Sunday, October 28, 2012

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Ataxic gait

This type of gait can be seen in cases of cerebellar or sensory ataxia.

Cerebellar ataxia and gait:

The problem here lies with the coordinating mechanisms in the cerebellum and its connecting systems. The gait is a clumsy, staggering, unsteady, irregular, lurching, titubating and wide-based. The patient may sway to either side, back or forward. Leg movements are erratic, and step length varies unpredictably.
The patient is unable to follow a straight line on the floor (to walk tandem).

With a lesion of the cerebellar vermis, the patient will exhibit a lurching, staggering gait but without laterality, the ataxia will be as marked toward one side as the other.
Cerebellar ataxia is present with eyes both open and closed; it may increase slightly with eyes closed but not so markedly as in sensory ataxia.

A gait resembling cerebellar ataxia is seen in acute alcohol intoxication.

With a hemispheric lesion the patient will stagger and deviate toward the involved side. In disease localized to one cerebellar hemisphere or in unilateral vestibular disease, there is persistent swaying or deviation toward the abnormal side. As the patient attempts to walk a straight line or to walk tandem he deviates toward the side of the lesion.
A patient with acute vestibulopathy will drift toward the involved side walking forward, and continue to drift during the backward phase. The resulting path traces out a multipointed star pattern. Walking a few steps backward and forward with eyes closed may bring out “compass deviation” or a “star-shaped gait”.
When attempting to walk a fixed circle around a chair, clockwise then counterclockwise, the patient will tend to fall toward the chair if it is on the side of the lesion, or to spiral out away from the chair if on the opposite side.

Either unilateral cerebellar or vestibular disease may cause turning toward the side of the lesion on the Fukuda stepping test. For all the tests that bring out deviation in one direction, other findings must be used to differentiate between vestibulopathy and a cerebellar hemispheric lesion. Unilateral ataxia may be demonstrated by having the patient attempt to jump on one foot, with the eyes either open or closed. The patient with bilateral vestibular disease may seek to minimize head movement during walking, holding the head stiff and rigid; having the patient turn the head back and forth during walking may bring out ataxia.

Sensory ataxia and gait:

The patient in this condition is extremely dependent on visual input for coordination. When deprived of visual input, as with eyes closed or in the dark, the gait deteriorates markedly. The difference in walking ability with and without visual input is the key feature of sensory ataxia. If the condition is mild, locomotion may appear normal when the patient walks eyes open. More commonly it is wide based, and poorly coordinated.

The term “steppage gait” refers to a manner of walking in which the patient takes unusually high steps. Sensory ataxia is one of the causes of a steppage gait. The patient takes a high step, throws out her foot and slams it down on the floor in order to increase the proprioceptive feedback. The heel may land before the toe, creating an audible “double tap.” An additional sound effect may be the tapping of a cane, creating a “slam,slam, tap” cadence. The sound effects may be so characteristic that the trained observer can make the diagnosis by listening to the footfalls.

The patient with sensory ataxia watches her feet and keeps her eyes on the floor while walking. With eyes closed, the feet seem to shoot out, the staggering and unsteadiness are increased, and the patient may be unable to walk. There is less reeling and lurching in sensory ataxia than with a comparable degree of cerebellar ataxia. The difficulty is even worse walking backward, since the patient cannot see where she is going. The patient with bilateral foot drops, however, also has a steppage gait and a double tapping sound striking.

In all of these tests, sensory ataxia can be differentiated from predominantly cerebellar ataxia by accentuation of the difficulty with eyes closed; and unilateral cerebellar or vestibular disease from vermis involvement by laterality of unsteadiness.


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