Ataxia is a lack of muscle coordination that may affect a person's speech, eye movements, and ability to swallow, walk, and pick up objects, among other voluntary movements.

Many and other factors can cause ataxia, including multiple sclerosis (MS), head trauma, excessive alcohol intake, a stroke, cerebral palsy, genetics, and tumors.

Ataxia may 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.

The following are some of the most common types of ataxia:

Cerebellar 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:

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.

Sensory ataxia

This is a type of ataxia that develops due to a .

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:

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.

Vestibular ataxia

woman with vertigo due to ataxia
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 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:

In time, other symptoms may appear, such as:

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 , often appears between the ages of 10 and 15 years.

Symptoms include:

  • 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.

Ataxia can result from:

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 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.

Acquired ataxia

The following events and conditions can also result in ataxia:

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.