The complexity of ANSD starts at the time of assessment

Transcription

1 The complexity of ANSD starts at the time of assessment ANHS Conference May 2017 Florencia Montes, Monica Wilkinson, Carolyn Cottier

2 Outline ANSD review of definition OAEs vs CM Our data: hearing results, Risk factors, MRI results Understanding MRI terminology Case studies Summary waveforms abnormalities Take home message 2

3 ANSD Review of definition ANSD is characterised by absent or severely abnormal ABR with normal cochlear outer hair cell function (OAE and/or CM).

4 Review of definition "severely abnormal waveform morphology" UNHS UK Protocol Guidelines for the Assessment and Management of Auditory Neuropathy Spectrum Disorder in Young Infants, 2012: There is some lack of consensus about the definition of severely abnormal ABR morphology. They suggest Sininger s definition: The neural response (ABR) will be poor or completely absent but will occasionally show a small wave V response (at high stimulus intensities). The majority of cases of ANSD have a poor ABR proceeded by a large inverting CM that can last up to 5 or 6 ms.

5 Review of definition: "severely abnormal waveform morphology" Ontario Infant Hearing Program Protocol: Auditory Neuropathy Spectrum Disorder (ANSD) Sub-Protocol, 2016 ABR is absent or at least significantly depressed and/or delayed. No clear ABR complex with a wave V latency between 5 and 10 ms Between normal and absent ABR lies a spectrum of ABR abnormality within which differential diagnosis of an ANSD component can be very difficult ANSD is a label for a pattern of test results, it is not a diagnosis

6 Review of definition: OAEs vs CM OAE responses and CM responses are not the same OAE: OHC responses CM: OHC+IHC. Click CM may be generated by IHCs even if the OHCs are extensively damaged CM may be present in normal ears, SN losses with reasonable low-mid frequencies, or ANSD

7 Our data: hearing results HEARING LOSS Total babies assessed (as 3 rd of May): 3021 Normal 1452 (48.06%) CHL 620 (20.52%) SNHL 681 (22.54%) ANSD 118 (3.9 %) 14.7% of SN Mixed 97 (3.21%) Other no results (DNA, incomplete, passed away) 53 (1.7 %) 7

8 Our data ANSD/retrocochlear (N=118):DP-OAEs Unilateral ANSD: 60 cases Bilateral ANSD: 58 cases DP-OAES In the Bilateral ANSD group, 64% present/partial, 29% absent, 7% not tested (flat tymps) In the unilateral ANSD group: 35% present/ partial, 57% absent, 8% DNT 8

9 Our ANSD/retrocochlear data (N=118): Risk factors RISK FACTORS No risk factors 64 (54 %) Risk Factors 54 (46 %). Of the risk factors, prematurity and VLBW (birth weight < 1500gm ) accounts for 60 % Other risk factors hydrocephalus, family history, jaundice 9

10 ANSD Risk factors: from the Literature Perinatal risk factors Extremely premature birth (<28 weeks gestation) Anoxia History of mechanical ventilation/ hypoxia or both Hyperbilirubinaemia Low birth weight (<2.5kg) Congenital brain abnormalities Genetics or family history of ANSD Associated with viral diseases, seizure disorders and high fever Accompanying neurological disorders including Friedrich ataxia, Charcot-Marie- Tooth syndrome (peripheral neuropathies) 10

11 Imaging procedure at SCH Before 3 months of age: feed and wrap, no sedation or anaesthetic required After 3 months of age: general anaesthetic required for MRI Mostly offering MRI rather than CT scan Radiation risks 11

12 ANSD: MRI findings (52 of the 118 patients had an MRI scan) Bilateral ANSD absent/hypoplastic nerves: 24% Normal nerves:76% Unilateral ANSD absent/hypoplastic nerves : 85% Normal nerves: 15% 12

