Ataxia is the term given to a form of movement disorder with a loss of balance and physical co-ordination leading to difficulty in walking normally.

The Cerebellum of the brain, the vestibular system of the inner ear, and the positional (proprioceptive) nerves in the spinal cord are normally responsible for maintaining balance. The cerebellun is responsible for co-ordination. Ataxia occurs when there is damage to the cerebellum, vestibular system or spinal cord.

Ataxia due to dysfunction of the vestibular system, is usually of sudden onset and associated with prominent vertigo, nausea and vomiting. 

Ataxia due to damage of the the positional (proprioceptive) nerves in the spinal cord is gradual in onset with an unsteady "stomping" gait with heavy heel strikes, as well as a postural instability in poorly lit environments. when the lack of proprioceptive input cannot be compensated for by visual input.

Ataxia due to damage to the cerebellum may initially present with poor balance. As the condition progresses, walking is characterized by a wide based and high stepping gait, as well as staggering and lurching from side to side and loss of balance while turning which could result in falls. 

Symptoms:

• Unsteady walk and a tendency to stumble
• Poor coordination
• Difficulty with fine-motor tasks, such as eating, writing or buttoning a shirt
• Change in speech
• Involuntary back-and-forth eye movements (nystagmus)
• Difficulty swallowing

Causes:

• Head trauma.
• Stroke caused by interruption to the  blood supply to a part of the brain is interrupted or severely reduced, with death of cells
• Transient ischemic attack (TIA) caused by a temporary decrease in blood supply to part of your brain
• Multiple sclerosis, a chronic, potentially debilitating disease that affects the brain and spinal cord.
• Viral infection such as Chickenpox.
• Degenerative disorders triggered by your immune system's response to a cancerous tumor
• Tumor or growth on the brain,
• Toxic reaction to certain medications, substances such as solvents and heavy metal poisoning
• Chronic degenerative disorders of the brain