Collect historical information about the entire symptom constellation, and ask about headache, nausea, fever, weakness, or numbness. A history of fever, review of medication history, or family history of ataxia may lead to the diagnosis in individual cases. The nature of onset of symptoms and the time course of the process guide the pace of investigations. For example, abrupt onset of gait difficulty in a patient with severe headache, drowsiness, nausea, and vomiting should suggest an acute process within the CNS, possibly a hemorrhage into the cerebellum. The possible consequences of that diagnosis are severe and may require immediate attention. At the other extreme, a patient without significant medical history who is brought to the ED with a stumbling gait after an episode of binge drinking requires examination but may need nothing other than observation unless history or physical examination suggest trauma or some alternative cause for the symptoms.
The following discussion of the neurologic examination assumes that the gait disorder is the dominating abnormality. Physical examination including testing of cranial nerves, mental status, sensation, and the motor system is necessary and may yield findings that lead to an unanticipated diagnosis.
General physical examination of a patient with ataxia or gait disturbance should include determination of orthostatic vital signs. Orthostatic hypotension may be present in hypovolemia, diabetic neuropathy, and other neurologic syndromes. Especially in the elderly, fluid replacement for simple hypovolemia may correct many symptoms of unsteadiness.
Gait testing is one of the most important parts of the directed neurologic examination. Observe the patient sitting upright in the stretcher, and then have the patient rise, stand, walk, and turn around. The patient should be asked to walk at a normal speed, then walk on the heels, and then the toes. Tandem gait is toe-to-toe walking and also tests many elements of the nervous system. Do not assume a normal examination without observing ambulation.
Cerebellar functions are tested by asking the patient to perform smooth voluntary movements and rapidly alternating movements. Dyssynergia (breakdown of movements into parts), dysmetria (inaccurate fine movements), or dysdiadochokinesia (clumsy rapid movements) may indicate a lateral cerebellar lesion. The rapid thigh-slapping test particularly examines rapidly alternating movements. This is correctly performed by asking the patient to pat the thigh with the palm then the back of the same hand in alternating fashion, making a sound with each rapid slap. The maneuver is performed with each hand in turn. The finger-to-nose test may be helpful in distinguishing between cerebellar and posterior column (proprioceptive) lesions. Performing this test with the eyes closed tests proprioception in the upper extremity. A test for cerebellar function that emphasizes the lower extremities is the heel-to-shin test. In cerebellar disease, the heel may initially overshoot the other shin or knee, and the action is done with a series of jerky movements. In posterior column disease, there may be difficulty locating the knee, and the movement down the shin typically weaves from side to side or falls off. Another test commonly used for cerebellar function is the Stewart-Holmes rebound sign (with sudden release of the flexed forearm, the individual fails to check the movement). Another example of rebound phenomena is when a tapped outstretched arm oscillates back and forth for several cycles.
The Romberg test is primarily a test of sensation, and if positive may distinguish sensory from motor ataxia. While standing with arms outstretched and eyes open, observe the patient for signs of unsteadiness. The feet should be narrowly spaced, and the posture should be easily maintained. The inability to maintain a steady standing posture (or, in extreme cases, a seated position) confirms that an ataxia is present but does not yet give any information about the type of ataxia. Then ask the patient to close the eyes, to eliminate visually orienting information. If the ataxia worsens with the loss of visual input, then the Romberg sign is present or positive, suggesting sensory ataxia with a problem of proprioceptive input (posterior column, vestibular dysfunction), or a peripheral neuropathy. Further neurologic examination is indicated to confirm the suspicion of sensory ataxia. In patients who show little or no change in unsteadiness with eye closure (Romberg test–negative), a motor ataxia is suggested, with possible localization of that problem to the cerebellum. Note that many normal individuals will have some small increase in unsteadiness with eye closure.
Historically, tabes dorsalis (neurosyphilis) was a common cause of sensory ataxia. In tabes dorsalis, the posterior columns and posterior spinal roots degenerate, primarily in the lumbosacral region. The loss of proprioceptive information from the lower extremities renders the patient dependent on visual cues for correct gait. The classic description is that of a patient who walks slowly with wide gait while staring at the ground. In darkness or with interruption of vision, the patient is unable to walk. The gait in this condition is peculiar, with the foot first raised and then slapped to the ground with each step. These abnormalities reflect the loss of proprioceptive information from the posterior roots and posterior columns. Consider vitamin B12 deficiency in patients with evidence of posterior column disease. If the deficiency is left untreated, an initial unsteady gait may progress to weakness, spasticity, and ataxia. The finding of a megaloblastic anemia may be a clue, but the neuropathy may precede the anemia.
Sensory examination in a patient with unsteady gait or movements should include position or vibration testing (posterior columns), as well as testing sensation to pinprick. Testing of the deep tendon reflexes will serve largely to discover asymmetry or spasticity that might suggest an alternative diagnosis. Acute cerebellar injury may result in muscle hypotonia for a few days or weeks.8
Nystagmus is seen in many different disorders due to lesions in a variety of different locations of the CNS, but the presence of nystagmus does suggest that the pathologic process is intracranial (CNS or vestibular) and not in the spinal cord or peripheral nervous system (see Chapter 164, Vertigo and Dizziness).