ENG & VNG Positional & Caloric Tests

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

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

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

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

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

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

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

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

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.

Vertebral Artery Test

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.

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

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

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.

Calorically Induced Nystagmus Right Warm Right Cool Left Warm Left Cool

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

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 (10 - 80)

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

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

Calculations from the previous slide… Unilateral Weakness (40 + 46) – (13 + 12) / 111 = 55% on the Left Directional Preponderance (40 + 12) – (13 + 46) / 111 = 6% on the Left

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)

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

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

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.  

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