ALAN M RICHARDS, PH.D.-- VNG BASICS

Primary Physician’s Guide to ENG/VNG Testing : 

3/12/2009 1 Primary Physician’s Guide to ENG/VNG Testing

Overview of ENG/VNG : 

3/12/2009 2 Overview of ENG/VNG Records nystagmus, involuntary eye movements. Used to diagnose causes of vertigo, dizziness, and other balance-related disorders. Evaluates the vestibular system. ENG uses electrodes, VNG uses infrared video. Provides objective assessment of the oculomotor & vestibular systems

Physician Check List for VNG Referral : 

3/12/2009 3 Physician Check List for VNG Referral Medication Relating to Dizziness be Stopped. Eating Stopped 4-6 Hours Prior to Testing. Ears Checked for Debris & Cerumen Perforation(s), If Any, of the TM be Noted. Patient’s Fears Allayed About Test Physical Limitations of Head, Neck, Back be Noted.

Basic ENG/VNG Test Battery : 

3/12/2009 4 Basic ENG/VNG Test Battery Oculomotor Evaluation Positional/Postural Testing Caloric Stimulation

ENG/VNG Subtests : 

3/12/2009 5 ENG/VNG Subtests Oculomotor Evaluation Saccadic Pursuit (Accuracy, Latency, Velocity) Gaze Nystagmus Tests (Center, Right, Left, Up, Down) Smooth Visual Pursuit (Symmetry, Pattern, Gain, Phase) Optokinetic Testing (Symmetry)

ENG/VNG Subtests(Continued…) : 

3/12/2009 6 ENG/VNG Subtests(Continued…) Positional Tests Sitting Supine Head Tilt (Supine Head Elevated 30 Degrees) Right Lateral (Supine Head Turned Right) Left Lateral (Supine Head Turned Left)

Two Basic Positions for VNG 30 degree Head Tilt and Sitting : 

3/12/2009 7 Two Basic Positions for VNG 30 degree Head Tilt and Sitting 30 Degree Position Sitting Position

Three Additional Positions : 

3/12/2009 8 Three Additional Positions

ENG/VNG Subtests(Continued…) : 

3/12/2009 9 ENG/VNG Subtests(Continued…) Caloric Stimulation Alternating Binaural Bithermal Test Right Ear Cool (RC) Left Ear Cool (LC) Right Ear Warn (RW) Left Warm (LW)

ENG/VNG Subtests(Continued…) : 

3/12/2009 10 ENG/VNG Subtests(Continued…) Caloric Results Outcomes Unilateral Weakness (UW) Score Symmetry between the ears in the amounts of calorically induced nystagmus (=> 20-25% is significant). Weaker ear is the side affected in most cases. Directional Preponderance (DP) Score Symmetry between right and left-beating nystagmus caused by the calorics (=>30% is taken as a significant). Non-specific site of origin.

Normal & Symmetrical Responses to Calorics : 

3/12/2009 11 Normal & Symmetrical Responses to Calorics Note Fixation Suppression RIGHT WARM RIGHT COLD LEFT WARM LEFT COLD

Asymmetrical Vestibular Responses to Calorics (Significant Unilateral Weakness) : 

3/12/2009 12 Asymmetrical Vestibular Responses to Calorics (Significant Unilateral Weakness) Right-Sided Calorics Left-Sided Calorics 12 WARM COLD WARM COLD

Computer Generated Pod Showing a Significant Unilateral Weakness (Nystagmic Response Over Time) : 

3/12/2009 13 Computer Generated Pod Showing a Significant Unilateral Weakness (Nystagmic Response Over Time)

Asymmetrical Responses with Spontaneous Nystagmus Present When Right ear was Tested : 

3/12/2009 14 Asymmetrical Responses with Spontaneous Nystagmus Present When Right ear was Tested

ENG/VNG Subtests(Caloric Findings Continued…) : 

3/12/2009 15 ENG/VNG Subtests(Caloric Findings Continued…) Bilateral Weakness (BW) Reduced caloric response both ears.May be peripheral or central in origin. Hyperactive Responses Greater than normal induced nystagmus and vertigo. May indicate CNS disorder Fixation Suppression Nystagmus should be suppressed after calorics by fixating on a target. If not CNS disorder is suggested.

Bilateral Vestibular Weakness : 

3/12/2009 16 Bilateral Vestibular Weakness RIGHT WARM RIGHT COLD LEFT WARM LEFT COLD

Bilateral Vestibular Weakness (Pod Representation) : 

3/12/2009 17 Bilateral Vestibular Weakness (Pod Representation)

Failure of Fixation Suppression : 

3/12/2009 18 Failure of Fixation Suppression Normal Fixation Abnormal Fixation Suppression

ENG/VNG Subtests(Continued…) : 

3/12/2009 19 ENG/VNG Subtests(Continued…) Dix-Hallpike Maneuver Classic Signs of BPPV. Assesses the presence or absence of Benign Paroxysmal Positional Vertigo (BPPV). Transient Onset of Vertigo Fatigability Report of Vertigo Latent Period Before Response

The Dix-Hallpike Maneuver : 

3/12/2009 20 The Dix-Hallpike Maneuver Hallpike Maneuver to the Left

The Mechanism of BPPV : 

3/12/2009 21 The Mechanism of BPPV Note Migration of Otoconia (Ear Rocks) to the Posterior Semicircular Canal

Primary Physician’s Guide to ENG/VNG Testing : 

3/12/2009 22 Primary Physician’s Guide to ENG/VNG Testing FINAL COMMENTS