What are the possible causes of dizziness on neck flexion (e.g., when looking at the armpit to shave)?

Dizziness with Neck Flexion: Benign Paroxysmal Positional Vertigo (BPPV)

Your symptoms of brief dizziness when bending your head to look at your armpit while shaving are most consistent with benign paroxysmal positional vertigo (BPPV), the most common cause of positional vertigo, accounting for 42% of all vertigo presentations. 1

Understanding the Mechanism

BPPV occurs when calcium carbonate crystals (otoconia) dislodge from the utricle and migrate into the semicircular canals of your inner ear 2, 3. When you move your head into certain positions—like flexing your neck to look downward—these free-floating particles shift and abnormally stimulate the vestibular receptors, triggering brief episodes of vertigo 3. The posterior semicircular canal is affected in 85-95% of cases 2.

Key Diagnostic Features

Your symptoms should have these characteristics if this is BPPV:

• Duration: Episodes last less than 1 minute (typically seconds) 1, 4
• Trigger: Provoked specifically by head position changes relative to gravity 5, 4
• No hearing symptoms: Absence of hearing loss, tinnitus, or ear fullness 1
• Fatigability: Symptoms may lessen with repeated movements 5

Immediate Next Steps

You need a Dix-Hallpike maneuver performed bilaterally to confirm the diagnosis. 1, 6 This bedside test involves:

1. Moving from sitting to supine with your head turned 45° to one side and extended 20° backward 1
2. Observing for characteristic findings:
   • Latency period of 5-20 seconds before symptoms begin 1, 6
   • Torsional, upbeating nystagmus toward the affected ear 1, 6
   • Vertigo and nystagmus that resolve within 60 seconds 1, 6

If the Dix-Hallpike is negative, a supine roll test should be performed to assess for lateral canal BPPV (10-15% of cases) 5. This involves rapidly turning your head 90° to each side while lying supine and observing for horizontal nystagmus 5.

Treatment

If the Dix-Hallpike confirms BPPV, the Epley maneuver (canalith repositioning procedure) should be performed immediately. 1, 6 This treatment:

• Achieves 80% success after 1-3 treatments 1, 6
• Reaches 90-98% success with additional maneuvers if initial treatment fails 1, 6
• Can be performed by any trained medical practitioner 3
• Requires no medications—vestibular suppressants are contraindicated as they prevent central compensation 1

When Imaging Is NOT Needed

No neuroimaging or vestibular testing is required if: 1, 6

• The Dix-Hallpike test is positive with typical nystagmus
• You have no additional neurological symptoms
• Your neurological examination is normal
• You have no "red flag" features (see below)

The American College of Radiology explicitly recommends against routine imaging for typical BPPV, as the diagnostic yield of CT is less than 1% 6.

Red Flags Requiring Urgent Evaluation

Seek immediate medical attention and neuroimaging if you develop: 1, 6

• Severe postural instability with falling (not just unsteadiness)
• New, severe headache accompanying the dizziness
• Downbeating nystagmus without a rotational component on testing
• Constant dizziness unaffected by position changes
• Any focal neurological symptoms (weakness, numbness, speech changes, vision changes)
• Hearing loss, tinnitus, or ear fullness (suggests Ménière's disease or other pathology)
• Failure to improve after appropriate canalith repositioning

These features suggest central pathology (posterior circulation stroke, cerebellar lesion) rather than benign BPPV and require MRI brain without contrast 1, 6.

Important Considerations

Age and vascular risk factors matter. If you are over 50 years old with hypertension, diabetes, atrial fibrillation, or prior stroke, even with typical BPPV symptoms, there is a 25% risk of posterior circulation stroke in acute vestibular presentations (rising to 75% in high-risk cohorts) 1, 6. In this scenario, MRI may be warranted even with a positive Dix-Hallpike 6.

Post-traumatic BPPV is common after head injury and requires repeated repositioning maneuvers in up to 67% of cases (compared to 14% in non-traumatic BPPV) 2.

Multiple vestibular disorders can coexist—BPPV may occur alongside Ménière's disease, vestibular neuritis, or even central nervous system disorders like multiple sclerosis 2. If your presentation is atypical or you have additional vestibular symptoms, further evaluation is warranted 1.

Follow-Up

Reassessment within 1 month is recommended to document symptom resolution 1, 6. You should be counseled about:

• Recurrence risk: BPPV can recur and may require repeat repositioning 1, 6
• Fall risk: Dizziness increases fall risk 12-fold, particularly in older adults 1, 6
• When to return: Promptly seek care if symptoms recur for repeat Epley maneuver 6

Common Pitfalls to Avoid

• Do not assume BPPV without performing the diagnostic maneuvers—the symptom pattern alone is insufficient 1
• Do not order imaging in the absence of red-flag features; it has extremely low yield and delays effective treatment 1, 6
• Do not prescribe vestibular suppressants (meclizine, diazepam) for BPPV—they are ineffective and prevent central compensation 1
• Do not dismiss symptoms in older adults—BPPV is present in 9% of elderly patients referred for geriatric evaluation, and three-fourths had fallen within the prior 3 months 1