Diagnosis:
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
MRI +GAD:
- 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
SPECT:
- 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
ECG
Echocardiography: hypertrophic cardiomyopathy in Friedrich’s ataxia, dilated cardiomyopathy in alcoholism
CXR
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:
Acute:
- Vertebrobasilar ischemia and infarction
- Cerebellar hemorrhage
- Drugs/toxins:
- Ethanol, phencyclidine
- Phenytoin, Benzodiazepines,
- B1 deficiency a.k.a. Wernicke’s encephalopathy (ataxia, confusion, ophthalmoplegia)
- Viral encephalitis:
- St. Louis encephalitis, AIDS dementia complex, VZV, mumps, poliomyelitis,
- EBV, lymphocytic choriomeningitis
- Bacterial: abscess,
- Acute cerebellar ataxia of childhood
- Acute disseminated encephalomyelitis (ADEM)
- Miller-Fisher variant of Guillain-Barre syndrome (ataxia, ophthalmoplegia, areflexia)
Chronic:
- Multiple sclerosis
- Alcoholic cerebellar degeneration
- Phenytoin-induced cerebellar degeneration
- Hypothyroidism
- Brain Tumor
- Paraneoplastic cerebellar degeneration
- Fragile X syndrome (Fragile X tremor ataxia syndrome)
- Autosomal dominant spinocerebellar ataxia:
- Friedreich’s ataxia
- Spinocerebellar ataxia SCA type 1-17
- Ataxia telangiectasia
- Wilson’s disease
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)
- Multiple sclerosis
- Acute transverse myelitis
- Spinal Cord compression e.g. Tumour
- Spinal Vascular malformation
- AIDS vacuolar myelopathy
- Those that also may affect the peripheral nerves:
- Friedreich’s ataxia
- Neurosyphilis (tabes dorsalis)
- Nitrous oxide
- Vitamin B12 deficiency a.k.a. subacute combined degeneration of the spinal cord
- Vitamin E deficiency
Medial lemniscus lesions, rare
Thalamic lesions (hemiataxia or gait ataxia), rare
Parietal lobe lesions (hemiataxia), rare