Ataxia

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Ataxia
ICD-10	R27.0
ICD-9	781.3

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor in Chief: M.Umer Tariq [2] Raviteja Guddeti, M.B.B.S. [3]

Overview

Ataxia (from Greek α- [used as a negative prefix] + -τάξις [order], meaning "lack of order") is a neurological sign and symptom consisting of gross incoordination of muscle movements. Ataxia is an aspecific clinical manifestation implying dysfunction of parts of the nervous system that coordinate movement, such as the cerebellum. Several possible causes exist for these patterns of neurological dysfunction. The term "dystaxia" is rarely used as a synonym.

The International Ataxia Awareness Day is observed on September 25th each year.

Types of ataxia

Cerebellar ataxia

The term cerebellar ataxia is employed to indicate ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits, such as antagonist hypotonia, asynergy, dysmetria, dyschronometria, and dysdiadochokinesia. How and where these abnormalities manifest depend on which cerebellar structures are lesioned, and whether the lesion is bilateral or unilateral. Vestibulo-cerebellar dysfunction presents with postural instability, in which the person tends to separate the feet on standing to gain a wider base, and avoid oscillations (especially posterior-anterior ones); instability is therefore worsened when standing with the feet together (irrespective of whether the eyes are open or closed: this is a negative Romberg's test). Spino-cerebellar dysfunction presents with a wide-based "drunken sailor" gait, characterised by uncertain start and stop, lateral deviations, and unequal steps. Cerebro-cerebellar dysfunction presents with disturbances in carrying out voluntary movements, including intention tremor (coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes as well as the limbs and torso), peculiar writing abnormalities (large, unequal letters, irregular underlining), and a peculiar pattern of dysarthria (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm).

Sensory ataxia

The term sensory ataxia is employed to indicate ataxia due to loss of proprioception (sensitivity to joint and body part position), which generally depends on dysfunction of the dorsal columns of the spinal cord, since they carry proprioceptive information up to the brain; in some cases, the cause may instead be dysfunction of the various brain parts that receive that information, including the cerebellum, thalamus, and parietal lobes. Sensory ataxia presents with an unsteady "stomping" gait with heavy heel strikes, as well as postural instability that is characteristically worsened when the lack of proprioceptive input cannot be compensated by visual input, such as in poorly lit environments. Doctors can evidence this during physical examination by having the patient stand with his / her feet together and eyes shut, which will cause the patient's instability to markedly worsen, producing wide oscillations and possibly a fall (this is called a positive Romberg's test). Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when the patient is standing with arms and hands extended toward the examiner, if the eyes are closed, the patient's finger will tend to "fall down" and be restored to the horizontal extended position by sudden extensor contractions ("ataxic hand").

Vestibular ataxia

The term vestibular ataxia is employed to indicate ataxia due to dysfunction of the vestibular system, which in acute and unilateral cases is associated with prominent vertigo, nausea and vomiting. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and dysequilibrium may be the sole presentation.

Causes

Causes by Organ System

(By organ system)

