Approach to the child with acute ataxia

INTRODUCTION — This topic will review causes, clinical features, and the evaluation of acute ataxia in children.

The evaluation of dizziness and syncope in children is discussed separately. (See "Evaluation of dizziness and vertigo in children and adolescents" and "Emergency evaluation of syncope in children and adolescents".)

BACKGROUND — Ataxia can be defined as a disturbance in the smooth, accurate coordination of movements. It is most commonly manifested as an unsteady gait, and in children, refusal to walk.

Ataxia is usually the result of cerebellar dysfunction. However, disturbances at many levels of the nervous system can also affect coordination [1]. As an example, ataxia that develops as the result of loss of sensory function (such as proprioception) would be described as a sensory ataxia.

Acute ataxia, defined as presence of ataxia for <7 days, is an uncommon presenting complaint in children. In the largest study conducted in a pediatric emergency setting, acute ataxia accounted for 0.02 percent of all emergency department visits by children 1 to 18 years of age [2]. Although causes of acute ataxia include life-threatening conditions such as mass lesions and central nervous system (CNS) infection, the majority of children have a benign, self-limited process. Historical features, specific physical findings, and selected ancillary studies can identify most causes of ataxia, particularly those that are serious and require stabilization and intervention.

CAUSES — Conditions that cause acute ataxia include acute infections, post-infectious inflammatory conditions, toxins, tumors, and trauma (table 1). Based upon observational series of patients referred to the emergency department or a pediatric neurology specialist, the most frequent diagnoses are [2-7]:

●Acute cerebellar ataxia

●Drug intoxication

●Guillain-Barré syndrome (GBS)

●Migraine-related disorders (vestibular migraine and benign paroxysmal vertigo)

Of these, acute cerebellar ataxia is most common [1-4,6,8]. Historical features such as the time course of the presentation and the age of the child may suggest a particular diagnosis. Conditions such as migraine syndromes, seizures, and certain inborn errors of metabolism cause recurrent ataxia. By comparison, chronic or progressive ataxia usually develops with congenital anomalies, degenerative diseases, or hereditary ataxias.

Life-threatening conditions — Life-threatening causes of acute ataxia in children are fortunately uncommon. For those conditions that create a mass effect, signs and symptoms of increased intracranial pressure (such as vomiting, headache, or papilledema) are typically evident. Focal neurologic deficits and mental status changes are worrisome [7]. Etiologies include tumors, hemorrhage, stroke, and infection.

Tumors — Of all childhood brain tumors, 45 to 60 percent arise in the brainstem or cerebellum [9,10]. Posterior fossa tumors may present with slowly progressive ataxia and symptoms of increased intracranial pressure. These symptoms include progressive night-time or early morning headache with nausea/vomiting. The absence of these symptoms, however, does not exclude the diagnosis of a brain tumor. In addition to ataxia, physical findings that may be noted with a posterior fossa tumor include papilledema, cranial neuropathies, and other focal neurologic abnormalities. Acute decompensation can occur as the result of obstructive hydrocephalus, hemorrhage into the lesion, or edema. (See "Clinical presentation, diagnosis, and risk stratification of medulloblastoma", section on 'Symptoms'.)

Acute ataxia in association with opsoclonus-myoclonus (rapid, dancing eye movements and rhythmic jerking) may be the presenting manifestation of an occult neuroblastoma. As many as half of children with opsoclonus-myoclonus-ataxia syndrome have a neuroblastoma [11,12]. (See "Clinical presentation, diagnosis, and staging evaluation of neuroblastoma" and 'Other conditions' below.)

Intracranial hemorrhage — Hemorrhage into the cerebellum or posterior fossa as the result of trauma or a vascular malformation can cause ataxia with dramatic, rapid deterioration and life-threatening elevation of intracranial pressure [13]. Injury that causes intraparenchymal hemorrhage is typically severe. In comparison, a child with a ruptured vascular malformation typically has no significant antecedent trauma. A history of trauma may not be immediately forthcoming for children with inflicted injury. (See "Child abuse: Epidemiology, mechanisms, and types of abusive head trauma in infants and children".)

