Case History

The 26-year-old mother was healthy throughout the term of the pregnancy and went into labor at 40-weeks' gestation. The pregnancy was complicated just prior to delivery with a possible abruption. There was significant bradycardia with the heart rate of the patient down to 40 beats per minute prior to delivery. This required a stat cesarean section.

At the delivery of the head, a deep scalpel injury occurred on the patient's scalp measuring about two centimeters in length for which stitches were required. After delivery, a large vasa previa was noted. Vasa previa occurs when fetal blood vessels from the placenta or umbilical cord cross the entrance to the birth canal, and can cause oxygen loss and bradycardia.

The patient did not cry at birth and had extremely poor perfusion with no activity and no respiratory effort. The patient was covered in a thick meconium and required suction and saline rinse of the mouth, nostrils, and nasopharynx, aspiration of the stomach, and chest physiotherapy. He was subsequently diagnosed with Meconium Aspiration Syndrome. The Apgar scores were two, five, and six, at one, five, and ten minutes, respectively.

Upon admission to the Neonatal Intensive Care Unit (NICU), umbilical arterial and venous catheters were placed immediately and the patient was given normal saline bolus to improve his blood gas. He was placed on nasal continuous positive airway pressure (CPAP). He had a sepsis workup performed and was started on ampicillin every 12 hours and gentamicin every 24 hours. The CPAP and antibiotics were discontinued after three days.

The patient was released from the NICU at five days old with no required follow-up. Prior to release, he passed his hearing screening in both ears at the 35-dB level.

TABLE 1. Pure-Tone Air-Conduction Test Results at Age Three Years, Zero Months
  500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
Right (dBHL) 10 10 10 25 55 55 60
Left (dBHL) 10 10 10 NT 20 NT NT

Pop Quiz

What are the high-risk factors of hearing loss related to this experience?

  1. NICU admission
  2. Ototoxic medications
  3. Meconium Aspiration Syndrome
  4. Scalpel injury
  5. Low Apgar scores

Risk factors for hearing loss in this case include: B. the use of ototoxic medicine, C. Meconium Aspiration Syndrome, and E. low Apgar scores (Biswas, et al, 2011; Eichwald and Mahoney, 1993; Halpern, et al, 1987; Kraft, et al, 2014; So, 2009).

B. The patient was given gentamicin for three days as a precautionary measure following the birth. The Joint Committee on Infant Hearing Year 2007 Position Statement lists ototoxic medications as a risk factor for hearing loss. Aminoglycosides, such as gentamicin, are considered ototoxic medications.

C. The patient was diagnosed with Meconium Aspiration Syndrome. According to Halpern et al (1987), meconium aspiration is a risk factor for permanent hearing loss, especially in term infants.

E. According to Biswas et al (2011) and Eichwald and Mahoney (1993), Apgar scores of 0–4 at one minute or 0–6 at five minutes are significant risk factors for hearing loss in children.

He was not admitted to the NICU long enough to be considered at risk for hearing loss. According to Kraft, et al (2014), a child is considered at risk with an intensive care unit stay of greater than five days. The scalpel injury only required stitches.

TABLE 2. Pure-Tone Air-Conduction Test Results at Age Three Years, Six Months
  250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 8000Hz
Right (dBHL) 50 45 20 15 30 75 75
Left (dBHL) 20 15 15 10 NT 15 35

Audiometric Findings

Distortion product otoacoustic emissions screenings were performed when the patient was eight weeks old. The right ear passed at 2000–3000 Hz, but absent responses were noted at 4000–6000 Hz. The left ear passed at 2000–5000 Hz, but absent responses were noted at 6000 Hz. This was repeatable. The results "passed" according to the settings of the equipment.

A screening audiogram using standard methods was performed at two years, ten months of age, and showed normal responses from 500–4000 Hz bilaterally.

An audiogram was performed using standard methods at three years, zero months old (see TABLE 1). Speech reception thresholds were consistent with these findings. Type A tympanograms were obtained bilaterally and ipsilateral acoustic reflex thresholds were within normal limits, with the exception of an elevated response at 2000 Hz in the right ear. Contralateral acoustic reflex thresholds were absent when stimulated on the right at 1000 Hz and 4000 Hz. Ipsilateral and contralateral acoustic reflex thresholds were normal in the left ear at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz.

A subsequent audiogram was performed at three years, six months old (see TABLE 2). Tympanograms were Type B on the right ear and Type A on the left ear. Pure-tone air- and bone-conduction testing for the right ear showed a moderate conductive hearing loss in the low frequencies and a severe mixed hearing loss in the high frequencies. The left results indicated normal hearing sensitivity from 250–4000 Hz, dropping to a mild hearing loss at 8000Hz.

A hearing screening was performed at preschool during this time and the patient was deemed "too inconsistent to test." It was recommended he ait until the following year for repeat screening.

At four years, one month old, pure-tone air-conduction results indicated the right ear results were within normal limits from 250–3000 Hz sloping to a moderate hearing loss from 4000–8000 Hz. The left ear results were within normal limits from 250–4000 Hz, sloping to a moderate loss at 6000Hz and 8000Hz (see TABLE 3).

Audiometric testing performed at five years old, eight years old, and 12 years old are all consistent with a moderate high-frequency sensorineural hearing loss bilaterally. Word recognition scores have consistently remained at 100 percent when performed at 40 dB SL. Extended high-frequency air-conduction thresholds obtained at eight years old are shown in TABLE 4.

TABLE 3. Pure-Tone Air-Conduction Test Results at Age Four Years, One Month
  250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz
Right (dBHL) 10 10 0 0 15 55 50
Left (dBHL) 5 15 5 0 5 5 50

Pop Quiz

What would your recommendation be if this were your patient?

  1. Fit the patient with hearing aids
  2. Make accommodations for the classroom
  3. Fit the patient with an FM system for the classroom
  4. None of the above

Course of Care

The patient was fit with bilateral receiver-in-the-canal hearing aids at eight years old, because he was unable to hear the differences between high-frequency fricatives if he could not see the speaker's face. He also had difficulty producing these sounds on a consistent basis in normal conversation. Prior to that time, no concerns were noted either at home or at school. After being fit with the hearing aids, he was able to consistently produce and identify high-frequency fricatives. His family reports he became more engaged in conversation and his overall attention to conversation improved.

A 504 plan was developed for the classroom to provide the patient with preferential seating, emphasizing the placement of his left ear closest to the instructor.

The patient was not fit with an FM system as he was successful in the classroom with the hearing aids alone. While his hearing aids did have a remote microphone option, the patient chose not to make use of it.

TABLE 4. Extended High-Frequency Air-Conduction Threshold at Age Eight Years
  10,000Hz 12,500Hz 14,000Hz 18,000Hz
Right (dBHL) 30 30 30 15
Left (dBHL) 45 35 30 15

Conclusion

The patient had several risk factors at birth for potential hearing loss, and multiple audiological tests were performed before the hearing loss was diagnosed and treatment initiated. Although his hearing loss is minimal, the patient did benefit from appropriate amplification and accommodations in the classroom.