Ataxia is a
neurological sign consisting of lack of voluntary
coordination of muscle movements that can include
gait abnormality
Gait abnormality is a deviation from normal walking (gait). Watching a patient walk is the most important part of the neurological examination. Normal gait requires that many systems, including strength, sensation and coordination, function in an ...
, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of the parts of the
nervous system
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...
that coordinate movement, such as the
cerebellum. Ataxia can be limited to one side of the body, which is referred to as hemiataxia. Several possible causes exist for these patterns of neurological dysfunction. Dystaxia is a mild degree of ataxia.
Friedreich's ataxia
Friedreich's ataxia (FRDA or FA) is an autosomal-recessive genetic disease that causes difficulty walking, a loss of sensation in the arms and legs, and impaired speech that worsens over time. Symptoms generally start between 5 and 20 year ...
has gait abnormality as the most commonly presented symptom. The word is from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
α-
negative prefix+ -τάξις
rder= "lack of order".
Types
Cerebellar
The term
cerebellar ataxia
Cerebellar ataxia is a form of ataxia originating in the cerebellum. Non-progressive congenital ataxia (NPCA) is a classical presentation of cerebral ataxias.
Cerebellar ataxia can occur as a result of many diseases and may present with symptom ...
is used to indicate ataxia due to dysfunction of the cerebellum. The cerebellum is responsible for integrating a significant amount of neural information that is used to coordinate smoothly ongoing movements and to participate in
motor planning. Although ataxia is not present with all cerebellar
lesion
A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals.
Types
There is no designated classif ...
s, many conditions affecting the cerebellum do produce ataxia.
People with cerebellar ataxia may have trouble regulating the force, range, direction, velocity, and rhythm of muscle contractions.
This results in a characteristic type of irregular, uncoordinated movement that can manifest itself in many possible ways, such as
asthenia
Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...
,
asynergy
Dyssynergia is any disturbance of muscular coordination, resulting in uncoordinated and abrupt movements. This is also an aspect of ataxia. It is typical for dyssynergic patients to split a movement into several smaller movements. Types of dyssyn ...
, delayed reaction time, and
dyschronometria
Dyschronometria is a condition of cerebellar dysfunction in which an individual cannot accurately estimate the amount of time that has passed (i.e., distorted time perception). It is associated with cerebellar ataxia, when the cerebellum has bee ...
. Individuals with cerebellar ataxia could also display instability of gait, difficulty with eye movements,
dysarthria
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...
,
dysphagia
Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right.
It may be a sensation that suggests difficulty in the passage of solids or liq ...
,
hypotonia
Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases ...
,
dysmetria
Dysmetria ( en, wrong length) is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It can also include an inability to judge distance or scale.
...
, and
dysdiadochokinesia
Dysdiadochokinesia (DDK) is the medical term for an impaired ability to perform rapid, alternating movements (i.e., diadochokinesia). Complete inability is called adiadochokinesia. The term is from Greek ''δυς'' ''dys'' "bad", ''διάδοχο ...
.
These deficits can vary depending on which cerebellar structures have been damaged, and whether the lesion is bi- or unilateral.
People with cerebellar ataxia may initially present with poor balance, which could be demonstrated as an inability to stand on one leg or perform
tandem gait Tandem gait is a gait (method of walking or running) where the toes of the first foot touch the heel of the next one at each step. Neurologists sometimes ask patients to walk in a straight line using tandem gait as a test to help diagnose ataxia, e ...
. As the condition progresses, walking is characterized by a widened base and high stepping, as well as staggering and lurching from side to side.
Turning is also problematic and could result in falls. As cerebellar ataxia becomes severe, great assistance and effort are needed to stand and walk.
Dysarthria
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...
, an impairment with articulation, may also be present and is characterized by "scanning" speech that consists of slower rate, irregular rhythm, and variable volume.
Also, slurring of speech, tremor of the voice, and
ataxic respiration
Ataxic respiration is an abnormal pattern of breathing characterized by complete irregularity of breathing, with irregular pauses and increasing periods of apnea. As the breathing pattern deteriorates, it merges with agonal respiration.
