Pediatric Otorhinolaryngology: Diagnosis and Treatment, 1st Ed.

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Pediatric Vestibular Dysfunction

Manali Shailesh Amin

Vestibular dysfunction in children is a commonly underdiagnosed problem. It is characterized by an inability to maintain visual acuity during movement. This impairment results in motor incoordination and places children at risk of injuries during normal play. Furthermore, vestibular dysfunction may impair a child's ability to integrate sensory stimuli.1

For a problem with such great health implications, vestibular dysfunction in the pediatric population is poorly understood. This is in large part the result of multiple barriers to diagnosis. To obtain a better understanding of pediatric vestibular dysfunction, one must first understand normal maturation and development of the vestibular system.

The vestibular system is the first of the sensory systems to develop. Embryologically, the membranous vestibular apparatus and the membranous cochlea both develop from ototcysts. The bony labyrinth develops from the surrounding mesoderm. Morphologically, the vestibular system is fully developed by the 49th day of gestation.2 Connections between the peripheral vestibular system and the central system and myelination continues until birth. The vestibular system is fully developed at birth but continues to mature with age. This maturation process is greatest during the toddler years and continues well into childhood. For instance, although the optokinetic response is present by 3 to 6 months of age, eye drift in a direction opposite to the rotating drum is seen up to 5 months of age when myelination of the visual pursuit system is completed. The saccadic system continues to develop until the age of 2. Furthermore, the ability to isolate these systems during routine activities and use them to complete more complex tasks such as reaching for an object while maintaining postural control continues to evolve into school age.3 An understanding of this maturation process is important when determining whether an abnormality exists.

In obtaining a history and performing a physical examination, one will often want to know if there are discrete vertiginous spells or an underlying balance disorder and whether the symptoms are associated with a hearing loss. This chapter is designed to provide an overview of some of the conditions that can present with a complaint of dizziness or balance dysfunction. It has been organized into two sections: (1) conditions associated with a hearing loss and (2) those conditions without a hearing loss. Knowing whether the vertigo spells are of an acute or chronic nature and whether or not they are episodic is also important. Time is often the best determinant of a diagnosis as some conditions may not become apparent until several spells have occurred.

Vestibular Disorders Associated with a Hearing Loss

It has long been known that children with hearing loss are more likely to have a vestibular problem. Unilateral or bilateral vestibular hypofunction may be seen with a congenital sensorineural hearing loss (SNHL) as well as some progressive mixed hearing losses. Vestibular hypofunction is seen in more than 30% of children with an autosomal dominant congenital hearing loss.1 Certain syndromes are associated with both vestibular dysfunction and hearing loss, such as Waardenburg syndrome, branchiootorenal syndrome, Pendred syndrome, Klippel−Feil syndrome, and Usher syndrome.

Acoustic Neuroma

Acoustic neuromas are the most common posterior fossa tumor in children. They may present rather insidiously. High frequency hearing loss and tinnitus often precede the vestibular complaints. Additional cranial nerve findings may also be apparent. In children, acoustic neuromas are most often associated with neurofibromatosis type 2. Audiologic testing may show worse speech discrimination than would be expected based upon pure-tone thresholds or auditory brainstem response (ABR) abnormalities. On ABR testing, an abnormal waveform or wave V latency of ≥ 0.2 ms may be noted. ABR abnormalities may not be apparent until the tumor is fairly large. By contrast, a magnetic resonance imaging (MRI) with gadolinium can detect tumors as small as 2 mm in size. The preferred treatment option in children is surgical excision. Gamma knife, which has been used in older adults, is not a good option in children given the effects of radiation over time.

