What is ataxia and what causes it?
Ataxia may also result from certain immunological disorders and infections.
There are many types of ataxia. In this article, we discuss some of the more common types, their causes, and the available treatments.
What is ataxia?
Ataxia can affect a person's ability to balance.
Ataxia is a symptom that can result from a range of conditions. It affects a person's coordination, speech, and balance. It can also make it hard to swallow and walk.
Some people are born with ataxia due to genetic factors. Others develop it over time. For some people, it can result from another condition, such as a stroke, MS, a brain tumor, or a head injury, or even from excessive alcohol consumption.
It can start suddenly, get worse over time, or stabilize. This depends partly on the cause.
The following are some of the most common types of ataxia:
This type of ataxia results from a dysfunction of the cerebellum, a region of the brain that plays a role in assimilating sensory perception, coordination, and motor control.
Cerebellar ataxia can cause neurological symptoms such as:
- jerking or shaking of the body or limbs when trying to move
- decreased muscle tone
- lack of coordination between organs, muscles, limbs, or joints
- difficulty controlling distance, power, and speed of an arm, hand, leg, or eye movement
- difficulty accurately estimating how much time has passed
- inability to perform rapid, alternating movements
How it affects the body and to what extent depends on where in the cerebellum the damage occurs, and whether lesions occur on one side (unilateral) or both sides (bilateral).
Ataxia can change a person's posture. If damage occurs in the vestibulocerebellum, it will affect the person's balance and eye movement control. They will typically stand with their feet wide apart to gain better balance and avoid swaying backward and forward.
Even when the person's eyes are open, it may be difficult for them to balance with the feet together.
If ataxia affects the spinocerebellum, a person will have an unusual gait with unequal sideways steps and stuttering starts and stops. This is because the spinocerebellum regulates body and limb movements.
When ataxia affects the cerebrocerebellum, a person may have problems with voluntary planned movements. The head, eyes, limbs, and torso may tremble as they carry out voluntary movements. They may slur their speech, with variations in rhythm and volume.
This is a type of ataxia that develops due to a loss of proprioception.
Proprioception is a person's sense of the relative position of neighboring parts of their body. It is a sense that indicates whether the body is moving with appropriate effort and gives feedback on the position of body parts relative to each other.
Sensory ataxia typically results in:
- an unsteady, stomping gait, with the heel striking hard as it touches the ground with each step
- postural instability that becomes worse in poorly lit environments
If a person stands with their eyes closed and feet together, the instability will worsen. This is because a loss of proprioception increases their reliance on visual data.
They may find it hard to perform smoothly coordinated voluntary movements with the limbs, trunk, pharynx, larynx, and eyes.
Some types of ataxia can lead to vertigo.
This type of ataxia affects the vestibular system, which plays a role in hearing. It can result from nerve damage in the ear.
In acute (sudden) unilateral cases, this can lead to:
In slow-onset chronic bilateral cases, a person may only experience unsteadiness.
There may also be a combination of causes, such as vestibulocerebellar ataxia.
Symptoms vary depending on the type and severity of ataxia. The age of onset will depend on the cause.
If ataxia develops due to genetic features, it can be present from birth. If it is due to an injury or another health condition, symptoms may emerge at any age.
In some cases, symptoms will improve and eventually disappear. Initial symptoms usually include:
- poor limb coordination
- speech problems, including slurred and slow speech, difficulty producing speech, and problems controlling volume, rhythm, and pitch
In time, other symptoms may appear, such as:
- difficulty swallowing, leading to choking or coughing
- tremors, shaking, or trembling in parts of the body
- nystagmus, an involuntary, rapid, rhythmic, repetitive eye movement that may be vertical, horizontal, or circular
- problems with balance
- walking difficulties that may lead to wheelchair use
- vision and hearing problems
- depression due to the challenges of living with the condition
Ataxia telangiectasia can appear in childhood. Apart from appearing to be "a bit wobbly," a child may also experience:
- spider veins in the whites of the eyes, the ears, or elsewhere on the face
- frequent infections
Another genetic, progressive type of ataxia, called Friedreich's ataxia, often appears between the ages of 10 and 15 years.
