Ataxia is a lack of muscle coordination which may affect speech, eye movements, the ability to swallow, walking, picking up objects, and other voluntary movements.
Many different things can cause ataxia, including multiple sclerosis, head trauma, alcohol abuse, stroke, cerebral palsy, genetics, or tumor. Ataxia may also be a symptom associated with certain infections.
There are many types of ataxia. In this article, we will discuss some of the more common types, causes, and available treatments.
Here are some key points about ataxia. More detail and supporting information is in the main article.
- Ataxia can be caused by a wide range of factors
- Symptoms can include poor coordination, slurred speech, tremors, and hearing problems
- Diagnosis of ataxia can be challenging and often involves a range of tests
- Although ataxia is not always curable, symptoms can often be alleviated
Types of ataxia
The following are some of the more common types of ataxia:
The cerebellum helps combine sensory perception, coordination, and motor control
This is ataxia caused by a dysfunction of the cerebellum - a region of the brain involved in the assimilation of sensory perception, coordination, and motor control.
Cerebellar ataxia can cause neurological problems such as:
- Floppiness (hypotonia)
- Lack of coordination between organs, muscles, limbs, or joints (asynergy)
- Impaired ability to control distance, power, and speed of an arm, hand, leg, or eye movement (dysmetria)
- Difficulty in accurately estimating how much time has passed (dyschronometria)
- An inability to perform rapid, alternating movements (dysdiadochokinesia)
The extent of symptoms depends on which parts of the cerebellum are damaged, and whether lesions occur on one side (unilateral) or both sides (bilateral).
If the vestibulocerebellum is affected, the patient's balance and eye movement control will be affected. The patient will typically stand with feet wide apart in order to gain better balance and avoid swaying backward and forward (posterior-anterior oscillations).
Even when the patient's eyes are open, balance may be difficult with feet together. If the spinocerebellum is affected, the patient will have an unusual gait with unequal steps, sideways steps, and stuttering starts and stops. The spinocerebellum regulates body and limb movements.
If the cerebrocerebellum is affected, the patient will have problems with voluntary, planned movements. The head, eyes, limbs, and torso may tremble as voluntary moves are carried out. Speech may be slurred, with variations in rhythm and loudness.
This is ataxia due to loss of proprioception. Proprioception is the sense of the relative position of neighboring parts of the body. It is a sense that indicates whether the body is moving with the required effort and gives feedback on the position of body parts relative to each other.
A patient with sensory ataxia typically has an unsteady stomping gait, with the heel striking hard as it touches the ground with each step. Postural instability becomes worse in poorly lit environments. If a doctor asks the patient to stand with eyes closed and feet together, their instability will worsen. This is because loss of proprioception makes the patient much more reliant on visual data.
The patient may find it hard to perform smoothly coordinated voluntary movements with the limbs, trunk, pharynx, larynx, and eyes.
The vestibular system is affected. In acute (sudden) unilateral cases, the patient may experience vertigo, nausea, and vomiting. In slow-onset chronic bilateral cases, the patient may only experience unsteadiness.
Causes of ataxia
Vitamin B-12 deficiency is one potential cause of ataxia. It can produce overlapping cerebellar and sensory ataxia, as well as other neurological abnormalities.
Ataxia can also be a symptom of another health condition. It can also be defined as inherited or non-inherited:
This means the ataxia is caused by a genetic defect inherited either from the mother or father, or both.
A faulty gene that is passed down through generations can cause cerebellar ataxia - in some cases, its severity worsens from one generation to the next and the age of onset gets younger.
The chance of inheriting ataxia from a parent depends on the type of ataxia the parent has. For a person to develop Friedreich's ataxia, the faulty gene would need to be carried by both the mother and the father (recessive inheritance).
Spinocerebellar ataxia, on the other hand, only requires one parent to carry the defective gene (dominant inheritance), and each of their offspring would have a 50 percent risk of developing the condition.
Even without a family history of ataxia, some people may still develop the condition. In some cases, doctors cannot identify the cause. The following can cause ataxia:
- Brain surgery
- Head injury
- Alcohol abuse
- Drug abuse
- Infections, such as chicken pox (usually goes away after infection has cleared)
- Brain tumor
- Exposure to toxic chemicals
- Multiple sclerosis, cerebral palsy, and some other neurological conditions
- Malformation of the cerebellum while the baby is still in the womb
Symptoms of ataxia
Symptoms may vary depending on the severity and type of ataxia. If the ataxia is caused by an injury or another health condition, symptoms may emerge at any age, and may well improve and eventually disappear.