Stroke — Acute ataxia may develop as the result of vertebral or basilar artery disease. Conditions that cause cerebrovascular disease are rare in children and include sickle cell disease, hypercoagulable states (as can occur with systemic lupus erythematous), and homocystinuria. (See "Acute stroke (ischemic and hemorrhagic) in children and adults with sickle cell disease" and "Childhood-onset systemic lupus erythematosus (SLE): Clinical manifestations and diagnosis", section on 'Thromboembolic'.)

Vertebrobasilar artery dissection following a neck injury can also cause stroke, manifested as acute ataxia [14].

Infection — Life-threatening infectious processes that cause acute ataxia generally produce other symptoms as well. Rarely, ataxia may be an early symptom of meningitis [14]. Patients with inflammatory post-infectious conditions, such as acute disseminated encephalomyelitis (ADEM), may also develop ataxia.

●Cerebellar abscesses, often caused by contiguous spread of infection from either otitis media or mastoiditis, can cause ataxia and fever [15,16]. Associated symptoms related to a mass effect in the posterior fossa include headache and vomiting. Rapid clinical deterioration with meningismus can occur when the abscess ruptures into the intraventricular or subarachnoid space [17]. (See "Pathogenesis, clinical manifestations, and diagnosis of brain abscess".)

●Brainstem encephalitis is a rare cause of acute ataxia that is associated with high morbidity. Patients are often febrile and have other neurologic findings such as cranial nerve abnormalities, mental status changes, and seizures [14]. Cerebrospinal fluid (CSF) pleocytosis and electroencephalographic (EEG) changes are commonly seen. Infectious agents associated with brainstem inflammation include Listeria monocytogenes, Lyme disease, EBV, and herpes virus (see "Clinical manifestations and diagnosis of Listeria monocytogenes infection", section on 'Spectrum of CNS involvement'). Reflexes are preserved in patients with encephalitis, which helps to differentiate them from those with GBS or Miller Fisher syndrome. (See 'Common conditions' below.)

●ADEM, an uncommon inflammatory demyelinating disease that typically follows an infection, may have ataxia as part of its presentation. Common neurologic features of ADEM include seizures, cranial neuropathies, weakness, hemiparesis, sensory deficits, and transverse myelitis. Systemic symptoms such as fever, headache, and meningismus may also occur. Altered mental status and the fulminant onset of multifocal neurologic deficits distinguish ADEM from benign etiologies such as acute cerebellar ataxia. Although most patients slowly recover and have no neurologic deficit, mortality from post-infectious ADEM may be as high as 5 percent. (See "Acute disseminated encephalomyelitis (ADEM) in children: Pathogenesis, clinical features, and diagnosis".)

●Acute cerebellitis, although often considered on the spectrum of post-infectious acute cerebellar ataxia, is a rare condition that has distinctive clinical and imaging features. Children with acute cerebellitis typically are ill with acute ataxia accompanied by vomiting, headache, altered consciousness, and increasing sedation. Some may present more fulminantly with severe cerebellar edema. Magnetic resonance imaging (MRI) will demonstrate cerebellar inflammation. (See "Acute cerebellar ataxia in children", section on 'Differential diagnosis'.)

Common conditions — Common conditions that cause acute ataxia in children are often treatable and/or self-limited.

Acute cerebellar ataxia — Acute cerebellar ataxia is the most common cause of childhood ataxia, accounting for about 30 to 75 percent of all cases [2]. It is a self-limited syndrome that is frequently post-infectious and typically seen in children between two and five years of age. Varicella infection-induced cases, once the most common single post-infectious cause, have diminished due to vaccination. Numerous other infectious agents have been implicated in the pathogenesis of acute cerebellar ataxia, including coxsackievirus, echovirus, enteroviruses, Epstein-Barr virus, hepatitis A, herpes simplex virus 1, human herpes virus 6, measles, mumps, parvovirus B19, Borrelia burgdorferi (Lyme disease), malaria, Mycoplasma pneumoniae, and typhoid fever. SARS-CoV2 has also been recently implicated [18]. The diagnosis of acute cerebellar ataxia can only be made after exclusion of other more serious illnesses such as toxic ingestions, central nervous system infection, structural intracranial lesions, metabolic derangement, or neurodegenerative disorders. (See "Acute cerebellar ataxia in children".)

