Ataxia
Ira Shah
Consultant Pediatrician, B J Wadia Hospital for Children, Mumbai, India
First Created: 01/03/2001 

Introduction

Ataxia is a disorder of movement characterized by incoordination, lack of precision, and speed of movement with the inability to maintain balance. The most prominent feature is an abnormal gait - which is wide-based, lurching, and staggering.

The pathology causing ataxia can be anywhere in the cerebellum, or its connections with other parts of the nervous system.

Differentiation Between Cerebellar and Sensory Ataxia

Sensory Ataxia:
It is due to loss of sensory input to the cerebellum because of peripheral nerve or posterior column disease. The patient often looks at the feet to know their position in space. Along with in co-ordination and wide-based gait, position and vibration sense is also impaired. The patient has a high stepping gait and the co-ordination tends to increase on closing the eyes. (Positive Rhomberg's test). The speech is invariably normal.

Cerebellar Ataxia:
Truncal Ataxia: The lesion is in the vermis of the cerebellum. The child has trouble keeping balance even while sitting and increases if asked to sit with legs crossed. This ataxia is better revealed on standing/running. The child has even more trouble keeping balance with eyes open. The gait is more lurching than seen in sensory ataxia (its almost staggering as seen in acute alcohol intoxication) and is more apparent when the patient is asked to turn quickly or hop on one foot. Titubation (to and fro bobbing of the head) may also be seen. The speech is usually slurred.

Ataxia with disturbance predominant in one direction and dysmetria and hypotonia in unilateral limbs is seen in lesions in the ipsilateral cerebellar hemispheres. There is a tendency to veer off in the direction of the affected hemisphere.

TRUNCAL ATAXIA AND INTENTION TREMORS ARE SIGNS OF CEREBELLAR INVOLVEMENT.

Other features of the cerebellar disease are a scanning speech, hypotonia, ocular, and limb dysmetria.

Acute Ataxia

  • Differential diagnosis of a child with acute or recurrent ataxia:
  • Drug Ingestion
  • Post-Infections Immune
    • Acute post infectious cerebellitis

    • Miller Fisher syndrome

    • Multiple sclerosis

    • Myoclonic encephalopathy and neuroblastoma

  • Brain Stem Encephalitis
  • Trauma
    • Hematoma

    • Post concussion

    • Vertebrobasilar occlusion

  • Genetic and Metabolic Disorders
    • Dominant Recurrent Ataxia

    • Hartnup's disease

    • MSUD (Maple Syrup Urine Disease)

    • Pyruvate dehydrogenase deficiency

  • Acute hemorrhage in Brain Tumor
  • Cerebral Hemorrhage - Vascular Disease

Acute ataxia occurs in children who were previously healthy and start with dizziness, nausea, and vomiting followed by nystagmus, intention tremor, imbalance, and staggering gait.

Acute Ataxia with Rapid Improvement

The two commonest causes are:

  • Drug Ingestion

  • Acute post infectious cerebellitis

Drug Ingestion:

Accidental drug ingestion is highest between 1 and 4 years of age. Overdose of hypnotics, tranquilizers, toxic doses of anticonvulsants especially phenytoin and carbamazepine may cause ataxia and nystagmus. If a child is on too high a dose of phenytoin, it usually takes 5-10 days for the ataxia to develop and about the same time after stopping or reducing the dose for the symptoms to disappear. Acute intoxication with glue, solvents, petrol, alcohol, antihistamines may also cause ataxia. It is diagnosed on the basis of history and urine examination for drug metabolites and blood for toxic analysis.

Acute cerebellar ataxia (Post-infectious acute cerebellitis):

It is usually seen in children between 2 to 7 years with a very sudden onset. It is often preceded by an exanthema (varicella), infectious mononucleosis, or other viral infections (polio, mumps, coxsackie, herpes, simplex, or ECHO viruses). It is thought to occur due to an autoimmune response to the viral agent. Ataxia is maximum at the onset. Symptoms are non-progressive for a couple of days or weeks and then subside. (Recovery may take 3 weeks to 5 months). Recovery is usually complete. It is a diagnosis of exclusion. Tendon reflexes are usually present (absence may suggest Miller Fisher syndrome). It's a self-limiting condition and treatment is usually not required.

