Audiology - Chapter 3

Chapter Three: Case History Assessment and Differential Diagnosis in Hearing Loss
Introduction to Differential Diagnosis

  • The chapter explores case history assessment and differential diagnosis specifically for individuals with hearing loss.

  • Differential Diagnosis Definition: The process of distinguishing between two or more conditions that share similar signs or symptoms (e.g., distinguishing between a processing disorder and a peripheral hearing loss).

  • The assessment process begins with a case history form aimed at gathering thorough patient information prior to evaluation.

Case History Forms

  • Usage and Importance:

    • Case history forms are typically sent to families or individuals via mail or online link for completion before the initial visit.

    • Incomplete forms may lead to needing on-site completion when the patient arrives, which can delay the clinical schedule.

  • Types of Forms:

    • Many commercially available case history forms exist, including several examples in textbook appendices.

    • Forms can be customized based on specific work settings (e.g., schools, clinics).

  • Discipline-Specific Forms:

    • Each discipline (Speech-Language Pathology, Occupational Therapy, Physical Therapy) may have unique forms focusing on relevant aspects within those fields, such as motor skills or language milestones.

  • Age-Specific Forms:

    • Forms can vary based on the targeted population: early intervention (focusing on birth history), school-age children (focusing on academic performance), or elderly patients in nursing facilities (focusing on cognitive status and isolation).

Prenatal, Perinatal, and Postnatal Factors

  • Key Historical Factors:

    • Prenatal History:

    • TORCH Complex: A group of infections that can be passed from mother to fetus, including Toxoplasmosis, Other (Syphilis, Varicella-Zoster), Rubella, Cytomegalovirus (CMV), and Herpes Simplex.

    • Cytomegalovirus (CMV): Currently a leading cause of non-genetic congenital hearing loss; it can be present at birth or manifest as late-onset/progressive loss.

    • Rubella: Was prevalent in the 1960s-70s, causing "Congenital Rubella Syndrome"; vaccinations have reduced incidences dramatically.

    • Perinatal and Postnatal History:

    • Hypoxia: Lack of oxygen during birth which can damage the delicate hair cells of the cochlea.

    • Hyperbilirubinemia (Jaundice): High levels of bilirubin can be toxic to the auditory system, potentially leading to Auditory Neuropathy Spectrum Disorder (ANSD).

    • Key factors include prematurity, low birth weight ( < 1500 grams), prolonged labor, and complications from STDs.

Hearing Screening and Follow-Up

  • Importance of Hearing Screening:

    • Screening records should include the test performed (e.g., OAE or AABR), date, results (Pass/Refer), and any referrals made.

  • The 1-3-6 Rule:

    • Pediatric guidelines suggest screening by 1 month, diagnosis by 3 months, and intervention by 6 months of age.

  • Concerns of Lost Follow-Up:

    • High attrition rates occur because many infants fail initial screenings but do not get referred for further evaluation, leading to missed diagnoses and delayed speech development.

Genetic Considerations

  • Congenital Hearing Loss:

    • Approximately 75%75\% to 80%80\% of congenital hearing loss is genetic in origin.

  • Syndromic vs. Non-Syndromic:

    • Non-Syndromic (70%70\% of genetic cases): Hearing loss occurs in isolation, often linked to mutations like GJB2 (Connexin 26).

    • Syndromic (30%30\% of genetic cases): Hearing loss is associated with other medical or physical findings (e.g., Usher Syndrome, Waardenburg Syndrome, Pendred Syndrome).

Common Issues in Young Children

  • Ear Infections (Otitis Media):

    • Common among toddlers due to the short, horizontal anatomical structure of eustachian tubes.

  • Chronic Ear Infections: Can lead to fluctuating conductive hearing loss, which may result in inconsistent auditory input during critical periods for speech and language development.

  • Recommendations:

    • Parents should monitor ear infections closely; persistent fluid (effusion) may require Myringotomy and Ventilation Tubes (PE tubes).

Allergies and Ototoxic Drugs

  • Impact of Allergies:

    • Allergies may cause chronic eustachian tube dysfunction, mimicking hearing issues through persistent congestion.

  • Ototoxicity:

    • Certain medications are known to damage the cochlea or vestibular system.

    • Aminoglycosides: Antibiotics like Gentamicin or Neomycin often used in NICU settings.

    • Chemotherapy Agents: Such as Cisplatin or Carboplatin.

Trauma and Other Considerations

  • Trauma and Neglect:

    • Physical trauma (e.g., temporal bone fractures) or emotional neglect can impact a child's overall development and response to testing.

  • Surgical Treatments:

    • Previous ear surgeries (e.g., mastoidectomy) can alter the physical structure of the ear and affect future audiometric results.

  • Seizure Disorders:

    • Certain anticonvulsant medications or the neurological nature of seizure disorders may correlate with auditory processing difficulties.

Behavioral Indicators of Hearing Loss

  • Red Flags:

    • Behavioral indicators include inattentiveness, turning up TV volume excessively, inability to follow multi-step directions, and literacy challenges.

  • Differential Diagnosis Challenge: Misdiagnoses can occur; children with hearing loss are sometimes incorrectly identified as having ADHD or Autism Spectrum Disorder (ASD).

Adult Considerations in Hearing Loss

  • Acquired Hearing Loss:

    • Presbycusis: Age-related hearing loss, typically characterized by a gradual decline in high-frequency sensitivity.

    • Occupational Noise: Long-term exposure to noise levels above 8585 dB can result in noise-induced hearing loss (NIHL).

  • Psychosocial Impact: Adults may experience increased social isolation, depression, and a higher risk of cognitive decline if hearing loss remains untreated.

Informal Observations

  • Clinical Interactions:

    • Observe patient behavior: Do they lean in to hear? Do they rely on lip-reading?

    • In children, formal play observations can assess turn-taking and vocalization quality.

Collaborative Approach to Care

  • Interprofessional Collaboration:

    • Coordination between Audiologists, SLPs, ENTs (Otolaryngologists), Pediatricians, and Teachers is essential.

  • Patient History Accuracy:

    • Verification of medical history is necessary, as patients or caregivers may sometimes provide conflicting or incomplete information regarding past diagnoses.

Conclusion

  • Emphasis on thorough assessment processes for both children and adults with hearing loss.

  • Successful differential diagnosis relies on sourcing accurate information, comprehensive medical and family histories, and recognizing the wide array of environmental and genetic factors.