DR. NEHZAT KOOHI

AUDIOLOGICAL SCIENTIST

SEPTEMBER 2016N E H Z A T . K O O H I . 1 1 @ U C L . A C . U K

An overview of central auditory processing disorders in adult

population

Auditory Processing Disorders

I can hear you but I

can’t

understand

you

Older adults have difficulty hearing in noise

Peripheral  hearing

memory

attention

central  hearing

Bottom-up and Top-Down Processing

E F F O R T F U L L I S T E N I N G

o B O T T O M - U P P R O C E S S I N G L E S S E F F I C I E N T

o T O P - D O W N P R O C E S S I N G M O R E N E C E S S A R Y

B O T T O M - U P ( E A R T O B R A I N )

o A N A L Y S I S O F A C O U S T I C S I G N A L

ª Better signal (faster)

ª Poorer signal (slower)

T O P - D O W N ( B R A I N T O E A R )

o P R I M I N G ( P R E - S I G N A L : E X P E C T A T I O N S F A C I L I T A T E S R E C O G N I T I O N )

o K N O W L E D G E C O N S T R A I N A L T E R N A T I V E

o R E P A I R A N D F I L L I N G I N G A P S

Knowledge

Sound

Meaning

Top-­Down

Bottom-­up

Older adults have difficulty hearing in noise

Peripheral  hearing

memory

attention

central  hearing

Overview

� Stages of ascending auditory pathway

§ Peripheral auditory system

§ Central auditory system

§ Auditory Cortex

� Vascular anatomy of auditory system

§ Vascular anatomy of peripheral auditory system

§ Vascular anatomy of central auditory system

� Disorders of auditory system

� Auditory processing disorders (ASHA and BSA)

� Symptoms of APD

� APD test battery

� Questionnaires as APD screening tools

� APD management

� Study of APD in stroke patients

Stages of ascending auditory pathwayPeripheral auditory system

The  peripheral  auditory  system,  including  the  

eardrum,  middle  ear  and  the  cochlea,  enables  the  

transformation of  sound  

waves  into  neural  signals  for  subsequent  cerebral  

processing.  

Stages of ascending auditory pathwayCentral auditory system

Stages of ascending auditory pathwayAuditory Cortex

Neurons originating in the medial geniculate body (MGB) and radiating outward to the auditory areas of the brain create the ascending auditory system that proceeds from the thalamic area to the cerebral cortex. The auditory cortex plays a key role in auditory perception although other areas of the human cerebral cortex (e.g., the frontal and parietal lobes) have also been implicated in processing sound information (Hackett et al, 2001).

Stages of ascending auditory pathway

Vascular anatomy of peripheral auditory system

The  internal  auditory  artery  (IAA),  which  usually  arises  from  the  anterior  

inferior  cerebellar  artery  (AICA),  supplies  the  inner  ear (figure  from  Kim  et  al.,  2009)

Inner  Ear  Dysfunction  Due  to  Vertebrobasilar Ischemic  Stroke,  

Kim  et  al.,  2009)

Disorders of Auditory SystemPeripheral hearing impairment

� Conductive hearing loss is a pathology affecting the external and middle ear which causes abnormalities of mechanical transmission of sound waves from the environment to the cochlea. Pathology of the cochlea and VIIIth nerve gives rise to ‘sensorineural’ hearing loss in which there is an inability to transduce the mechanical energy of sound waves into electrical activity within the cochlea or transmit the signals along the VIIIth nerve. Sensorineual hearing loss may be further divided into that of cochlear origin and that of neural origin.

Disorders of Auditory SystemAuditory Neuropathy

Auditory neuropathy (AN) refers to the impairment of listening ability caused by disordered conduction in the auditory nerve with relatively preserved outer hair cell function and cochlear amplification (Starr et al, 1996; Berlin et al, 2003). Diagnosis of AN is made on the basis of a. poor auditory nerve function b. normal outer hair cell function demonstrated by normal otoacoustic emissions and c. poor hearing demonstrated by either abnormal pure-tone audiometry or normal pure-tone audiometry, but poor speech perception, particularly in noise.

