Ataxia is a disorder of movement characterized by inco-ordination, lack of precision and speed of movement with inability to maintain balance. The most prominent feature is an abnormal gait - which is wide based, lurching and staggering.

The pathology causing ataxia can be anywhere in the cerebellum, or its connections with other parts of the nervous system.

Differentiation between cerebellar and sensory ataxia:

Sensory Ataxia:
It is due to loss of sensory input to the cerebellum because of peripheral nerve or posterior column disease. The patient often looks at the feet to know their position in space. Along with inco-ordination and wide based gait, position and vibration sense is also impaired. The patient has a high stepping gait and the inco-ordination tends to increase on closing the eyes. (Positive Rhomberg's test). The speech is invariably normal.

Cerebellar Ataxia:

• Truncal Ataxia: The lesion is in the vermis of the cerebellum. The child has trouble keeping balance even while sitting and increases if asked to sit with legs crossed. This ataxia is better revealed on standing/running. The child has even more trouble keeping balance with eyes open. The gait is more lurching than seen in sensory ataxia (its almost staggering as seen in acute alcohol intoxication) and is more apparent when the patient is asked to turn quickly or hop on one foot. Titubation (to and fro bobbing of the head) may also be seen. The speech is usually slurred.
  
  
• Ataxia with disturbance predominant in one direction and dysmetria and hypotonia in unilateral limbs is seen in lesions in the ipsilateral cerebellar hemispheres. There is a tendency to veer off in the direction of the affected hemisphere.

TRUNCAL ATAXIA AND INTENTION TREMORS ARE SIGNS OF CEREBELLAR INVOLVEMENT.

Other features of cerebellar disease are a scanning speech, hypotonia, ocular and limb dysmetria.

Ataxia may present with :

1. ACUTE ONSET :
   
   
   • WITH RAPID IMPROVEMENT
     
     
   • WITH PROLONGED OR INTERMITTENT COURSE
     
     
2. INSIDIOUS ONSET :
   
   
   • SLOW PROGRESSION OF ATAXIA
     
     
   • INTERMITTENT OR STATIONARY COURSE