Overview
Definition:
Acute ataxia refers to the sudden onset of impaired coordination, gait disturbance, and truncal instability in a child, primarily affecting cerebellar function
It can stem from diverse etiologies, with toxin ingestion and post-viral cerebellitis being critical differential diagnoses in pediatrics.
Epidemiology:
While precise incidence data for differentiating these two specific causes is scarce, acute ataxia in children is relatively uncommon, with a bimodal peak in early childhood and adolescence
Toxin ingestions are more frequent in toddlers, while post-viral cerebellitis can occur at any age following viral infections.
Clinical Significance:
Prompt and accurate differentiation is crucial as management strategies, prognoses, and potential for long-term sequelae differ significantly
Misdiagnosis can lead to delayed or inappropriate treatment, impacting patient outcomes and potentially causing avoidable morbidity.
Clinical Presentation
Symptoms:
Sudden onset of unsteady gait, wide-based stance
Difficulty walking, frequent falls
Slurred speech (dysarthria)
Nystagmus (involuntary eye movements)
Tremor, particularly intention tremor
Vomiting or nausea may be present, especially with toxin ingestion
Headache and lethargy can occur in both, but may be more prominent in cerebellitis.
Signs:
Gait ataxia, staggering
Impaired heel-to-shin and finger-to-nose testing
Dysmetria (inability to judge distance)
Hypotonia (decreased muscle tone)
Cranial nerve deficits are less common but can occur
Vital signs are usually stable but may show mild tachycardia or hypertension
Papilledema might be present in cases of increased intracranial pressure.
Diagnostic Criteria:
No universally accepted formal diagnostic criteria exist for distinguishing these two entities
diagnosis relies on a combination of history, examination findings, laboratory results, and response to treatment
However, a rapid, symmetrical onset of cerebellar signs in an otherwise well child, without significant fever or systemic illness, strongly suggests toxic etiology
Conversely, a preceding febrile illness and more gradual or fluctuating onset may favor post-viral cerebellitis.
Diagnostic Approach
History Taking:
Detailed history of potential toxin exposure: unsupervised access to medications (e.g., benzodiazepines, anticonvulsants, opioids), household chemicals, pesticides, alcohol
Inquiry about recent viral illnesses (fever, rash, respiratory symptoms, gastroenteritis) preceding ataxia onset
Parental recall of any unusual behavior or ingested substances
Timeline of symptom onset and progression is vital
Medication history of the child and family members.
Physical Examination:
Thorough neurological examination focusing on cranial nerves, motor strength, tone, reflexes, sensation, and coordination
Assess gait, station, and tandem gait
Ocular movements for nystagmus
Careful skin examination for signs of exposure or rash
Assess for signs of intoxication (e.g., pupil size, breath odor).
Investigations:
Urine toxicology screen: essential for suspected toxin ingestion, should include common ingestants like sedatives, anticonvulsants, and recreational drugs
Blood alcohol level
Serum electrolytes, glucose, BUN, creatinine to assess metabolic disturbances
Liver function tests
Complete blood count
Cerebrospinal fluid (CSF) analysis: typically normal in toxin ingestion
may show mild pleocytosis and elevated protein in post-viral cerebellitis, helping rule out meningitis or encephalitis
MRI brain with and without contrast: crucial to assess for cerebellar edema, inflammation, or demyelination in post-viral cerebellitis
typically normal in uncomplicated toxin ingestion
EEG: may be helpful if seizures are suspected or to rule out other encephalopathic processes.
Differential Diagnosis:
Other causes of acute ataxia include: acute cerebellar stroke or hemorrhage (rare in children), brain tumors (e.g., medulloblastoma, astrocytoma), metabolic disorders (e.g., hypoglycemia, electrolyte imbalances), drug-induced movement disorders (non-toxic), certain infections (e.g., bacterial meningitis with cerebellar involvement, neurocysticercosis), and autoimmune cerebellitis (distinct from post-viral).
