DIZZINESS, VERTIGO AND DISORDERS OF EQUILIBRIUM IN CHILDREN

Equilibrium is the ability to maintain orientation of the body and its parts to external space. A continuous input of visual, labyrinthine and proprioceptive stimuli are required, for integration in the brainstem and cerebellum. A disturbance in any of these pathways result in disorders of equilibrium, usually presenting with either vertigo or ataxia.¹ 

Definitions 

Vertigo is a sensation of movement of the patient or environment.² Dizziness is a sensation of unsteadiness with a feeling of movement with the head. Accurate description of the exact sensation is difficult, especially with the child. Other common descriptions may include a spinning sensation, light-headedness or a floating sensation. 

Ataxia refers to incoordination or clumsiness of movement which is not the result of muscular weakness. It can affect speech, eye movements, limbs, trunk, stance or gait.  

It is important to bear in mind that vertigo and dizziness are merely symptoms, and accurate establishment of a diagnosis is possible only after proper evaluation of a patient.

Approach to Giddiness and Vertigo in Children 

a) Non-vertiginous giddiness

Frequently in practice, the child complains of dizziness which is non-vertiginous in nature. He/she presents with light-headedness and faintness, and this may even culminate in syncope. These are conditions which impair blood, oxygen or glucose to the brain eg. excessive vagal stimulation, cardiac arrhythmia, orthostatic hypotension. They can also be a side-effect of certain medications. Hence in evaluation of the giddy child, a proper history to exclude the above are essential. 

b) Vertigo and localization

In true vertigo, the causes can be divided into peripheral and central in origin. 

Peripheral vestibular lesions affect the labyrinth of the inner ear or the vestibular division of the acoustic (VIII nerve). These lesions tend to be intermittent and last for briefer periods. They are commonly associated with hearing loss or tinnitus. Nystagmus is an associated sign, and is usually unidirectional and never vertical. The child has a normal neurological examination.^1,3 

In central causes, the brainstem vestibular nuclei and their connections are affected. Nystagmus, if present, may be multidirectional or unidirectional, including vertical. There may be associated brainstem and cerebellar signs, motor or sensory deficits, hyperreflexia, extensor plantar responses, dysarthria or limb ataxia.³ 

Causes of vertigo and giddiness in children 

Causes of vertigo and giddiness in children can range from traumatic, infective and malignant disorders of the central nervous system, to otological disorders, and a group of benign but unexplained conditions including migraine, benign paroxysmal vertigo and psychosomatic disorders.⁴ 

An etiological classification of vertigo in children is shown in Table 1.⁵

Table1. Diseases with symptoms of giddiness/ vertigo in children: Etiologic classification. (Adapted from reference)

Vascular Migraine Vertebrobasilar insufficiency Vascular malformation of posterior fossa Hypertension	Space-occupying Cerebellopontine angle Cerebellum Brainstem Intracranial tumours
Metabolic Uraemia Adrenal insufficiency Refsum’s disease (progressive deafness, retinal degeneration, vestibular dizziness) Hyperlipoproteinaemia acanthosis	Degenerative Olivo-ponto-cerebellar degeneration Spinocerebellar degeneration syndromes Friedrich’s ataxia Vestibular degenerative disease (Meniere’s)
Traumatic Labyrinthine concussions Post-traumatic concussion Fracture of temporal bone Barotrauma	Congenital malformations Posterior fossa malformations (Arnold-Chiari malformation)
	Drug-induced or Toxic
	Visually-induced dizziness Retinal degeneration

In various studies in children, including an Asian study involving Korean children, commonest causes of vertigo were migraine and benign paroxysmal vertigo of childhood (BPVC). These statistics were derived from the otolaryngology clinics, after excluding cases of otitis media.^6,7

In a study based in a paediatric neurology setting, questionnaire surveys on history-taking alone have also helped to accurately identify the causes of giddiness in  most children, with a sensitivity of  92% after confirmation with examination and laboratory evaluation.⁸ The final diagnosis is as presented in Table 2, with migraine and BPVC again being the commonest causes.

Table 2: Common causes of vertigo and giddiness in children

	N	(%)
Migraine	24	39
BPVC	10	16
Vestibular neuronitis	9	14
Anxiety	8	13
Orthostatic hypotension	5	9
Concussion	2	3
Seizure	2	3
Syncope	2	3
Total	52	100%

Migraine 

It is currently  unknown the exact mechanism of vertigo and giddiness that commonly accompanies migraine. Vasospasm of the labyrinthine arteries has been a postulated possible mechanism, though some other underlying neuronal metabolic disorder may also be possible.⁹ Though it is not a diagnostic criteria in migraine with or without aura under International Headache Society (IHS) classification¹⁰, its manifestation as central and peripheral vestibular dysfunction has certainly been described and recognized,^11,12 and is commonly an accompanying feature aiding migraine diagnosis.