13 ANSD: MRI findings (from the Literature) Systematic Review (Kachniarz et al, 2015) 4 studies (n=268 patients) evaluated findings on MRI in ANSD patients Diagnostic yield for ANSD ranged from % Cochlear nerve aplasia/hypoplasia ranged from 9-57% Diagnostic yield for brain specific findings of 33% Unilateral hearing loss :MRI or CT? (Tilea et al, 2010) 3078 children (seen between ), 234 had unilateral hearing loss 61 % had CT alone, 17% MRI alone and 22% CT and MRI CT showed 26 cases (11%) had IAM stenosis, MRI confirmed aplasia/hypoplasia of cochlear nerve in 10/26 and demonstrated 11 (4.7%) more Cochlear nerve aplasia/hypoplasia is nearly as common as labyrinthine malformations and only assessed by MRI 13

14 14 Case studies 14

15 Case 1 AC 2 K (Mark) Bilateral refer Type A tymps No risk factors Present DPOAEs 15

16 Case 1 0.5kHz waveforms (Mark) 16

17 Case 1 Clicks (Mark) 17

18 Case 1 (Mark) Textbook ANSD Absent ABR bilaterally with clear Click CM Present emissions 18

19 Case 2 ABR waveforms (Larry) Direct refer. Type A tymps Hydrocephalus with Rickham reservoir Present DPOAEs 19

20 Case 2 ABR waveforms (Larry) 20

21 Case 2 Click ABR waveforms (Larry) 21

22 Case 2 3rd ABR Tb waveforms (Larry) with Shunt 22

23 Case 2 3rd ABR (with shunt) Click waveforms (Larry) 23

24 Case 2 (Larry) Larry had 3 ABRs, after first ABR shunt inserted (at the time of first ABR Rickhan reservoir). RE remains ANSD type, LE has improved in waveforms morphology to normal. RE ANSD LE abnormal improved to normal 24

25 Case 3 waveforms Test 1 (Roger) Inconsistent refer. Type A tymps, No risk factors Present DPOAEs bilaterally 25

26 Case 3 Tb waveforms Test 3 (Roger) 26

27 Case 3 Click waveforms Test 3 (Roger) 27

28 Case 3 (Roger) Initial ABR abnormal waveforms with present emissions BUT present Acoustic reflex ABR gradually improved in morphology and thresholds to normal We are monitoring with VROA soon 28

29 Case 4 2 K waveforms (Mina) Bilateral refer. Type A tymps, No risk factors absent DPOAEs 29

30 Case 4 0.5kHz waveforms (Mina) 30

31 Case 4 Click waveforms (Mina) 31

32 Case 4 (Mina) Abnormal waveforms Click -CM with possible wave V MRI: Bilateral LVAS SN 32

33 Case 5 waveforms (David) Bilateral refer Normal tymps, absent DPOAEs No risk factors 33

34 Case 5 Click waveforms (David) 34

35 Case 5 Click waveforms (David) 35

36 Case 5 (David) Abnormal waveforms. Click +CM with possible wave V RE (8ms), +CM LE with no wave V?ANSD,?SN MRI: Bilateral LVAS 36

37 Case 6 Tb AC waveforms (Sarah) LE refer LE normal tymps No risk factors absent OAEs 37

38 Case 6 Click waveforms (Sarah) 38

39 Case 6 ASSR (Sarah) 39

40 Case 6 (Sarah) Abnormal Tb- ABR with very small Click CM.? Profound SN or ANSD LE ANSD pattern, based on ASSR thresholds at least in the severe range (stopped) No MRI 40

41 Case 7 2, kHz (Mary) Bilateral refer Normal tymps 31/40 weeks gestation. IVH (Brain bleed) Present DPOAEs bilaterally 41