Guillain-Barré syndrome — GBS is an acute inflammatory demyelinating polyradiculoneuropathy thought to result from a post-infectious immune-mediated process. It has also been reported following vaccination and Campylobacter jejuni infection. GBS predominantly affects motor nerves, although as many as 15 percent of children with GBS also lose sensory input to the cerebellum and develop sensory ataxia [1,3]. (See "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis".)

The Miller Fisher syndrome is a form of GBS classically characterized by the triad of ataxia, areflexia, and ophthalmoplegia. Ataxia can be profound and is often more marked in the extremities [1,19]. (See "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis", section on 'Miller Fisher syndrome'.)

Ataxia associated with GBS usually progresses over several days. The prognosis for children with GBS is generally better than that for adults. As many as 85 percent of children can be expected to have an excellent recovery.

Toxic exposure — Toxic exposure (typically ingestion of an oral medication) is responsible for up to 30 percent of cases of acute childhood ataxia [1,3]. Associated symptoms may include mental status changes such as lethargy, confusion, or inappropriate speech or behavior. (See "Approach to the child with occult toxic exposure".)

Exposures commonly associated with ataxia include anticonvulsants (phenytoin, carbamazepine, phenobarbital, and primidone), lead, carbon monoxide, inhalants (such as toluene), alcohol, benzodiazepines, and other drugs of abuse. Some substances associated with abuse can be identified in routine urine toxicology screens. A few medications and toxins (such as anticonvulsants, ethanol, and lead) can be identified with specific blood tests.

Labyrinthitis — Inflammation of the vestibular apparatus, often from bacterial or viral infections such as otitis media, causes acute labyrinthitis. Symptoms include hearing loss, vomiting, and intense vertigo exacerbated by head movements [20-22]. Labyrinthitis may be difficult to distinguish from acute cerebellar ataxia in a toddler. (See "Vestibular neuritis and labyrinthitis", section on 'Clinical manifestations'.)

Migraine syndromes and benign paroxysmal vertigo — Acute ataxia is a clinical feature of several migraine syndromes, including basilar migraines and familial hemiplegic migraines. Benign paroxysmal vertigo (BPV) can be difficult to distinguish from ataxia in young children. Children with BPV may have a family history of migraine, and some develop typical migraines later in life. (See "Types of migraine and related syndromes in children" and "Nonepileptic paroxysmal disorders in children", section on 'Benign paroxysmal vertigo'.)

Associated symptoms such as headache and vomiting without alteration in consciousness, as well as the episodic course, distinguish migraine syndromes from other causes of acute ataxia. However, the diagnosis may be difficult to establish at the initial presentation.

Trauma — Ataxia may occur following mild traumatic brain injury. Ataxia in association with post-traumatic vertigo is discussed separately. (See "Sequelae of mild traumatic brain injury", section on 'Posttraumatic vertigo and dizziness'.)

Other conditions — There are a number of other conditions that can cause acute, episodic, and chronic ataxia (table 1):

●Hypoglycemia – Younger children with hypoglycemia may appear ataxic [3,14].

●Seizure disorder – Ataxia can occur during the ictal or postictal phases of seizures [1,14]. Other epileptic features (such as mental status change or abnormal eye movements) may be noted. However, nonconvulsive seizures (without alterations of consciousness or abnormal movements) may manifest as ataxia alone [23].

●Opsoclonus-myoclonus-ataxia syndrome – Opsoclonus-myoclonus-ataxia syndrome, also known as opsoclonus-myoclonus, is a rare syndrome that includes opsoclonus along with diffuse or focal body myoclonus and truncal titubation with or without ataxia and other cerebellar signs. Ataxia of trunk and limbs with falling is often the first symptom [4]. Patients subsequently develop myoclonus and opsoclonus (spontaneous, involuntary, arrhythmic, conjugate, multidirectional saccades occurring in all directions of gaze without a saccadic interval). Encephalopathy of varying severity can accompany motor symptoms. In children, a moderate to severe sleep disturbance is common. All children with opsoclonus-myoclonus-ataxia syndrome should be evaluated for neuroblastoma. As many as 50 percent of children with opsoclonus-myoclonus-ataxia syndrome have an underlying neuroblastoma; symptoms of opsoclonus-myoclonus-ataxia syndrome precede the diagnosis of neuroblastoma in about one-half of patients. (See "Opsoclonus-myoclonus-ataxia syndrome", section on 'Pediatric syndrome'.)

