1.
A 58-year old woman has a paralysis on the right side of her face. She has difficulty in chewing and perceives sounds as annoyingly loud. Physical examination reveals a loss of taste on the anterior 2/3rds of her tongue. The hyperacusis in this case results from involvement of which of the following:
Correct Answer
B. Nerve to stapedius
Explanation
The paralysis on the right side of the woman's face, difficulty in chewing, and loss of taste on the anterior 2/3rds of her tongue suggest involvement of the facial nerve. The nerve to stapedius is a branch of the facial nerve that innervates the stapedius muscle in the middle ear. Dysfunction of this nerve can lead to hyperacusis, which is the perception of sounds as annoyingly loud. Therefore, the hyperacusis in this case is likely due to involvement of the nerve to stapedius.
2.
A 30-year old conscious woman is brought to the ER following an accident. The caloric test was performed by irrigating the left ear with cold water and then with warm water. The physician concluded that the vestibulo-ocular reflex was present since he observed which eye movements?
Correct Answer
A. Cold water induced the fast pHase of nystagmus to the right side
Explanation
The vestibulo-ocular reflex (VOR) is responsible for stabilizing the visual image on the retina during head movements. In a normal VOR response, when cold water is irrigated into the ear, it stimulates the semicircular canals and causes the eyes to move in the opposite direction (fast phase of nystagmus) to maintain visual fixation. In this case, the fast phase of nystagmus was observed to the right side, indicating that the vestibulo-ocular reflex was present and functioning correctly.
3.
A 50-year old man was admitted to the hospital complaining of a loss of hearing. The patient also reported unsteadiness in balance. Examination further revealed a facial
palsy on the side of the face ipsilateral to the hearing loss. The most likely cause of this disorder is:
Correct Answer
A. Acoustic neuroma of the cerebellopontine angle
Explanation
The most likely cause of the patient's symptoms of hearing loss, unsteadiness in balance, and facial palsy on the same side as the hearing loss is an acoustic neuroma of the cerebellopontine angle. Acoustic neuromas are benign tumors that arise from the Schwann cells of the vestibulocochlear nerve (CN VIII) and typically present with symptoms such as unilateral hearing loss, tinnitus, and balance problems. The presence of facial palsy suggests involvement of the facial nerve (CN VII), which runs close to CN VIII in the cerebellopontine angle.
4.
A 34-year old man reported episodes of dizziness and vertigo to his physician. Two weeks later he reported hearing loss and a slight tinnitus in his right ear. These symptoms started to get worse with time. A neurological examination revealed no other signs of neurological dysfunction. The most likely site of the lesion/dysfunction in this patient is?
Correct Answer
E. Abnormal volume of endolympH in the inner ear
Explanation
The most likely site of the lesion/dysfunction in this patient is an abnormal volume of endolymph in the inner ear. This is indicated by the symptoms of dizziness, vertigo, hearing loss, and tinnitus, which are characteristic of Ménière's disease. Ménière's disease is a disorder of the inner ear that results in an abnormal accumulation of endolymph, causing these symptoms. The absence of other signs of neurological dysfunction suggests that the lesion is localized to the inner ear rather than the brain or cranial nerves.
5.
A 52-year old man reported feeling unsteady while walking. History taking revealed that this balance problem developed after a hearing loss associated with the left ear. The patient's muscles of facial expression on the left exhibited marked weakness. In addition, the patient's corneal reflex was absent on the left side. The most likely explanation of these symptoms is?
Correct Answer
C. Acoustic schwannoma of cerebellopontine angle
Explanation
The most likely explanation for the symptoms described is an acoustic schwannoma of the cerebellopontine angle. This is supported by the patient's history of hearing loss associated with the left ear, as well as the presence of marked weakness in the muscles of facial expression on the left side and absence of the corneal reflex on the left side. Acoustic schwannomas are tumors that arise from the Schwann cells of the vestibulocochlear nerve, which can cause symptoms such as hearing loss, facial weakness, and balance problems.
