Ataxia The 5 Minute Pediatric Consult


	Ataxia

Peter M. Bingham

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

Ataxia is defined as any problem with orientation of movement. Though cerebellar dysfunction is the most common cause of ataxia in children, other sites of pathology should also be considered: peripheral nerve, dorsal-root ganglion, brainstem, and inner ear (labyrinth).

Appendicular ataxia affects limb movement.
Truncal ataxia, gait ataxia, dysarthria, and nystagmus often occur together in cerebellar ataxia.

CLINICAL PRESENTATION

Acute cerebellar ataxia following a benign viral infection is common in children.
Chronic ataxia usually signals serious underlying pathology (tumor, hereditary or metabolic disorder).

PATHOPHYSIOLOGY

The cerebellum “fine tunes” all coordinated movement and is sensitive to any structural (e.g., tumor, stroke) or metabolic (e.g., intoxication) injury. Ataxia is involved in any disturbance of pathways to (e.g., vestibular nerve, proprioceptive sensory nerves, dorsal-root ganglion cells) or from (e.g., superior cerebellar peduncles, brainstem) the cerebellum. It may impair coordination.

GENETICS

Hereditary causes of chronic ataxia include Friedreich ataxia, ataxia telangiectasia, mitochondrial disease, and aminoacidopathies.

ASSOCIATED CONDITIONS

Acute ataxia, in association with opsoclonus-myoclonus syndrome, may be symptomatic of underlying neuroblastoma/ganglioneuroma.
Friedreich ataxia is associated with cardiomyopathy, diabetes, and peripheral neuropathy.
Mitochondrial disorders: short stature, retinopathy, heart block, myopathy

DIFFERENTIAL DIAGNOSIS

Chorea, tremor, or athetosis may be mistakenly diagnosed as ataxia.

ACUTE ATAXIA

Intoxication: depressed mental status; toxicologic screen; medications at home
Posttraumatic: history/physical findings
Postinfectious: acute cerebellar ataxia (dysarthria, mild hypotonia)
Paraneoplastic: more indolent/subacute onset; ataxia may precede opsoclonus/myoclonus; neuroblastoma/ganglioneuroma
Migraine: resolves in hours; headache may precede ataxia
Labyrinthitis: fast phase of nystagmus is unidirectional
Acute disseminated encephalomyelitis (ADEM) white matter changes on MRI, variable on CT
Acute polyneuropathy: GBS (arreflexia, signs of sensory ataxia)
Stroke: focal deficits; abnormal imaging studies
Postictal: rapidly resolving ataxia with negative studies, slowing on EEG; history of convulsion
Familial periodic ataxia: family history
Acute ataxia: can be a rare presentation of meningitis/encephalitis
Psychogenic: “astasia abasia” (variable effort; no pathologic nystagmus, characteristic gait)

CHRONIC ATAXIA

Brain tumor (especially under 10 years): associated cranial neuropathies, papilledema, headache, pyramidal tract signs
Friedreich ataxia: onset 5 to 15 years; family history, associated cardiomyopathy, polyneuropathy, diabetes
Leukodystrophy: adrenoleukodystrophy, metachromatic leukodystrophy, Pelizaeus-Merzbacher disease (abnormal MRI signal in white matter)
Other metabolic diseases: Niemann-Pick, maple syrup urine disease (MSUD), Hartnup disease (amino acid screen)
Abetalipoproteinemia: onset in second decade; hypocholesterolemia/decreased LDL
Hereditary neuropathy: decreased reflexes, weakness usually more prominent, family history, molecular diagnosis
Hereditary ataxia: autosomal dominant, molecular diagnosis
Long-term phenytoin: primarily adults
Metabolic: variable onset; may be episodic, with other systemic symptoms; Hartnup disease, MSUD, organic acidemias, Niemann-Pick C (visceromegaly?, foam cells in marrow)
Intermittent or chronic ataxia may be a feature of mitochondrial disease, usually in association with other systemic signs/symptoms: retinopathy, sensorineural hearing loss, diabetes, growth delay, seizures, myopathy.
Rare: ataxic cerebral palsy, brain dysgenesis, Joubert syndrome, multiple sclerosis, Gerstmann-Straussler (familial; prion disease)

DATA GATHERING

HISTORY

You must establish acute versus chronic onset of ataxia to narrow the differential diagnosis.

In acute ataxia, history should be directed to possible intoxication, head trauma, or migraine.
History of episodic change in consciousness or convulsions points to seizure disorder (postictal ataxia).
Recent varicella or other infection suggests postviral cerebellar ataxia, labyrinthitis, or Guillain-Barré syndrome (GBS) (see chapter on Guillain-Barré syndrome).
Congenital heart disease or other known circulatory disorder raises the possibility of cerebellar stroke.
In chronic ataxia, history of extreme irritability or progressive macrocrania (from well-care records) in an infant or toddler suggests brain tumor.
History of recurrent vomiting (metabolic disorders), psychiatric disturbance (conversion disorders), or other family members with neurologic disease (hereditary neuropathies, ataxia telangiectasia) may all lead to the diagnosis.

