Introduction

Pediatric vestibular evaluation has become more established in audiology and otolaryngology clinics over recent years. Along with early identification of hearing impairment, early identification of vestibular disorders has allowed earlier and perhaps more effective remediation strategies in children complaining of dizziness or balance disorders. Researchers and clinicians have contributed valuable information related to vestibular disorders that may be diagnosed in the pediatric population. There has been a paucity of both clinical and research work related to vestibular evaluation techniques that may be used with young children. The current chapter focuses on the adaptation of adult vestibular evaluation techniques for use with pediatric patients, beginning with the medical/physical examination and progressing through major tests of vestibular function. An important concept recurring throughout is that the use of pediatric normative data is crucial so that results obtained after testing a child are not compared with adult normative data.

Taking the History

Many clinicians who perform vestibular evaluation have remarked that the case history is one of the most important diagnostic tools available when evaluating a dizzy patient. Although the author firmly believes that this premise also holds true for pediatric patients, a need exists within the profession for the development of a reliable parent questionnaire. Clearly, answers to certain questions are invaluable: concerns related to the child’s development and gross motor skills, description of episodes encountered, time course of symptoms, onset of symptoms, complaints that may be interpreted as peripheral signs, and complaints that may be interpreted as central signs. On searching the literature regarding vestibular evaluation in children, one may view several different bodies of work. On the one hand, physical therapy and occupational therapy studies document evaluation and remediation techniques used with disorders such as autism, motor delay, learning disability, and behavioral disorders. Although the evaluative tools are fascinating, they are very different from those discovered within the audiology and otolaryngology bodies of literature. Many studies within the latter group link vestibular disorders to entities such as migraine syndrome, benign paroxysmal vertigo of childhood, otitis media, sensorineural hearing loss, and a myriad of childhood syndromes. Additional research related to vestibular consequences of such syndromes is in order, including CHARGE (coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, ear abnormalities) association, Cogan syndrome, Usher syndrome, Waardenburg syndrome, and others. Inasmuch as evaluative tools and remediation strategies are highly variable among groups of practitioners, a secondary goal would be improved opportunities for interprofessional education and practice.

Many challenges have historically existed with regard to vestibular evaluation of children. One critical challenge is that pediatric patients may not be able to thoroughly describe dizziness and other “vestibular” symptoms, giving rise to the necessity of developing appropriate checklists and parent questionnaires. Another challenge related to vestibular evaluation in general is that the cost of many pieces of technologically advanced equipment is prohibitive, regardless of patient age. Here, we start with the basics, the history and physical examination.

The Informal Evaluation (Medical-Physical Examination)

Following the history, the physical examination is undertaken to search for possible etiologies of dizziness or balance disturbance. This section highlights the adaptation of adult screening techniques for pediatric patients and describes the relative ease of performance in an office setting with little or no elaborate equipment. The clinician starts with the standard physical examination with special attention to the eye/visual examination, ear examination, and neurologic examination. Of particular interest in the eye examination is the presence of nystagmus. The clinician begins the informal evaluation by checking for spontaneous nystagmus and/or gaze-evoked nystagmus. One simple method is to have the child look straight ahead, if the child is able to follow such verbal commands. This portion of the evaluation may be referred to as the “static evaluation,” in that the examiner is not eliciting nystagmus in any way. The examiner looks for horizontal or vertical nystagmus. Nystagmus in any direction should not be present under typical conditions (unless congenital), and additional testing helps determine if the disorder is peripheral or central in nature.

The “dynamic evaluation” involves a battery of testing that attempts to elicit nystagmus and observe various types of oculomotor tasks. While assessing gaze nystagmus, the examiner asks the child to follow the examiner’s finger as it moves to the right and left and in upward and downward directions. Modifications for young patients may include the use of puppets or cartoon videos to encourage the child to look in cardinal positions of gaze. Presence or absence of nystagmus is observed, bearing in mind that nystagmus should not be present with a typically functioning vestibular system. Tasking (keeping the child mentally alert through informal conversation, establishing rapport, easy mental “tasks” such as counting) is important with regard to many vestibular tests, including the assessment of spontaneous nystagmus and especially gaze-evoked nystagmus, such that any nystagmic response is robust and not suppressed. Tasking must be geared toward the child’s age and capabilities. It may be possible to use Frenzel lenses for eye magnification and alleviation of visual fixation suppression, depending on the child’s age. At this point, the clinician may also briefly check to determine that the eyes are moving conjugately.