Basilar-type Migraine

This is a recognized pattern of migraine where aura symptoms clearly originate from the brainstem and/or from both hemispheres, but there is no motor weakness. It is common in young adults, and many patients have concomitant aura symptoms. As the disturbance may be bihemispheric, and involvement of the basilar artery territory is uncertain, the term “basilar artery migraine” has been replaced by the current term “basilar-type migraine”.¹⁰  The diagnostic criteria according to IHS-II are as follows:

Table 3 : Basilar-type migraine 

A.    At least 2 attacks fulfilling B-D

B.    Aura consisting of at least two if the following fully-reversible symptoms, but no motor weakness: Dysarthria Vertigo Tinnitus Hypacusia Diplopia Visual symptoms simultaneously in both temporal and nasal fields of both eyes Ataxia Decreased level of consciousness Simultaneous bilateral paraesthesia

C.    At least one of the following: At least one aura symptom develops gradually over ³ 5 mins and/or different aura symptoms occur in succession over ³ 5 mins Each aura symptoms lasts ³ 5mins but £ 60 mins

D.   Headache fulfilling criteria for migraine without aura begins during the aura or starts  within 60 minutes

E.    Not attributed to another disorder

Benign Paroxysmal Vertigo in Children (BPVC)

This is a proxysmal, non-epileptic, recurrent event characterized by subjective or objective vertigo that occurs in neurologically intact children.¹² This is to be differentiated from benign positional vertigo, which is caused by a particular position of the head. 

BPVC has been recognized as a childhood periodic syndrome that is a precursor of migraine.^10,13 (see Table 3) Family history of migraine is positive in many sufferers of BPVC,14 and positive results have been obtained with migraine provocation tests (nitroglycerine, histamine, fenfluramine)¹⁵  

Various studies have suggested a prevalence of BPVC among school-children to be 2-2.6%.^4,13 The onset is in young children 2-4 years of age, and a sensation of anxiety or fear may be present as the child undergoes vertiginous giddiness. There may also be pallor, nausea, vomiting, perspiration, and there is occasionally loss of consciousness. Sleep or somnolence has often been reported after the episodes, with complete resolution to normal activity after.¹² There may be no trigger factors, though events capable of stimulating the labyrinth may provoke it eg. see-saw or swing. When a child presents to the neurologist, a diagnosis of epilepsy may need to be excluded. In BPVC, the neurological examination is normal except for nystagmus, which may be present. Electroencephalogram (EEG) during sleep and waking, as well as during the episodes are also normal.¹² 

Table 4: IHS-II classification of BPVC.

At least 5 attack fulfilling criterion B

Multiple episodes of severe vertigo, occurring without warning and resolving spontaneously after minutes to hours.

Normal neurological examination and audiometric and vestibular functions between attacks.

Normal electroencephalogram.

Benign paroxysmal positional vertigo (BPPV)

This is a condition mostly affecting adults and older patients, where there is free-floating degenerated otoconia lodged in the posterior semicircular canal. It seldom afflicts younger children unless there is a history of head trauma. The small floating particles affects the cupula sensing movements of fluid in the semicircular canals, and hence creates signals which are incongruous with head movements. This mismatch in information creates a sensation of vertigo.

 The history is usually classical where patients do not feel dizzy all the time. Positional changes and head movements usually trigger symptoms. The Hallpike manoeuvre is diagnostic of this condition. 

Vestibular neuronitis and labyrinthitis

The labyrinth is the organ of balance in the inner ear. These are three semicircular canals filled with fluid, arranged at different angles. With movement of the head, the rolling of the fluid tells the brain the speed and direction of movement. This information is relayed by the vestibular nerve. 

Vestibular neuronitis and labyrinthitis present similarly with vertigo, giddiness, nausea and vomiting, and unsteadiness and dysequilibrium. The definition of Selvoniemi¹⁶ however, strictly confines vestibular neuronitis to inflammation of the nerve, mostly caused by viruses. Hence, compared to labyrinthitis, hearing is unaffected. In labyrinthitis, hearing may be reduced or distorted. The causes of labyrinthitis are also viral, but in some cases can be secondary to bacterial middle ear infection. If associated with pain in the ear, acute bacterial infection or herpes infection must be suspected. 