6.
Opening of ion channels in stereocilia results in inner hair cell depolarization. If we were to take the ions responsible for this depolarization of hair cells and add these ions to the extracellular solution surrounding a cerebellar purkinje cell, what would happen to the resting membrane potential of the cerebellar purkinje cell?
Correct Answer
C. Depolarization
Explanation
When the ions responsible for the depolarization of hair cells are added to the extracellular solution surrounding a cerebellar Purkinje cell, the resting membrane potential of the Purkinje cell would depolarize. This is because the opening of ion channels in stereocilia causes an influx of ions into the hair cells, leading to depolarization. Therefore, when these ions are added to the extracellular solution surrounding the Purkinje cell, they would cause a similar depolarization effect on the membrane potential of the Purkinje cell.
7.
Your 82-year old patient is in very good overall health. He does have, however, some deficits in hearing. He cannot hear the full l range of sounds that a young person can normally hear. You explain to him that this loss of hearing is common with aging and that he shouldn't worry about it. The hearing loss he is experiencing is most likely?
Correct Answer
C. The result of damage to hair cells at base of basilar membrane
Explanation
As people age, they often experience a loss of hearing due to the natural aging process. This loss of hearing is typically caused by damage to the hair cells in the inner ear. The hair cells at the base of the basilar membrane are responsible for detecting high frequency sounds, while the hair cells at the apex of the basilar membrane are responsible for detecting low frequency sounds. Since the patient cannot hear the full range of sounds, it suggests that the damage is most likely occurring at the base of the basilar membrane, affecting the hair cells that respond maximally to high frequency sounds.
8.
What is the main function of the outer hair cells?
Correct Answer
B. Cochlear amplification
Explanation
The main function of the outer hair cells is cochlear amplification. These cells are responsible for amplifying and fine-tuning the sound vibrations that enter the cochlea. They enhance the sensitivity and selectivity of the auditory system, allowing us to hear soft sounds and distinguish between different frequencies.
9.
A 48-year-old woman, with triple cardiac valve prostheses, became completely deaf after a bitemporal embolism. Investigation confirmed intact peripheral and brainstem pathways, and the rare condition of cortical deafness was diagnosed. Which part of both temporal lobes was involved?
Correct Answer
D. Superior temporal gyrus
Explanation
The superior temporal gyrus is involved in auditory processing and is responsible for processing sound information. In this case, the patient became completely deaf after a bitemporal embolism, indicating damage to the auditory pathways. Since investigation confirmed intact peripheral and brainstem pathways, the condition of cortical deafness was diagnosed, suggesting involvement of the cortical areas responsible for auditory processing. Therefore, the involvement of the superior temporal gyrus is likely responsible for the patient's deafness.
10.
A 70-year old woman has suffered with hypertension and diabetes mellitus for the past 10 years. She now has presented with vertigo for the past 2 days. MRI showed a lesion in the lateral medulla. A lesion to which of the following structures is most likely responsible for the above symptoms?
Correct Answer
C. Inferior vestibular nucleus
Explanation
The symptoms of vertigo and the location of the lesion in the lateral medulla suggest that the inferior vestibular nucleus is most likely responsible. The inferior vestibular nucleus is involved in maintaining balance and is responsible for processing information related to head position and movement. Damage to this nucleus can result in vertigo, which is a sensation of spinning or dizziness.
11.
A 73-year aid woman experienced worsening diplopia. MRI examinations showed bilateral roundish parasellar and intracavernous masses, with homogeneous contrast-enhancement. CerebraI angiography revealed bilateral aneurysms of the intracavernous carotid artery. The aneurism was compressing the nerve directly next to the mass. The diplopia was due to progressive bilateral paresis of which muscles?
Correct Answer
C. Lateral rectus
Explanation
The diplopia experienced by the 73-year-old woman was due to the compression of the nerve next to the masses caused by bilateral aneurysms of the intracavernous carotid artery. The aneurysms were compressing the lateral rectus muscle, leading to progressive bilateral paresis of the muscle. This paresis of the lateral rectus muscle resulted in the woman experiencing double vision.
