Ataxia

Ataxia: Excerpt from The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter

Robert B. Sammel

Ataxia is the inability to coordinate voluntary movements.

Approach

Ataxia usually refers to an inability of the cerebellum to coordinate movement, but dysfunction in other regions can also produce ataxia. The many causes of ataxia and the syndromes that mimic it can be narrowed by consideration of the age, acuity, and circumstances of onset, and by associated findings (1–4).

History

A. Characteristics of gait and coordination. Disorders of gait and coordination are common, and many abnormal types of gait can suggest ataxia.

1. Parkinson’s disease (and other extrapyramidal syndromes) is characterized by a shuffling gait, deficiencies in movement initiation, en bloc movements, and bradykinesia. Normal pressure hydrocephalus and frontal lobe processes (gait apraxias) incorporate some of these features.

2. Hemiparetic and paraparetic gait are seen with unilateral and diffuse spasticity.

3. Motor neuropathies and myopathies interfere with the ability to walk through the limitation of muscular strength.

4. Hysterical gait is typified by a dramatic gait; the patient frequently lurching from point to point, swaying at the waist, and having more normal coordination in supine (astasia-abasia) and nonambulatory tasks.

5. Other neurologic processes (vertigo, myoclonic jerks, petit mal seizures, chorea) can either imitate or coexist with ataxia. Some elderly individuals adapt a wide-based gait because of the fear of repeating a fall, whereas a benign senile gait is also common.

B. Chronology of ataxia. The course of symptoms is valuable in the differential diagnosis of ataxia.

 1. Acute ataxia can have infectious, neoplastic, toxic, and traumatic causes.

 2. Chronic ataxia can be progressive, nonprogressive and persistent, or intermittent.

a. Chronic progressive ataxia is suggestive of toxins (lead), degenerative diseases, neoplasm, and some metabolic diseases.

 b. Chronic nonprogressive ataxia can be seen with brain malformation (Dandy-Walker syndrome, Arnold-Chiari syndrome), cerebral palsy, and residual damage of past insults (severe hypothermia, hypoglycemia, trauma, infection, toxin).

 c. Intermittent ataxia occurs with some hereditary and metabolic syndromes, migraine, and seizures.

 C. Other history. Obtain family history, and history of toxin ingestion [lead, thallium, mercury, acrylamide, toluene, and polychlorinated phencyclidine (PCP)], trauma, cancer, and recent infection. The exanthemas are associated with postinfectious ataxia, and varicella is especially associated with a truncal postinfectious cerebellitis. Drugs frequently causing ataxia include anticonvulsants (phenytoin, carbamazepine, and primidone), benzodiazepines, and antineoplastics. Lithium can cause ataxia even with therapeutic serum levels. Alcohol can cause acute Wernicke’s encephalopathy or a more chronic or subacute cerebellar degeneration (1–3).

Physical examination

A. Neurologic examination. Evaluate for dysmetria (finger-nose difficulty), saccadic eye movements (differentiated from nystagmus by multidirectionality), titubation (head bobbing), truncal swaying, and dysdiadochokinesia (difficulty with rapid alternating movements). Observe speech patterns (wandering pitch, volume). The typical ataxic gait is wide based. Cerebellar ataxia can be differentiated from sensory ataxia or poor proprioception by Romberg’s sign, where the removal of visual input dramatically reduces compensatory ability in sensory ataxia. Unilateral symptoms suggest a focal cerebellar insult (stroke, arteriovenous malformation, tumor), and deviation occurs ipsilateral to the lesion.

B. Associated symptoms can reveal specific processes. An older child with intermittent ataxia from basilar migraine, for example, will have a normal neurologic examination, whereas a child with hereditary periodic ataxia can present with nystagmus and more mild symptoms (1). Ataxia can precede the characteristic lesions of ataxia-telangiectasia, which tend to appear around 5 years of age. Opsomyoclonus warrants a search for neuroblastoma. The photosensitive rash of Hartnup’s disease and the specific findings of maple syrup urine disease can assist in diagnosis. Look for signs and symptoms of hypothyroidism (Chapter 14.4). Pes cavus and scoliosis are associated with Friedreich’s ataxia.

Testing

A. Diagnostic imaging. Most evaluations should begin with imaging of the brain, because clinical pictures suggest specific diagnoses only on occasion. Magnetic resonance imaging is superior to demonstrate tumors, multiple sclerosis, and malformations. Imaging differentiates between posttraumatic posterior fossa hemorrhage and postconcussion syndrome. Lumbar puncture may be necessary to rule out an infectious cause. An electroencephalogram helps uncover intermittent, seizure-related ataxia (“pseudoataxia”).

 B. Clinical laboratory tests. As indicated, check amino acid screening, toxin screening, and thyroid function. Younger individuals may benefit from testing for IgA, ceruloplasmin, and phytanic acid deficiency to rule out ataxia-telangiectasia, Wilson’s disease, and Refsum’s disease, respectively. Pyruvate is a marker of mitochondrial disease. Vanillymandelic acid and homovanillic acid levels occasionally help to detect occult neuroblastomas. Paraneoplastic cerebellar degeneration is an immunologic phenomenon, most often associated with small cell lung cancer, for which Hu and Yo antibodies may be diagnostic. Approximately 40% of patients with Friedreich’s ataxia have frank or occult glucose intolerance, and there are associated electrocardiogram abnormalities.

Diagnostic assessment.

 The list of conditions that cause ataxia is long, but most fall under the categories of neoplastic, infectious or immunologic, hereditary (metabolic or primary cerebellar), structural, degenerative (idiopathic or secondary), toxic, traumatic, or vascular disease. The time course can suggest more or less likely diagnoses. Although degenerative and hereditary diseases occur across the lifespan, certain diseases occur more frequently at certain ages.

References

1. Fenichel GM. Clinical pediatric neurology: a signs and symptoms approach, 3rd ed. Philadelphia: WB Saunders, 1997.

2. Lieber CS. Medical disorders of alcoholism. N Engl J Med 1995;333:1058–1065.

3. Marsden CD, Fowler TJ. Clinical neurology, 2nd ed. London: Arnold Med Publishers, Ltd., 1998.

4. Sudarsky L. Gait disturbances of the elderly. N Engl J Med 1990;322:1441–1446.

Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

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More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X

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