Acute Ataxia with Prolonged or Intermittent Course

The commonest conditions to keep in mind are:

  • Myoclonic Encephalopathy (Dancing eye syndrome)

  • Neuroblastoma syndrome

  • Brain Tumors

  • Multiple sclerosis

  • Metabolic disorders

Myoclonic encephalopathy/Dancing eye Syndrome:

It is an idiopathic encephalopathy. It has an acute onset of ataxia in children between 6 months to 6 years. The most predominant feature is chaotic eye movements (opsoclonus). The child cannot control the head, cannot maintain balance on sitting or standing and there are intention tremors in the limb. The symptoms evolve over a period of weeks or more. The symptoms may persist for months or years and may impair the child's mental development. The most common differential diagnosis would be occult neuroblastoma and diagnosis is made by exclusion. Treatment consists of either ACTH or prednisolone. Marked improvement may occur within 1 to 4 weeks after starting treatment. ACTH is given as an injection in the dose of 20 - 80 units/day either IV/IM for several weeks or months. Alternatively, oral prednisolone in the dose of 2 mg/kg/day can replace ACTH or may be given instead of ACTH. Partial or complete remission may occur in 80% of the patients.

Neuroblastoma Syndrome:

The patient has same features as seen in myoclonic encephalopathy. The tumor may occur anywhere in the body - commonly in the abdomen. It is diagnosed by measuring urinary excretion of homovanillic acid (HVA) and vanillylmandelic acid (VMA). Radio-isotope studies using Metaiodobenzyl guanidine (MIBG) - a specific isotope is the investigation of choice. Treatment is surgical removal, chemotherapy, and/or radiation.

Brain Tumors:

Although brain tumors do present with insidious onset, sudden bleeding into the tumor or hydrocephalus may cause acute ataxia. Diagnosis is by brain imaging.

Multiple Sclerosis:

It is usually seen in children above 12 years of age. It is an uncommon condition in India. It is commonly seen in females and may present as an attack of optic or retrobulbar neuritis, ataxia, regional paraesthesis, hemiparesis, or seizures. It is due to non - contiguous demyelination in different areas of the CNS. The diagnosis of multiple sclerosis can be established only after the patient has had 2 separate attacks of symptoms with different localization with attacks being separated by months or years. CSF studies may show increased proteins, the presence of oligoclonal bands, and the presence of plasma cells. MRI may detect demyelination. Treatment consists of Interferon - b and/or ACTH/Steroids. Long term outcome is unpredictable.

Ataxia with Insidious Onset (Chronic Ataxias)

Differential diagnosis of a child with chronic or progressive ataxia:

  • BRAIN TUMORS
    • Cerebellar astrocytoma

    • Cerebellar hemangioblastoma (Von Hippel - Lindau disease)

    • Ependymoma

    • Medulloblastoma

    • Supratentorial tumors

  • HEREDITARY ATAXIAS
    • Autosomal recessive inheritance

    • Ataxia telangiectasia
    • Friedreich's ataxia
    • Hartnup's disease
    • Hypobetalipoproteinemia
    • Refsum's disease
    • Wilson's disease
    • MSUD (Maple syrup urine disease)
    • Marinesco - Sjogren syndrome (ataxia + mental retardation + Bilateral cataracts + short stature)
    • Pyruvate dehydrogenase deficiency
    • Ramsay Hunt syndrome
    • Juvenile GM2 gangliosidosis
    • Juvenile sulfatide lipidosis
    • Mitochondrial disorders
    • Ataxia - oculomotor apraxia
    • Ataxia with episodic dystonia
    • Autosomal dominant inheritance

    • Olivopontocerebellar degeneration
    • Machado - Joseph disease
    • X linked inheritance

    • Adrenoleukodystrophy
    • Leber's optic neuropathy

  • CONGENITAL MALFORMATIONS
    • Basilar impression

    • Cerebellar aplasia

    • Dandy walker malformation

    • Vermal aplasia

    • Chiari malformation

Chronic ataxia with slow progression:

The commonest causes of chronic slowly progressive ataxia are brain tumors (cerebellar astrocytoma-commonest) and hereditary ataxias (Friedreich's Ataxia and Ataxia-Telangiectasia are the commonest).

Brain tumors

They are always suspected in a previously healthy child who develops progressive ataxia with/without headache. The commonest brain tumors causing ataxia are the infratentorial tumors seen commonly in children between 2 to 8 years. Supratentorial tumors may also cause ataxia when it involves the input fibers from the frontal lobes to the cerebellum.

Cerebellar astrocytoma

They are slow-growing tumors consisting of a large cyst with a mural nodule in the region of the cerebellar hemisphere. Headache, signs of raised ICT, and ataxia are the commonest features. The head may remain tilted to one side. (This is the earliest symptom to develop). Brain imaging is useful for diagnosis and treatment consists of surgical removal. Emergency shunting may be required with life-threatening hydrocephalus.

Ependymoma of the fourth ventricle

It is derived from the cells that line the roof and floor of the 4th ventricle. Patients may develop raised ICT over months and may develop truncal ataxia. CT or MRI is useful in diagnosis and treatment consists of surgical removal along with radiation therapy.