Cause
It ...
may occur. Cerebellar ataxia could result with incoordination of movement, particularly in the extremities. Overshooting (or hypermetria) occurs with finger-to-nose testing and heel to shin testing; thus,
dysmetria
Dysmetria ( en, wrong length) is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It can also include an inability to judge distance or scale.
...
is evident.
Impairments with alternating movements (dysdiadochokinesia), as well as
dysrhythmia, may also be displayed. Tremor of the head and trunk (
titubation
A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, fa ...
) may be seen in individuals with cerebellar ataxia.
Dysmetria is thought to be caused by a deficit in the control of interaction
torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
s in multijoint motion.
Interaction torques are created at an associated joint when the primary joint is moved. For example, if a movement required reaching to touch a target in front of the body,
flexion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...
at the
shoulder
The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder mak ...
would create a torque at the
elbow
The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the me ...
, while
extension of the elbow would create a torque at the
wrist
In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known as the carp ...
. These torques increase as the speed of movement increases and must be compensated and adjusted for to create coordinated movement. This may, therefore, explain decreased coordination at higher movement velocities and accelerations.
*
Dysfunction of the vestibulocerebellum (
flocculonodular lobe
The flocculonodular lobe (vestibulocerebellum) is a lobe of the cerebellum consisting of the nodule and the flocculus. The two flocculi are connected to the midline structure called the nodulus by thin pedicles. It is placed on the anteroinferio ...
) impairs balance and the control of eye movements. This presents itself with
postural instability
A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Balance ...
, in which the person tends to separate his/her feet upon standing, to gain a wider base and to avoid titubation (bodily oscillations tending to be forward-backward ones). The instability is, therefore, worsened when standing with the feet together, regardless of whether the eyes are open or closed. This is a negative
Romberg's test
Romberg's test, Romberg's sign, or the Romberg maneuver is a test used in an exam of neurological function for balance, and also as a test for driving under the influence of an intoxicant. The exam is based on the premise that a person requires ...
, or more accurately, it denotes the individual's inability to carry out the test, because the individual feels unstable even with open eyes.
* Dysfunction of the
spinocerebellum
The anatomy of the cerebellum can be viewed at three levels. At the level of gross anatomy, the cerebellum consists of a tightly folded and crumpled layer of cortex, with white matter underneath, several deep nuclei embedded in the white matte ...
(
vermis
The cerebellar vermis (from Latin ''vermis,'' "worm") is located in the medial, cortico-nuclear zone of the cerebellum, which is in the posterior fossa of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior s ...
and associated areas near the midline) presents itself with a wide-based "drunken sailor"
gait (called truncal ataxia),
characterised by uncertain starts and stops, lateral deviations, and unequal steps. As a result of this gait impairment,
falling
Falling or fallin' may refer to:
*Falling (physics), movement due to gravity
*Falling (accident)
*Falling (execution)
*Falling (sensation)
People
* Christine Falling (born 1963), American serial killer who murdered six children
Books
* ''Fall ...
is a concern in patients with ataxia. Studies examining falls in this population show that 74–93% of patients have fallen at least once in the past year and up to 60% admit to fear of falling.
* 'Dysfunction of the
cerebrocerebellum' (lateral hemispheres) presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia).
These include:
**
Intention tremor
Intention tremor is a dyskinetic disorder characterized by a broad, coarse, and low frequency (below 5 Hz) tremor evident during deliberate and visually-guided movement (hence the name intention tremor). An intention tremor is usually perpendi ...
(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)
** A peculiar pattern of
dysarthria
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...
(slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm)
** Inability to perform rapidly alternating movements, known as dysdiadochokinesia, occurs, and could involve rapidly switching from
pronation to
supination of the forearm. Movements become more irregular with increases of speed.
** Inability to judge distances or ranges of movement happens. This dysmetria is often seen as undershooting,
hypometria
Dysmetria ( en, wrong length) is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It can also include an inability to judge distance or scale.
...
, or overshooting,
hypermetria
Dysmetria ( en, wrong length) is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It can also include an inability to judge distance or scale.
...
, the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someone's finger or touch his or her own nose.