As the clinician continues with the dynamic evaluation, “head-shake nystagmus” (HSN) may be considered. According to Fife, the vestibulo-ocular reflex (VOR) should be readily observable by the age of 9–12 months in typically developing infants. The purpose of the VOR is to stabilize gaze, particularly as the body and head are moving. The horizontal VOR is the most commonly studied and is represented by the following example. When the head moves to the right in a sustained rotation, the right vestibular system is excited while the left is inhibited. This is often referred to as a “push–pull” mechanism. The eyes move to the left (slow phase in the opposite direction) and rapidly snap back to the right. This process continues, enabling the examiner to observe a right-beating nystagmus. Nystagmus direction is named for the fast phase and is measured according to its slow phase velocity in degrees per second. The opposite is true with leftward rotation, resulting in left-beating (fast phase) nystagmus.

The presence of nystagmus and other eye movements may be enhanced via Frenzel lenses, electrooculography (EOG), or infrared videooculography (VOG). As with adults, the child’s head may be gently rotated to the left and right (as though shaking the head “no”) in a rhythmic manner at approximately 1–2 Hz to check for the presence of HSN. Theoretically, symmetrically functioning vestibular systems do not induce symptoms in view of alternating the excitation and inhibition process between systems as the head moves from right to left. Some children may not be in a position developmentally to verbalize the presence of symptoms, such as dizziness or vertigo, on head rotation. Nystagmus should not be observed with symmetric peripheral vestibular systems, although it may be observed in the presence of an asymmetry. Such HSN screening may be advantageous in situations where caloric irrigations and/or rotary chair (RC) testing may not be feasible. If such measures are available, HSN screening may provide complementary information by incorporating higher frequencies of head motion. It should be noted that much of the standard vestibular test battery assesses low-frequency reactivity of peripheral vestibular organs.

Head thrust testing (HTT), also termed head impulse testing (HIT), may be performed with young children. This procedure is also based on the VOR. The examiner gently rotates the child’s head approximately 30 degrees to the right or left while asking the child to focus on the examiner’s nose or some other stable target. One may creatively devise placement of colorful stickers or cartoon characters for facilitation of such head movement and have the child focus on the target. The examiner incorporates a brief and rapid head thrust back to midline while making certain that visual fixation is maintained. A corrective “catch-up” saccade may be seen in the form of deviation from the target and a rapid refixation of the eyes on the target. This abnormality may indicate a disorder of the ipsilateral horizontal semicircular canal. Thus, if the refixation saccade is identified on head thrust to the right, it is the right horizontal semicircular canal that is impaired (and the converse is true for the left). Fig. 4.1 displays the successful demonstration of the HTT with a 3-year-old child. The technique for HSN would look very similar.

Example of clinician preparing to perform head impulse testing/screening with a 3-year-old child.

Children may also be evaluated via dynamic visual acuity (DVA) techniques, with modification of the typical Snellen eye chart for this population. Familiar to most, this chart is highly used during eye examinations as the patient reads smaller and smaller lines of various letter “E” configurations. Child-friendly characters may easily be substituted for the more traditional letters that become smaller with each line. With this procedure, a baseline is obtained in the form of the smallest line of characters that the child may discern from a calibrated distance. The child again attempts to read the smallest line of figures during horizontal rotation of the head, approximating 1–2 Hz. On reading, a loss of one line may be considered insignificant, whereas a loss of three lines or more may indicate VOR deficiency. Advances in computerized technology may facilitate obtaining results.

The clinician may also perform rudimentary oculomotor tasks, such as checking saccadic eye movement. This may be performed by rapidly moving a finger or some other target, ensuring that the child follows the rapidly moving stimulus and meets the target. With more formal measures, the child may follow a series of rapidly moving lights, even described as “ladybugs moving across a screen,” and the examiner assesses the latencies obtained. Latency refers to time parameters and indicates whether the speed of attaining each target is within normative data parameters. Oculomotor testing may also determine the “smoothness of pursuit” by asking the child to follow a visual target (e.g., finger, puppet, or cartoon) moving rhythmically from right to left. This cycle is repeated, and the eyes are observed to note any deviation from a smooth pursuit of the target.

Although children rarely demonstrate the true benign paroxysmal positional vertigo (BPPV) that may be present in adults, they may experience positional vertigo and/or sudden vertiginous episodes. They also may experience benign paroxysmal vertigo of childhood that is not positional but occurs at random times and is episodic. Positioning and positional testing, therefore, may be successfully performed with children.

With all procedures, establishing rapport with the child is critical, and the child’s comfort level may be increased by being seated on a parent lap and/or by having a parent present. The traditional Dix-Hallpike maneuver is the classic assessment tool for the determination of BPPV. This maneuver involves rapidly moving the patient from a seated position to a lying position with the head turned in one direction. The clinician observes the presence or absence of nystagmus. Subjective symptoms are also noted. A positive Dix-Hallpike maneuver occurs with the elicitation of torsional nystagmus and a report of dizziness. If positive, it is beneficial to repeat this measure to help determine if the response fatigues. The procedure is repeated as the patient lies back and turns the head in the opposite direction. As this positioning procedure is time-efficient and noninvasive, this procedure and more traditional positional testing may be performed with children. It is important for the child to be able to understand instructions and to receive continual reassurance, in view of a potentially darkened-room environment.

