Diseases » Rett's syndrome

Ataxia

Ataxia: Excerpt from The 5-Minute Pediatric Consult

Susan L. Perlman, MD

Ataxia - BASICS

Ataxia - description

• Incoordination or clumsiness of movement
• Caused by cerebellar, vestibular (inner ear), or proprioceptive sensory (e.g., large fiber/peripheral nerve, dorsal root ganglion, posterior column/spinal cord) dysfunction
  • Appendicular ataxia affects limb movement and results from disease of the cerebellar hemispheres.
  • Truncal ataxia, gait ataxia, dysarthria, and nystagmus often occur together and reflect dysfunction of cerebellar midline structures (vermis).
• Clinical presentation:
  • Cerebellar dysfunction due to intoxication is the most common cause of ataxia in children.
  • Acute cerebellar ataxia following a benign viral infection is common in children.
  • Chronic ataxia often signals serious underlying pathology (e.g., tumor, metabolic, or hereditary disorder).

Ataxia - general prevention

Accidental intoxications and ensuring vaccination against varicella

Ataxia - epidemiology

Ataxia - incidence

• ~1 in 1,000 children develop acute ataxia following varicella infection.
• The most common congenital cerebellar syndromes are caused by perinatal trauma and hypercoagulable or hemorrhagic vascular events (“ataxic cerebral palsy”). Fetal stroke is estimated to complicate 1 in 4,000 full-term births. The Dandy-Walker syndrome and structural cerebellar abnormalities are rarer causes of congenital cerebellar dysfunction.
• Metabolic/heredodegenerative causes are rare.
  • Friedreich ataxia incidence is 2–4 in 100,000.
  • Ataxia with oculomotor apraxia occurrence is near 5 in 100,000.

Ataxia - prevalence

Cerebellar medulloblastomas represent 20% of pediatric primary brain tumors (associated with (ataxia-telangiectasia, basal cell nevus syndrome). Cerebellar astrocytomas, fourth ventricle ependymomas, and brainstem gliomas are also more common in children than in adults.

Ataxia - risk factors

Ataxia - genetics

• Hereditary causes of chronic ataxia include the recessively inherited Friedreich ataxia, ataxia telangiectasia, and late-infantile/juvenile-onset forms of some inborn errors of metabolism (aminoacidopathies, hexosaminidase A deficiency, a beta/hypobetalipoproteinemia, Wilson disease, mitochondrial diseases and peroxisomal disorders, childhood neuronal ceroid lipofuscinosis).
• Dominantly inherited episodic ataxia is seen in the pediatric age group.
• Dominantly inherited, progressive spinocerebellar ataxias (SCA types 2 and 7) occasionally present in infancy.
• Episodic ataxia may signal a disorder of pyruvate or ammonia metabolism.

Ataxia - pathophysiology

• Unilateral cerebellar ataxia is produced by lesions of the ipsilateral cerebellum (Purkinje and granule cells in the cerebellar cortex, deep cerebellar nuclei) or its afferent or efferent connections.
• Lesions of the frontal cerebral cortex and the cerebellum may mimic a contralateral cerebellar problem.
• The cerebellum is sensitive to structural (e.g., tumor, stroke, malformation), infectious, or metabolic/toxic processes. It can also become the target of autoimmune phenomena or genetic defects.

Ataxia - associated conditions

• Acute ataxia is most often due to intoxication.
• Migraine or seizure (postictal)
• Opsoclonus-myoclonus syndrome: Underlyingneuroblastoma/ganglioneuroma
• Isolated, transient “cerebellitis” (EBV, VZV,...)
• Friedreich ataxia is associated with cardiomyopathy, diabetes, scoliosis, pes cavus, and peripheral neuropathy.
• Ataxia telangiectasia is associated with skin/conjunctival telangiectases, frequent bronchopulmonary infection, and leukemia/lymphoma or other cancers.
• Mitochondrial disorders commonly feature short stature, seizures, retinopathy, heart block, myopathy, mental retardation
• Langerhans cell histiocytosis and Wolfram syndrome manifest with diabetes insipidus.

Ataxia - DIAGNOSIS

Ataxia - signs & symptoms

Ataxia - history

Establish acute versus chronic onset of ataxia, to narrow the differential diagnosis:

• Acute ataxia: History directed to possible intoxication, head trauma, or migraine
• History of episodic change in consciousness or convulsions point to seizure disorder (postictal ataxia).
• Recent infection suggests postviral cerebellar ataxia, labyrinthitis, or Guillain-Barré syndrome (see “Guillain-Barré syndrome”).
• Congenital heart disease or other known circulatory disorder raises the possibility of cerebellar stroke.
• Irritability or progressive macrocrania, cranial neuropathy suggests brain tumor.
• Family history of ataxia suggests one of the SCAs.

