Untitled Quiz

Overview of Tests

• Saccades: Rapid eye movements between fixed points
• Smooth Pursuit: Following a moving target
• Optokinetic Nystagmus (OKN): Response to moving visual patterns

Saccade Testing

• Key Parameters:

  • Velocity: Peak movement speed between targets (+400 or 350 degrees/sec for larger amplitudes, >200 degrees/sec for smaller amplitudes)
  • Accuracy: Distance moved relative to target distance (>75% accuracy)
    • Hypometria: <75% accuracy (undershoot)
    • Hypermetria: >120% accuracy (overshoot)
  • Latency: Reaction time to target movement (<200ms for random saccades, <75ms for fixed/predictable saccades)

• Abnormal Findings:

  • Slow movements (bilateral)

Causes of Eye Movement Problems

• Fatigue, medications, drowsiness
• Associated with Pons lesions, superior colliculus issues, cerebral hemisphere problems
• Early myasthenia gravis
• Directional/unilateral slowing; Brainstem lesions, Cerebellar problems, Internuclear ophthalmoplegia (INO), Cranial nerve lesions (III, IV, VI)
• Accuracy problems; Hypometria (undershoot), Cerebellar flocculus or brainstem lesions, Visual problems (e.g., macular degeneration), Myasthenia gravis, Hypermetria (overshoot), Cerebellar lesions, AICA/PICA lesions

Smooth Pursuit Testing

• Less clinically valuable due to sensitivity to patient inattention

Optokinetic Nystagmus (OKN)

• Testing Requirements: Must cover 90% of visual field
• Patient should count stripes while staring straight ahead
• Normal gain should be >75% for each direction
• Symmetry within 25%

Clinical Applications

• Cross-checking abnormal pursuit results in adults
• Particularly useful in children 8-15 years
• Can indicate unilateral peripheral hypofunction
• Less useful than other ocular tests
• Abnormal OKN with abnormal pursuit and/or saccades: CENTRAL LESION

OKAN (Optokinetic After Nystagmus)

• Occurs in complete darkness after OKN stimulation
• Useful for detecting malingering
• Absent in bilateral vestibular weakness
• Asymmetrical in unilateral vestibular weakness

Clinical Cases

• Multiple Sclerosis cases showing: Bilateral INO, Unilateral INO, Square wave jerks, Cogwheel tracking, Unidirectional pursuit abnormalities
• Alcohol abuse cases demonstrating: Bidirectional symmetric pursuit abnormalities, Brainstem and cerebellar involvement
• Traumatic Brain Injury showing: Bidirectional symmetric pursuit abnormalities, Brainstem and cerebellar involvement

Positional and Positioning Testing

• Key Distinctions:
  • Positional nystagmus occurs in static positions due to head position relative to gravity
  • Positioning nystagmus is provoked by movement between positions and is typically transient (dynamic)
• Types of Nystagmus:
  • Positional Nystagmus: Present in supine, head R and/or head L only
  • Spontaneous + positional Nystagmus: Present in sitting with vision denied and changes direction or intensity during positional tests.
• Dix-Hallpike Test (DYNAMIC POSITIONAL TEST)
  • Gold standard test for BPPV diagnosis.
  • Should be performed before static positional testing (AKA los posicionales)
  • Used to diagnose anterior and posterior BPPV
  • Variations include: Standard Dix-Hallpike, Modified Dix-Hallpike (examiner stands behind patient), Fully-supported Dix-Hallpike (using pillow support), Side-lying maneuver (for patients with cervical problems)

BPPV Characteristics

• Latency of ~5 seconds for onset (canalithiasis)
• Nystagmus fatigues with repeated testing
• Dissipates in <1 minute (canalithiasis)
• Nystagmus reverses direction upon sitting (no siempre pasa- ej. anterior BPPV)
• Types of BPPV
  • Posterior Canal BPPV: Upbeat and torsional (geotropic) nystagmus (Most common type)
  • Anterior Canal BPPV: Downbeat and torsional nystagmus
  • Horizontal Canal BPPV: Purely horizontal nystagmus

BPPV Additional

• Nystagmus geotropic: will beat towards normal side
• Nystagmus apogeotropic: will beat toward affected side
• Nystagmus will reverse if head titled forward.
• Diagnosed using Roll Test
• Variants
  • Canialithiasis: Geotropic nystagmus (debris free-floating)
    • Latency 5-30 sec, Burst of Nys lasts about 10 sec, Reversal nys on sitting.
  • Cupulolithiasis: Apogeotropic nystagmus (debris is attached to cupula of one canal)
    • Controversial and unusual, Common in HC and least in PC, Persistent ageotropic weak nys (5 sec) that persists as long as the head is maintained in provoking head position, NO LATENCY; reverses with heads positioned such that canal is 180 degrees.

Abnormal Dix-Hallpike Findings

• Purely horizontal nystagmus
• Purely vertical nystagmus
• ROLL TEST- Horizontal BPPV, Transient nystagmus, dispel quickly over time
• If we have
  • HC- Canalithiasis: lasts about 1 min
  • HC- Cupulolithiasis: can last up to 5 mins
• HC BPPV will have a more severe response than PC or AC BPPV.
• Side-Lying Test for HC BPPV
  • Start from side-lying sitting, Pt will turn head towards one side (R/L), Move from sitting to side-lying position while keeping head turned; head will remain in flexion position lifted 30 degrees, Only to do one side as this will provoke both horizontal canals.
• Roll Test: Used to diagnose horizontal canal BPPV, Positive if provokes horizontal nystagmus, Geotropic.

