Diseases » Cerebellar ataxia syndrome

Ataxia

Ataxia: Excerpt from The Diagnostic Approach to Symptoms and Signs in Pediatrics

Definedas impaired control of posture or movement of trunk and limbs.

Results from dysfunction of cerebellumor structures relaying information to or from cerebellum, includingperipheral nerves or spinal cord tracts (sensory ataxia), labyrinthsor vestibular pathways (labyrinthine ataxia), and frontal lobesor cerebral pathways (frontal lobe ataxia).

2 cerebellar syndromes are seen clinically:syndrome involving cerebellar hemispheres and syndrome involvingvermis. Lesion in 1 of cerebellar hemispheres leads to disturbanceof ipsilateral limb movement, where child tends to veer in directionof affected hemisphere. Lesion of vermis produces bobbing of head(titubation) and unsteadiness of trunk while sitting, standing,or walking.

Useful way to classify disorders thatcause ataxia is by type of onset: acute, episodic, or chronic/progressive.

Neurologic symptoms or signs accompanyingataxia help narrow diagnostic possibilities.

Principal Causes of Ataxia

1. Acuteataxia
   1. Drugs,chemicals, and toxins
   2. Head trauma
   3. Infection/inflammation
      1. Meningitis
      2. Encephalitis
      3. Labyrinthitis
      4. Brain abscess
   4. Brain tumor
   5. Hydrocephalus
   6. Postinfectious/immune disorders
      1. Acutecerebellar ataxia of childhood
      2. Acute disseminated encephalomyelitis
      3. Miller Fisher syndrome
      4. Multiple sclerosis
      5. Myoclonic encephalopathy and neuroblastoma
   7. Vascular malformation
   8. Conversion reaction
2. Episodic ataxia
   1. Epilepsy
   2. Basilar artery migraine
   3. Benign paroxysmal vertigo
   4. Metabolic disorders
      1. Maplesyrup urine disease (intermittent)
      2. Hartnup disease
      3. Pyruvate dehydrogenase complex deficiency
   5. Dominant recurrent ataxias
3. Chronic or progressive ataxia
   1. Braintumor
   2. Hydrocephalus
   3. Multiple sclerosis
   4. Congenital malformations of the cerebellumand/or brainstem
   5. Cerebral palsy
   6. Previous brain insults
   7. Spinocerebellar degeneration disorders
      1. Friedreichataxia
      2. Spinocerebellar degenerations
   8. Ataxia telangiectasia
   9. Metabolic disorders
      1. Refsumdisease
      2. Urea cycle defects (argininosuccinicaciduria)
      3. Respiratory chain disorders
      4. Abetalipoproteinemia

Clinical Features and Diagnosis

Acute Ataxia

Drugs, Chemicals, and Toxins

Usual ageof accidental drug ingestion is 1–4 yrs.

Drugs that can produce ataxia includeanticonvulsants (especially phenytoin, carbamazepine, primidone),hypnotics, and sedatives.

Other causes include ethyl alcoholor hydrocarbon solvent ingestion, glue or gasoline sniffing, andheavy metal (lead, mercury, thallium) or insecticide (DDT, lindane)poisoning.

History of ingestion and physical examusually are diagnostic. Otherwise, UA or blood analysis of drug,chemical, or toxin may be diagnostic.

Head Trauma

Can occur after concussion, along with headacheand dizziness. More serious head injury may produce cerebellar contusionor posterior fossa hematoma with ataxia, alteration in consciousness,and seizures.

Infection/Inflammation

Viral URIsand acute otitis media are common causes of labyrinthitis, whichis discussed in Chap. 73, Vertigo.

Bacterial meningitis, encephalitis,and brain abscess are other causes, as discussed in Chap. 3, Alteration in Consciousness.

Brain Tumor

Acute orchronic ataxia may be due to posterior fossa tumors (astrocytoma,ependymoma, medulloblastoma). Persistent headache, vomiting, nystagmus,neck stiffness, and head tilt are common associated findings.

Tumors of frontal lobe, thalamus, brainstem,or spinal cord also may cause ataxia. Seizures, impaired cognition,speech disturbance, and abnormal behavior may occur with frontallobe tumors, whereas pyramidal tract signs (spasticity, hyperreflexia)and choreoathetosis occur frequently with thalamic tumors. Commonfindings with brainstem tumors are pyramidal tract signs, cranialnerve palsies, and nystagmus. Pyramidal tract signs, impaired positionand vibration sense, impaired sensation below level of lesion (typicallysensory level on trunk), and bowel and bladder dysfunction may occurwith spinal cord tumors.

MRI is study of choice to locate anddefine extent of tumor. Histologic diagnosis is definitive.