Ataxia - physical exam

The neuroanatomic localization of the ataxia must be determined:

• Dysarthria and “drunken” movements are classic. Other signs: Intention tremor/oscillations seen (e.g., on finger–nose testing; disdiadochokinesia (impaired rapid alternating movements); titubation, truncal ataxia, and nystagmus; cranial nerve findings point to possible brain tumor; asymmetric ataxia or weakness may signify tumor, stroke, or demyelinating disease.
• Sensory ataxia (e.g., disease of sensory ganglia or peripheral nerve) check Romberg sign—(indicates proprioceptive, or vestibular dysfunction); areflexia (not seen in central causes of ataxia)
• Toxic/metabolic causes (e.g., intoxications, postictal ataxia, and sleep drunkenness) usually alter consciousness.

Ataxia - tests

Ataxia - lab

• Toxicology screen: Screen in acute ataxia
• Spinal tap may reveal a few cells and mild increase in protein in benign acute cerebellar ataxia of childhood or in acute demyelinating encephalomyelitis.
• EEG if postictal ataxia is a possibility
• Full workup for neuroblastoma in ataxia-opsoclonus/myoclonus includes body CT, MIBG scan, serum ferritin, urine homovanillic/vanillylmandelic acid (HVA/VMA)
• Inborn errors of metabolism that may present with ataxia can be screened for with lysosomal hydrolases, ammonia, lactic acid, urine amino and organic acids, and very long chain fatty acids.
• Low cholesterol in chronic ataxia suggests abetalipoproteinemia:
  • Elevated α-fetoprotein and decreased serum IgA suggest ataxia telangiectasia.
  • Low serum albumin and elevated cholesterol suggest ataxia with oculomotor apraxia type 1.
  • Elevated CPK a α-fetoprotein suggest ataxia with oculomotor aproxia type 2.
• Genetic tests for Friedreich ataxia, ataxia telangiectasia, and the dominantly inherited SCAs (many subtypes)
• Laboratory testing for mitochondrial ataxia includes plasma or CSF lactate and pyruvate, genetic testing on blood, muscle biopsy

Ataxia - imaging

Radiologic studies are necessary when intoxication has been ruled out (rule out tumor, stroke, demyelination); MRI is superior to CT for imaging the cerebellum; noncontrast/contrast CT can rule out hemorrhage/ tumor.

Ataxia - pathological findings

Pathology is specific to the underlying etiology, although neurodegenerative cerebellar disease may show only nonspecific loss of Purkinje cells.

Ataxia - differencial diagnosis

• Simple postural or resting tremor, chorea, athetosis, or proximal limb weakness 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 (with dysarthria, mild hypotonia)
  • Paraneoplastic: Ataxia may precede opsoclonus/myoclonus due to 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 or CT
  • Acute polyneuropathy: Guillain-Barré syndrome (areflexia, 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
  • Metabolic disorders: Pyruvate dysmetabolism (attacks provoked by febrile illness, associated lactic acidosis), biotinidase deficiency (associated seizures, skin rash)
  • rarely due to meningitis/encephalitis
  • Psychogenic: Variable effort; no pathologic nystagmus; characteristic gait is grossly unsteady, corrective steps before falling
• Chronic ataxia:
  • Brain tumor (especially in children <10 years of age): Associated cranial neuropathies, papilledema, headache, pyramidal tract signs
  • Friedreich ataxia: Onset 5–15 years of age, other affected siblings, associated cardiomyopathy, diabetes, polyneuropathy, scoliosis, pes cavus
  • Ataxia telangiectasia: Onset <5 years of age, frequent bronchopulmonary infection, and leukemia/lymphoma (elevated α-fetoprotein)
  • Ataxia with oculomotor apraxia type 1: Onset 2–18 years of age, associated polyneuropathy, chorea, cognitive difficulty (hypoalbuminemia, hypercholesterolemia)
  • Ataxia with oculomotor apraxia type 2: Onset 2–22 years of age, associated polyneuropathy, chorea (elevated α-fetoprotein and CPK)
  • Leukodystrophy: Adreno, metachromatic, Pelizaeus-Merzbacher (abnormal MRI)
  • Other metabolic diseases: Niemann-Pick type C bone marrow biopsy); Refsum disease; juvenile-onset Tay-Sachs disease, neuraminidase deficiency (lysosomal disorders); maple syrup urine disease, Hartnup disease (amino acid screen); familial coenzyme Q10 deficiency; familial vitamin E deficiency; cerebral folate transport disorder (low 5-MHTF in CSF)
  • Abetalipoproteinemia: Hypocholesterolemia
  • Mitochondrial disease: Retinopathy, sensorineural hearing loss, diabetes, growth delay, seizures, strokelike episodes, myopathy, elevated pyruvate and lactate levels
  • Congenital disorders of glycosylation
  • Thiamine deficiency
  • Celiac disease
  • Autosomal dominant ataxias
  • Long-term phenytoin use: Primarily adults
  • Rare: Ataxic cerebral palsy, brain dysgenesis, Joubert syndrome, multiple sclerosis, Gerstmann-Straussler (familial, prion disease)

