Auditory Processing & Rehabilitation Following Blast Exposure & Mild Traumatic Brain Injury (mtbi)

Transcription

1 Auditory Processing & Rehabilitation Following Blast Exposure & Mild Traumatic Brain Injury (mtbi) Gabrielle Saunders, Frederick Gallun, Michele Hutter, Robert Folmer, M. Samantha Lewis, Melissa Frederick, Michelle Arnold, Theresa Chisolm, Paula Myers, Marjorie Leek

2 National Center for Rehabilitative Auditory Research (NCRAR) Rehabilitation Research & Development Center of Excellence VA Medical Center, Portland, Oregon

3 VA RR&D Centers of Excellence Limb Loss & Prosthetics (Seattle, WA) Functional Electrical Stimulation (Cleveland, OH) Wheelchair Technology (Pittsburgh, PA) Innovative Visual Rehabilitation (Boston, MA) Restorative & Regenerative Medicine (Providence, RI) + + Auditory Rehabilitation (Portland, OR) Spinal Cord Injury & MS (West Haven, CT) + Bone & Joint Rehabilitation (Palo Alto, CA) + + Spinal Cord Injury (Bronx, NY) Platform Technology (Cleveland, OH) Aging & Vision Loss (Decatur, GA) Brain Rehabilitation (Gainesville, FL) Spinal Cord Injury (Miami, FL) Exercise & Robotics (Baltimore, MD)

4 Diagnosis and Assessment Rehabilitation Strategies Prevention of Auditory Dysfunction

5 Disclosure The authors have no relevant financial or non-financial relationship with the products or services described, reviewed, evaluated, or compared in this presentation. The research described in this talk was funded by the Department of Veterans Affairs (#C7054R, #01807, #C775I) and Phonak, who provided study equipment. The views expressed in this presentation represent the personal opinions of the authors, however, and should not be taken as official position or policy of the Department of Veterans Affairs or Department of Defense.

6 Blast Exposure and Traumatic Brain Injury (TBI) One of the most common effects of blast exposure is mild TBI, also known as concussion.

7 Blast Exposure and TBI Injury from blasts can result from exposure to a blast wave without an official diagnosis of traumatic brain injury. Other times blast injury can occur along with TBI.

8 Blast Exposure and Traumatic Brain Injury (TBI) The exact number of blast exposed Veterans is unknown. Using the number of those diagnosed with TBI, however, begins to suggest the scope of the problem.

9 768,744 recently returned Veterans screened for possible TBI * 154,128 (20.1%) screened positive for TBI 144,787 seen for follow-up 62,545 of those seen were confirmed with TBI Estimated prevalence of TBI in the OEF/OIF Veteran population: 8.13%. More than 1.5 million U.S. military personnel have been deployed to Iraq or Afghanistan since 2001 Over 100,000 Veterans can be estimated to have suffered traumatic brain injury in the line of duty * as of August 31, 2013, Department of Veterans Affairs, Office of Patient Care Services, Office of Rehabilitation Services. TBI Comprehensive Evaluation Summary Report. September 2013.

10 Relevance Outside of VA ~50% of returning Veterans seek healthcare outside the VA system More than half of returning Iraq and Afghanistan Veterans report multiple blast exposures

11 Central Damage due to Blast Exposure: Model Predictions 1) injury to axons (stretching and shearing of axons) 2) bruising of the brain surface (contusion) 3) internal bleeding (subdural hemorrhage) from ruptured blood vessels Chafi et al (2010) Biomechanical assessment of brain dynamic responses due to blast pressure waves. Annals of Biomedical Engineering. 38(2):

12 Common Subjective Complaints of Blast Exposed Veterans I can t follow a conversation in a crowded room. I have difficulty with focus and concentration. Sometimes I get frustrated when people talk too fast or mumble. My hearing problem impacts both my work and family relationships.