Disorders of Auditory SystemCentral auditory impairment

Several different types of pathology (e.g., vascular pathology, trauma, demyelination) might potentially damage the auditory neural substrate within the central auditory nervous system (CANS) and thus result in audiological deficits. Hearing loss has been reported due to lesions of the pons in the brainstem (Egan et al, 1996) and bilateral lesions affecting the inferior colliculus in the midbrain (Hoistad and Hain, 2003; Musiek et al, 2004).

Disorders of the Auditory Brain:

A Neurological Perspective

o Cortical deafness

o Cortical agnosia

o Sound agnosia

o Impaired emotional sound analysis

AND

AUDITORY PROCESSING DISORDERS

Griffiths, Bamiou, Warren 2009

Auditory Processing DisorderASHA definition (2005)

• Deficits in the perceptual processing of auditory information in the central nervous system and the neurobiological activity that underlies that processing and gives rise to electrophysiological auditory potentials.

• APD can be demonstrated by poor performance in one or more of the following skills:

1. Sound localisation and lateralisation

2. Auditory discrimination

3. Auditory pattern recognition

4. Temporal aspects audition

5. Auditory performance in competing acoustic signals

6. Auditory performance with degraded acoustic signals

Auditory Processing DisorderBSA position statement on APD (2011)

• APD is characterised by poor perception of both speech and non-speech sounds, which results from impaired neural function (both afferent and efferent pathways in the auditory system) that is closely associated with impaired top-down cognitive function. The BSA categorises APD into 3 subtypes:

1. Developmental APD: Cases presenting in childhood with normal peripheral hearing and in the absence of other known aetiology or potential risk factors.

2. Acquired APD: Cases associated with a known post-natal event (e.g. neurological trauma, infection) that could plausibly contribute to APD.

3. Secondary APD: Cases where APD occurs in the presence, or as a result of peripheral hearing impairment.

Risk factors for APDBamiou, Musiek & Luxon 2001

• The risk factors for APD can broadly be classified

into three categories:

1. Neurological conditions (stroke, trauma, MS etc.)

2. Delayed maturation of the central nervous system

3. Other developmental disorders

Behavioural symptoms of APD

• Some of the commonly reported or observed behavioural symptoms of individuals with APD are:

1. Difficulty understanding speech in the presence of competing background noise

2. Difficulty following directions3. Difficulty following rapid speech

4. Frequent requests for repetition

5. Difficulty maintaining attention 6. Difficulty localising the source of a signal

7. Poor musical ability or appreciation of music8. Difficulty or inability to detect the subtle changes in prosody that underlie

humour and sarcasm

Caveat: The presence of one or more of these behavioural symptoms does not warrant a diagnosis of APD; rather it indicates a potential auditory related disorder that needs a multidisciplinary team approach to assessment.

The APD test battery

� There is no ‘gold standard’ for the diagnosis of

APD!

� Neither is there a minimal set of AP tests that are

universally agreed upon!

� APD has multiple causes, which very likely

cannot be detected with a single test

� Speech or non-speech tasks!

Test battery should include a variety of test

stimuli, as well as test procedures. It is strongly recommended that test batteries include both verbal and non-verbal test stimuli as well as

both behavioural and electrophysiological measures to explore different auditory

processing skills and levels of auditory processing within the CANS,

Assessment Issues

� Fatigue

� Motivation

� Appropriate to age, background, cognition, peripheral hearing loss

� A high comorbidity of other cognitive and linguistic

disorders in CAPD, it is important to involve other professionals (i.e., multidisciplinary team)

AP tests used at UCLH clinical setting

• Non-speech test

1. Gaps in Noise (Temporal resolution)

2. Frequency pattern test (Temporal ordering or sequencing)

3. Duration pattern test (Temporal ordering or sequencing)

4. Masking Level Difference (Binaural interaction)

• Speech-based test

1. Dichotic digits test

2. Competing sentences test

3. Monaural low redundancy speech tests

4. Listening in Specialized Noise –Sentences

Spatial Processing Disorder

� SPD is a deficiency in the ability to use binaural cues to selectively attend to sounds arriving from one direction while suppressing sound arriving from other directions