** The rebound phenomenon, also known as the loss of the check reflex, is also sometimes seen in patients with cerebellar ataxia, for example, when patients are flexing their elbows isometrically against a resistance. When the resistance is suddenly removed without warning, the patients' arms may swing up and even strike themselves. With an intact check reflex, the patients check and activate the opposing triceps to slow and stop the movement.
** Patients may exhibit a constellation of subtle to overt cognitive symptoms, which are gathered under the terminology of
Schmahmann's syndrome.
Sensory
The term
sensory ataxia
Sensory ataxia is both a symptom and a sign in neurology. It is a form of ataxia (loss of coordination) caused not by cerebellar dysfunction but by loss of sensory input into the control of movement.
Sensory ataxia is distinguished from cerebel ...
is used to indicate ataxia due to loss of
proprioception
Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense".
Proprioception is mediated by proprioceptors, mechanosensory neurons ...
, the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the
dorsal columns
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal c ...
of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain that receive positional information, including the cerebellum,
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
, and
parietal lobe
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory informa ...
s.
Sensory ataxia presents itself with an unsteady "stomping" gait with heavy
heel strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by
visual input, such as in poorly lit environments.
Physicians can find evidence of sensory ataxia during
physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ...
by having patients stand with their feet together and
eyes shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall; this is called a positive
Romberg's test
Romberg's test, Romberg's sign, or the Romberg maneuver is a test used in an exam of neurological function for balance, and also as a test for driving under the influence of an intoxicant. The exam is based on the premise that a person requires ...
. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when patients are standing with arms and hands extended toward the physician, if the eyes are closed, the patients' fingers tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").
Vestibular
The term vestibular ataxia is used to indicate ataxia due to dysfunction of the
vestibular system, which in acute and unilateral cases is associated with prominent
vertigo
Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
,
nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
, and
vomiting
Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose.
Vomiting can be the result of ailments like food poisoning, gastroenteri ...
. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and
dysequilibrium
A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Balance ...
may be the sole presentation.
Causes
The three types of ataxia have overlapping causes, so can either coexist or occur in isolation. Cerebellar ataxia can have many causes despite normal neuroimaging.
Focal lesions
Any type of focal lesion of the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
(such as
stroke,
brain tumor
A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and seconda ...
,
multiple sclerosis, inflammatory
uch_as_sarcoidosis.html" ;"title="sarcoidosis.html" ;"title="uch as sarcoidosis">uch as sarcoidosis">sarcoidosis.html" ;"title="uch as sarcoidosis">uch as sarcoidosis and "chronic lymphocytyc inflammation with pontine perivascular enhancement responsive to steroids syndrome" [CLIPPERS]) 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...to include cord compression by thickened ligamentum flavum or stenosis of the boney spinal canal...(and rarely in the
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
or
parietal lobe
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory informa ...
); or vestibular if in the vestibular system (including the vestibular areas of the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...
).
Exogenous substances (metabolic ataxia)
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
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
(alcohol), which is capable of causing reversible cerebellar and vestibular ataxia. Chronic intake of
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
causes atrophy of the
cerebellum by oxidative and endoplasmic reticulum stresses induced by
thiamine
Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...
deficiency.
Other examples include various prescription drugs (e.g. most
antiepileptic drugs have cerebellar ataxia as a possible
adverse effect
An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a " side effect", when judged to be secondary to a main or therapeutic effect. The term compl ...
), Lithium level over 1.5mEq/L,
synthetic cannabinoid HU-211 ingestion
and various other medical and recreational drugs (e.g.
ketamine
Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...
,
PCP or
dextromethorphan
Dextromethorphan (DXM) is a medication most often used as a cough suppressant in over-the-counter cold and cough medicines. It is sold in syrup, tablet, spray, and lozenge forms. In 2022, the FDA approved a formulation of it combined with bu ...
, all of which are
NMDA receptor antagonist
NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the ''N''-Methyl-D-aspartate receptor ( NMDAR). They are commonly used as anesthetics for animals and humans; the state of anesthesia they induce ...
s that produce a dissociative state at high doses). A further class of pharmaceuticals which can cause short term ataxia, especially in high doses, are
benzodiazepines.
