Synopsis
Distinguish cerebellar ataxia from sensory and vestibular imbalance, identify time-critical acute causes, and investigate subacute or chronic syndromes using a structured, cause-directed neurological pathway.
- Ataxia is impaired coordination not explained by weakness alone; localise it as cerebellar, sensory, vestibular or mixed before constructing the differential diagnosis.
- Sudden ataxia, severe gait inability, new headache, diplopia, dysarthria or focal signs is posterior circulation stroke until urgently assessed with brain and vascular imaging.
- Cerebellar disease produces broad-based gait, truncal instability, dysmetria, intention tremor, dysdiadochokinesia, gaze-evoked nystagmus and scanning or slurred speech.
- Sensory ataxia accompanies loss of joint position or vibration, pseudoathetosis and a positive Romberg sign; vision improves stance because proprioceptive input is impaired.
- Vestibular imbalance is dominated by vertigo, oscillopsia and nystagmus, with veering or falling; central eye signs or inability to stand requires urgent stroke expertise.
- Acute toxic and metabolic causes include alcohol, sedatives, antiseizure toxicity, lithium, hypoglycaemia, electrolyte disturbance and thiamine deficiency; medication and exposure history is essential.
- Subacute progression raises immune, paraneoplastic, nutritional, infectious and structural disease, whereas long progression suggests genetic or degenerative ataxia but treatable causes still need exclusion.
- MRI, targeted blood tests, neurophysiology, CSF and genomic testing should follow tempo, localisation and family history; indiscriminate panels create incidental results without replacing neurological assessment.
Key red flags
Abrupt onset, new severe headache, focal weakness, dysarthria, diplopia or inability to stand requires immediate posterior circulation stroke assessment.
Falling consciousness, repeated vomiting or progressive headache with cerebellar signs raises haemorrhage, hydrocephalus or posterior fossa mass effect.
Ataxia with confusion, ocular motor abnormality, malnutrition or alcohol dependence is possible Wernicke encephalopathy and needs immediate parenteral thiamine.
Fever, meningism, immunosuppression or rapidly progressive encephalopathy requires urgent assessment for infection or immune-mediated cerebellitis.
Rapid progression over weeks, weight loss or systemic cancer clues warrants expedited neurological and malignancy evaluation for paraneoplastic or structural disease.
Investigation priorities
Exclude haemorrhage and identify vertebrobasilar occlusion or dissection during sudden-onset ataxia.
Management branches
Coordination or gait impairment began suddenly or over a few hours.
- Activate emergency neurological assessment, establish last-known-well, check glucose and observations, and identify headache, neck pain, focal signs and anticoagulant exposure.
- Arrange urgent non-contrast CT and head-and-neck vascular imaging, with MRI when required, while assessing thrombolysis or thrombectomy eligibility.
- Review alcohol, medicines, overdose, infection and electrolyte disturbance in parallel and correct immediately dangerous metabolic abnormalities.
- Admit when stroke, persistent severe gait inability, swallowing risk or diagnostic uncertainty remains; do not discharge on a normal early CT alone.