12.
A 26-year old woman presented with diplopia. The abduction of both eyes were normal. The adduction of both eyes were quite limited in each eye. MRI revealed a multifocal lesion in the pons bilaterally next to the midline. Which structure is most probably affected?
Correct Answer
E. Medial longitudinal fascicle
Explanation
The given information suggests that the patient has limited adduction of both eyes, which indicates a problem with the medial longitudinal fascicle (MLF). The MLF is responsible for coordinating eye movements, specifically the adduction of the eyes. The presence of a multifocal lesion in the pons bilaterally next to the midline further supports the likelihood of the MLF being affected. Therefore, the most probable structure affected in this case is the medial longitudinal fascicle.
13.
A 56-year old male had a sexually transmitted disease 20 years ago after an unprotected sexual encounter. He now presents with neurological problems including cognitive and visual problems. On physical examination you would expect his pupils to:
Correct Answer
D. Not react to light and accommodate
Explanation
The patient's neurological problems, including cognitive and visual problems, suggest that he may have developed neurosyphilis as a complication of the sexually transmitted disease he had 20 years ago. Neurosyphilis can affect the nerves that control the pupils, leading to a condition called Argyll Robertson pupils. In this condition, the pupils do not react to light but still accommodate (constrict) when focusing on a near object. This is why the correct answer is "Not react to light and accommodate."
14.
A young boy is brought to the clinic. He appears quite small for his age and complains of not being able to see as well as he used to. Visual field examination reveals a bi-temporal hemianopsia . You suspect a tumor located near which of the following?
Correct Answer
A. Pituitary gland and stalk
Explanation
The presence of a bi-temporal hemianopsia suggests a lesion near the pituitary gland and stalk. This is because the optic chiasm, where the optic nerves partially cross, is located in this area. Lesions in this region can compress the optic chiasm, resulting in loss of vision in the outer (temporal) visual fields of both eyes. The other options, such as the calcarine sulcus, parieto-occipital sulcus, nucleus of cranial nerve III, and pineal gland, are not associated with the specific visual field defect described.
15.
A 52-year-old woman has difficulty reading small print in newspapers and magazines. Her ophthalmologist explains to her that she is suffering from a condition due to a loss of her ability to accommodate and focus on near objects. She most likely has which of the following?
Correct Answer
E. Presbyopia
Explanation
Presbyopia is the age-related loss of ability to focus on near objects due to the hardening of the lens in the eye. This condition commonly occurs in individuals over the age of 40 and is characterized by difficulty in reading small print. The symptoms described by the woman, along with her age, align with the diagnosis of presbyopia. Astigmatism, cataracts, optic atrophy, and macular degeneration are not typically associated with a loss of accommodation and focusing ability.
16.
A 50-year old taxi driver is currently hospitalized after suffering from a stroke. During the history, he denied impairment of his vision. The significant findings on physical examination were decreased vision and decreased movement of the vertical movements of his left eye. He also had left homonymous hemianopsia. Based on the findings, his stroke was most likely due to lesion affecting the area supplied which artery?
Correct Answer
B. Posterior cerebral arteries
Explanation
The patient's symptoms of decreased vision, decreased movement of vertical eye movements, and left homonymous hemianopsia suggest a stroke affecting the posterior cerebral arteries. The posterior cerebral arteries supply blood to the occipital lobe, which is responsible for vision and eye movement. Lesions in this area can lead to visual impairments and eye movement abnormalities.
17.
Imaging studies were ordered. If the deficits seen were due to the stroke, the lesion would most likely to be located in shaded area in:
Correct Answer
E. E
18.
During a routine neurological examination you perform a corneal reflex text. When you touch the right eye of your patient there is no direct reflex but an intact consensual reflex. This suggests damage to which region of the nervous system?