With positional testing, the examiner places the head and body in various positions to help determine if any such change in head/body position elicits nystagmus and/or dizziness. Typical head and body positions may be similar to those performed with adults: supine, head right, head left, right lateral, and left lateral. As the clinician searches for the presence of nystagmus, it is also important to supplement this information with any subjective reports of symptoms that the child may express.

Finally, the clinician may ask the child to perform various types of standing balance tasks for screening postural stability. Examples may include Romberg maneuvers where the child stands with feet together, and sway is noted with eyes both open and closed. A variation is the tandem Romberg, where such stability is evaluated with one foot in front of the other, touching heel to toe. Fig. 4.2 depicts the author teaching a 3-year-old patient the tandem Romberg test.

A 3-year-old child learning tandem Romberg techniques.

The examiner may ask the child to march in place with eyes closed to determine straightness versus deviation of marching or may encourage the child to walk forward in a heel-to-toe pattern. With the latter, cerebellar dysfunction may be suspected if difficulties arise. Other cerebellar signs may include slurring of speech, upper or lower extremity dysfunction, ataxia, muscle incoordination, dysmetria, tremors, or abnormalities noted on oculomotor tasks.

Formal Vestibular Evaluation Measures

Videonystagmography and Video-oculography

The formal vestibular evaluation is a battery of tests that assists the clinician in determining if dizziness is of central or peripheral origin. With the advent of infrared cameras mounted in eye goggles to replace electrodes for recording and measuring eye movement, VOG, or videonystagmography (VNG), has replaced EOG, also called electronystagmography (ENG), in most clinics. An example of such goggles is shown in Fig. 4.3 , with the clinician making use of the smallest size possible for evaluation of the pediatric patient. Electrodes may be challenging with children, in view of discomfort in application and removal. Many children accept the eye goggles used for VNG, especially if their placement is framed by the examiner in a “gamelike” manner.

Goggles used for videooculography and rotary chair testing.

Courtesy of and with permission from Micromedical Technologies, Inc.

VNG has revolutionized oculomotor assessment and vestibular testing, in that there are now mechanisms to better observe, record, and measure eye movements. If VNG results suggest peripheral vestibular dysfunction, components of the test battery may help the clinician determine the affected inner ear. Components of this test battery include testing for spontaneous nystagmus and gaze nystagmus, performing various oculomotor tests, measuring positioning and positional nystagmus, and performing caloric irrigations. Several investigators have effectively described some of the adaptations of adult VNG techniques that may be used with children.

As the parent makes certain that the child is optimally prepared for vestibular evaluation, it is important that certain medications (such as those for cough or cold) be withheld for 24–48 h under medical supervision. As some aspects of the test battery may induce nausea, it is important that the child eats only lightly before the appointment time. VNG should be performed in a darkened room so that visual fixation of nystagmus does not occur; therefore children may feel more comfortable when a parent is present in the examining room. At the beginning of the VNG, a calibration procedure is performed using a light bar, and the patient is asked to look repeatedly from left to right. Children’s attention may be maximized if asked to focus on interesting cartoon characters that illuminate in place of the lights. Oculomotor tests may also be performed with a light bar or flat-screen television. These tests include measurement of saccades or rapid eye movements, optokinetic testing (reflexively following lights that induce the slow and then fast phase of nystagmic eye movements), and sinusoidal tracking to evaluate smooth pursuit.

With all of these oculomotor tests, interesting cartoon characters may replace the traditional lighting, resulting in greater ease of testing the pediatric patient. Just as with audiometry, the clinician may wish to use an assortment of cartoon characters to regain attention, should habituation or fatigue take place.