Exposure to high levels of
methylmercury, through consumption of fish with high mercury concentrations, is also a known cause of ataxia and other neurological disorders.
Radiation poisoning
Ataxia can be induced as a result of severe
acute radiation poisoning with an absorbed dose of more than 30
grays.
Vitamin B12 deficiency
Vitamin B12 deficiency may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia. Neuropsychological symptoms may include sense loss, difficulty in
proprioception
Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense".
Proprioception is mediated by proprioceptors, mechanosensory neurons ...
, poor balance, loss of sensation in the feet, changes in
reflexs, dementia, and
psychosis
Psychosis is a condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior ...
, can be reversible with treatment. Complications may include a neurological complex known as
subacute combined degeneration of spinal cord, and other neurological disorders.
Hypothyroidism
Symptoms of neurological dysfunction may be the presenting feature in some patients with
hypothyroidism. These include reversible
cerebellar ataxia
Cerebellar ataxia is a form of ataxia originating in the cerebellum. Non-progressive congenital ataxia (NPCA) is a classical presentation of cerebral ataxias.
Cerebellar ataxia can occur as a result of many diseases and may present with symptom ...
,
dementia
Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
,
peripheral neuropathy
Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
,
psychosis
Psychosis is a condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior ...
and
coma. Most of the neurological complications improve completely after
thyroid hormone replacement therapy.
Causes of isolated sensory ataxia
Peripheral neuropathies
Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
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
alcohol use disorder,
head injury
A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
,
paraneoplastic
A paraneoplastic syndrome is a syndrome (a set of signs and symptoms) that is the consequence of a tumor in the body (usually a cancerous one), specifically due to the production of chemical signaling molecules (such as hormones or cytokines) by ...
and non-paraneoplastic
autoimmune
In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". ...
ataxia,
high altitude cerebral oedema,
coeliac disease
Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barle ...
,
normal pressure hydrocephalus
Normal-pressure hydrocephalus (NPH), also called malresorptive hydrocephalus, is a form of communicating hydrocephalus in which excess cerebrospinal fluid (CSF) occurs in the ventricles, and with normal or slightly elevated cerebrospinal fluid p ...
and infectious or post-infectious
cerebellitis.
Hereditary ataxias
Ataxia may depend on
hereditary disorders consisting of degeneration of the cerebellum 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
Spinocerebellar ataxia (SCA) is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a neurological condition in its own right. An estimated 150,000 people in the United States have a diagnosis of s ...
,
episodic ataxia
Episodic ataxia (EA) is an autosomal dominant disorder characterized by sporadic bouts of ataxia (severe discoordination) with or without myokymia (continuous muscle movement). There are seven types recognized but the majority are due to two recog ...
, and
dentatorubropallidoluysian atrophy, as well as
autosomal recessive disorders such as
Friedreich's ataxia
Friedreich's ataxia (FRDA or FA) is an autosomal-recessive genetic disease that causes difficulty walking, a loss of sensation in the arms and legs, and impaired speech that worsens over time. Symptoms generally start between 5 and 20 year ...
(sensory and cerebellar, with the former predominating) and
Niemann Pick disease Niemann is a Low German surname. Notable people with the surname include:
*Albert Niemann (chemist) (1834–1861), German chemist
* Albert Niemann (paediatrician) (1880–1921), German physician
*Albert Niemann (tenor) (1831–1917), German opera ...
,
ataxia-telangiectasia (sensory and cerebellar, with the latter predominating),autosomal recessive spinocerebellar ataxia-14 and
abetalipoproteinaemia. An example of X-linked ataxic condition is the rare
fragile X-associated tremor/ataxia syndrome or FXTAS.
