Ataxia vs apraxia

Neurological lesions have always been complicated as understanding the central nervous system and its numerous pathways is not a cake walk. Ataxia and apraxia are often confused for each other, but they are two very different neurological symptoms.

Ataxia is a neurological sign wherein there is loss of coordination of muscles. It is a type of movement disorder. Apraxia, on the other hand, is the inability to execute complex, purposeful movements which have already been learnt by the person. Apraxia is lack of performance of the task despite having the desire and the capability to bring about the movement. Apraxia is an acquired disorder of motor nerves due to inability to understand commands. Ataxia is due to lesions in the cerebellum but apraxia is due to lesions in the cerebrum. Ataxia is seen as ‘muscles giving way’ but apraxia is the result of a lack of a motor impulse in spite of having intact muscular power and the ability to do it. Ataxia is a sign of some cerebellar condition, it is the result of a lesion in the cerebellum but apraxia is a clinical condition itself. Apraxia can also be explained as inability to construct appropriate (voluntary) actions. While ataxia is loss of sensory and motor functions, apraxia is lack of just the motor functions i.e. muscular movements.

Causes of ataxia are lesions in the central nervous system especially the cerebellum, exposure to certain chemicals agents like ethanol, vitamin B12 deficiency, thyroid dysfunction, radiation poisoning etc. The cause of apraxia is a lesion in the cerebrum.

Types of ataxia are cerebellar ataxia, sensory ataxia, and vestibular ataxia. Cerebellar ataxia presents itself as disturbances in gait, difficulty in balancing, disturbances in walking and other motor disturbances like tremors and difficulty in taking a turn while walking. Sensory ataxia leads to swaying of person when asked to stand with feet close to each other and eyes closed i.e. Romberg’s sign. This is due to a fault in the proprio-reception (orientation of body) which is a function of the canals in the ears. Vestibular ataxia results due to pathological changes in the vestibular system situated inside the ear which leads to ataxia accompanied with nausea, vomiting, and vertigo.

The types of apraxia are ideomotor apraxia, conceptual apraxia, speech apraxia and constructional apraxia. Ideomotor apraxia manifests as an inability to plan or complete voluntary actions like closing the buttons of the shirt, etc. Conceptual apraxia is seen as not having the ability to think over the steps required to perform some action. The people affected with this type jumble up things and do last things first and first things last. An example of this type of apraxia is that a person puts vegetables in the pot first and then the oil needed for cooking. Speech apraxia is seen in both adults and children. It is typically seen in persons who previously had the ability of speech intact. It involves loss of already acquired speech levels. It usually involves articulatory errors while framing sentences. Treatment for ataxia is physiotherapy, occupational therapy and treating the lesion causing the ataxia. Treatment for apraxia is only physical therapy, physiotherapy and occupational therapy.

Summary:

Ataxia is loss of controlled and coordinated muscle movements due to muscle weakness whereas apraxia is inability to carry out purposeful movements despite proper coordination and muscle power. In ataxia, a person has inability due to defect in the nervous pathways crossing over at cerebellum, but in apraxia all the complex integrated movements are difficult to be performed.

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