13 Functions of the Central Auditory System Potentially Damaged by Blast Exposure Thalamus: Organization and updating of corticalbrainstem connections Inferior Colliculus: Coding of basic timing and frequency patterns Superior Olivary Complex: Spatial processing Cochlear Nucleus: Timing and frequency extraction

14 Functions of the Central Auditory System Potentially Damaged by Blast Exposure Corpus Callosum: Transfer of information between left and right hemispheres Auditory Cortex: Feature-specific processing of auditory information Parietal Cortex: Spatial information Frontal Cortex: Control of attention, task-dependent activity, and plasticity of the system over time.

15 Volume 49 Number 7, 2012 Pages Implications of blast exposure for central auditory function: A review Frederick J. Gallun, PhD;1-2* M. Samantha Lewis, PhD;1-2 Robert L. Folmer, PhD;1-2 Anna C. Diedesch, AuD;1 Lina R. Kubli, MS;3 Daniel J. McDermott, MS;1 Therese C. Walden, AuD;3 Stephen A. Fausti, PhD;1-2 Henry L. Lew, MD, PhD;4 Marjorie R. Leek, PhD1-2 1 Department of Veterans Affairs (VA) Rehabilitation Research and Development National Center for Rehabilitative Auditory Research (NCRAR), Portland VA Medical Center, Portland, OR; 2 Oregon Health & Science University, Portland, OR; 3 Audiology and Speech Center, Walter Reed National Military Medical Center (WRNMMC), Bethesda, MD; 4 Defense and Veterans Brain Injury Center (DVBIC), Richmond, VA

16 Volume 49 Number 7, 2012 Pages Performance on tests of central auditory processing by individuals exposed to high-intensity blasts Frederick J. Gallun, PhD;1-2* Anna C. Diedesch, AuD;1 Lina R. Kubli, MS;3 Therese C. Walden, AuD;3 Robert L. Folmer, PhD;1-2 M. Samantha Lewis, PhD;1-2 Daniel J. McDermott, MS;1 Stephen A. Fausti, PhD;1-2 Marjorie R. Leek, PhD1-2 1National Center for Rehabilitative Auditory Research (NCRAR), Portland Department of Veterans Affairs Medical Center, Portland, OR; 2Oregon Health & Science University, Portland, OR; 3Audiology and Speech Center, Scientific and Clinical Studies Section, Walter Reed National Military Medical Center, Bethesda, MD

17 Study 1: Blast Exposure in Hospitalized Service Members

18 Central Auditory Processing Disorders Associated with Blast Exposure NCRAR Marjorie R. Leek, Ph.D. Co-Principal Investigator Stephen Fausti, Ph.D. Co-Principal Investigator Samantha Lewis, Ph.D. Co-Investigator Frederick J Gallun, Ph.D. Co-Investigator Robert Folmer, Ph.D. Co-Investigator Anna Diedesch, AuD Research Audiologist Daniel McDermott, MA Research Audiologist WRAMC Therese Walden, AuD Co-Investigator Lina Kubli, MA Research Audiologist Funding provided by: VA RR&D Grant #01807

19 Participants Blast Exposed (n = 36) Tested at Walter Reed Army Medical Center Recently exposed to a blast 19 with mild TBI 17 without TBI diagnosis OEF/OIF soldiers Treated for other blast related injuries No greater than mild hearing loss Control Subjects (n = 29) Tested at NCRAR Non-blast exposed Age matched (+/- 5 years) Hearing matched (+/- 10dB at octave freq. s)

20 CAPD & Blast Exposure Test Protocol Speech in Noise and Competing Speech QuickSIN Dichotic Digits Test (DDT) Staggered Spondaic Words Test (SSW) Localization and Spatial Processing Binaural Masking Level Differences (MLD) Temporal Processing Gaps In Noise Test (GIN) Frequency Pattern Sequences Test (FPT) Electrophysiology ABR P300

21 100% 90% 80% Control Blast Exposed Percentage of Subjects 70% 60% 50% 40% 30% 20% 10% 0% Number of Abnormal Test Results (of 5 possible)

22 Conclusions Evidence suggests that blast exposed individuals are at risk for impaired performance on auditory processing tests. The patterns observed are more consistent with central than peripheral dysfunction. One important question unanswered by these data are whether these patterns resolve, persist, or worsen over time.