Autoimmune Inner Ear Disease

Autoimmune inner ear disease (AIED) is characterized by a fluctuating, often progressive hearing loss, vertigo, light-headedness, ataxia, and motion intolerance. Although it usually affects both ears, unilateral presentation may be seen. Patients will occasionally complain of tinnitus and/or aural fullness, making it difficult to distinguish from Ménière disease. AIED is associated with a systemic autoimmune disease in 15 to 30%. Symptoms generally progress over weeks to months and may improve on steroid treatment. There are isolated reports of vestibular dysfunction in the absence of hearing loss. Electronystagmogram (ENG) findings vary depending on whether one or both ears are affected. Partial recovery of vestibular function after steroid administration as measured in caloric testing and regression upon discontinuation has been reported. There are no definitive tests to diagnose AIED. Treatment of this relatively rare disease may be with steroids or chemotherapeutic agents.

Enlarged Vestibular Aqueduct

An enlarged vestibular aqueduct (EVA) is associated with a mixed or SNHL that may be mild to profound, fluctuating to progressive, or even sudden in presentation. Vestibular dysfunction ranges from mild clumsiness or imbalance to true vertigo and may be associated with oscillopsia or a tullio phenomenon. An EVA can be unilateral or bilateral and may be isolated or associated with a Mondini dysplasia of the cochlea. The mechanism for vestibular dysfunction is not well understood but is felt to result from a third window effect similar to the effect seen in superior canal dehiscence syndrome (SCDS). In fact, on vestibular-evoked myogenic potential (VEMP) testing, the thresholds may be lowered and amplitudes higher just as one would see in SCDS.

Eustachian Tube Dysfunction and Middle Ear Effusion

Eustachian tube dysfunction and middle ear effusion (MEE) are among the most common diagnoses resulting in a complaint of imbalance in younger children. A child may present with symptoms of clumsiness, unsteadiness, and falls. MEE generally presents with limited tympanic membrane mobility on pneumatic otoscopy, conductive hearing loss (CHL), and middle ear dysfunction on tympanometry. Vestibular dysfunction is equally likely with a unilateral effusion as it is with bilateral effusions. An ENG is not necessary for diagnosis. Treatment consists of watchful waiting for spontaneous resolution of the effusions or myringotomy and extraction of effusion with or without tube placement.

Labyrinthine Concussion

A labyrinthine concussion can follow some forms of head injury, especially one to the temporoparietal and occipitoparietal areas. Symptoms can include headaches, nausea/vomiting, visual disturbances, irritability, personality changes, and sleep disturbances. Vestibular symptoms include vertigo, a tilting sensation, dizziness, and unsteadiness. Vertigo will sometimes present as recurrent attacks which last 5 to 10 seconds and are associated with nausea. Unsteadiness usually manifests as sway to the affected side. Symptoms are usually present for a few days and then subside over a 4- to 6-week period but balance problems may be seen for years, especially with tandem gait and on Romberg testing with eyes closed. Dix−Hallpike testing may be positive for a nystagmus, consistent with an associated benign paroxysmal positional vertigo (BPPV). Rotational chair testing is usually normal.

Ménière Disease/Endolymphatic Hydrops

Ménière disease is extremely rare in children. Symptoms include recurrent paroxysmal vertigo, SNHL, aural fullness, and tinnitus. Hearing loss may be fluctuating to progressive and unilateral or bilateral. In adults, the hearing loss is often reported to be a low frequency loss. By contrast, in children, the hearing loss may initially be high frequency. There is often a positive family history for Ménière and a personal history of allergic rhinitis and/or AIED.

Hydrops can also manifest in individuals with congenital cytomegalovirus (CMV) or otosyphilis. Children with congenital CMV have variable vestibular function. Some may have normal function while others have unilateral or bilateral peripheral hypofunction and delayed ambulation. Alternatively, vestibular symptoms may not present for many years. Vestibular testing including cochlear hydrops analysis masking procedure and electrocochleography can assist in making the diagnosis.4 In addition, a unilateral weakness on caloric testing and asymmetry on rotational chair testing may be seen if only one ear is affected.

