March 2019 The Hearing Journal
Children with hearing loss are at great risk for vestibular dysfunction. However, vestibular function testing on children is not typically pursued by many hearing care providers. Perhaps children with vestibular disorders go unnoticed because they do not have the language to accurately describe symptoms of dizziness or imbalance. Today, advances in the niche area of paediatric vestibular testing have allowed clinicians to obtain more data on young children than ever before. Empowered with new technology, techniques, and more readily accessible treatment options, audiologists are able to offer families more information about a child's emerging balance function.
Professionals working with children with hearing and vestibular loss need to consider many significant factors, including the following:
- Many children with hearing loss and vestibular loss often do learn to walk, only slightly later.
- Some children have difficulty learning to ride a bike or participating in certain balance-related activities, such as skating or gymnastics.
- Reading acuity may be impaired due to abnormal vestibular ocular reflex function. Its impact on academic performance has yet to be investigated.
- Cochlear implant failure may be directly related to vestibular dysfunction.
Considering these risks as well as the high percentage of co-existing vestibular dysfunction among children with hearing loss, knowing which children need balance testing is important. Several vestibular screenings are available to aid audiologists in identifying these children:
A 2016 study compared subsections of the Bruininks Oseretsky Test of Motor Proficiency II (BOT-2) for differences in the balance function of hearing-impaired children with total vestibular loss and hearing-impaired children with normal vestibular function (4.8 years old and above). This test requires minimal equipment and the balance subsection takes minutes to complete. Results suggested that performing the single leg stance, eyes closed, using a cutoff of four seconds was the most sensitive measure for identifying the patients at risk of a total vestibular loss.
A more recent investigation into children with hearing impairment and various degrees of vestibular function showed that those with greater hearing loss had an increased chance of not learning to sit and walk until later in life, and had a greater reported parental concern for balance issues. The authors recommended using simple screening questions for children whose hearing loss is greater than 66 dB to determine who should be referred for comprehensive vestibular testing. These criteria include age of sitting (using a cutoff of 7.25 months), age of walking (using a cutoff of 14.5 months), or parental concern for gross motor delay.
Our group of paediatric audiologists at Cincinnati Children's Hospital started working closely with colleagues from a local oral school for the deaf to administer a multi-step vestibular bedside screening protocol. Specifically, the screening consisted of tests on vestibular ocular reflexes (VOR) and balance function to identify children with peripheral vestibular dysfunction of any degree. The school's audiologist was trained to perform the tests, which included the Head Impulse Test (HIT), Dynamic Visual Acuity (DVA) Screening, Single Leg Stance, and Standing on Foam with Eyes Open/Closed. A child who didn't pass any of the subtests was referred for diagnostic testing. Of the children initially screened, 39 percent were referred for a comprehensive test. Of those who underwent further comprehensive diagnostic testing, most of the children had bilateral vestibular loss (50%), some had peripheral vestibular system involvement (31%), one child had a normal examination (6%), and two had central vestibular dysfunction (13%). Those with vestibular loss were referred for vestibular rehabilitation and began treatment.
CLOSER LOOK: A CASE STUDY
One patient was 6 months old when he was diagnosed with global developmental delays and referred for an audiologic evaluation. He had no significant birth or medical history and passed his newborn hearing screening. He started getting speech and physical therapy through early intervention services. Behavioural hearing testing at this initial visit revealed bilateral severe-to-profound sensorineural hearing loss, which was later confirmed via auditory brainstem response testing. A sensorineural hearing loss workup revealed a normal MRI and positive cytomegalovirus swab testing. A genetic hearing loss panel workup was not approved by his insurance, and thus was not completed. He was fitted with hearing aids within one month of diagnosis. He was then enrolled in the local oral school for the deaf and received simultaneous bilateral cochlear implants by 12 months of age.
A vestibular screening questionnaire conducted at his school revealed that he did not sit independently until 10 months of age and started walking at 17 months of age. He had noted catch-up saccades in both the rightward and leftward directions on the Head Impulse Test. Now, at 21 months of age, he is unsteady and falls frequently, which prompted a referral for comprehensive vestibular testing at Cincinnati Children's Hospital.
Vestibular Test Findings. The patient's vestibular testing revealed bilateral vestibular hypofunction.
- Rotational Chair Test: Patient was seated in a 5-point harness car seat that was secured to the rotary chair. Eye movement recordings were obtained using an in-room camera (Fig. 2: C and D). No observable eye movements were noted in either the rightward or leftward directions.
- Cervical vestibular evoked myogenic potentials (cVEMP): Patient was seated on his mother's lap, facing her, in a reclined position. Toys and bubbles were used to engage the child and elicit a head elevation and turn to engage the sternocleidomastoid muscle. An EMG monitoring system was used to ensure appropriate contraction cVEMPs were absent bilaterally.
- Head Impulse Test (HIT): Patient was seated on his mother's lap facing the audiologist. A character sticker was placed on the tester's nose to stabilise the patient's gaze. Catch-up saccades were noted for both rightward and leftward head impulses.
- Videonystagmography (VNG): No spontaneous nystagmus was observed in the sitting position with or without fixation. Also, no nystagmus post-headshaking was observed with the in-room camera in the dark. These measures were recorded with the patient seated in the enclosure of the rotary chair.
Physical Therapy (PT) Vestibular Rehabilitation Evaluation. The physical therapist noted the following activity limitations beyond the patient's developmental age: He walked with a wide base of support with hands mid-guard. The patient required bilateral upper extremity support to go from squatting to standing. His static balance required a stable surface to maintain posture. He had difficulty with stair negotiation. Due to his bilateral vestibular hypofunction, he was observed to be reliant on vision and somatosensory input for maintenance of balance.
Vestibular Rehabilitation Therapy Goals. Skilled PT intervention focused on substitution strategies using vision (promoting scanning of environment and head turns in various directions) and somatosensory tasks (standing and walking on various surfaces) to improve standing balance and ambulation. The patient's therapy goals were to (1) walk 20 feet independently; (2) stand without upper extremity support without losing balance on compliant surfaces; and (3) walk up/down different surfaces. Transition from tile to mat independently without loss of balance.
The patient adhered to a daily home exercise program (HEP) and physical therapy visits once every other week. After six weeks at his third PT visit, he met these goals. Therapy was decreased from every other week to a follow-up recheck in six weeks. He was prescribed the following home exercises:
- Work on reaching up overhead/onto tiptoes without holding onto objects for balance
- Step up and down from small steps/curbs while holding parent's hand
- Stand and balance on a compliant surface (such as a pillow) while playing with toys
- Play activities requiring frequent head turns to improve VOR (walk to get a ball and bring it back to drop in a bucket)
- Jump on the floor and on the trampoline
- Walk up four stairs while holding a single rail and alternating his foot pattern
- Walk down the stairs while holding a single rail using a marking pattern
After a little over four months, the patient made excellent progress. He met all of his PT goals and now walks, runs, navigates stairs, and jumps independently. He is seen on an as-needed consultative basis with his physical therapist. Though our patient was being treated for delays in gross motor function with limited progress, the simple vestibular screening by his school audiologist effectively led to the diagnosis of a bilateral vestibular loss. This helped re-focus his physical therapy to address vestibular loss. Progress was made quickly with these additions to his treatment plan. As new developmental milestones emerge and are expected, he may again need vestibular rehabilitation therapy to achieve his age-appropriate skills.