Cardiovascular	Arteriosclerosis, Circulation disorders in area of brain stem, Morgagni's Syndrome,
Chemical / poisoning	No underlying causes
Dermatologic	No underlying causes
Drug Side Effect	Barbituates, Benzodiazepines, Morphine,
Ear Nose Throat	No underlying causes
Endocrine	Diabetic neuropathy, Hypothyroidism,
Environmental	No underlying causes
Gastroenterologic	Cirrhosis, Malabsorption,
Genetic	Familial periodic ataxia, Fredreich's Ataxia, Hartnup Syndrome, Hereditary spastic paraparesis, Inherited neuropathies,
Hematologic	Acanthocytosis, Ataxia-teleangiectasia,
Iatrogenic	No underlying causes
Infectious Disease	Chickenpox, HIV infection, Smallpox,
Musculoskeletal / Ortho	Myopathy,
Neurologic	Acoustic neurinoma, Arnold-Chiari Malformation, Cerebellar abscess, Cerebellar cortex atrophy, Cerebellar heredoataxia, Encephalitis, GALOP Syndrome (gait disorder, autoantibodies, late age onset, polyneuropathy), Multiple Sclerosis, Normal pressure hydrocephalus, Parkinsonism, Peripheral neuropathy, Polyneuritis, Spinal cord compression(and pressure on dorsal nerve roots), Tabes dorsalis, Wernicke's Encephalopathy,
Nutritional / Metabolic	Alcohol, Alpha-beta lipoproteinemia, GM2-gangliosidoses, Thiamine deficiency, Wilson's Disease,
Obstetric/Gynecologic	No underlying causes
Oncologic	Epiphyseal tumor, Paraneoplastic syndrome,
Opthalmologic	No underlying causes
Overdose / Toxicity	Intoxication,
Psychiatric	No underlying causes
Pulmonary	No underlying causes
Renal / Electrolyte	No underlying causes
Rheum / Immune / Allergy	Fisher's Syndrome,
Sexual	No underlying causes
Trauma	Brainstem or cortical lesions, Frontal lobelesion, Mann Syndrome, Parietal lobelesion,
Urologic	No underlying causes
Miscellaneous	Mitochondrial cytopathy,

Causes by Alphabetical Order

2,4,6-Trichlorophenol Abetalipoproteinemia Acanthocytosis Aceruloplasminemia Acoustic neurinoma Acrylamide Acute altitude sickness Acute Disseminated Encephalomyelitis Adult-onset adreno leukodystrophy Aftershave Alcohol intoxication Alexander Syndrome Alpers Syndrome Alpha-ketoglutarate dehydrogenase deficiency Aminoaciduria Amiodarone Amitraz Amyloidosis, oculoleptomeningeal X-linked sideroblastic anaemia Angleman syndrome Aniline Antifreeze Apple seed poisoning Arachnoid Cysts Argininosuccinase lyase deficiency - late onset Arginosuccinate synthetase deficiency Arizona Bark Scorpion poisoning Arnold-Chiari Malformation Arteriosclerosis ARTS syndrome Ataxia deafness reardon type Ataxia tapetoretinal degeneration Ataxia telangiectasia / Louis-Bar syndrome Ataxia with Vitamin E Deficiency Ataxia-oculomotor apraxia syndrome Bangstad syndrome Barbituates Basal ganglia calcification Basilar artery migraine Basilar impression / vertebral-basilar artery ischemia Bassen-Kornzweig syndrome Benign Paroxysmal Positional Vertigo Benzene Benzodiazepines Bhaskar-Jagannathan syndrome Biotinidase deficiency Blue-ringed octopus poisoning Bonnemann-Meinecke-Reich syndrome Brain abscess Brain cancer Brain cyst Brain injury Brainstem or cortical lesions Bronchogenic carcinoma Buckeye poisoning Carbon monoxide poisoning Celiac disease Central nervous system lymphoma, primary Cerebellar abscess Cerebellar ataxia Cerebellar cortex atrophy Cerebellar degeneration Cerebellar haemorrhage Cerebellar heredoataxia Cerebellar hypoplasia Cerebellar infarct Cerebellar mass Cerebral Amyloid Angiopathy, Familial Cerebral hemorrhage