Ataxia - TREATMENT

• As indicated for any underlying condition; precautions and limitation of activity to decrease the chance of injury/aspiration
• Steroids (2 mg/kg IV prednisolone) and IVIG (400 mg/kg/d for 5 days) have been used for ADEM, although there is no proven benefit.
• Immunomodulatory therapies have been tried (steroids, plasmapheresis, IVIG) for postviral cerebellitis and for paraneoplastic ataxia-opsoclonus/myoclonus, which may persist long after therapy for the tumor.
• Acetazolamide may be helpful for familial periodic ataxia; amantadine and buspirone may provide symptomatic relief in Friedreich ataxia; most drugs useful for tremor can be helpful for cerebellar tremor.
• Antioxidant therapy (coenzyme Q10, idebenone) may help the cardiomyopathy and possibly slow disease progression in Friedreich’s ataxia.
• Replacement therapies may stabilize or reverse ataxia in some conditions (deficiencies of vitamin E, thiamine, coenzyme Q10; biotin in biotinidase deficiency; folinic acid in cerebral folate transport disorder).
• Ataxia telangiectasia: Cautious use of radiomimetic chemotherapies and radiation therapy for associated malignancies.
• Physical and occupational therapy, speech and swallowing therapy, and other rehabilitation interventions can greatly improve quality of life in children with ataxia of any cause.

Ataxia - FOLLOW UP

Ataxia - prognosis

Acute postinfectious cerebellar ataxia usually resolves over days to weeks; if imaging studies show demyelination, recovery may take longer.

Ataxia - complications

• The greatest risks for patients with cerebellar deficits remain falls and injuries, aspiration and choking, secondary infections, and depression.
• Patients with ataxia telangiectasia should be monitored for immunodeficiency and hematologic or tissue neoplasia.

• Acute recurrent ataxia: Ornithine transcarbamylase deficiency, mitochondrial disorders, or one of the paroxysmal dyskinesias (ion channelopathies)
• Inadvertent intoxication with anticonvulsants may not be detected on routine toxin screen.
• CT or MRI should be done on a child with ataxia and a headache (Arnold-Chiari type 1 malformation, tumor)

Ataxia - bibliography

1. Connolly AM, Dodson WE, Prensky AL, et al. Course and outcome of acute cerebellar ataxia. Ann Neurol. 1994;35:673–679.
2. Dressler D, Benecke R. Diagnosis and management of acute movement disorders. J Neurol. 2005;252(11):1299–1306.
3. Fogel B, Perlman S. Clinical features and molecular genetics of autosomal recessive cerebellar ataxias. The Lancet Neurology 2007;6(3):245–257.
4. Mercuri E, He J, Curati WL, et al. Cerebellar infarction and atrophy in infants and children with a history of premature birth. Pediatr Radiol. 1997;27:139–143.
5. Palau F, Espinos C. Autosomal recessive cerebellar ataxias. Orphanet J Rare Dis. 2006;1:47–65.
Perlman SL. Diagnostic evaluation of ataxic patients. In: Pulst SM, ed. Genetics of Movement Disorders. San Diego, CA: Academic Press; 2003.
6. Ullrich NJ, Pomeroy SL. Pediatric brain tumors. Neurol Clin. 2003;21:897–913.
Internet Information for Parents: National Ataxia Foundation: http://www.ataxia.org Friedreich’s Ataxia Research Alliance: http://www.faresearchalliance.org A-T Children’s Project: http://www.atcp.org/

Ataxia - CODES

Ataxia - icd9

334.3 Other cerebellar ataxia

438.84 Ataxia

Ataxia - FAQ

• Q: What intoxications are most likely to cause ataxia?
• A: Benzodiazepines, the major anticonvulsants (except valproate), psychotropic medications, ethanol, tricyclics, and antihistamines.
• Q: How long can postinfectious cerebellar ataxia last?
• A: Rarely, it may last for months, but usually improves during that time.
• Q: What is the role of physical therapy for cerebellar ataxia?
• A: Rhythmic, repetitive exercise, exercise for balance and coordination, and muscle conditioning exercise may improve level of performance in patients with ataxia. Vestibular compensation exercise may improve symptoms of dizziness or vertigo in patients with vestibular ataxia.

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Book Source Details

• Book Title: The 5-Minute Pediatric Consult
• Author(s): M. William Schwartz MD; et al.
• Year of Publication: 2008
• Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

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More About This Book: Title: The 5-Minute Pediatric Consult Authors: M. William Schwartz MD; et al. Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7577-9

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