Management
Initial Management:
Secure airway, breathing, and circulation (ABC)
Monitor vital signs closely
Supportive care is paramount
If toxin ingestion is highly suspected and the child is asymptomatic or mildly symptomatic, gastric decontamination (e.g., activated charcoal) might be considered cautiously, but consultation with a poison control center is essential due to risks of aspiration and toxicity
If the child is symptomatic or has altered mental status, airway protection and intensive monitoring are prioritized.
Medical Management:
For toxin ingestion: supportive care focusing on fluid management, electrolyte correction, and supportive ventilation if needed
Specific antidotes are rarely available or indicated for common pediatric ingestions causing ataxia
For post-viral cerebellitis: management is primarily supportive
Intravenous fluids, antipyretics as needed
Steroids (e.g., methylprednisolone) are sometimes used, particularly in severe cases, though their efficacy is debated and they are not universally recommended
Anticonvulsants may be required if seizures occur.
Surgical Management:
Surgical intervention is generally not indicated for either toxin ingestion or uncomplicated post-viral cerebellitis
However, if imaging reveals a significant cerebellar mass lesion or evidence of hydrocephalus, neurosurgical consultation for potential cerebrospinal fluid diversion (e.g., ventriculostomy) or mass excision may be necessary.
Supportive Care:
Continuous cardiorespiratory monitoring
Close neurological assessment for any deterioration
Maintaining hydration and nutrition
Physical and occupational therapy can be initiated early to aid in recovery of gait and coordination
Preventing aspiration and pressure sores is important in non-ambulatory children.
Complications
Early Complications:
Respiratory depression and failure (especially with sedatives/opioids)
Aspiration pneumonia
Seizures
Hypoglycemia or electrolyte disturbances
Cerebral edema and increased intracranial pressure (more common in cerebellitis)
Dehydration.
Late Complications:
Persistent ataxia and gait difficulties
Dysarthria
Neurocognitive deficits or behavioral changes (rare but possible, especially after severe cerebellitis)
Developmental delay in younger children
Recurrence is generally rare unless there is ongoing exposure to toxins.
Prevention Strategies:
For toxin ingestion: strict child-proofing of households, secure storage of all medications and hazardous substances, supervision of children during outdoor activities
For post-viral cerebellitis: prevention of viral infections through vaccination and good hygiene practices
no specific preventive measures exist for the cerebellitis itself once a viral infection has occurred.
Prognosis
Factors Affecting Prognosis:
The specific toxin ingested and the dose are critical for toxic ataxia
The severity of cerebellar inflammation and the presence of complications like cerebral edema influence the outcome of post-viral cerebellitis
Age of the child, pre-existing neurological conditions, and promptness of diagnosis and supportive care also play a role.
Outcomes:
Prognosis for acute ataxia due to toxin ingestion is generally good with supportive care, with most children recovering fully within hours to days as the toxin is metabolized
Post-viral cerebellitis has a variable prognosis
most children recover substantially, but a significant minority may experience residual neurological deficits, particularly in gait and coordination, which can take months to years to improve or may persist long-term
Mortality is low for both conditions but can occur with severe complications.
Follow Up:
Children with acute ataxia, especially post-viral cerebellitis, should have close neurological follow-up to monitor for recovery and to assess for any persistent deficits
Neuroimaging may be repeated if there is concern for ongoing pathology or lack of improvement
Physical and occupational therapy follow-up is essential for rehabilitation.
Key Points
Exam Focus:
Distinguishing features between acute toxic ataxia and post-viral cerebellitis
Key investigations for each (urine tox screen, MRI brain)
Importance of supportive care and airway management in symptomatic children
Recognizing potential for residual deficits in post-viral cerebellitis.
Clinical Pearls:
Always consider toxin ingestion in a child with sudden onset ataxia, especially toddlers
A clear history of recent viral illness strongly favors post-viral cerebellitis, but overlap can occur
MRI brain is indispensable for ruling out structural lesions and assessing inflammation in cerebellitis.
Common Mistakes:
Failing to consider readily accessible toxins in the home
Delaying essential investigations like urine toxicology
Over-reliance on MRI findings without integrating clinical context
Misattributing ataxia to a single cause without a comprehensive differential workup.