Chapter 53

#### High-Yield Facts

• Ataxia can result from a variety of lesions, including damage to the peripheral nerves, spinal cord, cerebellum, and cerebral hemispheres. One of the most common etiologies is drug intoxication, especially with alcohol, benzodiazepines, or phenytoin.

• Findings of cerebellar dysfunction include nystagmus, staggering, wide-based gait, and titubation. In addition, a sensory examination for light touch and pinprick, position, and vibration sense should be performed because lower-extremity sensory impairment can cause ataxia.

• In a patient with acute ataxia, the history and physical examination focus on excluding acute infectious etiologies, such as meningitis or encephalitis, lesions that result in increased intracranial pressure, such as hemorrhage and tumors, and toxic ingestions.

• A common cause of ataxia in children younger than 6 years is acute cerebellar ataxia, a postinfectious phenomenon that often occurs about 2 weeks after a viral illness. The onset of ataxia is insidious and predominantly affects the gait, although dysmetria, nystagmus, and dysarthria can occur.

• In children, the most common cause of intermittent ataxia is a migraine headache that involves the basilar artery. Besides ataxia, associated symptoms include blurred vision, visual field deficits, vertigo, and headache.

• Chronic/progressive ataxia has an insidious onset and progresses slowly over weeks to months. The differential diagnosis consists of brain tumors, hydrocephalus, and genetic disorders.

• The combination of ataxia, headache, irritability, and vomiting in a child younger than 6 years is characteristic of a brain tumor.

• Hereditary causes of ataxia include spinocerebellar ataxias, of which there are over 30 types. Friedrich's ataxia is common autosomal recessive ataxia, which usually manifests before 10 years of age. It is characterized by ataxia, nystagmus, dysarthria, kyphoscoliosis, cardiomyopathy, and absent deep tendon reflexes.

• Patients with progressive ataxia require a thorough evaluation in the emergency department (ED). All patients are examined for signs of increased intracranial pressure, which in some cases can be severe enough to result in the threat of uncal herniation.

Ataxia is a disorder of intentional movement, characterized by impaired balance and coordination. It is usually due to a cerebellar disorder, which variably affects the trunk or extremities. Severe truncal ataxia is sometimes referred to as titubation. Ataxia affecting the extremities can result in a wide-based gait or can cause dysmetria, which is the tendency of the limbs to overshoot a target, with subsequent movements attempting to correct the overshoot.13

Ataxia is best classified as acute, episodic/intermittent, or chronic/progressive. Acute ataxia is usually acquired, whereas chronic/progressive usually is due to a congenital malformation, or a hereditary or degenerative disorder, although brain tumors can also result in progressive symptoms.13

#### Pathophysiology

Ataxia can result from a variety of lesions, including damage to the peripheral nerves, spinal cord, cerebellum, and cerebral hemispheres. Lesions of the cerebellum can be further categorized as affecting the hemispheres, which results in ipsilateral limb hypotonia, tremor, and dysmetria, but spare speech. With walking, these patients tend to veer to ...

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