Hydrocephalus

Ataxia maybe due to hydrocephalus where there is associated increased intracranial pressure.

CT is diagnostic.

See Chap.39, Macrocephaly.

Postinfectious/Immune Disorders

Acute Cerebellar Ataxia of Childhood

Precisecause is unknown, yet it often follows viral infections, includingvaricella.

Commonly occurs in children 1–5yrs of age.

Usual presentation is sudden onsetof unsteadiness while walking or inability to stand or walk. Slurredspeech and mild nystagmus also may occur.

Neurologic exam reveals clear sensorium,normal deep tendon reflexes, and normal sensation.

In most cases, recovery is completein 6–8 wks, but residual impaired speech, persistent ataxia,and disorders of behavior and learning may occur.

Because this is diagnosis of exclusion,drug screening and imaging study should be considered in each child.

Lumbar puncture is performed with suspectedencephalitis.

Acute Disseminated Encephalomyelitis

Definedas immune-mediated disorder that often occurs after viral infections.

Can present with ataxia or pyramidalsigns, and altered sensorium. Optic neuritis also may occur.

MRI is diagnostic method of choice.

Miller Fisher Syndrome

Consideredto be variant of Guillain-Barré syndrome.

In many cases, it is associated withstrains of C. jejuni.

Characteristic features are externalophthalmoplegia, ataxia, and areflexia.

Evolves over 1–2 wks withgenerally complete resolution.

Multiple Sclerosis

Definedas immune-mediated demyelinating disease that occurs in geneticallysusceptible individuals.

Occurrence is unusual before adolescence.

>1 anatomic area of nervoussystem is involved, and neurologic abnormalities tend to remit andrecur.

Can present with ataxia, vision disturbance(blurring, diplopia, loss of vision), numbness or paresthesia, headache,vomiting, vertigo, or combination of these findings.

CSF exam may be abnormal with mildpleocytosis, mild increase in protein, and sometimes presence ofoligoclonal bands.

MRI shows areas of demyelinization,especially affecting periventricular and spinal cord white matter,cerebellum, and brainstem.

Myoclonic Encephalopathy and Neuroblastoma

Characteristicfeatures are chaotic eye movements (opsoclonus), myoclonic movementsthat contribute to ataxia, and encephalopathy.

Pathogenesis is thought to be alteredimmune state.

Neuroblastoma is responsible for manycases and should be investigated. See Chap.1, Abdominal Masses.

Vascular Malformation

Spontaneouscerebellar hemorrhage can be due to rupture of arteriovenous malformation.

Headache and ataxia are major features.

CT is initial imaging study of choice.

Conversion Reaction

Hysteriain the form of conversion reaction can cause ataxia, especiallyin girls 10–15 yrs of age.

Individuals appear to sit without difficulty,but when asked to stand, they begin to sway from the waist. Insteadof assuming wide-based gait to assure stability, lurching and staggeringoccur.

History, clinical observation, andnormal physical and neurologic exams are diagnostic.

Episodic Ataxia

Epilepsy

Ataxia maybe the only evidence of seizure activity. It is episodic, and onsetis sudden. During episode, child may appear confused.

EEG is useful in diagnosis.

See Chap.59, Seizures.

Basilar Artery Migraine

Definedas episodic occurrences of brainstem or cerebellar dysfunction duringmigraine attack.

More common in girls during adolescencebut can occur at any age.

Episode often begins with visual disturbancefollowed by nausea and vomiting and sometimes ataxia. Paresthesias,vertigo, tinnitus, alternating hemiparesis, and alteration of consciousnessalso may occur. Neurologic symptoms are usually followed by throbbingoccipital headache.

Normal MRI and MRA exclude brain massesand vascular lesions. EEG excludes benign occipital epilepsy.

Benign Paroxysmal Vertigo

Usuallyoccurs in children 2–6 yrs of age.

Episodes are sudden and brief, usuallylasting a few minutes, and posture cannot be maintained. Child appearsfrightened and often lies on floor or asks to be held. Nystagmusalso may occur. Some children subsequently develop migraine headaches.

Complete recovery occurs between episodes.

Metabolic Disorders

Maple Syrup Urine Disease (Intermittent)

Onset ofintermittent form is usually between 5 mos and 2 yrs. Infection,surgery, or protein-rich diet may provoke episodes of ataxia andalteration in consciousness.

See Chap.3, Alteration in Consciousness and Chap. 13, Developmental Delay.

Hartnup Disease

Definedas autosomal-recessive disorder due to defect in intestinal andrenal transport of neutral amino acids. Gene locus has been mappedto chromosome 11q13.