Measurement of spontaneous nystagmus, addressed in a previous section, may be more formally measured as an initial component of the VNG test battery. The child is asked to sit quietly as the clinician records and analyzes eye movement with eyes open and with vision compromised (e.g., with Frenzel lenses). Contrasting of measurements with eyes open and vision compromised may better enable the examiner to pinpoint peripheral versus central pathology. Eye movement is not elicited in any way during spontaneous nystagmus testing, and the examiner exercises care in making certain that tasking measures appropriate for the individual child are carried out. For example, the child may listen to nursery rhymes or familiar children’s songs. As a more active approach, the child may be able to tell a story about a recent cartoon or movie. Gaze nystagmus may be recorded by having the child look at a light bar displaying interesting cartoons, or the clinician may ask the child to “look at the lightning bugs” if a traditional light bar is used. In this manner, it is feasible to measure gaze nystagmus in cardinal gaze positions. The Dix-Hallpike maneuver, traditionally performed with adult patients to help diagnose BPPV, may be easily performed with children. The clinician thoroughly explains to the child that a positioning procedure will take place as the clinician assists the child in progressing from the sitting to lying position with the head turned either to the right or the left. The examiner checks for the presence of nystagmus and elicits a subjective report of symptoms, if the child is capable of reporting such symptoms. Traditional positional testing may also be carried out with children, with the most common positions: supine, head right, and head left. The clinician may use judgment regarding expanding the test battery to include right and left lateral, as well as other, positions.

Such positioning and positional testing may prove challenging with young children, especially if the child has difficulty following instructions. Adaptations of positioning and positional testing with children include the establishment of excellent rapport, having a parent present, and ensuring that the child is comfortable at all times. The clinician should be conscious of allaying fears throughout the evaluation, especially if the testing is performed in a darkened room. Many children with hearing loss exhibit vestibular disorders and may be referred for vestibular testing. Such children may need specific modifications, such as making certain that hearing devices are in place and/or providing signs with written instructions when necessary. Children who communicate via sign language may be effectively tasked by asking them to sign stories or words to familiar children’s songs. The examiner may creatively think of additional modifications that may be implemented with children demonstrating other types of disability.

Bithermal caloric irrigation, considered “a gold standard” in evaluating the status of each ear independently, is arguably the most challenging to implement with a pediatric patient. In this author’s experience, this section of the test battery may reliably be performed by the developmental age of 5–6 years (although much variability exists among children). The clinician irrigates each ear canal with warm and cool water or air, stimulating the vestibular system and recording slow-phase eye movement velocity with each of four responses. Nystagmus should be induced here, as the vestibular systems are being excited (warm irrigations) and inhibited (cool irrigations) with such procedures. Small children may not tolerate this stimulating irrigation or lying still for several minutes as the postirrigation nystagmic response is measured. Children may be fearful of the irrigation equipment and procedure and also of becoming dizzy or experiencing the sensation of movement following stimulation. Fig. 4.4 displays state-of-the art VNG equipment that may be easily adapted for children, including the goggles, light bar/flat-screen television, and computerized recording equipment.

Videooculography equipment, including flat screen television, goggles, and computerized console for test performance and data analysis.

Courtesy of and with permission from Micromedical Technologies, Inc.

Adaptations are numerous, including selection of water, closed loop (water), or air irrigation systems. With a closed loop system, a balloonlike sleeve is placed upon the irrigator tip such that the water warms or cools the system while not actually touching the tympanic membrane. Some clinicians have experienced success with closed loop or air systems, whereas others have found that children enjoy a water and “bathlike” analogy. When using water irrigation, it is important to ensure the tympanic membranes are intact; water irrigation in the setting of a tympanic membrane perforation or ventilation (tympanostomy) tube is contraindicated.

Many pediatric evaluative techniques approach a screening, as opposed to thorough diagnostic evaluation, and this may be the case with caloric testing. The examiner, for example, may choose to perform two instead of four irrigations to achieve success in obtaining some type of reliable measure for each ear. Although there may be equipment challenges in doing so, it also may be possible to perform bilateral simultaneous irrigations to diminish test time, number of irrigations, and negative postirrigation patient response. Tasking during caloric testing is critical. It is also very important to calm fears and to view the resulting nystagmus on a video monitor, in addition to viewing computer calculations following each irrigation. In other words, one is observing the recording of eye movement as it occurs following each caloric irrigation and noting computer calculations in degrees of eye movement per second as a system of checks and balances. Fig. 4.5 demonstrates the image of the eye projected on a computer screen, so that the clinician may supplement computerized data analysis with subjective viewing of nystagmus.

Television monitor that allows clinician to subjectively view patient’s eye movements.

Courtesy of and with permission from Micromedical Technologies, Inc.

Along with advances in computerized technology, additional vestibular evaluative procedures have been developed for use with adults: rotary chair, video head impulse test (vHIT), gaze stabilization test (GST), computerized dynamic posturography (CDP), and vestibular evoked myogenic potentials (VEMPs). Adaptation of these techniques has been very valuable with children, especially in view of the challenges faced in performing some aspects of the VNG test battery with very young children.

Rotary Chair

Use of computerized RC has served to complement the vestibular evaluation battery with adult patients. RC results may help substantiate questionable VNG results and also may help evaluate the VOR at additional test frequencies. Fig. 4.6 shows an example of the RC equipment that is currently available and that may easily be adapted for patients of all ages.

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