23 Study 2: Blast Exposure in Veterans (Data Collection Ongoing)

24 Central Auditory Processing Deficits Associated with Blast Exposure Tests of functional hearing ability a) Behavioral Test of Spatial Release from Multitalker Masking b) Speech and Spatial Hearing Questionnaire c) Hearing Handicap Questionnaire Clinical Tests of Central Auditory Processing a) Gaps in Noise b) Adaptive Test of Temporal Resolution c) Staggered Spondaic Words d) Binaural Masking Level Differences e) Dichotic Digits f) Frequency Patterns VA RR&D Merit Review #C7755I PIs: Gallun & Leek Co-Is: Fausti, Folmer, Lewis Study Population 60 blast-exposed Veterans 60 age and hearing-matched controls 30 age and hearing-matched non-blast TBI Electrophysiology a) ABR b) Oddball (N100/P300) Paradigm c) Binaural Change Response d) Gaps in Noise Responses

25 Participants Tested So Far Blast (n = 17) Control (n=21) Younger Older Younger Older Number Tested Mean age (y) Mean PTA Right (db) Mean PTA Left (db)

26 Time since blast exposure Most subjects report exposure to multiple blasts Seven (out of 17) reported more than 5 blasts Date of most serious injury: 4 to 9 years ago Average of 7.5 years Photo: Marines.mil

27 Gaps in Noise (GIN) (Musiek, et al, 2005) Six-second long segments of white noise, each with 0 to 3 silent intervals (gaps). Respond with button press to each gap. Gap durations range from 2-20 milliseconds and are pseudo-randomized throughout the test items and their location in the noise segment. Each ear tested separately. Score reflects gap duration (in ms) at which gaps can be accurately detected Assesses temporal resolution. Sensitive to lesions of cortex and corpus callosum.

28 Gaps In Noise Approximate Threshold (ms) Young Control Older Control Younger Blast Older Blast

29 Proportion Abnormal on GIN Relative to Mean of Younger Control Group Younger Control: 13% Older Control: 8% Younger Blast: 37% Older Blast: 44%

30 Staggered Spondaic Word Test (SSW) (Arnst 1982) Each test item is made up of two spondees, which are two-syllable compound words such as cupcake. One spondee is presented to each ear.» Two syllables are presented in silence ( non-competing ).» Two syllables are presented simultaneously ( competing ). Subjects repeat the words in the order presented. Score reflects the total number of words correctly identified, out of 40 trials, each with four words. Sensitive to lesions of the corpus callosum

31 Staggered Spondaic Words Total Errors Young Control Older Control Younger Blast Older Blast

32 Proportion Abnormal on SSW Relative to Mean of Younger Control Group Younger Control: 0% Older Control: 8% Younger Blast: 37% Older Blast: 77%

33 Spatial Release from Masking Coordinate Response Measure sentences Virtual Spatial Array presented over headphones Target in front, two maskers either in front or at +/-45 degrees T/M Ratio varied from +10 to -8 db in 2 db steps (10 TMR values) 2 trials at each T/M Ratio (20 trials per track) 2 tracks obtained for each masker configuration Threshold estimated from total number of correct trials

34 Spatial Release (db) Control Blast Age (years)

35 Proportion Abnormal on Spatial Release Relative to Mean of Younger Control Group Younger Control: 0% Older Control: 46% Younger Blast: 63% Older Blast: 56%

36 Proportion Abnormal on Behavioral Tests 1 Younger Control (n=8) Blast Exposed Younger (n=8) Older Control (n=13) Blast Exposed Older (n=9) Proportion Abnormal Spatial Release from Masking Gaps In Noise Dichotic Digits SSW Total Errors Frequency Patterns Binaural Masking Level Difference (MLD)

37 Electrophysiology

38 Neuroscan Set-up

39 Long Latency Response (LLR) ABR

40 Neuroscan P300 Protocol Stimulus: 100 ms duration tones, 85 db SPL 200 (80%) 500 Hz tones 50 (20%) 1000 Hz tones Oddball Paradigm Presentation: Monaural through insert earphones Two runs (250 sweeps) each in R / L Subjects task: Count high-pitched tones silently to themselves BEEP! BOOP BOOP BOOP BOOP BOOP BOOP BEEP!

