The assessment of the vestibular system in children is an important part of the medical evaluation whenever hearing loss and/or dizziness are reported during the case history. Although the consequences of delayed treatment of hearing loss in children (e.g., impaired language development) are well known, the effects of vestibular system impairments in children are not as well understood.
Hearing impairment and vestibular impairments can occur simultaneously or in isolation (Brookhouser et al., 1982). Although it has been reported that the occurrence of vestibular disorders in children is low compared to adults, the effects are significant (O'Reilly et al., 2010). Russell and Abu-Arafeh (1999), for example, published an epidemiological study showing that in their sample of school-age children, 15% had experienced at least one episode of vertigo in the previous year. Numerous reports describing the most common disorders causing vertigo and imbalance in children have been published (e.g., O'Reilly et al,. 2010; Niemensivu et al., 2006; Riina et al., 2005; Bower & Cotton, 1995). These reports originate from different clinics and regions of the world, but show surprisingly good agreement regarding the primary causes of dizziness in children. Regardless of this fact, children suffering from vertigo and imbalance have received less attention in the literature than their adult counterparts.
There are several convincing reasons to assess a child's vestibular function. First, determining the integrity of the vestibular system can help physicians to diagnose the impairment and define the most appropriate course of treatment. Second, for those children with dizziness/vertigo who have serious health problems, the vestibular system assessment can help identify patients whose dizziness/vertigo stems from a significant neurological impairment (e.g., a brain tumor).
Episodic vertigo is rarely reported in children; when experienced, however, it may indicate the presence of vestibular dysfunction. Further, vertigo in children can manifest in many forms. For example, a child with acute vestibular system impairment may present with many of the same symptoms as adults (e.g. vomiting, nystagmus, hearing loss, or ataxia). As with adults, children with vestibular disorders also may present with a progressive or chronic loss of vestibular function that affects the development of postural control.
Despite the incidence of dizziness and vertigo in children, few dizziness clinics are dedicated to evaluating and treating this population. One explanation for this absence is the difficulty of extracting clinical and laboratory information from children. Children often will not report vertiginous symptoms because they cannot verbalize the abnormal sensations they are experiencing. Vestibular disorders in young children often are dismissed by professionals and caregivers alike (Tusa et al., 1994) and the symptoms consequently attributed to behavioral problems (e.g., finding ways to attract attention) or simply to being "clumsy." Finally, although there is interest in the development of techniques for assessing the vestibular system in adults, the same effort has not been applied to adapting these techniques for application to children.
David Cyr, one of the pioneers in the assessment of vestibular function in the pediatric population, focused much of his work in the 1980s on adapting existing adult protocols for use in children; many of these adaptations are still in use today. Interest in the assessment of the pediatric vestibular system has led manufacturers to develop both age-adjusted pupil-tracking algorithms and age-appropriate visual targets. The majority of manufacturers, however, do not offer videonystagmography goggles that are small and lightweight enough to accommodate small children. Despite these limitations, several groups of investigators have managed to identify the most common disorders that cause dizziness and vertigo in children and the abnormalities found on quantitative balance function testing (i.e. computerized rotary chair, video/electronystagmography, computerized dynamic posturography, and vestibular evoked myogenic potential testing).
Common Causes of Dizziness
A review of current literature indicates that the most common disorders reported to cause dizziness in children are otitis media, migraine headache, benign paroxysmal vertigo of childhood (BPVC), trauma, and vestibular neuritis (see Table 1 [PDF]). Interestingly, patients with any of these disorders can present with abnormal findings on balance function testing.
The most common diagnosis in children with vertigo and dizziness is migraine headache (i.e., migraine equivalent), although the temporal relationship has been reported to be variable (Casani et al., 2009). That is, migraine may precede, follow, or occur simultaneously with dizziness/vertigo, often with accompanying symptoms such as nausea and/or photophobia. However, the features also can be different from those seen in adults. In childhood, migraines often are localized to the frontal or periorbital region, last less than two hours, and may not manifest as the typical throbbing pain often described by adults. Approximately 20% of children with migraine have associated dizziness.
Benign Paroxysmal Vertigo of Childhood
The primary symptoms of BPVC include episodic attacks of vertigo lasting from seconds to minutes, resulting in the child being unable to stand without support. Additional symptoms include nystagmus, tinnitus, pallor, diaphoresis, and vomiting. BPVC is a pediatric migraine-equivalent (i.e. a migraine that manifests itself in a form other than head pain) recognized by the International Headache Society (IHS) classification system. During BPVC attacks there is no loss of consciousness; complete recovery follows an attack. A child who is capable will describe a sensation of spinning. The age of onset of BPVC has been reported to occur typically before 4 years (Finkelhor & Harker, 1987; Batson, 2004).