●Inborn errors of metabolism – Numerous inborn errors of metabolism affecting the central and peripheral nervous system may lead to episodic or recurrent presentations of acute ataxia. A child with one of these yet undiagnosed metabolic disorders may present acutely with the first episode of ataxia and metabolic decompensation in the setting of an intercurrent illness and poor dietary intake. Specific disorders include urea cycle disorders, amino acidopathies, mitochondrial disorders, and organic acidopathies. (See "Inborn errors of metabolism: Epidemiology, pathogenesis, and clinical features", section on 'Clinical manifestations' and "Overview of the hereditary ataxias".)

●Tick paralysis – Tick paralysis is a form of toxic exposure that may present with ataxia. Patients develop an unsteady gait that progresses to motor weakness, ascending paralysis, and areflexia. Fever, headache, and mental status changes are characteristically absent. A neurotoxin in the tick saliva causes the symptoms. The onset of symptoms of tick paralysis occurs only after a female tick has attached and begun feeding. (See "Tick paralysis".)

●Congenital anomalies – Congenital anomalies of the posterior fossa are sometimes associated with ataxia. Observers may not recognize coordination difficulties until maturational motor milestones are delayed, at which point the child may present for acute evaluation. Congenital anomalies of the posterior fossa include Dandy-Walker syndrome, Chiari malformation, encephaloceles, agenesis of the cerebellar vermis, and cerebellar aplasia, dysplasia, or hypoplasia [24].

●Degenerative/genetic conditions – Degenerative and/or genetic conditions associated with chronic and/or progressive ataxia include ataxia-telangiectasia, spinocerebellar ataxia, Pelizaeus-Merzbacher disease, neuronal ceroid lipofuscinosis, Niemann-Pick disease, sialidosis, Friedreich ataxia, abetalipoproteinemia, vitamin E deficiency, GM2 gangliosidosis, Refsum disease, dyssynergia cerebellaris myoclonica (previously, Ramsay Hunt syndrome type I), and multiple sclerosis. (See "Overview of the hereditary ataxias" and "Pathogenesis, clinical features, and diagnosis of pediatric multiple sclerosis".)

●Functional neurological symptoms – A functional neurological symptom disorder (conversion disorder) may be the cause of ataxia for a patient with physical findings that are physiologically incongruent, such as a narrow-based gait and elaborate "near falls." The clinician must take a thorough history and perform a careful physical examination to identify positive signs (eg, variability, distractibility, augmentation with attention) and exclude other causes before concluding that the cause of patient's symptoms is functional. (See "Functional neurological symptom disorder (conversion disorder) in adults: Clinical features, assessment, and comorbidity".)

EVALUATION

History — Most children with ataxia present with refusal to walk or with a wide-based, "drunken" gait. Specific features of the history that may help to identify the underlying cause of the ataxia include the following:

●Onset of symptoms – A rapid onset is typically indicative of a traumatic, infectious, post-infectious, or toxic etiology. Guillain-Barré syndrome (GBS) and metabolic syndromes usually present with a slower, more progressive onset of symptoms, usually over a few days.

A slower and relatively insidious course is characteristic of brainstem and cerebellar tumors, although medulloblastomas may grow rapidly, and acute decompensation may occur secondary to obstructive hydrocephalus or hemorrhage into the lesion.

●Associated symptoms – Important associated symptoms include:

•Otalgia, vertigo, and vomiting in association with acute ataxia suggest acute labyrinthitis. An older child with inner ear disease may complain of dizziness. Most children also have nystagmus.

•Recurrent night-time or early-morning headaches with or without vomiting are symptoms of increased intracranial pressure that may develop with a brain tumor. The absence of these symptoms, however, does not exclude the diagnosis. Personality and behavioral changes may also signal the presence of increased intracranial pressure with hydrocephalus.

•Abnormal mental status is a worrisome symptom that can develop in many conditions that cause acute ataxia, including mass lesions, central nervous system (CNS) infection, toxic exposure, trauma, stroke, cerebellitis, acute disseminated encephalomyelitis (ADEM), and inborn errors of metabolism.