Ototoxicity

Many medications are alleged to produce vestibular ototoxicity including aminoglycosides, various other antibiotics (such as minocycline, erythromycin, polymyxin, and chloramphenicol), loop diuretics, salicylates, quinidine, barbiturates, and certain chemotherapeutic agents including cisplatin. In addition to vestibulotoxicity, most of these medications typically destroy the outer hair cells in the basal turn of the cochlea leading to a high frequency SNHL. Patients may present with disequilibrium, an ataxic gait, and oscillopsia. Both the vestibulo-ocular reflex (VOR) and vestibulospinal reflexes are affected. Therefore, rotational chair testing may show reduced gains and time constant. Posturography will usually result in falls on sensory organization test 6.5 When oscillopsia occurs, it is generally with severe damage secondary to a loss of the VOR. These patients may have significant difficulty walking in the dark or on uneven surfaces and may have to navigate by holding onto walls and furniture.

Perilymph Fistula

Perilymph fistula (PLF) may result from a direct injury to the labyrinth or as a result of barotrauma or otologic surgery. Patients present with imbalance, vertigo, progressive SNHL, tinnitus, and nystagmus. The injury can be either unilateral or bilateral. On examination, positive pressure may result in nystagmus and is present in approximately 25% of patients. A computed tomography (CT) scan may show an anatomic abnormality which may predispose a child to a PLF such as a Mondini deformity. The definitive diagnosis is made by seeing perilymph on middle ear exploration.

Superior Semicircular Canal Dehiscence

In the late 1990s, Dr. Lloyd Minor first described the condition now commonly known as SSCD. This disorder was considered to be primarily one that affects adults. Children, like adults, present with symptoms of vertigo and oscillopsia with or without an associated nystagmus that may be induced by loud sounds (Tullio sign) or changes in pressure (Hennebert sign). Others may complain of autophony or hearing their own pulse or eye movements. On examination with Valsalva or holding their breath against a closed glottis, one may see vertical torsional eye movements. On audiogram, one may see a pseudo CHL in which bone conduction thresholds are better than 0 dB with normal pure tone averages or a CHL with air bone gaps at the lower frequencies. The stapedius reflex is usually normal. The dehiscence can be seen on high-resolution computed tomography (HRCT) scanning. VEMPs will almost always show a low threshold and high amplitude.

Temporal Bone Fractures

Temporal bone fractures are traditionally described as either transverse or longitudinal. Fractures which are parallel to the petrous bone are considered longitudinal while those which are perpendicular are transverse, although in reality most fractures are oblique. Transverse fractures may violate the internal auditory canal, semicircular canals, vestibule, cochlea, or facial nerve. Symptoms include hearing loss, vertigo, nausea, and vomiting. A spontaneous nystagmus may be seen. Hearing loss is usually immediate and severe but can be progressive if there is a PLF or if a patient develops endolymphatic hydrops. There are several theories on how hydrops may develop after a fracture including possible fracture and secondary occlusion of the vestibular aqueduct. Other mechanisms of injury that may result in vertigo include disruption of the membranous labyrinth, vascular vasospasm, thrombosis or hemorrhage, and disruption of the endosteum of the round window or oval window with resulting PLF. HRCT can establish the diagnosis. On vestibular function testing, one may see a spontaneous nystagmus toward the good ear. Sway on posturography is usually toward the injured ear and if rotary chair or caloric testing is done, abnormalities of the VOR may be seen.

Vestibular Labyrinthitis/Neuronitis

Vestibular neuronitis and labyrinthitis are characterized by sudden onset of vertigo that lasts for a few days with unsteadiness persisting for weeks to months. If it is associated with an acute hearing loss, it is considered vestibular labyrinthitis. In the absence of hearing loss, it is vestibular neuronitis. A horizontal nystagmus beating toward the healthy ear may be seen. It often follows an upper respiratory tract infection and is considered to have a viral etiology, possibly herpes simplex virus, measles, or mumps. The viral infection is felt to cause damage to the superior branch of the superior vestibular nerve. Utricular dysfunction can be seen in both while saccular dysfunction is seen primarily with labyrinthitis. Caloric testing will often show a decreased response in the affected ear. Rotational chair testing may show asymmetry and VEMPs may be absent in about one-third of patients. Subjective visual horizontal testing may show a deviation of the line from the horizontal with the affected side down.