Acutely, the giddiness is usually constant. After a few days, giddiness is provoked by sudden movements. While patients are usually sensitive to head position, it is usually not related to which side of the head is down (as in benign positional vertigo), but rather affected by a lying or standing posture.

Juvenile vertigo and anxiety-related vertigo

Juvenile vertigo refers to a vertigo syndrome commonly found in children from the ages of 4-14. This involves attacks lasting a few minutes in which the main symptom is anxiety. Vestibular abnormalities coexisting with anxiety disorders are also not uncommon in practice. Among patients presenting for evaluation of giddiness, panic disorders are elevated five to fifteen times higher than the general population.¹⁷ In various otolaryngology clinics studying adult and older children patients presenting for evaluation of giddiness, comorbid psychiatric disorders of anxiety, depression and somatization were found to be very common in this group, where there was also an absence of a demonstrable peripheral vestibular disorder. These patients were also more likely to have a history or to have concurrently unexplained medical symptoms.¹⁸ The postulated mechanism is postulated to be somatopsychic or psychosomatic interactions, with increased sensitivity of the vestibular system to anxiety and hyperventilation. These patients also commonly report agoraphobia, and hence a careful history is most helpful in this instance.¹⁹

Epilepsy

Ictal vertiginous sensations are not uncommon as a manifestation of partial seizures. They are also commonly associated with visuospatial illusions and somatosensory sensations.²⁰ Epileptic vertigo is due to stimulation of parts of the cortex with vestibular representation—parietal, temporal and frontal.²¹ Very rarely, there is associated tinnitus.

Exertional vertigo

This is an entity of vertigo provoked by exertion. These patients complain of giddiness during exercise, and may have a history of other autonomic events eg syncope during noxious stimuli. In studies involving such patients (aged 13-53), vertigo and giddiness were present on autonomic provocation tests. Hyperventilation also provoked symptoms easily in these patients. Hence exertional giddiness can be a clinical manifestation of autonomic nervous system dysregulation. ²² 

The table (Table 5) below summarises the common causes of vertigo in children based on the pattern of vertigo, and physical findings.⁵  

Approach to Ataxia in Children 

1. Ataxia can be largely divided into vestibular, central and sensory causes.a)   Vestibular ataxia can be caused by the similar lesions which cause peripheral and central vertigo. The ataxia is gravity dependant - ie. incoordination of movements cannot be demonstrated with the child lying down, but appears apparent once the patient attempts to stand or walk.

Table 5: Common problems of vertigo in children

Paroxysmal vertigo		Unremitting vertigo
Without hearing loss	With hearing loss	Without neurologic signs	With neurologic signs
Vestibular neuritis   BPVC Basilar artery migraine Migraine equivalent Epilepsy Vestibular concussion	Labyrinthitis   Meniere’s disease Head trauma Congenital malformation of cochlear	Metabolic   Endocrine Congenital anomalies of circulation Whip lash Toxicity Psychosomatic	Space-occupying lesions Multiple sclerosis Degenerative diseases

2. In cerebellar ataxia, there is associated hypotonia, dysmetria and dysdiadokinesia. There are irregularities in rate, rhythm, amplitude and force of voluntary movements. There may also be multidirectional nystagmus, ocular oscillations and defective saccadic and pursuit movements.
3. Sensory ataxia results from disorders affecting the proprioceptive pathways in peripheral sensory nerves, sensory roots or posterior columns of the spinal cord. These deficits may be compensated by other sensory cues, and hence compensated by vision.

Cerebellar Ataxia 

Anatomic regions of the cerebellum are functionally distinct, hence corresponding to the somatotopic organization of the motor, sensory, visual and auditory connections. The table below summarises clinical findings according to involvement of different areas of the cerebellum.

Ataxic conditions peculiar to childhood

1) Acute cerebellar ataxia

This usually results following a viral infection, commonly varicella²³, and also occasionally Ebstein-barr, coxsackie and echoviruses, and is thought to be secondary to an immune response involving the cerebellum.  There is usually progressive to complete recovery in weeks, though some children may have residual behavioural and speech disorders, with ataxia and incoordination. 

2) Congenital anomalies of the posterior fossa and cerebellum

These include Dandy-Walker malformation, and Arnold-Chiari malformation, with destruction and replacement of the cerebellum. A familial disease of Joubert’s disease presents as agenesis of the cerebellar vermis, associated with respiratory difficulties. 