Characteristic manifestations are photosensitiveskin rash (attributed to nicotinamide deficiency), cerebellar ataxia,emotional lability, and aminoaciduria. Marked increase in urinaryexcretion of neutral amino acids—alanine, asparagine, citrulline,glutamine, histidine, isoleucine, leucine, phenylalanine, serine,threonine, tryptophan, tyrosine, and valine—characterizesthis disorder. Serum amino acids are usually normal because transportsystem of small peptides remains intact.

Pyruvate Dehydrogenase Complex Deficiency

Consistsof several enzymes that catalyze oxidation of pyruvate to carbondioxide and acetyl CoA. 3 main enzymes are pyruvate decarboxylase(E1), dihydrolipoyl transacetylase (E2), and dihydrolipoyl dehydrogenase(E3). Deficiency of enzyme activity of any of these components resultsin lactic acidosis and CNS dysfunction.

Clinical spectrum varies from severelactic acidosis and cystic white matter lesions in neonates to lacticacidosis and psychomotor retardation in infants to mild acidosisand episodic ataxia in older children. Increased serum concentrationsof pyruvate and lactate are found.

Diagnosis is confirmed by deficiencyof one of the above enzymes in skin fibroblasts, leukocytes, ormuscle.

Dominant Recurrent Ataxias

2 distinctgenetic defects that cause episodic ataxia have been described—episodic ataxiatype 1 (due to mutations in the potassium channel gene on chromosome12) and episodic ataxia type 2 (due to mutations in the calciumchannel gene on chromosome 19). Genetic transmission in both defects isautosomal-dominant.

Onset of episodic ataxia type 1 isusually between 5 and 7 yrs. Duration of episode is usually ≤10mins but can last up to 6 hrs. Continuous movement (myokymia) ofsmall hand muscles may occur during and between episodes. Diagnosisis usually clinical and based on typical episodes and family history;however, electromyography can confirm diagnosis by demonstratingcontinuous motor unit activity, usually in the hands.

Onset of episodic ataxia type 2 isusually in school-aged children or adolescents. Episodes of ataxiamay be associated with vomiting, vertigo, and nystagmus. Episodesmay last between 1 hr and 1 day and may occur several times/mo.Diagnosis is usually clinical. Acetazolamide usually prevents recurrencesof episodes.

Chronic or Progressive Ataxia

Brain tumors, hydrocephalus, and multiplesclerosis are discussed in previous sections.

Congenital Malformations of the Cerebellum and/orBrainstem

Many malformations,including cerebellar hypoplasia, vermal aplasia, and Chiari malformations,and basilar impression may cause chronic ataxia.

MRI is diagnostic.

Cerebral Palsy

Ataxic form results in delayed attainmentof motor skills. Incoordination and hypotonia also may occur. Walkingmay not occur until 3–4 yrs and then with difficulty andfrequent falling.

Previous Brain Insults

Chronic ataxia may follow previous acutecauses of generalized brain insults such as bacterial meningitis,viral encephalitis, and head trauma.

Progressive Hereditary Ataxias

Friedreich Ataxia

Definedas autosomal-recessive disorder due to unstable triplet repeat offrataxin gene located on chromosome 9q13. Onset is usually at 2–16yrs.

Initial finding is many children isataxia. Slurred speech, sensorineural deafness, cardiomyopathy,and absence of deep tendon reflexes usually follow.

Molecular genetic diagnosis is definitive.

Spinocerebellar Degenerations

Definedas autosomal-dominant disorders characterized by involvement ofcerebellum and sometimes basal ganglia, brainstem, spinal cord,and optic nerve.

Clinical features are variable andinclude progressive ataxia, pyramidal and extrapyramidal signs,peripheral neuropathy, and visual loss.

In a number of these disorders, moleculargenetic analysis is available.

Ataxia Telangiectasia

Definedas autosomal-recessive disorder characterized by progressive truncalataxia, which usually begins during first year of life.

Telangiectasia usually occurs in childhoodand may be found on bulbar conjunctivae, ears, face, and extremities.

Recurrent sinus and pulmonary infectionsreflect underlying immunodeficiency.

See Chap.53, Recurrent Infection.

Metabolic Disorders

Refsum Disease

Definedas autosomal-recessive disorder due to decreased enzyme activityof phytanoyl-CoA hydroxylase, which catalyzes conversion of phytanicacid to pristanic acid. Gene locus has been mapped to chromosome10.

Characteristic features include retinitispigmentosa, cerebellar ataxia, and polyneuropathy. Night blindnessis often first symptom. Other findings include ichthyosis; cataracts;sensorineural hearing loss; cardiomyopathy; muscle weakness; andvariable loss of pain, touch, position, and vibration sensation.