� One type of APD

� Can diagnose it, unrelated to cognitive ability

� Have extensive normative data

� Can remediate it and remediation generalizes to real life

LiSN-S

� Adaptive speech in noise test

� Virtual auditory environment under headphones

� Target sentences from 0

� Distractor stories at 55db spl from either 0 or 90

� Stops when SE<1dB or max of 30 sentences

Four LiSN-S conditions

Abnormal Audiometry NOT an Exclusion Criterion

for Central Auditory Pathology

o Abnormal PTA may co-exist with, but be unrelated

to, a central auditory disorder:

o Eg, disorders of auditory perception following cortical stroke

tend to occur in an elderly

o In rare cases, the abnormal PTA may be directly

caused by the central auditory lesion

o Brainstem

o Midbrain

o Bilateral cortical lesions

Questionnaires

Questionnaires  can  confirm  difficulty  in  understanding,  but  not  identify  why  the  difficulty  exists

Questionnaires

� Amsterdam Inventory for Auditory Disability

� Speech, Spatial and Qualities of Hearing

� Montreal Cognitive Assessment (for cognition)

APD Management

ØEnvironmental modifications

ØSignal enhancement strategies

ØSpeaker based adaptations

ØFormal and informal auditory training

ØCompensatory strategies

ØHearing Therapist involvement

Bamiou et al., 2006

FM Systems

� Studies of children (Johnston et al., 2009; Kuk et al.,

2008; Hanschmann et al., 2010 ) with disordered AP, and adults with auditory neuropathy (Rance et al., 2010) and CAPD (Koohi et al., 2016), have

demonstrated that use of the FM systems significantly improve speech perception in noise

Auditory training

o Auditory training improves speech in noise test results in children and adult listeners, though generalisation to real life situation is largely unknown.

o Speech based broad auditory training improved speech in noise perception and functional listening/communication skills in children with APD.

o Correlation of improved functional listening to improved speech in noise perception suggests that improved listening was a direct generalisation effect of the auditory training

Loo, Rosen, Bamiou Ear Hear 2015

32

Points to Keep in Mind

o Tests: they all place cognitive demands on patient – be aware of load

o APD: to be thought of more as a disorder of “auditory cognition” rather than a “sensory” processing disorder.

o Similar as for other cognitive disorders: need for careful, detailed questioning of the patient to identify symptoms and hypothesize and test for deficits

Points to Keep in Mind

� “It is important that the individual who is

administering and interpreting a test battery do so in an ethical and efficient manner. The audiologist who is going to undertake central auditory assessments

must have the requisite knowledge, preparation, and skills necessary for the administration and

interpretation of the central auditory tests to be administrated.” Jane Baran, Central Auditory Processing Disorder 2015

APD and Aging

o Hearing in the elderly (Pichora-Fuller and Singh 2006) interaction of

o age-related changes in peripheral hearing (cochlear & neural)

o central auditory processing

o cognitive processing

o (C)APD in the elderly:

o in 10- 20% in normal (Cooper and Gates, 1991)

o >80% in audiological population (Stach et al., 1990)

o Deficits in temporal processing, speech recognition (Gordon-Salant and Fitzgibbons, 2001), interhemisphheric transfer (Bellis and Wilber, 2001)

o Rehabilitation plan ought to be informed by central auditory & cognitive assessment (Kricos, 2006; Pichora-Fuller and Singh 2006)

Hearing Characteristics of Stroke Patients: Prevalence and Characteristics of Hearing Impairment and Auditory Processing Disorders in Stroke

Patients

BackgroundStroke survivors may suffer from a range of hearing impairments that may restrict their participation in the post-acute rehabilitation programs. Hearing impairment may have a significant impact on listening, linguistic skills and overall communication of the affected stroke patient. However, no studies sought to systematically characterize auditory function of stroke patients in detail, in order to establish the different types of hearing impairments in this cohort of patients. Such information would be clinically useful in understanding and addressing the hearing needs of stroke survivors.

Hearing Characteristics of Stroke Patients

� Purpose: The present study aimed to characterize and classify the hearing impairments, using a detailed audiological assessment test battery, in order to determine the level of clinical need and inform appropriate rehabilitation for this patient population.

� Research Design: A case-control study.

� Study Sample: Forty-two recruited stroke subjects who were discharged from a stroke unit and 40 control subjects matched for age.

