Overview
Definition:
Ataxia in children refers to a lack of voluntary coordination of muscle movements
It can manifest as unsteady gait, tremors, dysmetria, and dysdiadochokinesia
Acute onset ataxia in children warrants urgent evaluation to rule out serious underlying causes, primarily acute cerebellar dysfunction or a rapidly growing posterior fossa mass.
Epidemiology:
Acute onset ataxia is a relatively common presentation in pediatric emergency departments
While many cases are self-limiting (e.g., post-infectious cerebellitis), a significant minority are due to structural lesions like brain tumors, particularly in the posterior fossa
Posterior fossa tumors are the most common solid tumors in childhood, with medulloblastoma and astrocytoma being frequent offenders.
Clinical Significance:
Differentiating between acute cerebellar dysfunction and a posterior fossa mass is critical due to their vastly different prognoses and management strategies
Delayed diagnosis of a mass lesion can lead to irreversible neurological damage or death, while misattributing symptoms to a tumor when it's a benign transient condition can lead to unnecessary interventions
Prompt and accurate diagnosis is paramount for optimal patient outcomes and is a frequent topic in board examinations.
Clinical Presentation
Symptoms:
Sudden onset of unsteadiness and gait disturbance
Difficulty walking, with a wide-based gait and tendency to fall
Clumsiness and incoordination of limbs
Slurred speech (dysarthria)
Vomiting, which may be projectile
Headache, particularly if due to increased intracranial pressure from a mass
Lethargy or irritability
Neck stiffness or pain may be present with meningeal irritation or cerebellar tonsillar herniation.
Signs:
Gait abnormalities: wide-based, unsteady, reeling gait
Limb ataxia: dysmetria (overshooting or undershooting targets), dysdiadochokinesia (inability to perform rapid alternating movements)
Truncal ataxia: difficulty maintaining balance while sitting or standing
Nystagmus: horizontal, vertical, or rotatory
Cranial nerve palsies: particularly VIth nerve palsy (ipsilateral gaze palsy and contralateral abducens nerve palsy) due to pressure effects
Papilledema: suggesting increased intracranial pressure
Signs of meningeal irritation: nuchal rigidity if infection or hemorrhage is suspected.
Diagnostic Criteria:
No formal diagnostic criteria exist for the broad category of "acute ataxia in children." However, the diagnosis of acute cerebellar dysfunction or suspicion of a posterior fossa mass is based on a combination of rapid onset of neurological deficits, characteristic examination findings, and the exclusion of other causes
Imaging (MRI brain with contrast) is the definitive diagnostic tool for identifying structural lesions.
Diagnostic Approach
History Taking:
Detailed chronological history of symptom onset and progression
Any preceding viral illness, fever, or vaccination
History of trauma
Presence of headache, vomiting, lethargy
Past medical history, especially of malignancy or neurological disorders
Family history of neurological conditions or tumors
Red flags: rapid progression of symptoms, vomiting, headache, altered mental status, focal neurological deficits, papilledema.
Physical Examination:
Complete neurological examination is crucial
Assess mental status, cranial nerves (especially eye movements, visual fields, and facial symmetry), motor strength and tone, reflexes, sensation, coordination (finger-to-nose, heel-to-shin, rapid alternating movements), gait, and balance
Fundoscopic examination to assess for papilledema
Palpate the spine for tenderness
Check for signs of meningeal irritation.
Investigations:
Neuroimaging: MRI brain with and without contrast is the gold standard for detecting posterior fossa masses and characterizing cerebellar lesions
CT scan may be used in emergencies but is less sensitive for posterior fossa lesions and subtle cerebellar changes
Lumbar puncture: if meningitis or post-infectious cerebellitis is suspected and no contraindications (e.g., papilledema, signs of herniation) exist
CSF analysis for cell count, protein, glucose, and cultures
Blood tests: Complete Blood Count (CBC) to rule out infection, electrolytes, glucose, blood urea nitrogen (BUN), creatinine
Coagulation profile if surgery is contemplated.
Differential Diagnosis:
Acute cerebellar dysfunction: Post-infectious cerebellitis (viral or post-vaccinal), acute disseminated encephalomyelitis (ADEM)
Posterior Fossa Mass: Medulloblastoma, astrocytoma (pilocytic astrocytoma), ependymoma, brainstem glioma, cerebellar abscess, hemorrhage, or infarct
Other causes: Migraine with aura, metabolic encephalopathy, intoxication (e.g., benzodiazepines), seizure disorder (post-ictal deficit), Guillain-Barré syndrome (rarely presents with prominent ataxia).