●Access to medications (prescription medications, anticonvulsants, over-the-counter drugs, drugs of abuse, and ethanol), and other toxic substances should be determined.

●A history of antecedent head trauma is consistent with an intracranial injury, whereas neck trauma suggests a stroke as the result of a vascular injury to the vertebral or basilar artery.

●Patients with a recent infection or vaccination may have a post-infectious demyelinating process such as acute cerebellar ataxia, GBS, or ADEM.

●Previous similar episodes of acute ataxia suggest a recurrent disorder such as a migraine syndrome, seizure, or inborn error of metabolism.

●Children with family members with ataxia may have migraine syndromes, hereditary ataxias, or inborn errors of metabolism.

Physical examination — A systematic, yet flexible, approach to the physical examination is necessary to localize the source of the child's symptoms. For young children who may be anxious or uncomfortable, careful observation of the patient's movements and social interactions with the caregiver may provide more information than some parts of the formal examination.

General examination — Abnormal vital signs must be recognized immediately. As an example, bradycardia, abnormal respiratory pattern, and hypertension may occur with increased intracranial pressure. The presence of fever is consistent with an infectious process. Other pertinent features of the general examination include the following:

●Bulging of the anterior fontanel may indicate increased intracranial pressure with a life-threatening cause of ataxia. (See 'Life-threatening conditions' above.)

●An ipsilateral head tilt may be associated with posterior fossa tumors.

●For the child who tolerates a funduscopic examination, papilledema indicates increased intracranial pressure as may occur in posterior fossa tumors that obstruct spinal fluid flow leading to hydrocephalus.

●Nystagmus can develop with vestibular, cerebellar, or brainstem disorders. Opsoclonus may be associated with an occult neuroblastoma.

●Otitis media and hearing loss in association with vomiting and intense vertigo indicate acute labyrinthitis.

●Meningismus with fever and a toxic appearance is concerning for a CNS infection.

●A healing rash or viral exanthem may be a clue to the infectious antecedent in acute post-infectious cerebellar ataxia. Tick paralysis may be the cause of ataxia when an attached tick is noted.

Neurologic examination — The neurologic examination includes specific examination techniques as well as observations made while taking the history and throughout the general physical examination. The approach to the neurologic examination of a child is discussed in detail separately. (See "Detailed neurologic assessment of infants and children", section on 'Neurologic examination'.)

Findings that are associated with various causes of acute ataxia include the following:

●Mental status – Abnormal mental status suggests ingestion, ADEM, meningitis, encephalitis, cerebellitis, or stroke. Lethargy may be present in many inborn errors of metabolism. By comparison, children with post-infectious acute cerebellar ataxia are normally alert and interactive.

●Focal neurological deficits – Focal findings on neurological examination are a "red flag" symptom of a potential serious neurological process such as stroke, intracranial hemorrhage, CNS tumor, or brain abscess.

●Cranial nerves – Abnormalities of cranial nerve function, such as ophthalmoplegia, suggest posterior fossa lesions, brainstem encephalitis, or the Miller Fisher syndrome.

●Motor examination – Children with the acute onset of weakness may stagger as an attempt to compensate. This gait abnormality may be mistaken for true ataxia and has been called "paretic" ataxia. Paretic ataxia is proportional to the degree of weakness. It may be due to GBS, botulism, myasthenia gravis, transverse myelitis, or tick paralysis [14]. Deep tendon reflexes are absent in patients with GBS, botulism, and tick paralysis.

●Sensory examination – Impairment of proprioceptive input may result in sensory ataxia, as may occur with GBS. (See 'Guillain-Barré syndrome' above.)

●Cerebellar examination – A cerebellar lesion is the likely cause of ataxia for a patient with an abnormal cerebellar examination. However, patients with significant cerebellar dysfunction may have no specific findings. Cerebellar signs include abnormalities in gait, speech, and coordination of voluntary movement. Gait is typically wide-based, unsteady, lurching, or staggering. Speech abnormalities include fluctuations in clarity, rhythm, tone, and volume. Patients may have difficulty maintaining truncal position (titubation). Coordination of voluntary movement, as demonstrated with over- or under-shooting (best seen on finger-nose testing) and difficulty with rapid alternating movements (dysdiadochokinesia), is poor. Hypotonia and tremor may also occur.