Cerebral infarction Cerebral palsy Cerebrorenodigital syndrome Cerebrovascular accident Ceroid lipofuscinosis Ceruloplasmin deficiency Cervical myelopathy Chickenpox Chitayat-Moore-Del Bigio syndrome Cholestanol storage disease Chorea familial benign Chronic progressive traumatic encephalopathy Cirrhosis Cockayne syndrome Coenzyme Q 10 (CoQ10), deficiency Combarros Calleja Leno syndrome Complex 2 mitochondrial respiratory chain deficiency Congenital Disorders of Glycosylation Corneal cerebellar syndrome Creutzfeldt-Jakob disease Cutler-Bass-Romshe syndrome Cystinuria -- lysinuria Dandy-Walker Syndrome DeSanctis-Cacchione syndrome Death Camas poisoning Dementia pugilis Demyelinating disorder Diabetic neuropathy Dinno-Shearer-Weisskopf syndrome Diphtheria Dravet syndrome Dykes-Markes-Harper syndrome Dysequilibrium syndrome Encephalitis Encephalocele frontal Encephalopathy due to sulphite oxidase deficiency English Ivy poisoning Epiphyseal tumor Episodic ataxia Erythrokeratodermia with ataxi Ethosuximide Fabry's Disease Familial isolated deficiency of vitamin E Familial periodic ataxia Feline spongiform encephalopathy Fisher's Syndrome Friedreich's ataxia Frontal lobe lesion Functioning pancreatic endocrine tumor Furukawa-Takagi-Nakao syndrome Gabapentin GALOP Syndrome (gait disorder, autoantibodies, late age onset, polyneuropathy) Gangliosidosis GM1 type 3 - gait ataxia Gasoline Gaucher disease type 2 Glioma Glutathione synthase deficiency Glycine encephalopathy, atypical mild form GM2-gangliosidoses Granulomatous Angiitis of the Central Nervous System Griscelli disease Guillain-Barré syndrome Hallervorden-Spatz disease Hartnup Disease Head trauma Heidenhain syndrome Hemangioblastoma Hepatocerebral degeneration Hereditary spastic paraparesis

Hexosaminidase deficiency HIV infection Homozygous hypobetalipoproteinemia Hydrocephalus Hydroxyacyl-coa dehydrogenase, type 2, deficiency Hyperammonemia Hypogonadism Hypothyroidism Hysteria Infantile polymyoclonus Infantile sialic acid storage disorder Inherited neuropathies Insulinoma Joubert syndrome Juvenile pilocytic astrocytoma Kearns-Sayre Syndrome Krabbe leukodystrophy Kuru Lactic acidosis congenital infantile Lamotrigine Lantana poisoning Lead Levetiracetam Lhermitte-McAlpine syndrome Lipoamide dehydrogenase deficiency Lithium toxicity Machado-Joseph Disease Macrocytic anemia Macrogyria, pseudobulbar palsy and mental retardation Mann Syndrome Maple syrup urine disease Marinesco-Sjogren-like syndrome (MSLS) Marinescu-Garland Syndrome Mayapple poisoning Measles Medulloblastoma Meinecke syndrome Meningoencephalocele Mental retardation progressive spasticity, X-linked Mental retardation, X-linked, with cerebellar hypoplasia and distinctive facial appearance Mercury Mescal poisoning Metachromatic Leukodystrophy Metastatic insulinoma Metronidazole Mevalonic aciduria Miller Fisher Syndrome Minamata disease Mistletoe poisoning Mitochondrial cytopathy Mitochondrial encephalomyopathy Mononeuropathy/radiculopathy affecting the lower extremities Morgagni's Syndrome Morphine Multiple sclerosis Myelopathy Myoclonus Myopathy Neuronal intranuclear hyaline inclusion disease Niemann-Pick disease Normal pressure hydrocephalus Olivopontocerebellar atrophy Opsoclonus myoclonus syndrome Oxcarbazepine Paraneoplastic syndromes Parietal lobe lesion Parkinson's disease Partington X-linked mental retardation syndrome Pelizaeus-Merzbacher disease