- a sideward curvature of the spine, or scoliosis
- weakened heart muscle
- high arching feet
Conditions that may occur alongside Friedreich's ataxia include diabetes and heart problems, and there may be complications relating to the spine, feet, heart, muscles, vision, and hearing.
A person with this type of ataxia will need supportive treatment throughout their life.
If ataxia results from an injury or illness, such as a stroke, symptoms often improve over time and may eventually go away completely.
A person with ataxia may need help walking.
There is not usually a cure for ataxia, but treatment can ease symptoms and help improve quality of life.
A healthcare provider may suggest a specific treatment option to target one of the following ataxia symptoms:
Coordination and balance issues: Adaptive devices such as walking sticks, crutches, walkers, and wheelchairs can help a person maintain independence. It may be necessary to make some home adaptations, such as to enable wheelchair access.
Tremor, stiffness, muscle spasms, and weakness: A doctor may prescribe medication and physical or occupational therapy to help improve a person's strength, maintain their mobility, and help them find new ways to carry out tasks.
Curvature of the spine: A doctor may recommend orthopedic care.
Depression: Counseling and medications may help.
Speech problems: A speech therapist can provide help with communication issues and muscle control to improve swallowing, coughing, and choking. If necessary, a speech therapist can help the person learn how to use speech aids.
Deficiencies: Taking vitamin supplements, following a special diet, or both may help people who have a deficiency. Sensitivity to gluten can occur with ataxia, so eating a gluten-free diet may also help.
Immune problems: Treatment for ataxia telangiectasia may include gamma-globulin injections to boost the immune system.
Uncontrollable eye movements: Medication may help.
Ataxia can result from:
- a genetic feature
- a health condition that leads to nerve damage, such as a stroke or MS
- a vitamin B-12 deficiency
- an immunological problem
In the following sections, we look at inherited and acquired ataxia.
Inherited ataxia can develop when a parent (or both parents) pass a genetic defect to their child.
In some cases, the severity can worsen from one generation to the next, and the age of onset can get younger.
If a person with an inherited form of ataxia is considering having children, a doctor may recommend genetic testing and counseling as part of the preparation.
The chance of inheriting the faulty gene depends partly on the type of ataxia. In the case of Friedreich's ataxia, both parents need to have the genetic feature to pass it on.
In the case of spinocerebellar ataxia, only one parent needs to carry the defective gene, and each of their offspring would have a 50% chance of developing the condition.
Sometimes, a person develops or is born with ataxia without a clear cause, such as when there is no family history of the condition. One reason for this may be a malformation of the cerebellum before birth.
The following events and conditions can also result in ataxia:
- brain surgery, a brain tumor, or a head injury
- excessive use of alcohol or drugs
- some infections, such as chickenpox
- exposure to toxic chemicals
- some neurological conditions, including MS and cerebral palsy
Some tumors cause ataxia due to a paraneoplastic syndrome. These tumors, which are typically ovarian, produce chemicals that impair the cerebellum. Ataxia is the main symptom.
The cause of ataxia will somewhat determine a person's outlook.
A person with signs of ataxia will likely see a neurologist, which is someone who specializes in conditions of the nervous system.
The neurologist will examine the person and check their medical history for possible causes, such as a previous brain injury, and their family history for indications of inherited ataxia.
They may also order the following tests:
- an MRI or CT scan, to look for lesions, tumors, or other forms of brain damage
- genetic tests, to assess for inherited ataxia
- blood tests, as some types of ataxia can affect blood composition
- urine tests, as these may reveal systemic changes that occur in some forms of ataxia
In Wilson's disease, for example, a 24-hour urine collection may show unusual amounts of copper in the system.
Ataxia that does not have an identifiable cause is called sporadic or idiopathic ataxia.
It can take time to confirm a diagnosis because the symptoms could point to several other conditions.
There is no cure for ataxia. The outlook will depend on the type, cause, and severity.
Some types of hereditary ataxia can shorten a person's lifespan, but many people will have the same life expectancy as those without the condition.
If ataxia develops due to an accident, surgery, or illness, the condition may stabilize or improve, but it may also get worse over time.
In many cases, receiving prompt treatment for acquired ataxia can result in a good outcome and possibly reverse the condition.