Identifying the underlying cause, and setting a diagnosis of ataxia is crucial, since therapies are available for some cases of immune-mediated or genetically acquired ataxias. A review of all diagnoses among a large sample of ataxia patients revealed that familial ataxias, including Friedreich’s ataxia, represent only a small proportion of all patients with this type of condition.
Gluten ataxia was the most common diagnosis among the sporadic cases. Given that the condition can be improved by avoiding gluten-containing food, the finding illustrates the importance of an accurate diagnosis.
While the study showed that next-generation sequencing (NGS) helped physicians establish a diagnosis, a large proportion of patients remain undiagnosed.
The study, “Causes of progressive cerebellar ataxia: prospective evaluation of 1500 patients,” mapped the medical abnormalities that caused ataxia among all patients that were evaluated at an ataxia specialist center in the U.K. The report was published in the Journal of Neurology, Neurosurgery and Psychiatry.
Ataxia in itself is not a diagnosis, but rather a collection of symptoms that arise because of an underlying disease. In many cases, finding the reason for the degeneration of the cerebellum — the brain region that allows people to move in a smooth and coordinated manner — is challenging. At times, physicians fail to identify the cause.
To get a better picture of the underlying causes of ataxia in the population, researchers at the Royal Hallamshire Hospital in the U.K. examined the results of diagnostic workups at the ataxia center for the past 20 years.
Findings showed that only 20% of patients had an inherited type of the condition, with Friedreich’s ataxia being the most common (found in 22% of the group).
Among those with sporadic disease, gluten ataxia was found in one-fourth of patients. Almost just as many patients had no identifiable cause. The third most common diagnosis was alcohol-related ataxia — a condition that arises after prolonged, excessive alcohol consumption.
Multisystem atrophy, a rare neurodegenerative disease that affects several brain regions, was found in 11% of ataxia patients. The remainder of patients developed the disease as a result of a host of different causes, each affecting only a few percent of patients.
During the early days of the 20-year period, only tests for Friedreich’s ataxia, spinocerebellar ataxia, and Dentatorubral-pallidoluysian atrophy (DRPLA) were available. The number of tests were increased gradually, but it was not until 2014 that the clinic got access to NGS methods for genetic analysis.
Since then, 146 patients had been screened with genetic tests with 42 different genes. Of the tested patients, 71 patients had a family history of disease. In addition, 33 had sporadic early-onset, and 42 had sporadic late-onset ataxia.
Only 32% of all patients received a diagnosis as a result of the genetic screening. Identification of the genetic cause was more likely among patients with inherited disease.
All told, a diagnosis could be made in 63% of all patients without an established diagnosis of Friedreich’s ataxia.
“Immune-mediated ataxias are common. Advances in genetic testing have signiﬁcantly improved the diagnostic yield of patients suspected of having a genetic ataxia. Making a diagnosis of the cause of ataxia is essential due to potential therapeutic interventions for immune and some genetic ataxias,” the researchers concluded.