ABSTRACT
INTRODUCTION Ataxia refers to instability of posture or lack of coordination of movement occurring independently of motor weakness. Characteristic manifestations of ataxia include postural and gait abnormalities, incoordination of limb movements, dysarthria and oculomotor disturbances. Postural changes are typified by swaying instability of the trunk while standing or even sitting. A wide-based stance is assumed, but patients may still have difficulty maintaining balance. Gait is irregular, wide-based and staggering, with loss of the ability to tandem walk. Limb abnormalities include dysmetria, an inability to perform movements with proper timing and trajectory. Intention tremor, loss of fluidity of movement, inability to control force of movement and dysdiadochokinesia are features of dysmetria. The last of these refers to a reduced ability to perform rapid, alternating movements. Dysarthria is defined by abnormalities of rhythm, fluency and clarity of speech. Oculomotor changes may consist of disorders of ocular fixation, ocular alignment, visual pursuit, saccadic movements and nystagmus. Several clinical assessment scales have been developed, ICARS108 and SARAS,94 to evaluate the degree of clinical involvement in ataxic patients. A guideline for the clinical diagnosis and management of adult ataxias has been published by the European Federation of Neurological Societies.111