Arnold–Chiari malformation (congenital ataxia)
Arnold–Chiari malformation
Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficu ...
is a malformation of the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
. It consists of a downward displacement of the
cerebellar tonsils
The cerebellar tonsil (Latin: tonsilla cerebelli) is a rounded lobule on the undersurface of each cerebellar hemisphere, continuous medially with the uvula of the cerebellar vermis and superiorly by the flocculonodular lobe. Synonyms include: tons ...
and the
medulla
Medulla or Medullary may refer to:
Science
* Medulla oblongata, a part of the brain stem
* Renal medulla, a part of the kidney
* Adrenal medulla, a part of the adrenal gland
* Medulla of ovary, a stroma in the center of the ovary
* Medulla of t ...
through the
foramen magnum, sometimes causing
hydrocephalus
Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary inc ...
as a result of obstruction of
cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...
outflow.
Succinic semialdehyde dehydrogenase deficiency
Succinic semialdehyde dehydrogenase deficiency is an
autosomal
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosom ...
-
recessive gene disorder where mutations in the ALDH5A1 gene results in the accumulation of
gamma-Hydroxybutyric acid (GHB) in the body. GHB accumulates in the nervous system and can cause ataxia as well as other
neurological
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal c ...
dysfunction.
Wilson's disease
Wilson's disease
Wilson's disease is a genetic disorder in which excess copper builds up in the body. Symptoms are typically related to the brain and liver. Liver-related symptoms include vomiting, weakness, fluid build up in the abdomen, swelling of the legs, ...
is an
autosomal
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosom ...
-
recessive gene disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
from the body.
Copper accumulates in the nervous system and liver and can cause ataxia as well as other
neurological
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal c ...
and organ impairments.
Gluten ataxia
Gluten ataxia is an
autoimmune disease triggered by the ingestion of
gluten
Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grai ...
.
Early diagnosis and treatment with a
gluten-free diet
A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of proteins found in wheat (and all of its species and hybrids, such as spelt, kamut, and triticale), as well as barley, rye, and oats. The incl ...
can improve ataxia and prevent its progression. The effectiveness of the treatment depends on the elapsed time from the onset of the ataxia until diagnosis, because the death of
neurons in the cerebellum as a result of gluten exposure is irreversible.
It accounts for 40% of ataxias of unknown origin and 15% of all ataxias.
Less than 10% of people with gluten ataxia present any gastrointestinal symptom and only about 40% have intestinal damage.
This entity is classified into primary auto-immune cerebellar ataxias (PACA).
Potassium pump
Malfunction of the
sodium-potassium pump may be a factor in some ataxias. The - pump has been shown to control and set the intrinsic activity mode of
cerebellar
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cereb ...
Purkinje neurons. This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the
cerebellum and the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
. Indeed, an
ouabain block of - pumps in the cerebellum of a live
mouse results in it displaying ataxia and
dystonia. Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations.
Cerebellar ataxia associated with anti-GAD antibodies
Antibodies against the enzyme glutamic acid decarboxylase (GAD: enzyme changing glutamate into GABA) cause cerebellar deficits. The antibodies impair motor learning and cause behavioral deficits.
GAD antibodies related ataxia is part of the group called immune-mediated cerebellar ataxias. The antibodies induce a synaptopathy. The cerebellum is particularly vulnerable to autoimmune disorders. Cerebellar circuitry has capacities to compensate and restore function thanks to cerebellar reserve, gathering multiple forms of plasticity. LTDpathies gather immune disorders targeting long-term depression (LTD), a form of plasticity.
Diagnosis
* Imaging studies - A
CT scan or
MRI of the brain might help determine potential causes. An
MRI can sometimes show shrinkage of the cerebellum and other brain structures in people with ataxia. It may also show other treatable findings, such as a blood clot or benign tumour, that could be pressing on the cerebellum.
* Lumbar puncture (spinal tap) - A needle is inserted into the lower back (lumbar region) between two lumbar vertebrae to obtain a sample of
cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...
for testing.
* Genetic testing - Determines whether the mutation that causes one of the hereditary ataxic conditions is present. Tests are available for many but not all of the hereditary ataxias.
Treatment
The treatment of ataxia and its effectiveness depend on the underlying cause. Treatment may limit or reduce the effects of ataxia, but it is unlikely to eliminate them entirely. Recovery tends to be better in individuals with a single focal injury (such as
stroke or a
benign tumour
A benign tumor is a mass of cells (tumor) that does not invade neighboring tissue or metastasize (spread throughout the body). Compared to malignant (cancerous) tumors, benign tumors generally have a slower growth rate. Benign tumors have re ...