Apogeotropic/Canalithiasis

• Side with more intense response has BPPV
• Canalithiasis: excitation of affected ear
• Side with less intense response has BPPV
• Cupulolithiasis: inhibitory response of affected ear

Vestibular Migraines

• Can mimic BPPV symptoms (pseudo BPPV)
• Nystagmus doesn't fatigue or extinguish over time
• Associated with headaches
• Migraineurs are 3x more likely to develop BPPV
• BEWARE, se pueden comportar como una cupulithiasis but does not respond to Tx.
• Se descarte después del holl test. Recurrent episodic positional vertigo (geo or ageo)

Gray Areas in BPPV

• Anterior Canal BPPV
  • Dix may be + both sides
  • Nys will beat towards affected ear in deep head hanging
  • Vertical component. Horizontal too small.

Posterior Canal BPPV

• Nyst horizontal component
• Apogeotropic Posterior Canal BPPV
• Nyst DB with ageotropic torsion
• Almost never reverses upon sitting
• No latency
• Lasts less than 2 mins and sometimes does not extinguish or fatigue
• Head hanging: Horizontal component beat towards affected side (Not always present)
• Almost never resolve on its own.
• Do not resolve with traditional repositioning maneuvers.
• Short-arm BPPV
  • Otoconia is in the short-arm of the posterior canal (entre utricule and cupula)
  • Provoke UBN with torsion towards the opposite side

Static Positional Testing

• Imbalance in the central vestibular pathways

Caloric Testing

• Evaluates one labyrinth at a time
• Heat causes endolymph to become less dense and rise (excitatory response)
• Creates nystagmus beating towards irrigated ear
• Cold irrigation makes endolymph denser and fall (inhibitory response)
• Creates nystagmus beating away from irrigated ear
• Limitations: Variable stimulation amounts between patients, Only tests one semicircular canal, Tests at 0.003 Hz (optimal at 0.1-3 Hz), Can be uncomfortable and poorly tolerated, Primarily affects slow head movements
• Irrigation Methods:
  • 1. Open-loop water: 44°C warm, 30°C cool, 30 seconds, 250mL volume (contraindicated for perforated tympanic membranes)
  • 2. Air irrigation, 3. Closed-loop water: No longer commercially available, Required silicone sheath replacement per patient.

Testing Procedures

• Otoscopic inspection and cerumen removal, Avoid using water for cerumen removal, Patient positioning (supine with 30° elevation)

Instructions for Patient

• Cover the googles for VNG or have patient close the eyes for ENG
• Spontaneous nystagmus in caloric position
• Complete caloric irrigation (3-60 sec)
• Task/alert patient to keep him (peak response should be around 30 sec after irrigation)
• Introduce fixation light 10 sec after peak response
• Remove fixation and continue recording for 5-10 sec
• Wait 3 minutes before next irrigation.

Testing Sequence

• Standard order: warm right, warm left, cool right, cool left, 30-60 second irrigation
• Peak response around 30 seconds (90 seconds for air)
• Fixation light introduction 10 seconds after peak
• 3-minute wait between irrigations
• VNG: no need to re-calibrate before calorics or between irrigations; ENG: monitor your CRP and determine if there is a need for calibration.
  • Key Measurements: SPV (Slow Phase Velocity)

Specific Data/Abnormal Findings

• Bilateral weakness, Total response <12 deg/sec in both ears (Common causes: ototoxicity, bilateral vestibular neuritis, meningitis), Symptoms: unsteadiness, oscillopsia, It can be due to peripheral or central lesions (unknown etiology)
• Total caloric response. Use peak SPV to calculate: Total RE: Cool-Warm, Total LE: Warm-Cool, Compensation is limited and are likely to experience impaired balance indefinitely, Pt with saccadic disorders might show unusual calorics that mimic BW (Saccadic).
• Unilateral weakness, asymmetry >25% (Causes: labyrinthitis, head trauma, Meniere's Disease, vestibular neuritis, Can also indicate some central pathologies), Important: Positive result indicates UW in left, Negative result indicates UW in right ear.
• Directional preponderance (DP), Abnormal if >30%

Clinical Significance

• Peripheral and Central, Asymmetry in the horizontal VOR pathways.
• Lesion in vestibular nuclei or CNS.
• Fixation Index F1: Abnormal if >60%, Indicates central lesions

Hyperactive Response

• Total (R/L or both) response >140 deg/sec

Special Considerations

• Ice calorics used when traditional responses are <6 deg/sec
• Place pt in caloric position with head tilted so the test ear is up, Place ice cold water in ear, wait 20 sec or use syringe to irrigate with ice cold water for 20-30 sec, If there is a measurable caloric response, turn pt to prone position
• Vertical nystagmus may indicate canal stimulation or lesions, Caloric inversion (wrong-direction beats) suggests central lesion, Line crossing patterns indicate different conditions
• Butterfly Chart: If lines cross inside the box: no UM or DP, If lines cross to the sides of the box, then UW, If lines cross above or below the box, then DP.

Vertical Nystagmus during caloric testing

• Vertical canal was stimulated; Normal, More common for warm irrigation, Peripheral lesions. Focal damage to horizontal SCC, Central Lesions, Caloric inversion: all 4 irrigations cause beats to the wrong side.

Other reasons for wrong direction nystagmus

• Strong spontaneous nystagmus + BW, Residual moisture in ear canal, TM perforation, Electrodes are inverted (in ENG), Irrigated wrong with relation to computer.