41 Results: P300 grand averages (right ear) Rare stimuli 12.5 Control subjects (n=16) Blast-exposed subjects (n=13) 10.0 P Amplitude (µv) P N2-5.0 N Time post-stimulus onset (ms)

42 Results: P300 P300 Mean Latencies P300 Mean Amplitudes Latency (ms) Amplitude (µv) Right ear Left ear 270 Blast Control 0 Blast Control Right ear Left ear Blast Control Latency (ms) Amplitude (µv) Latency (ms) Amplitude (µv)

43 Conclusions These data, while still preliminary, suggest that the difficulties observed in the first study persist over time and may even worsen with aging. Current approaches to treatment of traumatic brain injury largely ignore the potential impairments of auditory processing. There is clearly a need for additional research into the best ways to characterize, diagnose, and provide rehabilitation for those exposed to highintensity blasts.

44 I am a research audiologist working at the National Center for Rehabilitative Auditory Research (NCRAR). I m currently working on studies looking at the effects of blast injury on combat veterans. Outside my career my greatest interests are science, fly fishing, cross-fit, the New England Patriots and my dog, Brady. My greatest fears are snakes and talking in front of large audiences. Then why on Earth am I here? I am passionate about helping veterans And my boss made me do it!

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47 A Comparison of Two Veterans Blast exposed Non blast exposed 43 years old Veteran Deployed to Middle East (3x) PT Thresholds in normal range PTSD Hx No official Dx of TBI Sensitive to loud sounds and bright lights Trouble concentrating Severe depression (38/40 on BDI) 37 years old Veteran Deployed to Middle East (1x) PT Thresholds in normal range PTSD Hx No official Dx of TBI Sensitive to loud sounds and bright lights Trouble concentrating Moderate depression (21/40 BDI) Remarkably similar!

48 Blast exposed Blast exposed, >50m Non blast exposed No blast exposure Blast exposure is the only significant difference between these two Veterans.

49 Staggered Spondaic Word Test (Precision Acoustics; Katz and Smith, 1991)

50 Staggered Spondaic Word Test Number of errors Norm

51 Gaps in Noise Test (Musiek, F., Shinn, J., Jirsa, R., Bamiou, D., Baran, J., and Zaida, E. (2005). GIN (Gaps-In-Noise) test performance in subjects with confirmed central auditory nervous system involvement. Ear and Hearing, 26, )

52 Gaps in Noise Test milliseconds (ms) Norm

53 What do these abnormal results mean for the subject? SSW (binaural integration) GIN (temporal processing )

54 P300 Results for Our Two Comparison Veterans Left Ear Control Blast Exposed P3 (318 ms, 9.4 μv) P3 (373 ms, 4.1 μv) N1

55 P300 Results for Our Two Comparison Veterans Right Ear P3 (308 ms, 8.1 μv) Control Blast Exposed P3 (383 ms, 3.6 μv) N1

56 EP Summary No differences in ABR latency & amplitude Differences in P300 latency & amplitude

57 So what s next for this population of new veterans? Most vets are sent to audiology for a routine hearing test and many have normal audiograms which suggests normal peripheral hearing function. In these instances many individuals feel like their subjective complaints are not validated. So it is our mission to explore beyond the cochlea.

58 Our Mission at NCRAR Our Veterans fought for us. It s our responsibility as professionals and human beings to fight for them by providing them the validation and services they need and deserve!