Management
Initial Management:
Stabilization of the patient
Airway, breathing, circulation (ABCs)
If increased intracranial pressure is suspected, elevate head of bed, consider hyperosmolar therapy (mannitol or hypertonic saline) cautiously
Prompt neuroimaging is the priority
Consult pediatric neurology and neurosurgery services immediately.
Medical Management:
For post-infectious cerebellitis or ADEM: typically involves supportive care, hydration, and potentially corticosteroids (prednisolone) or IV immunoglobulin (IVIG) in severe cases, guided by pediatric neurology
For cerebellar abscess: appropriate antibiotics based on culture and sensitivity, and neurosurgical drainage
For suspected mass lesions, surgical intervention is usually primary.
Surgical Management:
For confirmed posterior fossa mass: Surgical resection is often the mainstay of treatment
The goal is maximal safe resection
Depending on the tumor type and location, this may involve suboccipital craniotomy, infratentorial supracerebellar approach, or endoscopic techniques
Ventriculoperitoneal (VP) shunt insertion may be required if obstructive hydrocephalus is present
Neurochirurgical biopsy may be performed if complete resection is not feasible.
Supportive Care:
Pain management, antiemetics for nausea and vomiting
Fluid and electrolyte balance
Nutritional support, including consideration of feeding tubes if oral intake is compromised
Seizure prophylaxis if indicated
Regular neurological monitoring and vital sign assessment
Physiotherapy and occupational therapy for rehabilitation.
Complications
Early Complications:
Hydrocephalus and increased intracranial pressure leading to herniation
Respiratory compromise due to brainstem compression
Cranial nerve deficits
Status epilepticus
Hemorrhage or edema within the lesion.
Late Complications:
Permanent neurological deficits including persistent ataxia, motor weakness, visual impairment, hearing loss, cognitive dysfunction, and endocrine abnormalities (especially with pituitary or hypothalamic involvement)
Seizures
Neuropsychological sequelae
Recurrence of tumor.
Prevention Strategies:
Early diagnosis and prompt, appropriate management are key to preventing severe complications
For posterior fossa masses, vigilant monitoring for signs of increased intracranial pressure and timely surgical intervention can mitigate risks
For inflammatory conditions, prompt initiation of appropriate medical therapy is crucial.
Prognosis
Factors Affecting Prognosis:
The prognosis depends heavily on the underlying cause
Post-infectious cerebellitis generally has an excellent prognosis with full recovery, though some residual ataxia may persist
For posterior fossa tumors, prognosis varies widely based on tumor type, grade, extent of resection, presence of metastasis, and response to adjuvant therapy (chemotherapy, radiation).
Outcomes:
Children with benign, self-limiting causes of ataxia typically regain full neurological function
Those with posterior fossa tumors have a more guarded prognosis, with survival rates and long-term quality of life dictated by the specific tumor characteristics and treatment efficacy
Multidisciplinary care is essential for optimizing outcomes.
Follow Up:
Long-term follow-up is essential for all children who have experienced acute ataxia
This includes regular clinical assessments, neuroimaging surveillance for tumor recurrence, monitoring for late treatment-related toxicities, and rehabilitation services
Neuropsychological assessments may be needed to monitor cognitive and behavioral development.
Key Points
Exam Focus:
Always suspect a posterior fossa mass in a child with acute or subacute onset ataxia, especially if accompanied by vomiting, headache, or papilledema
MRI brain with contrast is the investigation of choice
Medulloblastoma and pilocytic astrocytoma are common posterior fossa tumors in children
Differentiate from post-infectious cerebellitis, which is usually benign.
Clinical Pearls:
A thorough neurological examination, particularly of coordination and gait, is paramount
Do not miss the fundoscopic examination for papilledema
In a child with vomiting and ataxia, think posterior fossa mass before thinking gastroenteritis or simple viral illness
Urgent neurosurgical and neurological consultation is vital for any suspected mass lesion.
Common Mistakes:
Delaying neuroimaging in a child with persistent ataxia and signs of increased intracranial pressure
Misattributing symptoms of a rapidly growing tumor to a benign viral illness
Not performing a complete neurological examination
Failing to consider inflammatory or infectious causes in the differential diagnosis of acute ataxia.