Methods

� The inclusion criteria:

üa. adults aged between 18 and 80 years old

üb. clinical history of a single stroke verified by magnetic resonance imaging (MRI) of the brain.

� Exclusion criteria:

üsevere aphasia, cognitive impairment (as shown on the Montreal Cognitive Assessment), significant

psychiatric illnesses, other neurological disorders (except stroke) and severe concurrent medical

illnesses.

Methods

÷ Background Assessmenta. Cognitive Assessment (Montreal cognitive assessment)

b. Brain Imaging Acquisition (MRI)

÷ Baseline Audiological Assessments

c. Pure-Tone Audiometry

d. [Stapedial] Acoustic Reflexes Thresholds

e. Transient Evoked Otoacoustic Emissions

f. Auditory-evoked Brainstem Responses

Methods

o Selection of Non-verbal Auditory Processing Assessments

a. Gaps in noise

b. Perceptual property processing

c. Apperceptive processing

d. Semantic processing

o Patient grouping

a. Age Groups

b. Audiological Assessment Outcomes

1) Normal 2) Peripheral hearing loss (cochlea to auditory nerve) 3) Central auditory processing disorder (brainstem to cortex and beyond) (ASHA 2015; BSA 2011) 4) combination (peripheral hearing loss and central auditory processing disorder).

Results

Hearing thresholds in 42 stroke patients and 40 controls

Although overall mean thresholds for the stroke group were

more elevated compared to normal control, there was no

statistically significant difference between the control and

stroke.

Results

Types of hearing impairment as a function of age group

Results

a. Type of hearing in control subjects

Age group CAPD Normal Peripheral Peripheral and CAPD Total

< 61 years old 1(4%) 21(81%) 4(15%) 0(0%) 26(65%)

≥ 61 years old 0(0%) 4(29%) 9(64%) 1(7%) 14(35%)

Total 1(2%) 25(62%) 13(32%) 1(2%) 40

a. Type of hearing in stroke patients

Age group CAPD Normal Peripheral Peripheral and CAPD Total

< 61 years old 8(40%) 5(25%) 3(15%) 4(20%) 20(48%

≥ 61 years old 1(4%) 1(4%) 8(36%) 12(56%) 22(52%)

Total 9(21%) 6(14%) 11(26%) 16(38%) 42

Types of hearing impairment in stroke and controls. Number of patients

with different types of hearing impairment.

Discussion

first study to examine types of hearing impairment, using detailed audiological assessments, in stroke patients. Although overall mean thresholds (PTA average and HF average) for the stroke group were more elevated compared to healthy controls, there was no statistically significant difference between the control and stroke groups in the overall group and when divided into two age subgroups (18–60 and 61–80-year-olds).

Discussion

Aging is accompanied by a decline in hearing

sensitivity due to sensory changes in the ear. Other changes in the central auditory nervous system may contribute to the difficulty for the older adults to

understand speech in background noise. Pathological conditions such as stroke can further compromise

auditory function.

Discussion

Although the proportion of people with peripheral

hearing loss did not significantly differ from the healthy control group, our results indicate that the most common type of hearing impairment in our

stroke patients was the combination of peripheral and central hearing impairment in the

61–80-year-olds subgroup (55%), and disordered auditory processing in the 18–60-year-olds (40%), which were both significantly higher than controls.

Conclusion

Conventional hearing aids may be a suitable

option for those with peripheral hearing loss, while counselling, directional microphone hearing aids with built-in FM, educating the patients and caregivers may

be an appropriate rehabilitation plan to meet the need of older stroke patients with a mixed peripheral

and central hearing loss.

FM benefits in Stroke PatientsKoohi et al., 2016

Background

� No studies to date have assessed the efficacy of

personal FM systems for stroke patients with disordered AP. We conducted a feasibility study in order to investigate whether stroke survivors with

difficulties hearing speech-in-noise due to disordered auditory processing, despite normal pure

tone thresholds, may benefit from binaural FM systems use and the level of benefit of these systems in laboratory tests.