Whiplash Injury

Whiplash can result in symptoms of dizziness, tinnitus, and occasionally hearing loss and visual disturbance. It typically follows a motor vehicle accident. The mechanism of action is not understood but theorized to result from cervical muscle spasm or decreased blood flow through the vertebrobasilar circulation as a result of sudden acceleration and deceleration. Before proceeding with any testing, it is important to ensure that the C-spine has been cleared. This injury is felt to primarily affect the cervico-ocular reflex (COR). COR gains are likely to be reduced generally as a result of reduced neck movements. A positional nystagmus may be seen with the head hyperextended. A spontaneous nystagmus or gaze-evoked nystagmus may also be seen as well as VOR abnormalities. Otolithic dysfunction has only been sporadically reported.

Dizziness with Normal Hearing

A majority of the children who present to an otolaryngology practice with complaints of dizziness or vertigo do not have an associated hearing loss. In fact, most will not have a vestibular problem. However, it is important to understand some of the other common disorders that may result in a consultation to appropriately manage the patient. Often, a neurology, ophthalmology, or cardiac evaluation may provide additional information.

BPPV

BPPV, the most common vestibular etiology for dizziness in the adult, is an uncommon finding in children. When it is seen, it most often follows a traumatic event in older children. Some theorize that the otoconia in children are more tightly adherent to the macula and, therefore, less likely to become dislodged. The classic description is of posterior canal BPPV and is characterized by sudden attacks of vertigo, nausea, and vomiting triggered by certain head movements and positions. A Dix−Hallpike maneuver will result in a rotary nystagmus which begins after a latency of a few seconds and is of limited duration. It fatigues with repeated provocation. The proposed mechanisms are canalithiasis, in which otoconial debris floats freely within the semicircular canal and cupulolithiasis, in which the debris adheres to the cupula of the canals. In both situations, the resulting disruptions of endolymphatic flow within the semicircular canal leads to a nystagmus and sensation of vertigo with head movement. Treatment consists of an Epley maneuver or one of its many modifications. In rare cases, surgical intervention with canal plugging, singular neurectomy, vestibular nerve section, or labyrinthectomy may be considered for intractable vertigo.

Chiari Type I Malformation

Chiari type I malformation is characterized by a herniation of the cerebellar tonsils through the foramen magnum. Before the availability of MRI, this was an uncommon diagnosis. The age of onset of symptoms is variable. Children with a Chiari malformation often present with torticollis, headaches, vocal cord paralysis, swallowing difficulties, ataxia, and opisthotonus. Vestibular symptoms are variable and can include oscillopsia, diplopia, blurred vision, and vertigo. On examination, horizontal or downbeat nystagmus is most commonly seen. Other findings include a jerky motion on pursuit and abducens palsy. Chiari malformation results in oculomotor and central vestibular dysfunction. Central abnormalities may be seen on electronystagmography. An MRI showing herniation of the cerebellar tonsils is diagnostic and posterior fossa decompression may result in improvement and/or resolution of symptoms.

Migraine/Migraine Variant

Migraine and migraine variants are the most common etiology of pediatric dizziness. A possible etiology for this condition may arise from paroxysmal ischemia of the vestibular nuclei. Paroxysmal torticollis and benign paroxysmal vertigo (BPV) of childhood are childhood periodic syndromes that are felt to be migraine precursors. In fact, some children who initially present with paroxysmal torticollis will later go on to develop BPV and possibly migraines or migraine variants as an older child. These children should generally be referred to a neurologist.

Paroxysmal torticollis is characterized by episodic torticollis which lasts between 4 hours and 4 days and can be associated with pallor, vomiting, and behavioral changes. It typically presents between the age of 2 to 8 months and has a female predilection. The frequency and duration of the episodes decline as a child grows older. Treatment includes watchful waiting, avoidance of triggers if they can be identified, and in rare cases, pharmacologic intervention.