), compared to those who have a neurological degenerative condition.
A review of the management of degenerative ataxia was published in 2009.
A small number of rare conditions presenting with prominent cerebellar ataxia are amenable to specific treatment and recognition of these disorders is critical. Diseases include vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann–Pick type C disease, Refsum's disease, glucose transporter type 1 deficiency, episodic ataxia type 2, gluten ataxia, glutamic acid decarboxylase ataxia. Novel therapies target the RNA defects associated with cerebellar disorders, using in particular anti-sense oligonucleotides.
The movement disorders associated with ataxia can be managed by pharmacological treatments and through
physical therapy and
occupational therapy to reduce
disability
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physical, ...
.
Some drug treatments that have been used to control ataxia include:
5-hydroxytryptophan
5-Hydroxytryptophan (5-HTP), also known as oxitriptan, is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitter serotonin.
Uses
5-HTP is sold over the counte ...
(5-HTP),
idebenone
Idebenone (pronounced eye-deb-eh-known, trade names Catena, Raxone, Sovrima, among others) is a drug that was initially developed by Takeda Pharmaceutical Company for the treatment of Alzheimer's disease and other cognitive defects. This has bee ...
,
amantadine
Amantadine, sold under the brand name Gocovri among others, is a medication used to treat dyskinesia associated with parkinsonism and influenza caused by type A influenzavirus, though its use for the latter is no longer recommended due to wi ...
,
physostigmine
Physostigmine (also known as eserine from ''éséré'', the West African name for the Calabar bean) is a highly toxic parasympathomimetic alkaloid, specifically, a reversible cholinesterase inhibitor. It occurs naturally in the Calabar bean a ...
,
L-carnitine
Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, ...
or derivatives,
trimethoprim/sulfamethoxazole
Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...
,
vigabatrin
Vigabatrin, brand name Sabril, is a medication used to treat epilepsy. It became available as a generic medication in 2019.
It works by inhibiting the breakdown of γ-aminobutyric acid (GABA). It is also known as γ-vinyl-GABA, and is a stru ...
,
phosphatidylcholine
Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup.
They are a major component of biological membranes and can be easily obtained from a variety of readily available sources, such as egg yolk or soybea ...
,
acetazolamide
Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, altitude sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), urine alkal ...
,
4-aminopyridine,
buspirone
Buspirone, sold under the brand name Buspar, among others, is a medication primarily used to treat anxiety disorders, particularly generalized anxiety disorder. Benefits support its short-term use. It is taken by mouth, and it may take up to fo ...
, and a combination of
coenzyme Q10 and
vitamin E
Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vi ...
.
Physical therapy requires a focus on adapting activity and facilitating
motor learning
Motor learning refers broadly to changes in an organism's movements that reflect changes in the structure and function of the nervous system. Motor learning occurs over varying timescales and degrees of complexity: humans learn to walk or talk over ...
for retraining specific functional motor patterns.
A recent systematic review suggested that physical therapy is effective, but there is only moderate evidence to support this conclusion.
The most commonly used physical therapy interventions for cerebellar ataxia are vestibular habituation,
Frenkel exercises
Frenkel exercises are a set of exercises developed by Professor Heinrich Sebastian Frenkel to treat ataxia, in particular cerebellar ataxia.
They are a system of exercises consisting of slow, repeated movements. They increase in difficulty over t ...
,
proprioceptive neuromuscular facilitation
Stretching is a form of physical exercise in which a specific muscle or tendon (or muscle group) is deliberately flexed or stretched in order to improve the muscle's felt elasticity and achieve comfortable muscle tone. The result is a feeling ...
(PNF), and balance training; however, therapy is often highly individualized and gait and coordination training are large components of therapy.
Current research suggests that, if a person is able to walk with or without a
mobility aid
A mobility aid is a device designed to assist walking or otherwise improve the mobility of people with a mobility impairment.
There are various walking aids which can help people with impaired ability to walk, and wheelchairs or mobility scoot ...
