This syndrome a clinical diagnosis and has many underlying causes.

Clinical features:

Uncoordinated or inaccurate movement not due to paresis, sensory disturbances, increased tone or involuntary movements. A combination of any of the following features may occur:

  • Gait: broad based, staggering & swaying, unsteady,
  • Truncal ataxia: inability to sit or stand without support
  • Dysmetria: Past-pointing,
  • Asynergia/dyssynergia
  • Intension (kinetic) tremor, postural tremor

Investigations to consider: consider as appropriate depending on clinical assessment

Blood tests:

  • FBC, U&E, LFTs
  • TFT: hypothyroidism
  • B1 thiamine, B12 & methylmalonic acid,

Infectious tests to consider:

  • Syphilis serology: VDRL
  • Serology & cold agglutinins: Mycoplasma pneumoniae,
  • Legionella pneumophilia serology
  • Tests for Rickettsia rickettsii (Rocky mountain spotted fever)
  • CSF: VZV PCR positive,

Other metabolic tests to consider:

  • Ceruloplasmin & slit lamp examination
  • Iron studies: hemochromatosis
  • Vitamin E levels: low in ataxia with vitamin E deficiency AVED
  • Drug levels & toxicology:
  • Lithium levels, Phenytoin PHT levels,
  • Alcohol levels
  • Lead levels
  • Toluene
  • CO poisoning

Autoimmune tests to consider:

  • Coeliac disease antibodies: anti tissue transglutaminase, anti endomysial: Gluten ataxia
  • Antibodies to Purkinje cell antigens (anti-Yo antibodies), Anti-Hu antibodies (ANNA-1), anti-Ri antibodies
  • Anti-GAD antibodies: Cerebellar ataxia, downbeat nystagmus.
  • Anti-GALOP (IgM against central myelin antigen): Gait Disorder, Autoantibody Late-age Onset Polyneuropathy
  • Anti-GD1b antibodies and anti‐GQ1b IgG antibodies: Guillain-Barre syndrome Miller-Fisher variant

Urine amino acids:

  • Maple syrup urine disease, Hartnup disease


  • Brainstem or cerebellar hemorrhage, infarction, multiple sclerosis, neoplasms (medulloblastoma, pilocytic astrocytoma, ependymoma, ATRT, metastasis, glioblastoma, vestibular schwannoma, hemangioblastoma), CJD, abscess, Superficial siderosis, Acute postinfectious cerebellitis
  • Malformations (Chiari-malformation, Dandy-Walker malformation, congenital acquiductal stenosis)
  • Atrophy: cerebellar degeneration, paraneoplastic, alcoholic, Multiple system atrophy


  • Increased perfusion: Acute postinfectious cerebellitis

Genetic tests to consider:

  • Hereditary spinocerebellar ataxias
  • Adult form of Fragile X syndrome (Fragile X tremor ataxia syndrome)
  • Immunoglobulins & alpha fetoprotein: Ataxia telangiectasia

CSF analysis:

  • Pleocytosis: paraneoplastic cerebellar degeneration, postinfectious, viral cerebellar encephalitis,
  • Miller-Fisher syndrome
  • Whipple’s disease a.k.a. Tropheryma whippelli PCR
  • Protein 14-3-3 & S100: CJD

Nerve conduction studies
Echocardiography: hypertrophic cardiomyopathy in Friedrich’s ataxia, dilated cardiomyopathy in alcoholism
Endoscopy & intestinal biopsy: Coeliac disease (gluten enteropathy), Whipple’s disease

Causes of ataxia:

Cerebellar ataxia:

  • See causes of cerebellar ataxia

Sensory ataxia:

  • See causes of sensory ataxia

Vestibular ataxia:

  • See ‘vertigo’ peripheral vestibular causes
  • See ‘vertigo’ central vestibular causes


Causes of cerebellar ataxia:




Causes of sensory ataxia:

Peripheral sensory neuropathy:

  • Diabetes
  • Hypothyroidism
  • Diphteria
  • Immune:
    • GALOP syndrome, anti-MAG syndrome, Miller Fisher syndrome (anti‐GQ1b IgG), anti-GD1b antibody syndrome
    • Paraneoplastic anti-Hu antibody
  • Drugs:
    • Isoiazid, Pyridoxine, Cisplatin, Paclitaxel
  • Hereditary:
    • Autosoma dominant sensory ataxic neuropathy
    • HMSN-type III (Dejerine-Sottas disease)
    • Refsum’s disease
  • Those that may also affect the posterior columns, see below
    Sensory nerve root lesions

Myelopathy: (Posterior columns)

Medial lemniscus lesions, rare
Thalamic lesions (hemiataxia or gait ataxia), rare
Parietal lobe lesions (hemiataxia), rare

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