Tuesday 14 February 2017

MIDDLE EAR MEASUREMENTS IN CHILDREN

MIDDLE EAR MEASUREMENTS IN CHILDREN
  1. INTRODUCTION
      Vital in Audiological evaluation
      Tympanometric and Acoustic reflexs
      Provide information about
  1. Middle ear
  2. Cochlea
  3. Auditory nerve
  4. Auditory brainstem
  5. Focial nerve(cr nerve)

Cross check for other test eg behaviral,ABR
6< months use 1000 HZ (226HZ not accurate)
Otoscupy precedes tympanometric
Quantive description of tympamgram (description and shape)
Infant Acoustic stapedial refers tested using 1000HZ.
Acoustic reflects activator  stimuli for insects ear phones in 2cc cavity mg be reported in Dbhl.
Underestimated in infant ears

(ii) PROCEDURE
                        Biological chach of Tympammeter
                        Multiple frequencies probe tone generator
                        Rapid pressure sweet rate best for children (time span)
                       Seal should be hermetic
                      Straighten pinna gently
                     Most equipment have start pressure at +200dBa
                    Sweep pressure fm positive to negative
                    Negative to positive sweeps- increased completely

(iii) INTERPRETATION
 1.  Types A-normal
              B-Flat( Effusion perforation)
             C-Excessive Negative pressure
         As-Normal pressure peal
                 Abnormal shallow amphtude (Otosclerosis)

.Normal Limits
      Flat tympamgram,large canal volume (Vea>?cm3) =potent Eust tube or perforation
     Flat –Normal Ear canal Volume, or Low peal= One low peal
     Wide Typammetric width (  <0.2 mm nos) in 6-30 months.
    Peals y>0.3 mm hos, TW >235Db pa(Roushet al,1995) MEE

2. Acoustic Stapedial Reflects Tests
Follow tympammetry
Activator admittance  for 226 HZ probe tone 0.02 or 0.03 mm hos
In infants 226HZ-results in absent reflects in majority with 1000 Hz ready all report measurably remarks reflects.
ASR thresholds for children= adult values

(iv) NORMATIVE VALUES
  1. TYMP         STATIC ADMITTANCE    Tympametric width  Canal Volume
Children  3-1o yr old          Y                              TW/GR                         Vea
                                             0.52                         80-15g                      0.3-0.9
                                                                                *60-150                   0.4-1


                    Fail <0.2 dapa
                             <0.3,+                                >160                           >1.0
                               (0-2-0.9)

ADULTS 18yrs       0.30-1.70                      51-114                   0.9-2.0
                               0.3dapa                            >115                      >2.0
                               <0.4+
                               0.3-1.4m                            50-110               0.6 to 1.5

2.ACOUSTIC REFLEXES
                            80-85 Dbhl IN 500 TO 4000 HZ
                             BBN is 10dB lower than tonal stimuli(Wilson Margolis, 1990)