Methods

¤Inclusion Criteriaa. adults, between 18- and 80-years-old, b. clinical history of a single stroke verified by Magnetic Response Imaging (MRI) of the brain c. patient reported hearing-in-noise difficulty with z score > 2 on the speech-in-noise subscale of the Amsterdam Inventory for Auditory Disability as per departmental normative data d. abnormal performance in the speech in babble AND in at least one non-speech auditory processing test e. Pure Tone Audiogram (PTA) average (from 500 to 8000 Hz at octave levels) better than 25dBHL.

¤Exclusion Criteriasevere aphasia [cut-off of 93.8 on the complete Western Aphasia Battery test ], psychiatric or other neurological disorders (except stroke) or severe concurrent medical illnesses.

Methods

¤Phase I: Identification of Participants

Forty-two patients with an acute ischemic or haemorrhagic cerebral stroke, who had been admitted to the Stroke Units at the University College London Hospitals were identified as fulfilling inclusion criteria (a) and (b) and all exclusion criteria.

Ten out of these fulfilled inclusion criteria c-f, and were invited to participate in the FM feasibility study. One declined due to other research involvement. nine patients attended the clinic on a second occasion to complete the feasibility study test protocol.

Methods

¤ Initial assessments

Brain MRI

Baseline Audiometry (PTA, Tyms, AR, OAEs, ABR)¤ Auditory Processing Assessment

Speech in Babble test (Spyridakou et al., 2012)

Gaps in Noise (Musiek et al., 2005)

Perceptual Property processing (Goll et al., 2010)

Apperceptive Processing (Goll et al., 2010)

Semantic Processing (Goll et al., 2010)¤ Questionnaires

The (modified) Amsterdam Inventory for Auditory Disability and Handicap (AIAD) The Hearing Handicap Inventory for Elderly (HHIE)

Phase I: Feasibility FM study

All nine stroke patients were fitted with personal FM

systems binaurally and were tested with and without the FM systems on a speech (sentence) perception test in the Crescent of Sound.

Speech in Noise Test with and without FM systems in the Crescent of Sound

Each participant completed twelve test runs of the Sentences in Noise test: 1) Aided condition: Two runs with the noise in each of three positions (straight ahead, 0°; left −90°; right +90°) with bilateral personal FM systems in the ears and 2) Unaided condition: Two runs without FM systems. The order of the runs was counterbalanced across participants and all runs were administered in a single session. No sentence was repeated in order to prevent potential learning effects.

Speech  and  babble  presented  from  0°

Condition

1

ZoomLink

Speech  presented  from  0°

Condition

2

Babble  presented  from  -­90°

ZoomLink

Speech  presented  from  0°

Condition

3

Babble  presented  from  +  90°

ZoomLink

Results Summary of Audiological assessments

Participant #Age (Y) Sex Lesion Disease Duration (Days)

1 64 MaleParamedial right thalamus and left

cerebellar hemisphere infarct 100

2 24 MaleLeft frontal, temporal lobes and insula

infarct 169

3 44 MaleRight putamen / corona radiata

infarct96

4 52 Male

Left medulla oblongata, right

cerebellum, left occipital lobe and

hippocampal tail infarct

207

5 53 Female Right superior parietal lobule infarct 125

6 32 Male Right temporal lobe infarct 110

7 78 Male Left Occipito-temporal infarct 265

8 64 Male Right temporal lobe infarct 179

9 32 Male Right insula infarct 301

Summary of AP Assessment. Cross (+) signifies the presence of a deficit

GIN Perceptual

Property

Apperceptive Semantic SiB

Participant # Rt Lt Rt Lt

1 + + _ _ _ + +

2 + + + + _ + +

3 + + _ + _ + +

4 + + _ _ _ + +

5 _ + + _ _ _ +

6 _ + + _ _ + +

7 + + _ + _ + +

8 + + + + _ + +

9 _ + + _ _ + +

Sentences in Noise With and Without Personal FM Systems

Discussion

� All 9 stroke patients had deficits in temporal

resolution, in perceptual and/or appereceptive spectral processing and in speech in noise test performance, but without semantic deficits, and

without clinically significant aphasia.

� They all reported high levels of auditory disability and auditory related social and emotional handicap in their everyday life on questionnaires.

� No cognitive impairment or aphasia (Montreal

Cognitive Assessment & Western Aphasia battery)

Discussion

� All cases significantly improved speech perception in

noise with the FM systems, when noise was spatially separated from the speech signal by 90°, by 9.2 dBSPL compared to the unaided listening condition.