According to the U.S. Centers for Disease Control and Prevention, head traumas in young children are common. Children suffering from trauma-induced head injuries present with headaches, cognitive impairments, changes in personality, and sleep disturbances. Dizziness/vertigo is also a common diagnosis for a significant portion of children presenting with trauma (Faul et al., 2010). Head traumas are frequently subdivided into blunt head traumas and penetrating head traumas. Blunt head injuries, including whiplash injuries, can result in dizziness from fracture of the temporal bone or labyrinthine concussion. In cases of a fracture or concussion in which the labyrinth or vestibular nerve is affected, children can experience severe vertigo with nystagmus and nausea, indicating unilateral impairment in the peripheral vestibular system (i.e., end-organ or vestibular nerve). Penetrating head injuries have been reported to cause vertigo secondary to perilymphatic fistula. As in adults, pediatric benign paroxysmal positional vertigo (BPPV) secondary to head trauma also can occur.
Vestibular neuritis (i.e., inflammation of the nerve) in adults presents as a sudden onset of rotary vertigo and vomiting lasting for several days to weeks, and children suffering from an attack of vestibular neuritis often present with the same symptoms. The causative mechanism of vestibular neuritis continues to be controversial. The prevailing theory is that vestibular neuritis is viral in origin (Strupp & Brandt, 2009; Baloh, 2003). That is, a reactivated latent virus (e.g., herpes zoster oticus) could be responsible for transiently disrupting the transmission of neural activity from the end-organ ipsilateral to the impaired nerve. Others, however, have set forth that ischemic events as well as bacterial and other types of infections could also produce similar symptoms (Bartual-Pastor, 2005; Davis, 1993).
Different theories have been proposed as to how middle-ear pathologies can affect the vestibular labyrinth. One postulate is that toxins present in middle-ear fluid enter the inner-ear fluid and cause serous labyrinthitis. Other researchers have proposed that pressure changes in the middle ear cause displacements of the round and oval windows, leading to secondary movement of labyrinthine fluids (Golz, Netzer, & Angel-Yeger, 1998; Casselbrandt et al., 1995). Many published research studies have focused on how balance is affected by otitis media with effusion, although the etiology continues to be unclear (Waldron et al., 2004; Koyuncu et al., 1999; Golz, Angel-Yeger, & Parush, 1998; Jones et al., 1990).
Determining the cause of a vestibular disorder in a young patient requires a thorough team assessment with pediatric-specific adaptations.
Case History and Physical Exam
The case history is an important diagnostic tool for a child demonstrating a vestibular disorder. Most clinicians engage in informal observation prior to more formal evaluative measures. Informal observations may include measuring spontaneous and gaze nystagmus, ensuring conjugate eye movement, and oculomotor testing (such as pursuit and saccades). The clinician may check for head-shake nystagmus: After the child's head is gently moved back and forth, the clinician should see no nystagmus if peripheral vestibular function is symmetrical. Head-thrust testing also may be conducted to help determine status of the vestibulo-ocular reflex (VOR): The clinician gently turns the child's head to a 45-degree angle while the child maintains focus on the examiner's nose; as the head is guided to midline, the intact VOR should allow steady fixation on the target (see photo on p. 13).
Although benign positional vertigo (BPV) is uncommon, the clinician may easily test for it with Dix-Hallpike maneuvers. In this positioning test, the clinician guides the child from a sitting to lying position while turning the child's head right or left; children with BPV may experience nystagmus and/or dizziness after this maneuver.
Clinicians also may perform positional testing—if tolerated by the patient—to identify nystagmus and symptoms while the child's head and body are placed in supine, head right, head left, right lateral, and left lateral positions. Positional testing may be part of a more formal videonystagmography (VNG) battery. With VNG, goggles on the child's head allow infrared technology to record and analyze nystagmic activity. If the goggles are too large or the child will not tolerate them, electronystagmography (ENG) electrodes may be used.
Finally, the clinician may perform gait and balance tests, such as the Romberg test, in which the child stands with feet together while clasping the hands in front of the body; the clinician looks for sway when the patient's eyes are open and closed. The Tandem Romberg is performed in a similar manner, as the child places one foot in front of the other (see photo at left).