, physical therapy should include an exercise program addressing five components: static balance, dynamic balance, trunk-limb coordination, stairs, and
contracture prevention. Once the physical therapist determines that the individual is able to safely perform parts of the program independently, it is important that the individual be prescribed and regularly engage in a supplementary home exercise program that incorporates these components to further improve long term outcomes. These outcomes include balance tasks, gait, and individual activities of daily living. While the improvements are attributed primarily to changes in the brain and not just the hip or ankle joints, it is still unknown whether the improvements are due to adaptations in the cerebellum or compensation by other areas of the brain.
Decomposition, simplification, or slowing of multijoint movement may also be an effective strategy that therapists may use to improve function in patients with ataxia.
Training likely needs to be intense and focused—as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining.
Their therapy consisted of
constraint-induced movement therapy
Constraint-induced movement therapy (CI, CIT, or CIMT) is a form of rehabilitation therapy that improves upper extremity function in stroke and other central nervous system damage patients by increasing the use of their affected upper limb. which resulted in improvements of their arm function.
Treatment should likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of
balance
Balance or balancing may refer to:
Common meanings
* Balance (ability) in biomechanics
* Balance (accounting)
* Balance or weighing scale
* Balance as in equality or equilibrium
Arts and entertainment Film
* ''Balance'' (1983 film), a Bulgaria ...
or poor
coordination. Severe ataxia may eventually lead to the need for a
wheelchair
A wheelchair is a chair with wheels, used when walking is difficult or impossible due to illness, injury, problems related to old age, or disability. These can include spinal cord injuries ( paraplegia, hemiplegia, and quadriplegia), cerebr ...
. To obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increasing fatigue and poorer movement patterns.
There are several assessment tools available to therapists and health care professionals working with patients with ataxia. The
International Cooperative Ataxia Rating Scale (ICARS) is one of the most widely used and has been proven to have very high reliability and validity.
Other tools that assess motor function, balance and coordination are also highly valuable to help the therapist track the progress of their patient, as well as to quantify the patient's functionality. These tests include, but are not limited to:
* The
Berg Balance Scale
The Berg Balance Scale (or BBS) is a widely used clinical test of a person's static and dynamic balance abilities, named after Katherine Berg, one of the developers. For functional balance tests, the BBS is generally considered to be the gold sta ...
* Tandem Walking (to test for
Tandem gait Tandem gait is a gait (method of walking or running) where the toes of the first foot touch the heel of the next one at each step. Neurologists sometimes ask patients to walk in a straight line using tandem gait as a test to help diagnose ataxia, e ...
ability)
* Scale for the Assessment and Rating of Ataxia (SARA)
* tapping tests – The person must quickly and repeatedly tap their arm or leg while the therapist monitors the amount of
dysdiadochokinesia
Dysdiadochokinesia (DDK) is the medical term for an impaired ability to perform rapid, alternating movements (i.e., diadochokinesia). Complete inability is called adiadochokinesia. The term is from Greek ''δυς'' ''dys'' "bad", ''διάδοχο ...
.
*
finger-nose testing
Dysmetria ( en, wrong length) is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It can also include an inability to judge distance or scale.
...
– This test has several variations including finger-to-therapist's finger, finger-to-finger, and alternate nose-to-finger.
Other uses
The term "ataxia" is sometimes used in a broader sense to indicate lack of coordination in some physiological process. Examples include optic ataxia (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects) and ataxic respiration (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the
medulla oblongata). Optic ataxia may be caused by lesions to the posterior parietal cortex, which is responsible for combining and expressing positional information and relating it to movement. Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention. Optic ataxia is usually part of
Balint's syndrome, but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between visual-association cortex and the frontal premotor and motor cortex.
See also
*
Ataxic cerebral palsy
*
Locomotor ataxia
Locomotor ataxia is the inability to precisely control one's own bodily movements.
__TOC__ Disease
People afflicted with this disease may walk in a jerky, non-fluid manner. They will not know where their arms and legs are without looking (i.e. a f ...
*
Bruns apraxia
National Ataxia Foundation
References
Further reading
*
*
*
External links
{{Authority control
Symptoms and signs: Nervous system
Stroke