Overview
Definition:
Ataxia refers to a lack of voluntary coordination of muscle movements
In pediatrics, acute onset ataxia can be alarming, requiring prompt evaluation to differentiate between toxic ingestions and inflammatory processes like post-infectious cerebellitis
Toxic ataxia is typically due to exogenous substances affecting cerebellar function, while post-infectious cerebellitis is an inflammatory demyelination of the cerebellum, often occurring after a viral infection.
Epidemiology:
Acute onset ataxia is a common pediatric neurological emergency
Toxic ingestions are a frequent cause, particularly in toddlers
Post-infectious cerebellitis is less common but significant, with an incidence estimated at 1 in 10,000 to 1 in 20,000 children, often following common viral illnesses like varicella, influenza, or Epstein-Barr virus
It is the most common cause of acute focal neurological deficit in children.
Clinical Significance:
Prompt and accurate differentiation is crucial for appropriate management and prognosis
Untreated cerebellitis can lead to significant neurological sequelae
Conversely, identifying a toxic ingestion allows for targeted detoxification or supportive care, preventing potentially life-threatening complications
This distinction is critical for pediatric residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Sudden onset of gait disturbance: difficulty walking, falling
Truncal ataxia: unsteady, wide-based gait
Limb ataxia: dysmetria (inability to judge distance), dysdiadochokinesia (inability to perform rapid alternating movements)
Nystagmus: involuntary eye movements
Dysarthria: slurred speech
Vomiting
Headache
Lethargy
Fever may be present in cerebellitis but absent in many toxic cases
History of recent illness or exposure to toxins is key.
Signs:
Gross motor delay or regression
Cerebellar signs: intention tremor, hypotonia, rebound phenomenon
Cranial nerve palsies may be present in cerebellitis
Altered mental status
Signs of intoxication may include pupillary abnormalities, altered heart rate, or respiratory depression depending on the toxin
Lumbar puncture may show pleocytosis and elevated protein in cerebellitis, but is normal in toxic causes.
Diagnostic Criteria:
No formal diagnostic criteria for distinguishing between the two
diagnosis is primarily clinical and supported by investigations
For post-infectious cerebellitis, criteria include: acute onset of cerebellar signs, preceding infection (typically 1-3 weeks prior), exclusion of other causes (toxic, metabolic, structural), and characteristic neuroimaging findings (often diffuse or focal cerebellar edema)
For toxic ataxia, a clear history of toxin ingestion or exposure, and resolution of symptoms after removal of the offending agent are diagnostic clues.
Diagnostic Approach
History Taking:
Detailed history of symptom onset and progression
Inquiry about recent infections (e.g., URI, GI upset, rash)
Detailed medication and substance use history (prescription, OTC, illicit drugs)
Accidental ingestion risks (accessibility of medications, household chemicals)
Family history of neurological disorders
Travel history
Exposure to sick contacts
Diet history.
Physical Examination:
Complete neurological examination focusing on cranial nerves, motor strength, tone, reflexes, coordination, and gait
Assess for dysmetria, dysdiadochokinesia, and nystagmus
Evaluate for signs of meningeal irritation
A thorough physical exam for signs of intoxication (e.g., odor on breath, skin changes, vital sign abnormalities).
Investigations:
Basic laboratory tests: complete blood count (CBC), electrolytes, glucose, renal and liver function tests, urinalysis
Toxicology screen: urine and serum drug screen, blood alcohol levels
Lumbar puncture: CSF analysis for cell count, protein, glucose, and any specific antibodies or PCR if infection is suspected
Neuroimaging: MRI brain with and without contrast is the investigation of choice
typically shows diffuse or focal T2/FLAIR hyperintensities in the cerebellum in cerebellitis, often with contrast enhancement
MRI can also rule out other structural lesions like tumors or stroke
EEG may be useful if seizures are suspected.
Differential Diagnosis:
Acute toxic encephalopathy (various agents)
Acute cerebellar ataxia of childhood (post-infectious)
Brain tumor (e.g., medulloblastoma, astrocytoma)
Stroke (cerebellar infarction/hemorrhage)
Metabolic disorders (e.g., hypoglycemia, inborn errors of metabolism)
Viral encephalitis affecting the cerebellum
Post-ictal state
Friedreich's ataxia (usually chronic)
Guillain-Barré syndrome (can have cerebellar involvement).
