When testing doesn’t give an answer

    Diagnosing and treating primary autoimmune cerebellar ataxia (PACA)

Many people with ataxia are not given a specific diagnosis for the cause of their ataxia. This is known as idiopathic ataxia.
In two new publications, Professor Hadjivassiliou (below) at the Sheffield Ataxia Centre, and his colleagues, describe a type of ataxia that could
be responsible for a number of idiopathic ataxia cases. They explain how neurologists can make this diagnosis and how this type of ataxia can be treated.
Immune-mediated cerebellar ataxias are caused when the body launches
an unnecessary immune reaction against the cerebellum (the balance centre) causing damage, resulting in ataxia. Gluten ataxia is an example
of an immune-mediated cerebellar ataxia. In patients with gluten sensitivity, the body recognises gluten as harmful and produces antibodies against it. These antibodies travel to the brain and attack cells of the cerebellum, which results in ataxia. In this case, gluten is known as the ‘trigger’. However, in some cases of immune-mediated ataxias, the trigger is unknown, which is when the condition is called primary autoimmune cerebellar ataxia (or PACA).
There is no specific test that will definitively diagnose PACA. However, an International Task Force on immune-mediated cerebellar ataxias, of which Prof Hadjivassiliou is the lead, have written a comprehensive list of clues that neurologists should look for when considering the possibility that a patient has PACA. A diagnosis of PACA can be made if certain criteria outlined in this document are fulfilled, and if an experienced neurologist or ataxia specialist has ruled out other possible causes (such as genetic ataxia).
In the second article, the team from the Sheffield Ataxia Centre describe
a possible treatment for PACA. They treated 22 PACA patients with an immunosuppressive drug called Mycophenolate, which reduces the immune response that causes the ataxia. This treatment is expected to prevent further damage to the cerebellum and salvage any sick cells. Their results using brain scans and ataxia rating scales showed that those receiving treatment improved or stabilised, and those who did not got progressively worse.
Prof Hadjivassiliou said: “Identifying patients with PACA is incredibly important to allow them to receive the appropriate treatment, and early diagnosis could prevent permanent neurological damage.”
If you have been diagnosed with idiopathic ataxia and would like to explore the possibility of PACA, we recommend you speak to your neurologist about these new publications. If you do not see
a neurologist regularly, email help@ataxia.org. uk for details of Specialist Ataxia Centres.
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