the following clinical scenario. A 72-year-old man He states that his trouble with hearing began approximately 7-8 years ago. He is able to hear when someone is speaking to him, however,

he has difficulty with understanding what is being said, especially when there is background noise. In addition to his current symptoms, he reports a steady ringing in both ears, and at times experiences dizziness. Medical history is significant for three prior episodes of acute otitis media. Family history is notable for his father being diagnosed with cholesteatoma. His temperature is 98.6 degrees Fahrenheit.

or 37 degrees Celsius. Blood pressure is 138 over 88. Pulse is 84 beats per minute, and respirations are 13 breaths per minute. On physical exam when a tuning fork is placed in the middle of the patient's forehead sound is appreciated equally on both ears. When a tuning fork is placed by the external auditory canal and subsequently on the mastoid process

air conduction is greater than bone conduction. Which of the following is most likely the cause of this patient's symptoms? And the answer choices are, choice one, accumulation of desquamated keratin debris. Choice two, eustachian tube obstruction secondary to nasopharyngeal inflammatory edema. Choice three, stapedial abnormal bone growth. Choice four, cochlear hair cell degeneration. Or choice five,

endolymphatic hydrops. The best answer to this question is choice four, cochlear hair cell degeneration. This patient's age and progressive bilateral sensorineural hearing loss is suggestive of presbycusis, which can result from degeneration of cochlear hair cells. Hearing loss can be divided into conductive and sensorineural.

Conductive hearing loss describes an impairment in transmitting sound from the external environment into the inner ear. Sensory neural hearing loss describes an impairment in transducing sound into neuronal signals. Therefore, Conductive hearing loss results from pathology affecting the outer and middle ear and sensory neural hearing loss from pathology affecting the inner ear. Pressed bicusis appears to be associated

with a disorder affecting cochlear structures, such as the stria vascularis, hair cells, and spiral ganglion. Let's also discuss why the other choices are incorrect. is suggestive of cholesteatoma, which results in conductive hearing loss. Choice 2. Eustachian tube obstruction secondary to nasopharyngeal inflammatory edema can be seen in acute otitis media.

AOM results in a conductive hearing loss. Also, the absence of fever, otalgia, and upper respiratory symptoms makes AOM less likely. Choice 3. Stapedial abnormal bone growth can be seen in otosclerosis, which results in a conductive hearing loss. Choice 5. Endolymphatic hydrops can be seen in Meniere's disease, which results in sensory neural hearing loss.

Typically, the sensory neural hearing loss is unilateral. Patients with this disease classically present with a sense of ear fullness and or ipsilateral tinnitus, vertigo, and hearing loss. These clinical findings are usually observed during attacks. Finally, a bullet summary. Pressed bicusis results in bilateral sensory neural hearing loss that can result from cochlear hair cell degeneration.

That's all for this review about conductive versus sensory neural hearing loss. We hope that was helpful. This is the MedBullets Step 2 in 3 podcast, a daily audio review session for MedBullets. the free learning and collaboration community for medical student education. As a reminder, you can follow along with these podcast episodes by reviewing the topics directly on medbullets.com.

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