Management
Initial Management:
Stabilize airway, breathing, and circulation (ABCs)
Assess vital signs and level of consciousness
Secure intravenous access
Continuous cardiac and pulse oximetry monitoring
If intoxication is suspected, assess need for gastric decontamination (gastric lavage, activated charcoal) based on agent and time of ingestion
Close monitoring for respiratory depression or seizures.
Medical Management:
For suspected toxic ataxia: supportive care, hydration, and removal of the offending agent
Specific antidotes may be available for certain toxins (e.g., naloxone for opioids, fomepizole for methanol/ethylene glycol poisoning)
For confirmed post-infectious cerebellitis: typically involves supportive care
Corticosteroids may be considered in severe cases, though evidence is mixed
Antivirals are generally not effective unless a specific treatable viral agent is identified
Treatment of any underlying infection.
Surgical Management:
Rarely indicated
Surgical intervention may be considered for complications of cerebellitis such as cerebellar infarction or hydrocephalus requiring CSF diversion (e.g., ventriculostomy)
Management of brain abscess if present.
Supportive Care:
Intensive care unit (ICU) monitoring may be required for airway protection, hemodynamic stability, and seizure management
Nutritional support via nasogastric or parenteral feeding if unable to tolerate oral intake
Physical and occupational therapy to aid recovery and prevent complications of immobility
Regular repositioning to prevent pressure sores.
Complications
Early Complications:
Respiratory compromise
Seizures
Increased intracranial pressure (ICP) due to edema or hydrocephalus
Herniation
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Rhabdomyolysis.
Late Complications:
Persistent gait abnormalities
Dysarthria
Nystagmus
Cognitive deficits
Developmental delays
Recurrence is rare but possible for certain autoimmune cerebellitis syndromes
Long-term neurological impairment.
Prevention Strategies:
For toxic ataxia: strict adherence to medication storage guidelines, childproofing homes, public education on poison control
For cerebellitis: prompt recognition and management of underlying infections, although preventative strategies for cerebellitis itself are limited as it often follows common viral illnesses.
Prognosis
Factors Affecting Prognosis:
For toxic ataxia: the specific toxin, dose, and speed of intervention are key prognostic factors
Many toxic ataxias are reversible with prompt treatment
For post-infectious cerebellitis: prognosis is generally good, with most children making a full recovery
Factors influencing prognosis include the severity of inflammation, presence of complications like hydrocephalus or infarction, and promptness of diagnosis and supportive care
Age at presentation can also be a factor.
Outcomes:
Most cases of acute toxic ataxia resolve completely with supportive care and removal of the toxin
Post-infectious cerebellitis has a good prognosis, with over 80% of children recovering fully within weeks to months
Some may have residual subtle neurological deficits
Severe cases or those with complications may have longer recovery times or permanent deficits.
Follow Up:
Regular neurological follow-up is recommended for children with post-infectious cerebellitis to monitor for recovery and address any residual deficits
Follow-up may include neurodevelopmental assessments and rehabilitation services
For toxic ingestions, follow-up is guided by the specific toxin and any identified long-term effects.
Key Points
Exam Focus:
Differentiate acute toxic ataxia from post-infectious cerebellitis based on history, examination, and investigations
Understand the neuroimaging findings (MRI) for cerebellitis
Recognize common toxins causing pediatric ataxia
Be familiar with lumbar puncture findings in cerebellitis.
Clinical Pearls:
Always consider toxicology in acute onset ataxia in a child, especially without fever
A preceding infection strongly suggests cerebellitis, but co-occurrence is possible
MRI is the most crucial investigation to differentiate structural lesions and inflammatory processes
Prompt supportive care is paramount for both conditions.
Common Mistakes:
Attributing all acute ataxia to cerebellitis without considering toxic etiologies
Delaying neuroimaging, especially MRI, when cerebellitis is suspected
Inadequate toxicological workup in the absence of clear history
Misinterpreting CSF findings or neuroimaging
Failing to monitor for complications like increased ICP.