Formal Assessment Measures
ENG and VNG. VNG, the most common measure used for adult vestibular assessment, is a test battery that includes measuring spontaneous and gaze nystagmus, oculomotor testing, positional and positioning testing, and bithermal caloric irrigation. Gaze-evoked nystagmus is recorded via calibrated light bar with gaze 20 degrees to the right, left, upward, and downward. Oculomotor testing involves observance of smooth pursuit, optokinetic nystagmus (OKN), and saccadic eye movements. The light bar may adapt cartoon characters for the pediatric patient. Positioning and positional testing are performed. In bithermal caloric irrigation (BCI), which allows independent assessment of each peripheral vestibular system, the examiner stimulates the vestibular system with warm or cool air or water. Warm irrigations result in nystagmic activity beating toward the ipsilateral side and cool irrigations result in beating toward the opposite side. Contributions of each ear toward the total eye speed are calculated to determine presence of unilateral peripheral weakness.
VNG has proved to be a challenge with children younger than 6 or 7 years of developmental age. Advanced technology has brought more sophisticated measures, as discussed below, that have facilitated testing with younger populations.
Computerized Rotary Chair (CRC) Testing. Cyr (1980) successfully performed CRC on infants as young as 3 months. The simple harmonic acceleration subtest involves rotating the head and body at various test frequencies and time durations. Pediatric adaptations include seating the child on a parent's lap, developing a child-friendly enclosure, testing at only select frequencies, and tasking with familiar nursery rhymes.
Primary measures for analysis include gain (conveying information related to vestibular system output), phase (comparing head/eye movement timing), and symmetry (comparing right/left slow component eye velocity). Because of the nonlinearity of the anatomical system, patients should be tested at several frequencies (Valente, 2007). Step velocity testing has been performed successfully with children; time constant measures are calculated after reaching constant acceleration and rotational cessation.
Computerized Dynamic Posturography (CDP). This test measures functional balance and relative contributions of the visual, proprioceptive, and vestibular systems. Examiners have found it to be effective with children as young as 3 years of age. The sensory organization test (SOT) places the patient on a movable platform containing sensors for measuring force of the feet in response to movement. The patient faces a visual surround that may remain stable or be sway-referenced.
The SOT involves six conditions, with the patient relying on vestibular cues in the last two. Condition and composite scores are calculated for:
Platform and visual surround stable, eyes open.
Platform and visual surround stable, eyes closed.
- Platform stable and visual surround sway-referenced, eyes open.
Platform sway-referenced and visual surround stable, eyes open.
Platform sway-referenced and visual surround stable, eyes closed.
Platform and visual surround sway-referenced, eyes open.
Motor control testing places the child on a platform that undergoes unexpected perturbations. Forward and backward movements are of varying magnitude, dependent upon patient height and weight. Latency—the time from perturbation initiation to foot force in maintaining balance—is determined in milliseconds. Abnormally latent measures may indicate dysfunction. Pediatric adaptations include a child-friendly visual surround and diminishing numbers of trials, if attention span is limited, but they have not been studied extensively. Unexpected platform movements progress toward "toes upward" and "toes downward" positions. Each test involves several trials, results of which allow the clinician to note learning or practice effects as the session progresses. This information may prove invaluable, as applied toward any remediation strategies that may be recommended.
Vestibular Evoked Myogenic Potentials (VEMPs). The VEMP is an electrophysiologic measure that provides information to the clinician regarding status of the saccule. Because VEMP is quick and objective, numerous investigators have successfully performed it with children (Sheykholeslami et al., 2005; Kelsch et al., 2006; Valente, 2007). The test is performed by placing surface electrodes on the contracted sternocleidomastoid (SCM) muscle and sternum, with ground placement on the forehead. High-intensity auditory stimuli are presented through the ear canal to elicit a VEMP tracing (see photo above left).
Stimuli travel afferently toward the inner ear where the saccule and VIII nerve are stimulated and impulses are transmitted toward the central vestibular nuclei. The efferent pathway includes impulse travel toward the motoneurons of the neck musculature. The tracing consists of a positive peak (P1) and a negative peak (N1). A latency measure is defined as time in milliseconds between P1 and N1 peaks. The amplitude measure also is crucial, measured from P1 to N1 and expressed in microvolts. A third measure is threshold, the softest intensity level necessary for a VEMP waveform to be interpretable. Pediatric adaptations include seating the child on a parent's lap, having the child focus on cartoon characters to maintain proper position, and using selected frequencies. Research is needed related to age-differentiated normative data and findings that assist with differential diagnosis.
Any child with a vestibular disorder, even one that is subtle, should undergo extensive evaluation. As with hearing impairment, children receive great benefit from early identification. These benefits include the consequent early intervention that may be implemented via a team approach. Management strategies with the pediatric population are individualized and may include various types of medical treatment, surgical treatment, referral to other disciplines for vestibular (re)habilitation, and instigating a monitoring program to oversee possible effects of compensation and maturation.