**5. Neuroanatomy and neuropathology of ataxia**

Ataxia is a condition that affects the cerebellum and its afferent and efferent connections, the vestibular system, and the proprioceptive sensory pathway (**Figure 4**). The cerebellum is often divided into the cerebellar hemispheres and the midline cerebellum. A separate form of ataxia may manifest after lesions in any of these areas. For instance, injury to the unilateral cerebellar hemisphere typically results in ipsilateral cerebellar ataxia, whereas damage to the midline cerebellar structures typically manifests as gait impairment and truncal ataxia.

### **Figure 4.**

*The cerebellum's afferent and efferent connections. Climbing fibers from the inferior olives pass through the inferior cerebellar peduncles to link to the cerebellum, whereas pontine mossy fibers pass through the middle cerebellar peduncles. The superior cerebellar peduncles receive cerebellar outputs from the dentate nucleus and other deep cerebellar nuclei.*

A lesion that disrupts the sensory transmission to the cerebellum may be the cause of ataxia. Spinal ataxia or sensory ataxia may result from this disease. Cerebellar ataxia is brought on by a break in the cerebellum's cortical impulses. Both of the aforementioned disorders can lead to spinocerebellar ataxias. They are caused by chromosomal CAG repetition and are autosomal dominant. Characteristic findings vary depending on where the lesion is located and include:


Localization can be aided by comprehension of this neuroanatomy and its relationship to coordination. Despite the fact that there is considerable clinical overlap among them, the relationships are presented in **Table 3**.


### **Table 3.**

*Clinical characteristics and neuroanatomical relationships in ataxia.*
