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Update your Knowledge with MKSAP 18 Q&A: Answer and Critique

Answer

B: Labyrinthitis

Educational Objective

Diagnose labyrinthitis.

Critique

The most likely diagnosis in this patient with vertigo is labyrinthitis. Patients with vertigo often describe a spinning or whirling sensation, which is frequently associated with concomitant nausea, vomiting, and sudden-onset fatigue. Once vertigo is suspected, the next important step is to distinguish central from peripheral causes. The Dix-Hallpike maneuver can help with this task but could not be performed in this patient. The identification of central vertigo is important because it can be associated with ischemia, infarction, or hemorrhage of the cerebellum or brainstem and may be life threatening. More than 80% of patients with central vertigo have focal neurologic signs, and many have experienced recurrent symptoms over days to weeks. In this patient's case, he has no risk factors for stroke (hypertension, diabetes mellitus), no focal signs, and a preceding upper respiratory tract infection, making central vertigo unlikely. Common causes of peripheral vertigo include benign paroxysmal positional vertigo (BPPV), vestibular neuronitis, labyrinthitis, and Meniere disease. Labyrinthitis is caused by postviral inflammation of both branches of the vestibulocochlear nerve (cranial nerve VIII), resulting in sudden-onset, severe, persistent vertigo and hearing loss. This patient has signs and symptoms consistent with labyrinthitis preceded by an acute viral infection, making it the most likely diagnosis.

BPPV is the most common cause of peripheral vertigo. It is characterized by sudden-onset, recurrent, and brief (usually <1 minute) vertiginous symptoms, which are provoked and worsened with positional changes of the head. Although prolonged head positioning can trigger BPPV, BPPV is not associated with auditory changes, as seen in this patient.

Meniere disease presents with recurrent, spontaneous, and brief episodes of vertigo, tinnitus, and hearing loss. Nystagmus may be present. Symptoms resolve completely between episodes. In patients with Meniere disease, episodes of vertigo typically last hours, whereas this patient has experienced unremitting symptoms for the past 2 days.

Vestibular neuronitis is a peripheral vestibular condition caused by inflammation of the vestibular branch of the vestibulocochlear nerve, leading to vertiginous symptoms and nystagmus. It is most often preceded by a viral infection. Symptoms are sustained, ranging from days to weeks; however, auditory symptoms are not present, which is the key distinction between vestibular neuronitis and labyrinthitis.

Key Point

Labyrinthitis is characterized by sudden-onset, severe, persistent peripheral vertigo accompanied by hearing loss; it is most often preceded by a viral infection affecting both branches of the vestibulocochlear nerve (cranial nerve VIII).

Bibliogrpahy

Kim JS, Zee DS. Clinical practice. Benign paroxysmal positional vertigo. N Engl J Med. 2014;370:1138-47. [PMID: 24645946] doi: 10.1056/NEJMcp1309481

Back to the January 2019 issue of ACP International