Posted by: Thixia | November 4, 2008

Ataxia 2 of 2

Autosomal dominant ataxias

These include:


Spinocerebellar ataxias.  To date, researchers have identified 28 autosomal dominant ataxia genes.  The first was called spinocerebellar ataxia type 1 (SCA1), with subsequent ataxia genes generally numbered according to their order of discovery.  Cerebellar ataxia and cerebellar degeneration are common to all types, but other signs and symptoms, as well as age of onset, differ depending on the specific gene mutation.


The most common of the autosomal dominant ataxias in North America is SCA3, also known as Machado-Joseph disease.  Onset can occur at any age, but most commonly occurs in the 30s and 40s.  Signs and symptoms generally include speech and swallowing difficulties; eyelid retraction, which gives the impression that you’re staring fixedly; and verbal and visual memory defects.


Episodic ataxia.  There are two types of hereditary ataxias that are episodic rather than progressive.  Type 1 involves brief ataxic episodes that may last seconds or minutes.  Getting startled or exercising may bring on an episode.  Type 2 involves longer episodes, which may last days.  If you have this type of ataxia, you also may experience dizziness (vertigo), nausea, vomiting, headache and weakness during your episodes.  Both types of episodic ataxia may respond to treatment with acetazolamide (Diamox), which also is used to treat seizures.  Type 1 also may respond to the anticonvulsant phenytoin (Dilantin). 


When to seek medical advice


If you lose muscle coordination in an arm or leg or slur your speech and aren’t aware of having a condition, such as multiple sclerosis, that causes it, see your doctor.


Tests and diagnosis


Your doctor is likely to take a medical history, ask about when and how your ataxia developed and what signs and symptoms you’re having, ask about drug and alcohol use and potential exposure to toxins, and conduct a physical exam and a neurological exam.  A neurological exam includes checking your memory and concentration, vision, hearing, balance, coordination and reflexes.


In addition, to help determine the underlying cause, your doctor may request these laboratory tests:


Blood tests.  Depending on what your doctor suspects is causing your ataxia, he or she may request certain blood tests to confirm or exclude the suspected condition.  The specific tests will depend on the suspected cause, but most likely will include a complete blood count (CBC), which helps evaluate your overall health and detect a range of disorders, including infection and heavy metal poisoning. 


Urine tests.  Urinalysis may suggest certain systemic abnormalities that can be related to some forms of ataxia.  If your doctor suspects Wilson’s disease, you may be asked for a 24-hour urine collection to determine the amount of copper in your system. 


Imaging studies.  A computerized tomography (CT) scan or magnetic resonance imaging (MRI) of your brain may help determine potential causes. 


Genetic testing.  Your doctor may recommend genetic testing to determine whether you or your child has the gene mutation that causes one of the hereditary ataxic conditions. 


Treatments and drugs


Treatment for ataxia depends on the underlying cause.  There’s no treatment specifically for ataxia.  However, in some cases, such as ataxia that follows chickenpox or other viral infection, it’s likely to resolve on its own over time.


For ataxia caused by conditions such as multiple sclerosis or cerebral palsy, ataxia might not be treatable.  In that case, your doctor may be able to recommend adaptive devices that help you with your affected movements, such as a cane for walking or modified utensils for eating.


You also might benefit from certain therapies, such as physical therapy and occupational therapy to help your walking.  If slurred speech is a problem, speech therapy may help.  If your slurred speech is severe, your therapist may recommend communication aids, such as a speech synthesizer, an electronic device that turns written text into speech.


Coping and support


Living with ataxia can be extremely frustrating.  The challenges ataxia represents, such as loss of independence, may lead to depression and anxiety.  You may find that talking to a counselor or therapist can help you cope.  Or you may find encouragement and understanding in a support group, either for ataxia or for your underlying condition, such as cancer or multiple sclerosis.


Although support groups aren’t for everyone, they can be good sources of information.  Group members often know about the latest treatments and tend to share their own experiences.  If you’re interested, your doctor may be able to recommend a group in your area.












By Mayo Clinic Staff


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