Medulloblastoma

It is a primitive neuroectodermal tumor and presents either in the vermis or fourth ventricle. Patients present with rapidly evolving raised ICT and truncal ataxia due to the rapid growth of the tumor. Treatment consists of surgical removal, radiation, and chemotherapy.

Cerebellar Hemangioblastoma

It is a neurocutaneous syndrome inherited in an autosomal dominant fashion and consists of hemangioblastomas of the cerebellum and retina (Retinal hemangioblastomas occur earlier), renal carcinoma, and pheochromocytoma.

Hereditary Ataxias

Friedreich's ataxia: It is inherited as an autosomal recessive condition. The symptoms begin in the first decade of life as unsteady gait and rapid progression. Rhomberg's test is positive and patients have an impaired vibration & position sense. The deep tendon reflexes are absent showing involvement of the posterior column and posterior roots. The patients have an extension plantar reflex due to spasticity and involvement of the cortical tracts. Patients always develop dysarthria. Along with CNS involvement, the patients develop skeletal deformities in form of scoliosis and flexion contractures of the knees and pes cavus. Cardiomyopathy may also be seen. These patients have increased susceptibility to develop diabetes. EMG shows decrease conduction of sensory nerves. The patients are usually confined to the wheelchair by the early twenties. Treatment is only symptomatic.

Ataxia Telangiectasia: It is an autosomal recessive neurocutaneous syndrome. Ataxia, predominantly truncal, starts early in childhood. Telangiectasias may be present at 2 years of age but become apparent at 4-6 years. They appear first on bulbar conjunctiva and then spread in a butterfly distribution on the face, ears, and neck, Mental development may slow over a period of time. These children have recurrent sinopulmonary infection and serum IgA levels are decreased or absent. The thymus has an embryonic appearance and they also have impaired cellular immunity. They have an increased propensity to neoplasia due to generalized disorder of tissue differentiation and cellular repair. Elevated alpha fetoproteins (AFP) and carcinoembryonic antigens (CEO) are found commonly. The prognosis is poor.

Chronic ataxia with intermittent or stationary course:

It is seen commonly in patients with chronic drug ingestion (antiepileptics), Hartnup's disease, Refsum's disease and congenital malformations (They are usually associated with mental retardation)

Hartnup's disease:
It is an autosomal recessive metabolic error associated with massive aminoaciduria and nicotinamide deficiency. Tryptophan, instead of being converted to nicotinamide is converted to indole derivatives. Patients present with pellagra like itching eruptions on visible parts of the skin, ataxia, nystagmus, double vision, and exaggerated deep tendon reflexes. Mental changes in form depression, confusion, hallucination may also be seen. Treatment is by giving large doses of oral nicotinamide along with a high protein diet.

Common Causes of Ataxia in Different Age Groups

Ataxia in children before 1 year of age:

  • Congenital malformations

  • Mild arrested hydrocephalus

  • Cerebral Palsy

  • Marinesco - Sjogren syndrome

Ataxia in children between 1-5 years of age:

  • Drug Ingestion

  • Acute cerebellar ataxia

  • Myoclonic Encephalopathy and Neuroblastoma

  • Inborn errors of Metabolism

  • Brain tumors

  • Ataxia Telangiectasia

  • Refsum's disease

Ataxia in Children between 5-10 years

  • Drug Ingestion

  • Acute Cerebellar Ataxia

  • Brain tumors

  • Wilson's disease

  • Adrenoleukodystrophy

  • Hereditary Ataxias

Ataxia in children above 10 years of age:

  • Friedreich's Ataxia

  • Miller Fisher Syndrome

  • Cerebellar hemorrhage

  • Multiple Sclerosis

  • Olivopontocerebellar degeneration

  • Hereditary Ataxias

Presentation

Acute Onset:

  • With Rapid Improvement
  • With Prolonged or Intermittent Course
  • Insidious Onset:

  • Slow Progression of Ataxia
  • Intermittent or Stationary Course

Investigations in Acute Cerebellar Ataxia

  • CT/MRI of the brain

  • Lumbar Puncture

  • Drug screen

Other investigations:

  • MIBG/VMA

  • METABOLIC SCREENING (UAA/PAA/LACTATE/PYRUVATE/CHOLESTEROL/LIPOPROTEINS)

Optional Investigations:

  • ECG

  • 2D Echo, Friedreich's Ataxia and Refsum's disease

  • Funduscopy

  • Serum IgA Ataxia Telangiectasia


1. Clinical Pediatric Neurology - A sign and symptoms Approach 3rd edition - Gerald M. Fenichel.
2. Pediatric Neurology - Ingrid Gamstorp, 2nd edition(1985).


Ataxia Ataxia 01/03/2001
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