Sporadic adult-onset ataxia of unknown…

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Sporadic adult-onset ataxia of unknown etiology

ORPHA:247234Disease

Also called Idiopathic late-onset cerebellar ataxia · SAOA

What it is

A rare non-hereditary degenerative ataxia disease characterized by a slowly progressive cerebellar syndrome (with ataxia of stance and gait, upper limb dysmetria and intention tremor, ataxic speech, and oculomotor abnormalities), presenting in adulthood (at around 50 years of age), that is not due to a known cause. Extracerebellar symptoms (e.g., decreased vibration sense and absent or decreased ankle reflexes), polyneuropathy and mild autonomic dysfunction may also be present. Mild cognitive impairment has also rarely been reported.

Key facts

Prevalence
1-9 / 100 000 (Italy)
Age of onset
Adult, Elderly
Inheritance
Not applicable
Classified as
Disease

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

ICD-10 codes

G31.8filed under a broader ICD-10 category — shared with 38 other rare diseases

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references

MONDO 0016591UMLS C4518339

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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