Initial ataxia symptoms usually include:
- Poor limb coordination.
- Dysarthria - slurred and slow speech that is difficult to produce. The patient may also have difficulties controlling volume, rhythm, and pitch.
If the ataxia progresses, other symptoms may also appear:
- Swallowing difficulties, which may sometimes result in choking or coughing.
- Facial expressions become less apparent.
- Tremors - parts of the body may shake or tremble unintentionally.
- Nystagmus - involuntary, rapid, rhythmic, repetitive eye movement. Movements may be vertical, horizontal, or circular.
- Cold feet - because of a lack of muscle activity.
- Problems with balance.
- Walking difficulties - in severe cases, the patient may need a wheelchair.
- Vision problems.
- Hearing problems.
- Depression - as a result of having to live and cope with the symptoms.
Early onset cerebellar ataxia usually emerges between the ages of 4 and 26. Late onset ataxia generally appears after the patient is 20. Late-onset ataxias usually present less severe symptoms, compared with early-onset ataxia.
Ataxia telangiectasia symptoms generally include:
- Small veins appear around the corner of the eyes, cheeks, and ears
- Physical and sexual development is usually delayed
Friedreich's ataxia symptoms generally include:
- The spine curves sideways (scoliosis)
- The heart muscle becomes weaker (cardiomyopathy)
- Pes cavus (high arching feet)
For patients whose ataxia is caused by injury or illness, symptoms often improve over time and eventually go away completely.
Diagnosis of Ataxia
A doctor who suspects the patient may have ataxia will refer them to a neurologist - a doctor specialized in diagnosis, treatment, and prevention of conditions and illnesses related to the nervous system.
The specialist will check the patient's medical history for causal factors, such as brain injury, as well as the patient's family history for indications of inheritance. The following tests may also be ordered:
- MRI or CT scan - to determine whether there is any brain damage.
- Genetic tests - to determine whether the patient has inherited ataxia.
- Blood tests - some types of ataxia affect the make-up of blood.
- Urine tests - urinalysis may suggest specific systemic abnormalities that are linked to some forms of ataxia. If the specialist suspects Wilson's disease, the patient may be asked for a 24-hour urine collection to determine how much copper is in the system.
In some cases, the specialist may not be able to determine the cause of ataxia; this is known as sporadic or idiopathic ataxia.
Reaching a conclusive diagnosis of ataxia can sometimes take a long time because the symptoms could point to several other conditions.
Treatments for ataxia
Although ataxia is generally not curable, a great deal can be done to ease symptoms and improve the quality of life of the patient. Treatment for coordination and balance problems usually involves the use of adaptive devices that help the patient attain as much independence as possible. These may include the use of a cane (walking stick), crutches, walker, or a wheelchair.
Symptoms such as tremor, stiffness, spasticity, sleep disorders, muscle weakness, depression (or frustration, sadness, and anger) may be addressed with targeted physical therapy, speech therapy, medications, and counseling.
- Occupational therapy - the occupational therapist can help the patient manage better around the house and at work; this may involve some home adaptations, wheelchair assessments, and making the kitchen more practical for the patient.
- Speech therapy - the speech therapist can help with swallowing, coughing, choking, and speech problems. If speech becomes very difficult, the speech therapist can help the patient learn how to use speech aids.
- Orthopedic care - this can help patients with curvature of the spine (scoliosis).
- Physical therapy - a physical therapist can help maintain strength and improve mobility.
- Counseling - patients with ataxia commonly become frustrated and depressed; this usually results from having to cope with some symptoms that affect physical mobility and coordination. Talking to a well-qualified counselor, such as a psychotherapist, can help.
- Supplements and nutrition - some patients with ataxia have very low levels of vitamin E and require supplements and/or a special diet. As sensitivity to gluten may occur among some patients with ataxia, a gluten-free diet may help.
- Medication - some patients with ataxia telangiectasia are prescribed gamma-globulin injections to boost their immune systems. There are also drugs for muscle spasms and uncontrollable eye movements.