42 Case 7 Click waveforms (Mary) 42

43 Case 7 ASSR(Mary) 43

44 Case 7 (Mary) Bilateral ANSD pattern? peaks with Tb- ABR RE only at a 100 db nhl for 2 K, at expected latency (8ms) BUT morphology is unusual. Presence of OAEs and Click showing +CM with no wave V makes diagnosis of ANSD most likely ASSR at moderate levels or better MRI showed good auditory nerve and cochlear structures bilaterally. Presence of blood around the nerve,? No long term impact, unlikely the cause of the hearing loss 44

45 Case 8 Tb waveforms 1 st ABR (Harry) Inconsistent screening result Type A tymps, No risk factors Present DPOAEs bilaterally 45

46 Case 8 Click waveforms 1 st ABR (Harry) 46

47 Case 8 Tb waveforms 2nd ABR (Harry) 47

48 Case 8 Click waveforms 2nd ABR (Harry) 48

49 Case 8 Tb waveforms 3 rd ABR GA (Harry) 49

50 Case 8 Click waveforms 3 rd ABR GA (Harry) 50

51 Case 8 (Harry) 1 st Assessment: Click ABR showed no CM and possible wave III and V in the RE and possible wave V LE. But abnormal Tb- ABR, with present DPOAEs 2 nd Assessment: LE +CM with abnormal ABR, RE +CM with possible wave III and V Repeat BERA under GA showed clear CM and absent ABR Bilateral ANSD 51

52 Case 9 2&4K AC (Sam) RE refer LE all normal RE normal tymps Jaundice, family history unilateral loss absent RE DPOAEs 52

53 Case 9 1 K AC waveforms(sam) 53

54 Case 9 Click waveforms (Sam) 54

55 Case 9 (Sam) RE ANSD pattern Tb peaks at high intensity unlikely to be wave V due to no change in latency with decreasing intensity.?too short latency (6ms for 2 and 4 K) Click +CM with no clear wave V MRI: Cochlear nerve absent 55

56 Case 10 AC 2 K (Trent) LE refer Absent DPOAEs No risk factors RE normal 56

57 Case 10 1K AC (Trent) 57

58 Case 10 Click (Trent) 58

59 Case 10 ASSR(Trent) 59

60 Case 10 (Trent) Click wave V larger than CM and of normal latency and morphology Tb -ABR abnormal waveforms LE ASSR thresholds in the mild to moderate range MRI: Absent/hypoplastic LE cochlear nerve 60

61 Case 11 2kHz & 0.5kHz (Jerry) RE refer RE normal tymps No risk factors Absent OAEs 61

62 Case 11 Click (Jerry) 62

63 Case 11(Jerry) RE ANSD pattern Repeatable peaks with Tb at 100 db may cause confusion (?wave V) But? wave V would be too short for neonate. Click showed +CM with no wave V MRI: Right cochlear nerve absent 63

64 Case 12 2, 0.5 & 4kHz (Eli) Bilateral refer. RE Type A, LE type B, No risk factors absent DPOAEs both ears 64

65 Case 12 1KHz (Eli) 65

66 Case 12 Click (Eli) 66

67 Case 12 ASSR (Eli) 67

68 Case 12 (Eli) RE severe SNHL LE ANSD pattern. LE Questionable CM but Type B tymp. First assessment Type A tymps with clear CM ASSR RE similar thresholds to ABR. LE in the profound to severe range?abr latencies too short for a neonate,?mainly 0.5K and 1 K (<9ms) MRI showed absent LE cochlear nerve, RE nerve difficult to visualise 68

69 Case 13 4, 2, 0.5kHz (Isla) LE refer. RE all normal No risk factors LE Type B 69

70 Case 13 (Isla) LE moderate mixed hearing loss. Type B Click not done as ANSD not suspected Tb latencies too short again?? LE cochlear nerve not seen 70

71 Case , 4kHz (Anna) RE refer No risk factors 71

72 Case 14 2kHz (Anna) 72

73 Case 14 Click waveforms (Anna) 73

74 Case 14 (Anna) Moderate RE unilateral hearing loss. Click was not done as ANSD was not suspected (thresholds in the moderate range RE, normal LE)) Not doing well with speech and language development. Had MRI showing bilateral absent/hypoplastic nerves. GA BERA at age 4 to rule out ANSD/retrocochlear Click CM with clear waves III and V No ANSD pattern but latencies RE much shorter than LE 74