The magnitude of the benefit is considerable, as one dB improvement equals approximately a 10%

improvement in speech recognition scores at barely audible (threshold) speech levels (Vorländer et al., 2011)

The observed improvement was more marked for the stroke patients in our study as

compared to reports assessing the benefit of FM systems in other neurological populations with auditory processing deficits. Only eight out of ten patients with multiple sclerosis [MS] (Lewis et al., 2006) and four out of six adults with an auditory neuropathy due to Friedreich’s ataxia (Rance et al., 2010) improved. The common denominator between these three different clinical populations is the presence of impaired temporal processing

due to the three different types of neural pathology. Friedreich’s ataxia is a progressive peripheral de-afferentation type lesion, while MS involves often progressive, widely distributed demyelination in the brain, and it may be that the nature of pathology affects FM outcome. Alternatively, use of more stringent patient selection criteria in our study, in terms of severely impaired speech-in-noise test performance, self-reported speech-in-noise

difficulties and non-speech AP deficits, may explain why all our patients showed FM related benefit compared with only 70-80% of patients in the aforementioned studies

Discussion

� This observed speech performance improvement

may arise from enhanced attention to the speech signal, or enhanced neural synchrony and representation of the speech signal in the central

auditory nervous system, due to the louder speech signal ( Song et al., 2008)

� Alternatively it could be due to a passive auditory discrimination training (task-irrelevant learning)

due to the improved access to the acoustic speech contrasts (Seitz et al., 2005)

Discussion

� Whether the FM technology assists the top-down

(cognitive driven) or bottom-up (sensory driven) auditory processing, our study indicates that the benefits gained from the personal FM

systems may be a promising intervention to address hearing needs in stroke patients in whom the

auditory brain is affected but peripheral hearing is preserved.

FM Clinical Trial Phase II

Aim: To evaluate the potential benefits in speech-

perception of personal FM system, when used for a set period of time by stroke patients with a diagnosis of auditory processing deficits, and investigate

whether neuroplasticity occurs after a prolonged use of FM systems.

Methods:

Wearing Schedule and Monitoring

Fitting

Data Collection Schedule

Participant Age Sex PTA Lesion

I (1) 64 M 22.5 Paramedial right thalamus

I (9) 32 M 15 Right insula infarct

I (4) 52 M 25

Left medulla oblongata, occipital

lobe, hippocampus & right cerebellum

infarct

I (6) 32 M 5.5 Right temporal lobe infarct

SC (3) 44 M 8.3Right putamen / corona radiata

infarct

SC (5) 53 F 25 Right superior parietal lobule infarct

SC (2) 24 M 18.3 Left frontotemporal and insula infarct

SC (7) 78 M 25 Left Occipito-temporal infarct

SC (8) 64 M 22.5 Right temporal infarct

Lesion description, age, sex, PTA (average in dB HL at 500, 1000, 2000, 4000 Hz) KEY: I = intervention; SC= standard care; M, male; F, female; PTA, pure-tone average; dB, decibel; HL, hearing level)

the SRT individual scores for intervention and standard care subjects. The

standard care subjects are shown in the shaded area. KEY: SRT, speech reception

threshold, S, subject

In conclusion, we found clinically significant

improvements in speech in noise perception even when not using the FM system after prolonged use of binaural FM devices by stroke patients with speech in

noise deficits due to disordered auditory processing. This improvement may well be due to auditory-driven

brain plasticity. Around 21% of the stroke population (Koohi et al., 2016) might benefit by this intervention.

Conclusion

� Hearing requires not only the ability to detect sounds in the ear, but also involves complex processing of auditory signals encoded in the form of neural activities in the brain to derive meaningful information.

� It is important to note that hearing impairment could be one of central origin and is not only mediated at the periphery

� When hearing impairment with central origin is present, they can be diverse (Polster and Rose, 1998), may go undetected unless specifically sought for (Blaettner et al, 1989), and may impact on patient communication in everyday life

� Patients may receive conventional hearing aids if an apparent peripheral hearing loss is detected. However, hearing aid amplification in a case of a patient with auditory processing deficits may not alleviate this specific disorder.

Thank you