A 68-year-old woman presents to the clinic with a 2-day history of intense dizziness. She describes the symptoms as a sensation that the room is spinning, which occurs only when she rolls over in bed to her right side or when she tilts her head back to reach for items in her pantry. Each episode lasts for approximately 30 to 45 seconds and is accompanied by mild nausea. She denies any hearing loss, tinnitus, or headache. Her medical history is significant for hypertension and a recent minor head injury when she bumped her forehead on a cabinet. On physical examination, when the patient is moved rapidly from a seated to a supine position with her head turned 45° to the right and extended 20° back, there is a 5-second latency followed by up-beating, torsional nystagmus that lasts for 30 seconds. The symptoms resolve when she sits back up. Neurological examination is otherwise unremarkable.
Which of the following is the most likely diagnosis?
The correct answer is:
A) Benign paroxysmal positional vertigo
The patient's clinical presentation is classic for benign paroxysmal positional vertigo (BPPV), the most common cause of peripheral vertigo. The pathophysiology involves the displacement of calcium carbonate crystals (otoconia) from the utricle into the semicircular canals, most commonly the posterior canal. These displaced otoconia create abnormal fluid displacement during head movement. The hallmark features include brief, episodic vertigo typically lasting less than 1minute that is triggered by specific changes in head position, such as rolling over in bed or looking up. The physical examination maneuver described is the Dix-Hallpike maneuver, which is the gold standard for diagnosing posterior canal BPPV. A positive test is characterized by a brief latency followed by paroxysmal nystagmus (typically up-beating and torsional toward the affected ear) and the reproduction of vertigo.
Answer choice B: Labyrinthitis, is incorrect. While labyrinthitis is a peripheral cause of vertigo, it typically presents with continuous, severe vertigo rather than brief positional episodes. Crucially, labyrinthitis is associated with acute sensorineural hearing loss, which this patient does not have.
Answer choice C: Meniere disease, is incorrect. Meniere disease is characterized by episodes of vertigo that last much longer than BPPV (20 minutes to several hours). It is also associated with a triad of symptoms including sensorineural hearing loss, tinnitus, and aural fullness.
Answer choice D: Orthostatic hypotension, is incorrect. While orthostatic hypotension causes dizziness upon standing, it is described as lightheadedness or faintness (presyncope) rather than true room-spinning vertigo. It would not be triggered by rolling over in bed or be associated with nystagmus during the Dix-Hallpike maneuver.
Answer choice E: Vestibular neuritis, is incorrect. Similar to labyrinthitis, vestibular neuritis presents with acute, continuous, and severe vertigo that can last for days. While it can be worsened by head movement, it is not triggered only by head movement, and hearing is preserved.
Key Learning Point
Benign paroxysmal positional vertigo (BPPV) is caused by otoconia in the semicircular canals. It presents with short-lived (<1 minute) episodes of vertigo triggered by head position changes. Diagnosis is confirmed by the Dix-Hallpike maneuver, and the definitive treatment is the Epley maneuver (canalith repositioning), which aims to move the otoconia back into the utricle.
