Hidden Hearing Loss  & Diabetes

Editor’s note: We are fortunate to have a commentary this month by Kathy Dowd, Executive Director of The Audiology Project (TAP) which has been front and center for involving Audiology in diabetes related hearing loss – a much needed movement.

by Kathy Dowd,  Executive Director of The Audiology Project (TAP), Charlotte NC

The common phrase ‘What you see is what you get’ does not apply to the audiogram.  Creating a picture on a graph of pure tone thresholds and speech discrimination causes many professionals to move on to correcting the hearing problem with hearing aids.  When the hearing assessment is only an audiogram testing the peripheral system, a gap is created in assessment of the more hidden issue of Central Auditory Processing Disorders (CAPD).

This need for CAPD in audiological care is now being recognized with the emergence of diabetes effects of microangiopathy: disruption of small blood vessels causing leaking of blood into surrounding areas in the brain and other parts of the body.  Diabetes has been shown to negatively affect cerebral microcirculation including auditory centers of the brain (1).  Neural degeneration from diabetes along the auditory pathway from the peripheral auditory system, through the brainstem to the auditory cortex and finally to the frontal lobe may also impact auditory processing at the cortical level resulting in hearing difficulties for complex acoustic events (2).   

Audiology is moving to a medical management model of care due to the need for comprehensive audiological evaluations for chronic diseases, severe infections, ototoxic medications and traumas.   Research for decades has pointed to the effects of medical illnesses, injuries and trauma on hearing and auditory processing.  While audiologists have been cautioned to not do ‘routine hearing testing’, routine audiology testing means the underlying contributing medical conditions are not known or investigated.  It is important to understand the impact of diabetes and other diseases on hearing, vestibular, and cortical function with a comprehensive audiology evaluation that includes CAPD.

 

Case History

 

An extensive case history may review decades of medical care for a patient.  Questions to ask include:

  • What medications are you on? Treating what medical issue?  Can I see a list of Rx?
  • What chronic diseases do you have or have you been treated for? Are these diseases well managed? (e.g., is your blood sugar under control)
  • Any previous hearing tests?
  • Any hospitalizations in the past 20-30 years? For what problems?  (e.g., car wreck, falls, joint replacements, infections, etc.)
  • Noise exposure over your lifetime? (e.g., lawn mowers, leaf blowers, chain saws, guns, etc.) Did you wear ear protection?
  • Have you fallen or do you have a fear of falling?

The medical reasons for hearing problems due to illness, injury and trauma arise from these questions.  The case history begins the process of audiological medical management.  Diagnosis codes for case history findings can be included on the patient’s ICD-10 billing.  The patient’s referring physician may also provide this information if requested.

 

Audiology Evaluation

 

The core evaluations of pure tones, speech discrimination and tympanometry reveal the status of the peripheral system.   From these results the degree of hearing loss and how well the person understands in each ear in quiet is known.  To learn more about the path of the auditory signal beyond the ears, to the brainstem, auditory cortex and prefrontal/frontal lobe, additional testing is needed.  Ipsi and contralateral acoustic reflexes and reflex decay can add diagnostic value to the evaluation.

Some additional CAPD tests that can be performed are the speech in noise tests, dichotic digits test, gaps in noise tests and staggered spondaic word test.  The results from these tests will expose an auditory processing problem and a path to addressing each patients listening needs.

 

Recommendations

 

The audiologist is best prepared to make recommendations armed with a comprehensive audiological evaluation.  Armed with the medical reasons for the patients hearing loss and auditory processing issues, there are several suggestions for next steps.  Examples for persons with diabetes include:

  • Retest hearing in one year due to diabetes and a confirmed hearing loss or Retest in 2 months due to diabetes, CVD and ototoxic medications…
  • Refer to a diabetes educator for special education for blood sugar monitoring, eating, exercise, to maintain A1c levels
  • Refer to (podiatry, optometry, pharmacy) for diabetes evaluation
  • Recommend hearing aids and CAPD treatment based on today’s test results.

Audiologists are trained to assess and treat hearing and auditory problems.  Some of these problems may be perceived to be cognitive issues, especially when a person is unable to hear well and has already been treated with hearing aids.  Cognitive evaluations and treatment are not in audiology’s scope of practice.  When a cognitive issue is found by the audiologist during a cognitive screening,  the referral should be initiated to a psychologist, who has a doctorate specializing in cognitive treatments.

Specials tests performed by the audiologist are usually not reimbursed directly by the insurance company.  These tests can be billed direct to the patient with a signed ABN and the physician order for testing.  The patient can pay privately for the special diagnostic tests, and then file the invoice and MD order documents with their insurance.   The patient will be reimbursed directly by the insurance company for the special testing and CAPD treatment, when there is documented medical necessity associated with the treatments (illness, injury, trauma and complaint).

 

Readings

  • Brain injury with diabetes mellitus: evidence, mechanisms and treatment implications. Hamed SA. Expert Rev Clin Pharmacol. 2017 Apr;10(4):409-428).
  • Gaps-in-noise test performance in subjects with type 2 diabetes mellitus. –Pirasteh, E., Esmailzadeh, N.L., Absalan, A., Nahrani, M.H., Nosratzehi, M., & Nosratzehi, S. Auditory and Vestibular Research, 27, (2018): 200-207.

About Pathways

Pathways is both a column that covers topics related to CAPD and Neuroaudiology and a society for people interested in central auditory disorders that regularly meets to discuss these issues.

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