75 Cochlear nerve deficiency with ABR responses We had 6 cases of CND and ABR responses in the mild to severe range Most cases of CND have reported ABR as absent One study reported 7 cases (out of 28) with unilateral CND and Click ABR ranging from moderate to severe. Polarity of the click stimulus not specified. CND deficiency defined by CT cochlear canal aperture measure It is important to do imaging in patient s with hearing loss regardless of auditory threshold Cochlear Nerve Deficiency and Associated Clinical Features in Patients with Bilateral and Unilateral Hearing Loss, Atsuko et al, Otology and Neurotology 75

76 Summary of waveform results in ANSD cases Absent ABR Abnormal but not absent: Poor suprathreshold growth in amplitude over a large intensity range Poor reproducibility Small and or late wave V above 75 db Unusual or inconsistent response morphology Abnormal latency

77 Take home message ANSD is not always a straight forward diagnosis. Peaks occur but be sure to assess morphology, replicability, amplitude growth and latency. If only doing ASSR for threshold estimation, check for CM regardless of degree of the hearing loss The value of ASSR with ANSD is still to be determined.? Useful in differential diagnosis Use Click when waveforms are abnormal, regardless of thresholds Use Click when thresholds are above 70 db nhl Repeat assessment at some stage to rule out maturation/improvement (Eg hydrocephalus and hypoxia) One should stress to families that ANSD is a pattern of results and not a diagnosis If unilateral ANSD the possibility of cochlear nerve deficiency is high Regular waveform reviews Improves quality of testing, learning opportunity,. May also help to have an external person to review complex cases.

78 Thanks! 78

79 ANSD Sub-Protocol Test AC 2 and 0.5 K If the response is absent or abnormal, high intensity Click (90 db nhl) with separate polarities, rate 39.1 p/s, to check for CM Procedure: 2 Condensation averages. Add C 2 Rarefaction averages. Add R 1 condensation tube off/clamped 1 rarefaction tube off/clamped Butterfly plot

80 ANSD Sub-Protocol continuation Click High intensity with a rate of 88.1 p/s to examine CM region in more detail, wave V may be degraded Procedure: 2 Condensation averages. Add C 2 Rarefaction averages. Add R 1 condensation tube off/clamped 1 rarefaction tube off/clamped Butterfly plot

81 Waveform manipulation C+R summed: attenuates CM activity and enhances neural activity C-R subtraction: enhances CM and attenuates neural activity 81

82 ANSD Outcome categories (Ontario Program) DEFINITE ANSD component: present DPOAEs (2,3,4K) and Click ABR V-V <0.1uV PROBABLE ANSD component: present DPOAEs and Click ABR V-V 0.1uV-0.2uV If DPOAEs absent or unreliable, apply table below: CM, pk-pk, uv Click ABR V-V pk-pk, uv < >0.2 <0.1 NS NS NS probable See ratio NS Ratio: calculate the amplitude ratio CM/ABR using peak-to-peak values. If >1.5 probable ANSD, >0.2 definite probable See ratio otherwise not suspected

83 CT and MRI scans: the Risks CT scan risks Radiation risks include brain malignancy may arise in 1 in 4000 brain CTs (BMJ 2013), one excess case of leukaemia per head CTs (Lancet 2012), risk of thyroid cancer after temporal bone CT is 8 per 1,000,000 (European Radiology 2007) MRI scan risks Related to need for sedation 1 in 400 sedations experience stridor, laryngospasm or apnoea and 1 in 200 require airway ventilation; approx 1% of sedated parent develop serious complications requiring resuscitation Following CI, MRI not useful due to implant associated image distortion (additional procedure required to address internal magnet) 83