Pellagra-like syndrome Peripheral neuropathy Pernicious anemia Phenytoin toxicity Phosphoribosylpyrophosphate synthetase superactivity Polyneuritis Polyneuropathy Post-infective polyradiculopathy Posterior column ataxia with retinitis pigmentosa Posterior fossa tumor Primidone Progressive Multifocal Leukoencephalopathy Prolonged anoxia Purine nucleoside phosphorylase deficiency Pyruvate dehydrogenase deficiency Quaternary syphilis Ramsay-Hunt syndrome Reardon-Wilson-Cavanagh syndrome Refsum Disease Rett syndrome Revesz Debuse syndrome Rhombencephalosynapsis Richards-Rundle syndrome Roussy-Levy syndrome Rubinstein-Taybi syndrome Schroer-Hammer-Mauldin syndrome Segawa syndrome, autosomal recessive Selective vitamin E deficiency Shy-Drager syndrome Sialidosis type 1 and 3 Smallpox Spastic paraplegia Spinal cord compression (and pressure on dorsal nerve roots) Spinal cord tumor Spinocerebellar ataxia Spinocerebellar degenerescence, book type sporadic ataxia SSADH deficiency (succinic semialdehyde dehydrogenase deficiency) Stroke Susac syndrome Tabes dorsalis Telencephalic leukoencephalopathy Thalamic syndrome Thallium poisoning Thiamine deficiency Thoracic dysplasia -- hydrocephalus syndrome Tick paralysis Tolterodine toxicity Toxic mushrooms -- Anticholinergic Toxic mushrooms -- Monomethylhydrazine Toxic mushrooms -- Psychedelic Tranebjaerg-Svejgaard syndrome Transient ischemic attack (TIA) Transthyretin amyloidosis Transverse myelitis Treft-Sanborn-Carey syndrome Triglyceride storage disease with impaired long-chain fatty acid oxidation Varnish makers' and painters' Naptha Vascular dementia Vertebral Artery Dissection Vertebrobasilar dolichoectasia Vertigo, benign paroxysmal, in childhood - ataxic gait Vitamin B12 deficieny Wernicke-Korsakoff psychosis Westphal's Disease Wilson's Disease Xeroderma pigmentosum Xylene Zinc deficiency

Causes of ataxia

The three types of ataxia have overlapping causes, and can therefore either coexist or occurr in isolation.

Focal lesions

Any type of focal lesion of the central nervous system (such as stroke, brain tumour, multiple sclerosis will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum, sensory if in the dorsal spinal cord (and rarely in the thalamus or parietal lobe), vestibular if in the vestibular system (including the vestibular areas of the cerebral cortex).

Exogenous substances

Exogenous substances that cause ataxia mainly do so because they have a depressant effect on central nervous system function. The most common example is ethanol, which is capable of causing overlapping cerebellar and vestibular ataxia. Other examples include both prescription drugs (e.g. most antiepileptic drugs have cerebellar ataxia as a possible unwanted effect) and recreational drugs (e.g. ketamine, PCP).

Vitamin B₁₂ deficiency

Vitamin B₁₂ deficiency may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.

Causes of isolated sensory ataxia

Peripheral neuropathies may cause generalised or localised sensory ataxia (e.g. a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.

Non-hereditary cerebellar degeneration

Non-hereditary causes of cerebellar degeneration include chronic ethanol abuse, paraneoplastic cerebellar degeneration, high altitude cerebral oedema, coeliac disease, and normal pressure hydrocephalus.

Hereditary ataxias

Ataxia may depend on hereditary disorders consisting of degeneration of the cerebellum and/or of the spine; most cases feature both to some extent, and therefore present with overlapping cerebellar and sensory ataxia, even though one is often more evident than the other. Hereditary disorders causing ataxia include autosomal dominant ones such as spinocerebellar ataxia, episodic ataxia, and dentatorubropallidoluysian atrophy, as well as autosomal recessive disorders such as Friedreich's ataxia (sensory and cerebellar, with the former predominating), ataxia-telangiectasia (sensory and cerebellar, with the latter predominating), and abetalipoproteinaemia. An example of X-linked ataxic condition is the rare fragile X-associated tremor/ataxia syndrome.

Treatment

There is no specific treatment for ataxia as such, altough there may be for the underlying cause. The disability of ataxia may be reduced by physical therapy, including exercises, along with leg braces or shoe splints, if foot alignment has been affected; a cane or walker is often used in the effort to prevent falls.

References

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