Correct Answer
A. Damage to the facial nerve fibers that innervate the ipsilateral orbicularis oculi muscles
Explanation
The corneal reflex is mediated by the trigeminal nerve (cranial nerve V) and the facial nerve (cranial nerve VII). When the cornea is touched, sensory fibers from the trigeminal nerve carry the stimulus to the brainstem, which then sends motor signals through the facial nerve to the orbicularis oculi muscles, causing the eye to blink. In this case, there is no direct reflex when the right eye is touched, but there is an intact consensual reflex when the left eye is touched. This suggests that there is damage to the facial nerve fibers that innervate the ipsilateral (same side) orbicularis oculi muscles, leading to a loss of direct reflex but preservation of the consensual reflex.
19.
A 21-year old professional female basketball player was advised by her coach to go to see her physician. She could not perform so well lately, she often did not notice the ball coming from the back and she had constant headaches. She said it was probably due to her emotional state, because she broke up with her boyfriend a few months ago. Even her period became very irregular the last few months. The coach wanted the doctor to prescribe some calming pills for her, but the doctor became suspicious that there were some other problems, since he found visual field loss on both temporal sides. His suspicion was confirmed later by MRI. Which of the following is most possible based on the symptoms?
Correct Answer
B. Pituitary adenoma, causing compression of the optic chiasma and leading to hormonal deficiencies.
Explanation
The symptoms described in the scenario, such as visual field loss on both temporal sides, irregular periods, and hormonal imbalances, are consistent with a pituitary adenoma. A pituitary adenoma is a tumor that grows in the pituitary gland, which is located near the optic chiasm. The tumor can compress the optic chiasm, leading to visual field loss. Additionally, the pituitary gland is responsible for producing hormones that regulate the menstrual cycle, so a tumor in this area can also cause hormonal deficiencies and irregular periods. Therefore, the most likely explanation for the symptoms is a pituitary adenoma causing compression of the optic chiasm and leading to hormonal deficiencies.
20.
The electron micrograph below was taken of a section of the eye. The positions of the landmarks "Photoreceptor outer segments" and "Cap" (designating a capillary) are shown. Of the choices below, the arrow is pointing to the nucleus of which cell type?
Correct Answer
D. Melanocyte
Explanation
The arrow is pointing to the nucleus of a melanocyte. This can be determined by the fact that the question states that the electron micrograph was taken of a section of the eye, and the landmarks "Photoreceptor outer segments" and "Cap" are shown. Melanocytes are cells that produce melanin, which is responsible for pigmentation in the eye. Therefore, it is logical to conclude that the arrow is pointing to the nucleus of a melanocyte.
21.
Shown above is a drawing of a portion of the iris of the eye. What is the function of the structure located at the tip of the arrow?
Correct Answer
B. Pupil constriction
Explanation
The structure located at the tip of the arrow is responsible for pupil constriction. Pupil constriction is the process of narrowing the opening of the pupil, which is the black circular area in the center of the iris. This function helps regulate the amount of light entering the eye, protecting it from excessive brightness. It is controlled by the muscles of the iris, which contract to decrease the size of the pupil.
22.
Which of the following statements about the choroid of the eye is INCORRECT?
Correct Answer
D. The choroid touches the neural retina
Explanation
The choroid does not directly touch the neural retina. The choroid is located between the sclera and the retina, providing blood supply to the retina. The choroid is mostly composed of loose connective tissue and contains many melanocytes. It also contains venous plexuses. However, it does not make direct contact with the neural retina.
23.
Oescemet's membrane is found in which structure of the eye?
Correct Answer
E. Cornea
Explanation
Descemet's membrane is a thin, transparent layer that is found in the cornea of the eye. It is located between the corneal stroma and the endothelium, and it helps to maintain the shape and structure of the cornea. This membrane plays an important role in protecting the eye from damage and maintaining clear vision.
24.
An astigmatism is caused by a region of unequal curvature in
Correct Answer
C. A or B.
Explanation
An astigmatism is caused by a region of unequal curvature in either the lens or the cornea.