Findings that localize the disorder within the cerebellum include the following:

•Vermis (midline cerebellar) lesions cause dysarthria, truncal titubation and gait abnormalities.

•Lesions of the cerebellar hemispheres result in ipsilateral limb dysmetria, hypotonia, and tremor. Children may veer in the direction of the affected cerebellar hemisphere when walking.

Ancillary studies — Ancillary studies, as indicated by a thorough history and physical examination, may identify serious and/or treatable causes of acute ataxia.

Laboratory

●Toxicologic testing – A urine screen for drugs of abuse or blood for specific drug levels (as suggested by the history) may be the most useful diagnostic test for children with acute ataxia, especially those with altered mental status [1]. In a retrospective review of 40 cases of acute childhood ataxia evaluated in the emergency department at one institution, nearly half of the 35 drug screens sent were positive [3]. Frequently identified agents include benzodiazepines, cannabinoids, anticonvulsants, ethanol, and opioids [2].

●Blood glucose – A bedside test for blood glucose will quickly identify children with ataxia due to hypoglycemia.

●Metabolic evaluation – For children with episodic acute ataxia and other features that suggest an inborn error of metabolism (such as altered mental status or family history), the following tests may be useful: liver function tests, blood pH, CBC, quantitative amino acid determinations of blood and urine, serum lactate, pyruvate and ammonia levels, and urine organic acids. (See "Inborn errors of metabolism: Identifying the specific disorder".)

●Cerebrospinal fluid (CSF) examination – CSF examination is rarely indicated for the emergency evaluation of a child with acute ataxia. Moderate CSF protein elevation can occur in acute cerebellar ataxia, ADEM, and multiple sclerosis. CSF protein is also usually elevated in GBS, but it may be normal in as many as 20 percent of children within a week of symptom onset [1]. Neuroimaging should be obtained before a lumbar puncture is performed when there is concern for increased intracranial pressure.

CSF should be obtained whenever there is concern for CNS infection, such as meningitis or encephalitis. (See "Bacterial meningitis in children older than one month: Clinical features and diagnosis", section on 'Clinical features' and "Acute viral encephalitis in children: Clinical manifestations and diagnosis", section on 'Clinical features'.)

Imaging — Neuroimaging should be obtained for patients with acute ataxia who have altered levels of consciousness, focal neurologic signs, cranial neuropathies, marked asymmetry of ataxia, concern for a mass lesion, or a history of trauma [2,5]. Imaging may also be helpful when considering a diagnosis of exclusion, such as acute cerebellar ataxia or functional neurological symptoms, especially in patients with atypical or persistent signs and symptoms.

Magnetic resonance imaging (MRI) is the imaging modality of choice for patients with acute ataxia, although emergency MRI may be difficult to obtain. It is superior to computed tomography (CT) for detection of posterior fossa lesions such as tumors, strokes, and abscesses. In addition, patients with demyelinating diseases, acute cerebellitis, or brainstem encephalitis may have abnormalities detected with MRI. (See "Acute cerebellar ataxia in children", section on 'Neuroimaging'.)

CT is generally more available emergently than MRI. CT can usually detect conditions that require immediate surgical intervention such as hydrocephalus, traumatic injury, hemorrhage, impending herniation, and many mass lesions.

Electrophysiologic studies — Electrophysiologic studies are rarely necessary for the evaluation of acute ataxia. In consultation with a pediatric neurologist, EEG is indicated for children who may be having seizures, as suggested by altered levels of consciousness and/or fluctuating clinical signs. EEG may also demonstrate nonspecific abnormalities that are clues to a metabolic etiology or toxic exposure. Although electrophysiologic studies are the most specific and sensitive tests for diagnosis of GBS, they may not be helpful early in the disease. (See "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis", section on 'Diagnosis'.)

ALGORITHMIC APPROACH — Children with acute ataxia have a disturbance in the smooth, accurate coordination of movements that is most commonly manifested as an unsteady gait. Although many causes of acute ataxia are benign, patients with life-threatening processes must be quickly identified (table 1). Clinical manifestations and selected ancillary testing can identify conditions requiring stabilization and intervention (such as increased intracranial pressure from a tumor or intracranial hemorrhage) (algorithm 1).

