1. ENG & VNG Positional & Caloric Tests

2. Measuring Nystagmus
Speed (slope) of the slow phase in degrees per second (°/s)

3. Positions & Responses Sitting erect Supine Right lateral Left lateral
Head in primary position
With head turned R/L
Supine
Right lateral
Left lateral
Head hanging
Eyes closed/eyes open
NORMAL , symmetrical responses to head position = No resp. w/ eyes open
Eyes Closed and mentally busy:
direction-fixed positional nys
direction changing (w/ change in position)
some intermittent, some persistent

4. Pathologic responses:
direction changing in single position
persistent in 3 or more of the 5 positions
intermittent in 4 or more positions
Speed of slow phase is 6 deg/s or more at greatest

5. Right Lateral Position: Eyes Closed
Left Lateral Position: Eyes Closed
Erect Position: Eyes Closed

6. Direction-Changing Across Positions
Right Lateral Position: Eyes Closed
Left Lateral Position: Eyes Closed

7. Direction Changing Nystagmus within one position
Head Hanging Position: Eyes Closed

8. Abnormalities: Positional nys w/ eyes open: CNS lesions
Direction-fixed positional nys.: peripheral
differs from spont. in that it varies in intensity with position, or is absent in some positions.
appears in vestibular disease, e.g. Meniere's
does not show which side is abnormal.
Direction-changing nystagmus in a single position.
CNS
Positional alcohol nystagmus

9. Positional Alcohol Nystagmus
Right Lateral Position: Eyes Closed
Left Lateral Position: Eyes Closed
Top 2 tracings: 1 hour post ingestion
Lower 2 tracings: 6 hours post ingestion
Right Lateral Position: Eyes Closed
Left Lateral Position: Eyes Closed

10. Vertebral Artery Test Rationale Procedure 1. Avoid Basilar Stroke.
2. Differential diagnosis.
Procedure
1. Sitting or Supine.
2. Patient turns head.
3. Hyper-extension of
neck and posterior head
pitch.

11. Vertebral Artery Test

12. The Dix-Hallpike Maneuver:
Detection of BPN.
Positioning: from sitting to head hanging R or L.
Shows Benign Paroxysmal Positional Vertigo (BPPV)
then back to sitting.

13. BPPV: Rotary/torsional movement latency: ~~10 sec
fatigues within 30 to 45 sec
usually beating to lower ear.
accompanied by vertigo
R, L, or in both positions

14. BPPV: A very common finding. Etiologies:
Canalithiasis: presence of free-floating otoliths in the Post. SCC
Cupulithiasis: otoliths adhering to the cupula of the Post. SCC

16. Caloric Testing Via Water or Air Right Cold 30º C. 24 º C.
Left Cold 30º C. 24 º C.
Left Warm 44º C. 50 º C.
Right Warm 44º C. 50 º C.
Wait 5 mins in between, 10 between LC and LW
Recheck Calibration in between.
Eyes closed first 1-1\2 mins then open for 10 secs.

17. Calorically Induced Nystagmus
Right Warm
Right Cool
Left Warm
Left Cool

18. Cold-Opposite-Warm-Same
COWS:
Warm builds cupulopetal
flow
Thus, nystagmus beats
toward warm ear, away from cold ear.
Cold- beats to the opposite side.
Warm- beats to the same side.
Cold-Opposite-Warm-Same

19. Measures of Caloric Strength:
Duration: onset of irrigation to last beat (200 secs)
Frequency of most intense nystagmus(?Beats/sec)
Speed of slow phase at most intense part ( )

20. Caloric Response Analysis:
Unilateral Weakness: best index of periph lesion
(RC + RW) - (LC + LW) / (Sum of All 4)
> 0.25
Directional Preponderance: of little dx value
(RW + LC) - (RC + LW) / (Sum of All 4)
> 0.35

21. An Abnormal Set of ResultsRW
An Abnormal Set of Results RC
Can you tell
where the
problem is just
by eyeballing it? LW LC

22. Calculations from the previous slide…
Unilateral Weakness
( ) – ( ) / 111 = 55% on the Left
Directional Preponderance
( ) – ( ) / 111 = 6% on the Left

24. More Caloric Analysis:
Bilateral weakness: Avg response less than 6 deg/sec OR total of less than 20 deg/sec
Fixation Index: Eyes Open / Eyes Closed*
> 0.60 = Lack of fixation: CNS lesion.
*(speed with eyes closed just prior to eyes open)

25. Normal Fixation Suppression
Eyes
Open
Nystagmus is normally reduced with vision by at least 40%, commonly more.

26. Failure of Fixation Suppression
Eyes closed: 24°/s
Eyes open: 24°/s
Fixation Index = 1.0
Eyes Open

27. Premature Caloric Reversal: CNS lesion.
if before 140 s,
and speed > 6-7 deg/sec
must be distinguished from resumption of a pre-existing nystagmus.  

28. Caloric Inversion, Perversion:
Inversion: entire response beats wrong direction
TESTER ERROR
BRAINSTEM LESION
Perversion: vertical or oblique nystagmus.