BPV of childhood begins before the age of 5 and resolves within 2 years of onset. Unlike migraines, males and females are affected equally. It is characterized by rotary vertigo lasting from seconds up to 5 minutes. It may be associated with pallor, nausea, vomiting, and diaphoresis. There are usually no complaints of headaches or tinnitus. Younger children may cry inconsolably and appear frightened. Episodes eventually resolve spontaneously. Treatment consists of watchful waiting and avoidance of identifiable triggers. In severe cases, prophylactic cyproheptadine may be considered.

Migraine variant vertigo typically begins around the age of 8 and is characterized by vertigo of several minutes’ duration. Children may have associated pallor, nausea, vomiting, and noise or light sensitivity. There is usually a family history of migraines. Triggers are similar to migraine triggers and include fatigue, stress, missing a meal, travel, climate changes, and bright lights. Symptoms usually resolve with sleep but can be severe enough to warrant medication.

Finally, no discussion on migraines and dizziness is complete without a mention of basilar migraines. Basilar migraines present in older children and adolescents. Symptoms include vertigo, tinnitus, decreased hearing, headaches, ataxia, dysarthria, visual symptoms, diplopia, paresthesias, and decreased level of consciousness. It is felt to be secondary to decreased blood flow through the basilar artery and resulting ischemia of the occipital lobe and brainstem.

Ocular Abnormality

Vision problems should not be overlooked in children who complain of dizziness. In one study, 5% of children referred for vestibular testing had an ocular disorder.6

Posttraumatic Epilepsy/Epileptic Vertigo

Posttraumatic epilepsy presents in 5 to 7% of children after a closed-head injury. The central vestibular system is affected including the frontal, parietal, and temporal lobes. In particular, damage is most often seen in the superior temporal lobe, middle temporal gyrus, and supramarginal and angular gyrus. The resulting epileptic discharges often present as vertigo. Hearing is usually normal. In some instances, the seizure may stem from pursuit eye movements rather than presenting as vestibular dysfunction. An electroencephalography will be abnormal but may need to be completed in the sleep-deprived state. Finally, an ENG may show directional or labyrinthine preponderance.

Vertebrobasilar Insufficiency

Vertebrobasilar insufficiency (VBI) is the result of occlusion of a vertebral artery or of one of the posterior inferior cerebellar arteries or its branches. Lateral medullary infarction (also known as Wallenberg syndrome) or cerebellar infarction can result. Although less likely, VBI may also occur secondary to an arterial dissection. Patients complain of vertigo and headache on examination, they may be ataxic, dysarthric, and exhibit a nystagmus. Several types of nystagmus have been described including horizontal, horizonto-rotary, torsional, see-saw, and others. A lateral medullary infarct, in particular, is characterized by a horizontal nystagmus that beats away from the side of the lesion. Vestibular testing may show multiple abnormalities. On VEMP testing, one may see normal latencies but contralateral large amplitude. Dysmetria may be seen on saccade testing. Usually the patient overshoots to the side of the infarct and undershoots to the contralateral side. On smooth pursuit testing, mildly saccadic eye movements are noted and the child may fall on sensory organization tests 5 and 6 on posturography. The results of caloric testing when done are usually normal.

References

1. Phillips JO, Backous DD. Evaluation of vestibular function in young children. Otolaryngol Clin North Am 2002;35(4): 765–790

2. Nandi R, Luxon LM. Development and assessment of the vestibular system. Int J Audiol 2008;47(9):566–577

3. Saavedra S, Woollacott M, van Donkelaar P. Effects of postural support on eye hand interactions across development. Exp Brain Res 2007;180(3):557–567

4. Lee JB, Choi SJ, Park K, et al. Diagnostic efficiency of the cochlear hydrops analysis masking procedure in Ménière's disease. Otol Neurotol 2011;32(9):1486–1491

5. Black FO, Pesznecker SC. Vestibular ototoxicity. Clinical considerations. Otolaryngol Clin North Am 1993;26(5):713–736

6. Anoh -Tanon MJ, Bremond-Gignac D, Wiener-Vacher SR. Vertigo is an underestimated symptom of ocular disorders: dizzy children do not always need MRI. Pediatr Neurol 2000;23(1):49–53

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