PHYSICAL EXAMINATION

The neuroanatomic localization of the ataxia must be determined.

Cerebellar ataxia often interferes with speech; consciousness is normal despite “drunken” movements and gait. Signs include:
- Intention tremor: oscillations seen (e.g., on finger-nose testing) when agonists and antagonists cocontract to orient limb movement
- Disdiadohokinesia: impairment of rapid, alternating movements
- Titubation, truncal ataxia, and pathologic nystagmus: point to cerebellar or vestibular disease
- Cranial nerve findings, especially third, sixth, or lower cranial nerves: point to possible brain tumor; hyperreflexia or upgoing toes may be present.
- Asymmetric ataxia or weakness: may signify tumor, stroke, or demyelinating disease
Sensory ataxia also spares consciousness; other signs include:
- Romberg fall: ataxia worsened by eye closure; indicates sensory dysfunction, either proprioceptive (peripheral nerves, dorsal-root ganglia), or vestibular (inner ear, vestibular nerve).
- Arreflexia: not seen in central causes of ataxia; key sign in distinguishing sensory ataxia (as in GBS) from cerebellar ataxia
Toxic/metabolic causes: intoxications, postictal ataxia, and sleep drunkenness usually alter consciousness.

LABORATORY AIDS

Toxicologic screen is usually a good initial screen in acute ataxia.
Radiologic studies are necessary when intoxication has been ruled out (rule out tumor, stroke, demyelination); MRI is superior to CT for imaging the cerebellum, though contrast CT is adequate to rule out posterior fossa tumor.
Spinal tap may reveal a few cells/mild increase in protein in benign acute cerebellar ataxia of childhood or in acute demyelinating encephalomyelitis.
EEG if postictal ataxia is a possibility.
Full work-up for neuroblastoma in ataxia opsoclonus/myoclonus includes body CT, serum ferritin, urine homovanillic/vanillylmandelic acid (HVA/VMA).
Low cholesterol in chronic ataxia suggests abetalipoproteinemia.
Genetic test for Friedreich (chronic) ataxia may soon become available.
Laboratory testing for mitochondrial ataxia, which may produce intermittent or chronic ataxia, usually with other systemic abnormalities (see above) includes urine organic acids, plasma lactate/pyruvate, genetic testing on blood, muscle biopsy.

THERAPY

As indicated for any underlying condition; precautions and limitation of activity to decrease the chance of injury/aspiration
Steroids (2 mg/kg IV prednisolone) often used for ADEM, though there is no proven benefit.
Immunomodulatory therapies have been tried (plasmapheresis, IVIG) for paraneoplastic ataxia-opsoclonus/myoclonus, since the movement disorder may persist long after therapy for the tumor.
Acetazolamide may be helpful for familial periodic ataxia.

FOLLOW-UP

Acute postinfectious cerebellar ataxia usually resolves over days to weeks; if imaging studies show demyelination, recovery may take longer and the chance of recurrence may be higher.
If initial studies in opsoclonus/myoclonus do not reveal a neoplasm, follow-up studies should be repeated.

PITFALLS

Children with acute recurrent ataxia should be evaluated for metabolic disease, even if examination is normal between attacks. Possibilities include ornithine transcarbamoylase deficiency, mitochondrial disorders.
Inadvertent intoxication with anticonvulsants in the household may not be detected on routine toxin screen. Ask about carbamazepine, phenytoin.
Symptoms of progressive herniation of the cerebellar tonsils in a child or adolescent with Arnold-Chiari type 1 malformation may mimic migraine. A head scan should be done on a child with ataxia and a headache.

COMMON QUESTIONS AND ANSWERS

Q: What intoxications are most likely to cause ataxia?
A: Benzodiazepines, the major anticonvulsants (except valproate), ethanol, tricyclics, antihistamines, others.

Q: How long can postinfectious cerebellar ataxia last?
A: Rarely, it may last for months, but should be improving during that time.

Q: What is the role of physical therapy for cerebellar ataxia?
A: Physical therapy for ataxia is of limited value.

ICD-9-CM 334.3

BIBLIOGRAPHY

Connolly AM, Dodson WE, Prensky AL, Rust RS. Course and outcome of acute cerebellar ataxia. Ann Neurol 1994;35(6):673–679.

DeAngelis C. Ataxia. Pediatr Rev 1995;16(3):114–115

Salih AM, Ahlsten G, Stalberg E, et al. Friedreich ataxia in 13 children: presentation and evolution with neurophysiologic, electrocardiographic, and echocardiographic features. J Child Neurol 1990;5:321–326.

Steinlin M, Zangger B, Boltshauser E. Non-progressive congenital ataxia with or without cerebellar hypoplasia: a review of 34 subjects. Dev Med Child Neurol 1998 40:148–154.

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