WBR0130

Author	PageAuthor::Sapan Patel, M.B.B.S.
Exam Type	ExamType::USMLE Step 3
Main Category
Sub Category	SubCategory::Head and Neck, SubCategory::Neurology
Prompt	[[Prompt::A 67-year-old man presents with a 2-day history of severe dizziness. The symptoms are exacerbated by turning his head and relieved by lying still. He reports nausea and vomiting for the first 2 days of his illness, but successfully eats breakfast on the day he is seen in clinic. He denies hearing loss and tinnitus. His past medical and surgical histories are unremarkable. He has no previous exposure to ototoxic drugs and denies further neurologic symptoms. Physical examination reveals an obviously uncomfortable white male in a wheelchair.Otologic examination is without abnormality. Weber testing with a 512 Hz tuning fork is to midline. Romberg testing indicates right-sided pathology. Cranial nerve examination is normal except left beating nystagmus. Vertigo is experienced after the Dix-Hallpike maneuver. Nystagmus is observed after a few seconds of lying down during the maneuver.The patient is treated with diazepam, which, on follow up, has relieved his symptoms. What is the most likely diagnosis?]]
Answer A	AnswerA::Meniere's disease
Answer A Explanation	[[AnswerAExp::The presence of episodes of vertigo along with fluctuating hearing loss are consistent with the diagnosis of Meniere's disease, which is also characterized by tinnitus or a ringing sound in the ear. Some patients also experience a pressure sensation in the ear. Episodes occur at regular intervals for years, and may also be marked by periods of remission. The cause is an increase in the volume of endolymph.]]
Answer B	AnswerB::Acoustic neuroma
Answer B Explanation	[[AnswerBExp::Acoustic neuroma (sometimes termed a neurolemmoma or schwannoma) is a benign (noncancerous) tissue growth that arises on the eighth cranial nerve leading from the brain to the inner ear. Acoustic neuromas usually grow slowly over a period of years. They expand in size at their site of origin, and when large, can displace normal brain tissue. The brain is not invaded by the tumor, but the tumor pushes the brain as it enlarges. The slowly enlarging tumor protrudes from the internal auditory canal into an area behind the temporal bone called the cerebellopontine angle. Since the balance portion of the eighth nerve is where the tumor arises, unsteadiness and balance problems may occur during the growth of the neuroma. The most common presentation is unilateral hearing loss.]]
Answer C	AnswerC::Benign positional vertigo
Answer C Explanation	[[AnswerCExp::Benign positional vertigo (BPV) is the most likely cause of this patient’s vertigo. BPV is not typically associated with hearing loss. Patients have brief episodes of vertigo with positional changes, typically when turning over in bed. This patient had a positive response to the Dix-Hallpike maneuver, which confirms the diagnosis. BPV is due to deposition of calcium debris in the semicircular canals. Medications such as diazepam or meclizine as well as canalith repositioning (Epley’s maneuver) are used to treat the condition. The latter is a series of head rotational positions intended to relocate free floating particles in the semicircular canals.]]
Answer D	AnswerD::Viral labyrinthitis
Answer D Explanation	[[AnswerDExp::Labyrinthitis is an inflammation or dysfunction of the vestibular labyrinth, which is a system of intercommunicating cavities and canals in the inner ear. The syndrome is defined by the acute onset of vertigo that commonly is associated with head or body movement. Nausea, vomiting, and malaise often accompany the vertigo. The pathophysiology of this syndrome is not completely understood. However, a dysfunction of the vestibular apparatus is clearly present when labyrinthitis occurs. Many cases of labyrinthitis are associated with systemic or viral-like illnesses. Suppurative or bacterial labyrinthitis is rare, but it should be considered in patients with acute or chronic otitis media. Cases are reported in association with meningitis, but the presentation of the meningitis often overwhelms the vestibular symptoms.]]
Answer E	AnswerE::Vestibular neuronitis
Answer E Explanation	[[AnswerEExp::Vestibular neuronitis presents as acute onset of vertigo, nausea, and vomiting lasting for several days. As this condition is not clearly inflammatory in nature, neurologists often refer to it as vestibular neuropathy. The etiology is unknown, but it appears to be a sudden disruption of afferent neuronal input from the left and right inner ears. This imbalance in vestibular neurologic input to the central nervous system causes symptoms of vertigo. Besides the unilateral caloric weakness, electronystagmography reveals a directional preponderance and beating nystagmus away from the affected side. Work-up of patients with vestibular neuronitis begins with thorough history and physical examination. Audiometry and vestibular testing are the cornerstones of diagnosis, with imaging and laboratory studies being guided by findings on examination. Bedside examination includes Doll's eye test, head shaking nystagmus, dynamic visual acuity, caloric testing, rotational testing, past pointing, Romberg and Fukuda tests, and tandem walking. Patients with this condition do not generally have auditory symptoms.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation:: Educational Objective: References: ]]
Approved	Approved::Yes
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