Increased serum level of phytanic acidis diagnostic. Enzyme assay in cultured fibroblasts is definitive.

Other

Respiratorychain disorders, argininosuccinic aciduria, and abetalipoproteinemiaalso may cause chronic ataxia.

See Chap.3, Alteration in Consciousness and Chap. 14, Diarrhea.

Diagnostic Approach

Types of Ataxia

History—including mode of onset(acute, episodic, chronic/progressive)—and physicalexam help distinguish between different types of ataxia (cerebellar,labyrinthine, sensory, and frontal lobe).

Cerebellar Ataxia

Most commoncauses are acute cerebellar ataxia of childhood, drug intoxication,head trauma, and posterior fossa neoplasm.

Besides ataxia, other signs of cerebellarinvolvement include nystagmus, intention tremor, and swaying orlurching during tandem walking.

Labyrinthine Ataxia

Most commoncause is acute labyrinthitis secondary to viral upper respiratoryinfection or acute otitis media.

Nystagmus, vertigo, and hearing lossare common associated findings.

Sensory Ataxia

Causes includemultiple sclerosis and spinocerebellar degeneration disorders.

Signs of peripheral sensory loss (touch,pain, temperature, vibration, and position sensation), paresthesias,absent deep tendon reflexes, and limb weakness may be found withsensory ataxia.

Frontal Lobe Ataxia

Most commoncauses of frontal lobe ataxia are acute head trauma and frontallobe tumors.

Seizures, impaired higher corticalfunction (speech, behavior, cognition), and increased intracranialpressure in association with ataxia may signify frontal lobe lesion.

Evaluation

Type ofataxia, mode of presentation, and inheritance pattern help narrowdiagnostic possibilities.

History may indicate drug ingestion.

CT or MRI can diagnose congenital malformation,hydrocephalus, cerebral tumor, brain abscess, and cerebellar hemorrhage.

Lumbar puncture should be performedwith suspected meningitis, encephalitis, or multiple sclerosis afterneuroimaging has excluded mass lesion.

Electromyography and measurement ofnerve conduction velocity are useful with suspected sensory ataxia.

Vestibular function tests may be usefulwith suspected labyrinthine ataxia.

With ataxia and suspected metabolicdisorder, the following tests should be performed initially: serumelectrolytes, glucose, ammonia, lactate, and pyruvate; and quantitativeblood and urine amino acids. Other investigations depend on suspecteddiagnosis.

References

1. Behrman RE, et al., eds. Nelson textbookof pediatrics, 16th ed. Philadelphia: WB Saunders, 2000.
2. Berman PH, Packer RJ. Ataxia. In: Fleisher GR, LudwigS, eds. Textbook of pediatric emergency medicine, 3rd ed. Baltimore:Williams & Wilkins, 1993:112–115.
3. Fenichel GM. Clinical pediatric neurology: a signsand symptoms approach, 4th ed. Philadelphia: WB Saunders, 2001.
4. Friday JH. Ataxia. In: Fleisher GR, Ludwig S, eds.Textbook of pediatric emergency medicine, 4th ed. Philadelphia:Lippincott Williams & Wilkins, 2000:153–155.
5. Gieron-Korthals MA, et al. Acute childhood ataxia:10-year experience. J Child Neurol 1994;9:381–384.
6. Long SS, et al., eds. Principles and practice of pediatricinfectious diseases. New York: Churchill Livingstone, 1997.
7. Menkes JH, Sarnat HB. Child neurology, 6th ed. LippincottWilliams & Wilkins, 2000.
8. Noseworthy JH, et al. Multiple sclerosis. N Engl JMed 2000;343:938–952.
9. Online Mendelian Inheritance in Man (OMIM). McKusick-NathansInstitute for Genetic Medicine, Johns Hopkins University (Baltimore,MD) and National Center for Biotechnology Information, NationalLibrary of Medicine (Bethesda, MD), 2000. World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim.
10. Rudolph AM, ed. Rudolph's pediatrics, 20thed. Stamford, CT: Appleton & Lange, 1996.
11. Stumpf DA. The inherited ataxias. Pediatr Neurol 1985;1:129–133.
12. Swaiman KF, Ashwal S, eds. Pediatric neurology: principles & practice,3rd ed. St. Louis: CV Mosby, 1999.

Book Source Details

• Book Title: The Diagnostic Approach to Symptoms and Signs in Pediatrics
• Author(s): Paul S. Bellet
• Year of Publication: 2006
• Copyright Details: The Diagnostic Approach to Symptoms and Signs in Pediatrics, Copyright © 2006 Lippincott Williams & Wilkins.

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