Historical features typically distinguish recurrent and chronic conditions that cause ataxia from those that are acute (with the exception of the initial presentation of a recurrent condition).

●Recurrent conditions – Migraine syndromes such as basilar migraines usually have clinical features such as headache and vomiting. There may be a family history of migraine. (See "Types of migraine and related syndromes in children".)

The recurrence of ataxia with altered awareness suggests the diagnosis of a nonconvulsive seizure disorder, although some patients may have neither altered awareness nor abnormal movements.

Patients with inborn errors of metabolism typically have other symptoms such as altered mental status. (See "Inborn errors of metabolism: Epidemiology, pathogenesis, and clinical features", section on 'Clinical manifestations' and "Overview of the hereditary ataxias".)

●Chronic or congenital conditions – For children with chronic conditions (such as congenital anomalies and degenerative neurologic conditions), ataxia is typically longstanding and/or progressive, rather than acute. A sudden change in symptoms, however, may be the result of an acute condition. As an example, a child with chronic ataxia taking anticonvulsants who becomes acutely worse may have a toxic drug level. (See "Overview of the hereditary ataxias" and "Manifestations of multiple sclerosis in adults".)

Trauma — Children with the acute onset of ataxia following head or neck trauma require emergency head CT to diagnose conditions such as intracranial hemorrhage, cerebellar contusion, or a stroke (as the result of vascular injury). Although a negative CT scan is reassuring, patients with neck trauma may require further evaluation to identify a vertebrobasilar artery dissection. (See 'Life-threatening conditions' above.)

Acute ataxia in a patient with head injury and a normal CT scan may result from a post-concussive syndrome. (See "Sequelae of mild traumatic brain injury", section on 'Posttraumatic vertigo and dizziness'.)

No trauma — Among patients with acute ataxia without a history of trauma, those with life-threatening conditions often have worrisome signs or symptoms.

Life-threatening signs/symptoms — Patients with evidence of increased intracranial pressure (papilledema, headache, and/or vomiting), focal neurologic examination, altered level of consciousness, or fever with meningismus should receive emergency neuroimaging. Either computed tomography (CT) of the head or magnetic resonance imaging (MRI) are indicated depending on the clinical circumstances and availability. (See 'Life-threatening conditions' above.)

●CT – Life threatening conditions that may be diagnosed on CT include posterior fossa tumor, hydrocephalus, cerebellar abscess, increased intracranial pressure with tonsillar herniation, hemorrhage, and stroke. The CT scan is typically normal for patients with meningitis, brainstem encephalitis, or ADEM. If the CT scan is negative, a lumbar puncture is indicated if meningitis is suspected to obtain CSF for analysis and culture. (See "Acute disseminated encephalomyelitis (ADEM) in children: Pathogenesis, clinical features, and diagnosis" and "Lumbar puncture: Technique, contraindications, and complications in adults", section on 'Indications'.)

●MRI – MRI is superior to CT in the evaluation of ADEM and stroke and in the delineation of posterior fossa tumors. (See "Initial assessment and management of acute stroke", section on 'Neuroimaging' and "Clinical manifestations and diagnosis of central nervous system tumors in children", section on 'Neuroimaging' and "Acute disseminated encephalomyelitis (ADEM) in children: Pathogenesis, clinical features, and diagnosis", section on 'Neuroimaging'.)

No life-threatening signs/symptoms

●Toxic exposure – Toxic exposures include accidental ingestions, recreational ingestions, or toxic levels of a prescribed medication. Appropriate subsequent management includes supportive care, administering an antidote (when one is available), or adjusting the medication dose. (See "Approach to the child with occult toxic exposure".)

●Weakness, areflexia – Children with acute ataxia, weakness, and areflexia are likely to have Guillain-Barré syndrome (GBS) or Miller Fisher syndrome. Further diagnostic evaluation may include electrophysiologic studies. Treatment focuses on supportive care, although some patients may receive immune globulin therapy or plasma exchange. (See "Guillain-Barré syndrome in children: Treatment and prognosis".)

