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Difficulty: Very hardPhysical Examination Findings

A 61-year-old woman is evaluated in the emergency department for the sudden onset of severe, continuous room-spinning dizziness that began 6 hours ago. The dizziness is present even when she is perfectly still, but it is severely exacerbated by any head movement. She also reports intractable nausea and two episodes of vomiting. Her medical history includes hypertension and hyperlipidemia. Her blood pressure is 154/90 mm Hg, and her pulse is 88/min. She is unable to walk without assistance. On physical examination, the patient is awake and alert. Oculomotor examination reveals spontaneous, horizontal-torsional nystagmus that beats toward the left; the nystagmus increases in amplitude when she looks to the left but does not change direction when she looks to the right. The examiner asks the patient to fixate on a target and rapidly rotates her head to the right; a corrective saccade is observed as her eyes snap back to the target. Rapid head rotation to the left produces no corrective saccade. An alternate cover test reveals no vertical misalignment of the eyes. Otoscopic and hearing examinations are unremarkable. A basic metabolic panel shows a serum sodium of 133 mEq/L and potassium of 3.8 mEq/L. Which of the following is the most appropriate diagnostic interpretation and next step in management based on these physical examination findings?

  1. The physical examination reliably localizes the lesion to the right peripheral vestibular system; the patient should receive symptomatic medical therapy without the need for urgent neuroimaging.Answer
  2. B
    The patient's vascular risk factors and profound gait instability supersede the bedside examination, mandating urgent magnetic resonance imaging of the brain to exclude a posterior circulation stroke.
  3. C
    The presence of prominent nystagmus in the setting of acute vertigo is diagnostic of benign paroxysmal positional vertigo; an immediate canalith repositioning maneuver is indicated.
  4. D
    The observation of a unilateral corrective saccade requires the immediate performance of the Dix-Hallpike maneuver to accurately identify the involved semicircular canal.
  5. E
    The clinical presentation is a direct neurologic manifestation of the isolated hyponatremia; targeted intravenous correction of the serum sodium is the primary required intervention.

Answer

The physical examination reliably localizes the lesion to the right peripheral vestibular system; the patient should receive symptomatic medical therapy without the need for urgent neuroimaging.
This patient presents with Acute Vestibular Syndrome (AVS), characterized by the acute onset of continuous vertigo, nausea, vomiting, and gait instability. The critical diagnostic step is differentiating a benign peripheral cause (such as vestibular neuritis) from a central cause (such as a posterior circulation stroke). The HINTS examination is specifically designed for this purpose. In this patient, the exam demonstrates: 1) An abnormal head impulse test with a corrective saccade when the head is turned to the right, indicating a deficient vestibulo-ocular reflex originating from a right peripheral vestibular lesion; 2) Unidirectional, horizontal-torsional nystagmus that does not change direction with gaze, which is typical of a peripheral lesion; 3) Absence of skew deviation on the alternate cover test. This specific triad of physical examination findings is highly sensitive and specific for a peripheral vestibulopathy (right vestibular neuritis) and effectively rules out a central etiology with greater accuracy than an early MRI. Therefore, the patient can be safely managed with symptomatic therapy (e.g., antiemetics) and vestibular rehabilitation without the need for urgent neuroimaging.

Step-by-Step Solution

1
Analyze the temporal pattern of the patient's vertigo.
The patient has acute, continuous vertigo lasting hours (Acute Vestibular Syndrome), rather than brief, episodic vertigo.
Differentiating continuous from episodic vertigo rules out benign paroxysmal positional vertigo (BPPV) and shifts the focus to differentiating between vestibular neuritis and a posterior circulation stroke.
2
Interpret the nystagmus characteristics.
The nystagmus is unidirectional and horizontal-torsional, beating towards the left.
Unidirectional nystagmus strongly correlates with a peripheral vestibular lesion. In contrast, direction-changing or purely vertical nystagmus suggests a central etiology.
3
Evaluate the head impulse test (HIT) and test of skew.
The HIT is abnormal (corrective saccade present) when turning the head to the right, and the test of skew is normal (no vertical misalignment).
An abnormal HIT indicates a deficient vestibulo-ocular reflex on that side, which is classic for a peripheral lesion (e.g., vestibular neuritis). A normal test of skew further rules out brainstem pathology.
4
Synthesize the HINTS exam findings to determine the next step.
The combination of abnormal HIT, unidirectional nystagmus, and absent skew deviation confidently diagnoses a peripheral lesion (right vestibular neuritis).
In Acute Vestibular Syndrome, a 'benign' HINTS exam is highly specific for a peripheral cause and is more sensitive than an early MRI for ruling out a stroke, making advanced neuroimaging unnecessary.

Key Concept

The HINTS examination (Head Impulse, Nystagmus, Test of Skew) is a highly sensitive physical examination sequence used in Acute Vestibular Syndrome to differentiate benign peripheral causes (e.g., vestibular neuritis) from life-threatening central causes (e.g., posterior circulation stroke).
Estimated Time:1m 30s
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Physical Examination Findings

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