What Is the mFARS Rating Scale in Friedreich Ataxia?

The modified Friedreich Ataxia Rating Scale (mFARS) is a standardized, clinician-administered neurological examination used to measure specific physical effects of Friedreich ataxia (FA). It is a streamlined version of the older, original FARS test ^[1].

By testing certain physical movements during your appointments, your care team can track changes in your neurological function ^[2]. However, it is important to know that the mFARS is just one tool used alongside your own self-reported symptoms and other medical tests. It measures selected neurological functions, not how FA affects your entire body, and should not be used alone to judge your overall health or treatment response.

What Does the mFARS Measure?

The exam is broken down into four main categories, called subscores, that evaluate specific nerve and muscle functions ^[1]:

• Bulbar function: This is a brief rating of your facial and throat muscles, testing speech clarity and basic swallowing ability ^[1]. Note: This is not a comprehensive swallow safety study. If you have coughing during meals, choking, or a wet-sounding voice, tell your doctor—you may need a formal swallowing assessment by a specialist.
• Upper limb coordination: This tests how well you can control your arms and hands, usually through tasks like touching your finger to your nose or rapidly moving your hands ^[1].
• Lower limb coordination: This tests your ability to control your legs and feet, such as sliding your heel down your opposite shin ^[1].
• Upright stability: This evaluates your functional postural control and balance—such as sitting, standing stance, and gait-related tasks ^[3].

(To make the overall scale more focused, the mFARS omits the peripheral nervous system subscore and specific bulbar items that were included in the complete FARS test ^[1]).

What the mFARS Does Not Measure

The mFARS provides a specific neurological snapshot, but it does not capture the full impact of FA. A stable mFARS score does not mean that everything is stable. The mFARS does not measure:

• Heart disease (cardiomyopathy) or arrhythmias
• Diabetes or blood sugar levels
• Curvature of the spine (scoliosis)
• Vision or hearing problems
• Fatigue, pain, mood, or cognitive changes
• How the disease impacts your daily quality of life

Understanding Your Score

In the mFARS scoring system, a higher number indicates greater neurological impairment in the tested areas ^[1][2].

• Group averages versus you: In one matched natural-history cohort study, scores worsened by an average of about 2.2 points per year over a three-year period ^[4]. However, this is a group average, not a personal forecast. Your individual progression depends heavily on your age of onset, how long you have had FA, and your overall disease severity ^[3][5].
• Walking and balance: For patients who are still able to walk (ambulatory), the upright stability portion of the test is often the main driver of any decline seen in the total score ^[3].
• Measurement variability: Your score can fluctuate for reasons unrelated to disease progression. Fatigue, a recent illness, different examiners, or even the time of day can alter your performance.
• The “practice effect”: If you take the test frequently, your scores in arm and leg coordination might actually improve simply because you are practicing the specific movements ^[6]. Because of this, clinicians look for long-term trends rather than over-analyzing a single minor change ^[6].

Safety and What to Expect During the Test

Because the examination includes balance and walking tasks, safety is the top priority. The exam should be supervised by your clinician. Always report recent falls, dizziness, pain, unusual fatigue, or if you use a cane, walker, or wheelchair. The examiner can adapt or stop tasks based on your abilities. Never push yourself to attempt an unsafe movement just to get a better score.

Why Might Your Care Team Repeat the mFARS?

Testing frequency varies by clinician, disease stage, and whether you are in a clinical trial. Neurologists may repeat this examination for a few reasons:

1. Informing your care: It helps your care team understand which specific physical abilities are changing. This information—alongside your daily experiences—can help guide decisions about physical therapy, mobility aids, or daily routines.
2. Tracking outcomes in clinical trials: The mFARS is a commonly used and validated clinical outcome measure in FA research. For example, in the MOXIe randomized trial for the medication omaveloxolone, the mFARS was used as a primary endpoint to measure the difference in neurological function between the treatment group and the placebo group over 48 weeks ^[7].