How do you check for nystagmus?

How to Check for Nystagmus

Nystagmus is assessed through direct observation of the eyes during specific positional maneuvers, most importantly the Dix-Hallpike test for posterior canal involvement and the supine head roll test for lateral canal involvement, with the clinician observing for characteristic rhythmic eye movements that have specific latency, duration, and directional patterns. 1

Primary Examination Techniques

Dix-Hallpike Maneuver (Posterior Canal Assessment)

The Dix-Hallpike test is the gold standard for detecting posterior semicircular canal BPPV and associated nystagmus 1:

• Patient positioning: Bring the patient rapidly from upright sitting to supine position with the head turned 45 degrees to one side and neck extended 20 degrees backward 1
• Observe for nystagmus: Watch the eyes carefully for characteristic eye movements 1
• Key diagnostic features to identify 1:
  • Latency period: 5-20 seconds (occasionally up to 60 seconds) between completing the maneuver and onset of nystagmus
  • Duration: Nystagmus increases then resolves within 60 seconds from onset
  • Associated vertigo: Patient reports rotational spinning sensation concurrent with nystagmus
• Repeat on opposite side: Return patient to sitting, then perform maneuver with head turned 45 degrees to the other side 1

Supine Head Roll Test (Lateral Canal Assessment)

The supine roll test diagnoses lateral semicircular canal BPPV 1:

• Initial position: Place patient supine with head in neutral position 1
• First rotation: Quickly rotate the head 90° to one side while observing for nystagmus 1
• Return to neutral: After nystagmus subsides, return head to straight face-up position 1
• Second rotation: Quickly turn head 90° to the opposite side and observe again 1
• Interpret nystagmus pattern 1:
  • Geotropic type (most common): Horizontal nystagmus beating toward the undermost ear on both sides, more intense on the affected side
  • Apogeotropic type: Horizontal nystagmus beating toward the uppermost ear on both sides

Additional Assessment Components

Binocular Alignment and Motility Testing

When checking for nystagmus in strabismus contexts 1:

• Assess eye position: Check for latent or manifest nystagmus in primary gaze 1
• Test versions and ductions: Evaluate binocular and monocular eye movements, noting any limitations or incomitance 1
• Gaze position testing: Observe for gaze-evoked nystagmus in different directions of gaze 1

Specialized Nystagmus Characteristics

Look for specific patterns that indicate central versus peripheral causes 1, 2:

• Spontaneous nystagmus: Present in primary position (upbeat, downbeat, torsional) suggests central pathology 2, 3
• Gaze-evoked nystagmus: Nystagmus in all directions indicates cerebellar dysfunction; purely vertical suggests midbrain lesion; purely horizontal suggests pontomedullary lesion 3
• Abduction nystagmus: May accompany sixth nerve palsy 1
• Convergence-retraction nystagmus: Associated with dorsal midbrain syndrome, requires neuroimaging 4

Important Clinical Pitfalls

When Video-Oculography May Be Helpful

Video-assisted examination can be beneficial when 1:

• Nystagmus findings are equivocal or unclear (occurs in approximately 13% of BPPV cases) 1
• The eye can be enlarged on screen for detailed analysis 1
• Recording allows replay for second opinion or further study 1

However, comprehensive vestibular testing is not routinely indicated if diagnostic criteria are already met through clinical examination 1.

Contraindications and Modifications

Avoid or modify positional testing in patients with 1:

• Cervical stenosis, severe kyphoscoliosis, or limited cervical range of motion
• Down syndrome, severe rheumatoid arthritis, or cervical radiculopathies
• Paget's disease, ankylosing spondylitis, low back dysfunction, or spinal cord injuries
• Morbid obesity

Red Flags Requiring Neuroimaging

Obtain MRI of the brain when 1, 4:

• Convergence-retraction nystagmus is present 4
• Additional cranial neuropathies or neurologic signs accompany nystagmus 1
• Papilledema or signs of elevated intracranial pressure are present 1
• Patient is young without vasculopathic risk factors 1
• Nystagmus is asymmetrical or unilateral 5

Documentation Requirements

Record the following for each examination 1:

• Specific maneuver performed (Dix-Hallpike vs. supine roll test)
• Presence or absence of refractive correction during testing
• Latency period before nystagmus onset
• Duration of nystagmus
• Direction and intensity of nystagmus
• Associated symptoms (vertigo, oscillopsia)
• Patient's level of cooperation with examination