3) Metabolic disorders

Abetalipoproteinaemia is an example of metabolic disorder associated with ataxia. There is steatorrheoa and failure to thrive, with acanthocytosis in the blood, and absent serum beta-lipoproteins. There is ataxia, retinitis pigmentosa, peripheral neuropathy and mental retardation, with absent detectable Vitamin E in neurologically affected patients.²⁴ Other metabolic diseases commonly described in association with ataxia include Hartnup disease, Refsum’s disease and neuronal ceroid lipofuscinoses and late-onset GM2 gangliosidosis.

Table 6: Clinical patterns of cerebellar ataxia¹

Pattern of involvement	Signs	Causes
Midline	Nystagmus, head and trunk titubation (oscillation), gait ataxia	Tumour Multiple sclerosis
Superior vermis	Gait ataxia	Alcoholic encephalopathy Tumour Multiple sclerosis
Cerebellar hemisphere	Nystagmus, ipsilateral gaze paresis, dysarthria (esp left hemisphere), ipsilateral hypotonia, ipsilateral limb ataxia, falling to side of lesion	Infarction Tumour Haemorrhage Multiple sclerosis
Pancerebellar	Combination of midline and bilateral cerebellar involvement ie. titubation, nystagmus, bilateral gaze paresis, dysarthria, bilateral hypotonia, bilateral limb ataxia, gait ataxia	Drug intoxication Hereditary cerebellar degeneration Paraneoplastic syndromes Wilson’s disease Infectious and parainfectious encephalomyelitis Multiple sclerosis

 4) Degenerative diseases and familial ataxias

Friedrich’s ataxia represents the most commonly inherited ataxia, due to the GAA repeat expansion located on chromosome 9q13.²⁵ Familial episodic ataxias (EA), the commoner types being EA1 and EA2, are postulated to be due to potassium channel KCNA1 and calcium channelopathy CACNL1A4 respectively. The latter is located on chromosome 19p, mutations of which are also found in familial hemiplegic migraine²⁶, and spinocerebellar ataxia type 6 (SCA-6). These patients therefore may also have vertigo and headaches.  

Spinocerebellar ataxias (SCA) represent disorders where there is progressive pancerebellar dysfunction, with various combinations of central system abnormalities. These include pigmentary retinopathy, extrapyrimidal movement disorders (parkinsonism, dyskinesia, dystonia, chorea), pyramidal signs, cortical symptoms and peripheral neuropathy.²⁷ The autosomal dominant forms are genetically heterogenous and many are due to CAG trinucleotide repeats coding for ataxins and the α_1A subunit of the P/Q type calcium channel, which is found in nerve terminals. Other types include expanded CTG and ATTCT pentaneucleotide repeats.²⁸  There has also been a recent explosion in the genetic basis of several other autosomal recessive ataxias eg. sensory ataxias, cerebellar ataxia with sensory-motor polyneuropathies, and other purely cerebellar ataxias. The pathogenetic basis of such disorders have now been linked to free-radical injury and defects of DNA single or double-strand break repair.²⁹ 

The olivoponto-cerebellar atrophies (OPCA)have at least five familial subtypes and are dominantly inherited, the patients presenting with ataxia, cranial nerve palsies and sensory neuropathies. 

Sensory Ataxias

These result from disorders of impaired proprioceptive sensation at the level of peripheral nerves or roots, posterior columns of the spinal cord, or sensory pathways in the brain. There are usually findings of abnormalities of impaired joint and vibration sense, with unstable stance of slapping or steppage quality, with a positive Rhomberg’s test. Causes are polyneuropathies and myelopathies. 

The table (Table 7) below summarises differences in vestibular, cerebellar and sensory ataxias.

Drug Treatment in Vertigo 
 

There are various neurotransmitters affecting vestibular responses. These are involved in the neuronal arc between vestibular hair cells and oculomotor nuclei that drives the vestibulocular reflex.³⁰ The excitatory neurotransmitters include glutamate, while the inhibitory ones include gamma-aminobutyric acid (GABA-A and GABA-B) and glycine.³¹ Receptors for acetylcholine are also found in the pons and medulla, mediating giddiness.³² Histamine is found diffusely in central vestibular connections and modulate symptoms of motion sickness.³³ Norepinephrine modulates the intensity of reactions to vestibular stimulation³⁴, while dopamine affects vestibular compensation and serotonin is involved in nausea.