In a 46-year-old female with hypertension and type 2 diabetes who presents with recurrent brief positional vertigo, nausea, vomiting, unsteady gait, tachycardia, elevated blood pressure, unilateral horizontal nystagmus lasting less than one minute, a positive head‑impulse test with catch‑up saccades, and no skew deviation, what is the most appropriate next step in management?

MRI of the Brain is the Most Appropriate Next Step

This patient requires urgent MRI of the brain (answer c) because her clinical presentation includes red flags that suggest a central cause of vertigo rather than benign paroxysmal positional vertigo (BPPV), despite some superficially similar features.

Critical Red Flags Present in This Case

This patient's presentation contains several concerning features that distinguish her from typical BPPV:

The Positive Head-Impulse Test with Catch-Up Saccades

• This is the most critical finding. A positive head-impulse test indicates peripheral vestibular dysfunction (vestibular nerve or labyrinth pathology), NOT BPPV 1.
• In true BPPV, the head-impulse test should be normal because the vestibulo-ocular reflex remains intact 1.
• The presence of catch-up saccades suggests acute vestibular neuritis or, more concerning in this context, a central lesion affecting the vestibular pathways.

Severe Gait Instability Requiring Assistance

• While BPPV patients may feel unsteady during acute episodes, inability to walk without assistance is disproportionate for BPPV 1.
• This degree of imbalance raises concern for cerebellar or brainstem pathology.

Cardiovascular Instability

• Tachycardia (110-120 bpm) and elevated blood pressure (155/85 mmHg) with minimal orthostatic change suggest systemic stress or autonomic involvement.
• Combined with her diabetes and hypertension, she has significant vascular risk factors for posterior circulation stroke 2.

Why This is NOT Typical BPPV

The 2017 AAO-HNS BPPV guidelines 1 specify diagnostic criteria that this patient does not fully meet:

• Nystagmus characteristics: While she has unidirectional horizontal nystagmus lasting <1 minute, the guidelines emphasize that posterior canal BPPV should produce torsional, upbeating nystagmus on Dix-Hallpike testing 3, 1.
• Head-impulse test should be normal in BPPV—the presence of catch-up saccades is inconsistent with this diagnosis 1.
• The severity of functional impairment (unable to walk) exceeds typical BPPV presentation.

The HINTS Examination Context

This patient's examination findings align with components of the HINTS (Head Impulse, Nystagmus, Test of Skew) examination used to differentiate peripheral from central causes of acute vestibular syndrome 4:

• Abnormal head-impulse test (catch-up saccades present) = suggests peripheral OR central pathology
• Unidirectional horizontal nystagmus = could be peripheral or central
• Negative skew deviation = reassuring but does not rule out stroke

The combination of an abnormal head-impulse test with severe functional impairment in a patient with vascular risk factors warrants neuroimaging 4, 2.

Why Not the Other Options?

a. Canalith Repositioning Maneuver

• Inappropriate as first-line because the diagnosis of BPPV is not confirmed 1.
• The abnormal head-impulse test contradicts BPPV 1.
• Guidelines state: "Clinicians should not obtain radiographic imaging in a patient who meets diagnostic criteria for BPPV" 3, 1—this patient does NOT meet criteria.

b. IV Normal Saline Bolus

• While she has tachycardia, there's minimal orthostatic change (BP 155/85→140/80, HR 110→120).
• This does not explain her neurological symptoms or abnormal vestibular examination.
• Treating presumed dehydration would delay diagnosis of a potentially serious central lesion.

d. CT Scan of the Head Without Contrast

• CT has very low sensitivity for posterior fossa stroke, particularly in the first 24-48 hours 4.
• MRI with diffusion-weighted imaging is the gold standard for detecting acute ischemia in the posterior circulation 4, 2.
• Given her presentation suggests possible vertebrobasilar pathology, CT would be inadequate.

Clinical Algorithm for This Scenario

When evaluating acute vertigo with these features:

1. Perform HINTS examination (if trained) or assess for red flags:

   • Abnormal head-impulse test
   • Direction-changing nystagmus
   • Skew deviation
   • Severe gait ataxia out of proportion to symptoms

2. Assess vascular risk factors:

   • Hypertension, diabetes (both present here)
   • Age >45 years (she is 46)

3. If ANY red flags present + vascular risk factors → MRI brain immediately 4, 2

4. Only proceed with canalith repositioning if:

   • Classic BPPV history confirmed
   • Appropriate nystagmus on Dix-Hallpike (torsional, upbeating)
   • Normal head-impulse test
   • No severe functional impairment
   • No neurological red flags 1, 3

Common Pitfall to Avoid

Do not assume all positional vertigo is BPPV. Central causes, particularly posterior circulation stroke, can present with positional symptoms 1, 2. The guideline statement that imaging is not needed applies only to patients who fully meet BPPV diagnostic criteria 3, 1—this patient does not. Her abnormal head-impulse test, severe functional impairment, and vascular risk factors mandate neuroimaging before any therapeutic maneuvers.

The presence of diabetes and hypertension further increases her risk for both stroke and BPPV recurrence if BPPV were present 5, 6, 7, but the immediate priority is excluding life-threatening central pathology given her atypical presentation.