Tick paralysis also presents with ataxia in conjunction with motor weakness and areflexia. The presence of an attached tick and improvement in symptoms after tick removal clinches this diagnosis. (See "Tick paralysis".)

●Opsoclonus-myoclonus – Neuroblastoma is common among children with opsoclonus-myoclonus-ataxia syndrome (although the percentage of children with neuroblastoma who have this paraneoplastic syndrome is small). Consequently, children with opsoclonus-myoclonus-ataxia syndrome should receive an aggressive oncologic evaluation. (See "Clinical presentation, diagnosis, and staging evaluation of neuroblastoma".)

●Acute otitis media/vertigo – Inflammation of the vestibular apparatus (with or without infection) may cause vertigo. Vertigo may be difficult to distinguish from ataxia in young children. Suppurative otitis media that causes labyrinthitis may require myringotomy, in addition to antibiotic therapy [25].

●Recent viral illness – Post-infectious acute cerebellar ataxia is one of the most common causes of acute ataxia in children [1,3,14]. Patients are typically afebrile, with normal mental status. A careful history and physical examination may exclude many other causes of acute ataxia. To establish the diagnosis of acute cerebellar ataxia, a urine toxicologic screen, examination of CSF (to exclude meningitis or encephalitis) and/or imaging (to exclude a significant intracranial process) may be considered, particularly for children who are irritable or have an equivocal neurologic examination. (See 'Acute cerebellar ataxia' above.)

●Functional neurological symptom disorder – Functional neurological symptom disorder (conversion disorder) is a clinical diagnosis based on characteristic clinical features and positive signs (eg, variability, distractibility, augmentation with attention). Patients typically have physical findings that are physiologically incongruent, such as a narrow-based gait and elaborate "near falls," and internally inconsistent, with symptoms that change over time. Evaluation for this condition should include a urine toxicologic screen and, for post-menarchal girls, a urine pregnancy test. Some patients may require imaging to be certain that there is no significant intracranial lesion associated with the symptoms. A psychosocial evaluation or referral should be considered. (See "Functional neurological symptom disorder (conversion disorder) in adults: Terminology, diagnosis, and differential diagnosis", section on 'Diagnosis'.)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Acute cerebellar ataxia in children (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Definition – Acute ataxia is a disturbance in the coordination of movement. In children, it most commonly presents as an unsteady gait or refusal to walk. (See 'Background' above.)

●Causes – Patients with life-threatening processes (eg, brain tumors, intracranial hemorrhage, cerebellar stroke, meningitis, cerebellar abscess, acute demyelinating encephalitis, brainstem encephalitis, or acute cerebellitis) must be quickly identified (table 1). (See 'Causes' above.)

Common, self-limited conditions in children presenting for emergency evaluation include acute cerebellar ataxia, drug intoxication, Guillain-Barré syndrome (GBS), vestibular migraine, and benign paroxysmal vertigo.

●Evaluation – The etiology of ataxia can usually be identified with a careful history, physical examination, and selected ancillary testing.

Features suggesting serious underlying conditions are as follows (see 'Evaluation' above):

•Slow, insidious course

•Personality or behavioral changes

•Antecedent head trauma

•Meningismus

•Opsoclonus-myoclonus

•Abnormal neurologic findings (especially abnormal mental status, ophthalmoplegia or other cranial neuropathy, focal cerebellar findings, and/or hyporeflexia)

•Signs of increased intracranial pressure (eg, history of progressive headache, morning vomiting, bulging fontanelle in infants, papilledema, hypertension with bradycardia)

Ancillary studies are indicated based upon a thorough history and physical examination. Rapid blood glucose and toxicologic testing are potentially helpful studies in patients with an acute onset of ataxia. (See 'Laboratory' above.)

●Neuroimaging – Neuroimaging should be obtained for patients with acute ataxia who have altered levels of consciousness, focal neurologic signs, cranial neuropathies, marked asymmetry of ataxia, concern for a mass lesion, or a history of trauma. It may also be necessary in other patients with atypical or persistent symptoms. Whenever available, magnetic resonance imaging (MRI) is the imaging modality of choice. (See 'Imaging' above.)

●Diagnostic approach – A diagnostic approach to acute ataxia in children is provided (algorithm 1). (See 'Algorithmic approach' above.)