What causes dizziness when bending the head?

Dizziness on Bending the Head: Diagnosis

Benign paroxysmal positional vertigo (BPPV) is the most likely diagnosis when dizziness occurs with head bending, and this should be confirmed with the Dix-Hallpike maneuver for posterior canal involvement or the supine roll test for lateral canal involvement. 1

Primary Diagnostic Consideration

BPPV is the single most common cause of triggered episodic vertigo and accounts for 42% of vertigo cases in primary care settings. 1 The condition is characterized by:

• Brief episodes of vertigo lasting seconds to less than 1 minute, triggered by specific head position changes 1
• Symptoms provoked by bending the head forward (bowing position) or backward (leaning position) 1
• Dizziness when lying down or turning in bed, which increases the likelihood of BPPV by an odds ratio of 60 2

Diagnostic Testing Algorithm

Step 1: Perform Positional Testing

The Dix-Hallpike maneuver is essential for diagnosing posterior canal BPPV (the most common form), looking for characteristic torsional upbeating nystagmus. 1, 3

The supine roll test must also be performed to identify lateral canal BPPV, which would be missed if only Dix-Hallpike testing is done. 1

The bow and lean test specifically evaluates head bending positions:

• In geotropic lateral canal BPPV: bowing (face down) produces nystagmus beating toward the affected ear; leaning (face up) produces nystagmus beating away from the affected ear 1
• In apogeotropic lateral canal BPPV: the pattern is reversed 1

Step 2: Identify Red Flags for Central Causes

Critical warning signs that indicate a central nervous system disorder rather than BPPV include: 4, 5

• Downbeat nystagmus without a torsional component 4, 5
• Direction-changing nystagmus that doesn't follow typical BPPV patterns 4, 5
• Baseline nystagmus present in primary position 4
• Associated cerebellar signs (ataxia, dysmetria, dysdiadochokinesia) 5
• Continuous dizziness lasting days to weeks rather than brief episodes 1

Comprehensive Differential Diagnosis

Otologic Disorders to Consider

When BPPV is not confirmed, consider these peripheral vestibular causes: 1

• Ménière's disease: characterized by episodic vertigo lasting 20 minutes to 12 hours with associated hearing loss, tinnitus, and aural fullness 1
• Vestibular neuritis: acute persistent vertigo lasting days without hearing loss 1
• Superior canal dehiscence syndrome: vertigo triggered by loud sounds or Valsalva maneuvers 1
• Perilymphatic fistula: vertigo with pressure changes 1

Neurologic Disorders to Consider

Central causes that can mimic positional vertigo include: 1

• Vestibular migraine: episodic vertigo lasting minutes to hours, often with headache history 1
• Posterior circulation stroke or transient ischemic attack: sudden onset with neurologic deficits 1
• Demyelinating diseases (multiple sclerosis): vertigo with other neurologic symptoms 1
• Central nervous system lesions including intracranial tumors 1, 4
• Vertebrobasilar insufficiency: vertigo with brainstem symptoms 1

Other Entities to Consider

Non-vestibular causes of positional dizziness include: 1

• Postural hypotension: dizziness when moving from supine to upright, not with head turning alone 1
• Cervicogenic vertigo: triggered by neck rotation relative to the body while upright, not by head position changes relative to gravity 1
• Medication side effects: antihypertensives, anticonvulsants, vestibular suppressants 1
• Anxiety or panic disorder: vague lightheadedness rather than true spinning vertigo 1, 6

Clinical History Pearls

Focus on timing and triggers rather than the patient's descriptive terms for dizziness: 1

• BPPV fits the "triggered episodic vestibular syndrome" pattern: brief episodes (<1 minute) triggered by obligate head position changes 1
• Ask specifically: "Do you get dizzy when bending over, looking up, lying down, or rolling over in bed?" 1, 2
• BPPV does NOT cause: constant severe dizziness, hearing loss, fainting, or loss of consciousness 1

When to Obtain Neuroimaging

MRI of the brain is indicated when: 4, 5

• Any red flag features suggesting central pathology are present 4, 5
• Downbeat nystagmus is identified on examination 4
• Patient fails to respond to appropriate BPPV treatment maneuvers 1
• Atypical nystagmus patterns that don't fit peripheral vestibular disorders 4, 5

Note: CT scans are inadequate for evaluating posterior fossa structures and should not be used as the primary imaging modality for suspected central causes. 4, 5

Common Pitfalls

BPPV is frequently underdiagnosed or misdiagnosed despite being the most common cause of peripheral vertigo. 1

Failure to perform both Dix-Hallpike AND supine roll testing will miss lateral canal BPPV in up to 30% of cases. 1

Central positional nystagmus can be mistaken for BPPV if proper attention is not paid to nystagmus characteristics—always check for downbeat nystagmus and baseline nystagmus in primary position. 4, 5

Posttraumatic BPPV is more likely to be bilateral and require repeated treatments (67% vs 14% in non-traumatic cases), so always ask about recent head trauma. 1