6Test for gaze evoked nystagmus Examiner’s finger kept 30 cm from pt's eyes in centre. Moved in horizontal & vertical planes. Pt is asked to follow it with his eyes. Keep displacement from midline to maximum of 30° (to avoid physiological end-point nystagmus).
7Fistula testTransmission of increased air pressure in E.A.C., via middle ear, into inner ear through a labyrinthine fistula causes vertigo + nystagmus towards affected ear. E.A.C. pressure is by intermittent tragal pressure or Siegelization.
13MechanismConvection current formation in endo-lymph due to temperature gradient → ampullo-petal flow or ampullo-fugal flow due to warm or cold water activation of Vestibulo-Ocular Reflex → vertigo + horizontal nystagmus
16ProcedurePt supine + 30° head elevation. Each ear irrigated in turn for 40 sec with warm water at 44°C & then cold water at 30°C.Duration of nystagmus is from start of irrigation to end point of nystagmus. Normal = 90–140 secDirection of fast component:Cold → Opposite ear; Warm → Same ear
18Canal Paresis Duration of nystagmus with both 44°C & 30°C irrigations in one ear is 30 % lessthan opposite ear. Seen in same sidedperipheral vestibular lesion.C. P. (%) = (R30 + R44) – (L30 + L44) X 100R30 + R44 + L30 + L44
20Directional Preponderance Duration of nystagmus in one direction is 30 % more than opposite direction. Seen in same sided central vestibular lesion & opposite peripheral vestibular lesion.D.P. (%) = (L30 + R44) – (R30 + L44) X 100R30 + R44 + L30 + L44
23Modified Kobrak's TestE.A.C. irrigated for 60 sec with ice cold water in increasing quantity (5, 10, 20 & 40 ml) till nystagmus is noticed.Nystagmus noticed with:5 ml = Normal vestibular labyrinth.10 / 20 / 40 ml = Hypoactive labyrinth.No nystagmus (40 ml) = Dead labyrinth
24Dundas Grant Cold Air Caloric Test Done in T.M. perforation as water syringing is contraindicatedAir in coiled copper tube is cooled by pouring ethyl chloride in itEffluent cool air is blown into E.A.C. to produce vertigo + nystagmus
32Dix-Hallpike Manoeuvre 1. Pt in sitting position on a couch.2. Pt’s head turned 45° towards diseased ear.3. Pt moved rapidly into supine position withhead hanging 30° below couch. Pt’s eyesobserved for nystagmus for 1 minute.4. Pt moved rapidly back into sitting position.5. Manoeuvre repeated for opposite ear.
33Nystagmus in B.P.P.V. Latent period (2–20 sec) before nystagmus Rotatory Fixed direction, towards ground (geotropic) Duration < 1 minute due to adaptation Direction reversal on return to sit position Fatiguing on repeating Hallpike maneuver Associated vertigo & autonomic symptoms
44Epley’s Manoeuvre 1. Pt in sitting position on a couch 2. Pt’s head turned 45° towards diseased ear3. Pt moved rapidly into supine position withhead hanging 30° below couch4. Pt’s head rotated by 90° to opposite side5. Further 90° head + trunk rotation6. Pt moved rapidly back into sitting position
45Epley’s Manoeuvre 7. Pt’s head brought in midline 8. Slight flexion of pt’s head Cervical collar given to pt for 48 hours Pt to sleep in 30o head end elevation &avoid violent head jerks Pt must have nystagmus at every step of Epley’s manoeuvre if it is done properly