Chapter 163

Ataxia and gait disturbances may be symptoms of a variety of disease processes and generally are not themselves diagnoses. Ataxia is the failure to produce smooth intentional movements. Gait disorders include ataxic gait as well as a variety of other conditions. The presenting complaint may be articulated by the patient or family as weakness, dizziness, stroke, falling, or another nonspecific or even inaccurate chief complaint. These symptoms must always be viewed in the context of the patient’s overall clinical picture. For example, in a patient with the inability to walk, hemiplegia would not be considered primarily a gait disturbance. However, if the intraparenchymal hemorrhage were in the cerebellum, the inability to walk may be one of the dominating signs and symptoms. In this chapter, acute ataxia and disorders of gait are emphasized and the more common disorders are listed in Table 163-1.

Table 163-1 Common Etiologies of Acute Ataxia and Gait Disturbances

Ataxia or gait disturbances may result from many conditions that affect different elements of the central and peripheral nervous systems as well as systemic conditions. Clinicians tend to think that these disorders result primarily from cerebellar lesions. Cerebellar lesions may indeed cause ataxia, but isolated lesions of the cerebellum are not the most common cause of these complaints.

Ataxia may be roughly categorized into motor and sensory ataxias. Motor ataxias (also referred to as cerebellar ataxias) are usually caused by disorders of the cerebellum. The sensory receptors and afferent pathways are intact, but integration of the proprioceptive information is faulty. Involvement of the lateral cerebellum (one of the cerebellar hemispheres) may lead to a motor ataxia of the ipsilateral limb. Lesions affecting primarily the midline portion of the cerebellum often cause problems with axial muscle coordination reflected in difficulty maintaining a steady upright standing or sitting posture.

There are many reports of lesions in what would seem to be unlikely locations producing motor ataxia. Supratentorial infarctions, particularly small deep infarctions or lacunae of the posterior limb of the internal capsule, have been reported to cause isolated hemiataxia. It is postulated that interruption of either ascending or descending cerebellar to cortical pathways are the cause of this motor-type ataxia.1 Small infarctions or hemorrhages in thalamic nuclei may produce a clinical ...

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