Ataxia vs. Dysmetria: What’s the Difference?

Dysmetria happens when your brain has trouble producing smooth and accurate movements. It can lead to you miscalculating the distance between yourself and another object. Dysmetria can make actions like walking, writing, or reaching for an object difficult.

Dysmetria can be caused by different types of ataxia, and it’s a type of ataxia itself. Think of ataxia as a broad umbrella term for overall clumsy or uncoordinated movement, while dysmetria is one specific, classic symptom under that umbrella. In this piece, we’ll discuss how dysmetria and ataxia are related and ways in which they differ.

Dysmetria Starts in the Brain

The cerebellum is a part of the brain that helps you coordinate voluntary motor actions — those you choose to do. Anytime you decide to move, for instance, walking through a door or reaching for a cup of coffee, your cerebellum is instantly calculating distance and speed so your movement is accurate.

Your cerebellum functions by predicting where your body is and where it will be in the future based on past movements.

Dysmetria usually occurs when the cerebellum is damaged, making it harder to do these calculations and make predictions about movement.

Dysmetria can show up in two main ways:

• People might overshoot their movements (reach too far, past the coffee cup they want to grab), which is called hypermetria.
• They may also undershoot their movements (not reach far enough for the cup), which is called hypometria.

Because everyone’s brain is unique, symptoms of dysmetria can look different depending on the cerebellar disorder and part of the cerebellum affected.

Ataxia and Dysmetria Can Differ in Causes

Dysmetria can be caused by:

• Brain tumors
• Cerebral palsy
• A deficiency of thiamine or vitamin B12
• A traumatic brain injury
• A stroke
• A brain infection
• Paraneoplastic syndrome
• Alcohol use disorder
• Multiple sclerosis
• Creutzfeldt-Jakob disease
• Multiple system atrophy

At the same time, dysmetria frequently overlaps with progressive disorders called ataxias. Some of these ataxias are genetic, passed down through families (like Friedreich ataxia and spinocerebellar ataxia, while others are acquired due to toxins, autoimmune diseases, or infections, damaging the cerebellum in ways that lead to dysmetria.

Dysmetria Has a Narrower Range of Symptoms Than Ataxia

A person living with dysmetria will have problems with motor control due to overshooting or undershooting movements. They may:

• Struggle to grab objects
• Run into walls or door frames
• Have problems with tasks like writing (where one must bring pen to paper)
• Battle to keep their balance
• Have issues using a computer mouse
• Struggle to feed themselves

Ataxia, on the other hand, can have dysmetria as a symptom, but it generally also has other symptoms, too. Ataxia refers to a wide variety of problems with muscle coordination and can include having an unsteady gait or slurred speech (dysarthria) and shaky eyes (nystagmus) in addition to dysmetria.

You can have dysmetria along with some forms of ataxia. Interestingly, you can actually have ataxia without dysmetria. For instance, “sensory ataxia” happens when the nerves in your legs fail to tell your brain where your feet are on the ground. Your walking is uncoordinated, but your brain’s targeting system (the cerebellum) is still perfectly healthy.

Ataxia and Dysmetria May Be Diagnosed Differently

If you have signs of ataxia, your doctor will likely start by getting a detailed history to understand what symptoms you’ve been experiencing.

Next, they might run tests including blood tests, imaging tests (like a CT scan or an MRI), genetic testing, and even a lumbar puncture (spinal tap) or genetic analysis. The tests can help your doctor check for possible causes of ataxia. They may also be used to rule out conditions that might be causing your symptoms.

To check for dysmetria, there are specific neurological examinations that doctors may perform.

People who don’t have any damage to their cerebellum are able to do these tests easily. People with dysmetria may not be able to do them, or may have to pause and make new mental calculations along the way.

Treatments for Ataxia and Dysmetria May or May Not Overlap

If dysmetria is caused by ataxia, then the treatment for both conditions may be the same. However, treatment for dysmetria varies according to the cause of the cerebellar damage.

If a person is diagnosed with dysmetria due to a stroke or multiple sclerosis, then their treatment plan will look very different from someone diagnosed with an inherited genetic form of ataxia.

Thus, it’s key to get an accurate diagnosis not only of dysmetria, but of what caused it. That way, you can get proper medical treatment.

But no matter the cause, the absolute cornerstone of managing dysmetria and ataxia is neurorehabilitation. Dedicated physical and occupational therapists can teach you brilliant “compensatory strategies.” This includes using weighted utensils to steady a tremor, performing targeted balance exercises, or learning sensory cueing techniques to help your brain find its place in space.

If you or a loved one are noticing changes in your balance or hand coordination, please reach out to a neurologist. They can partner with you to unravel the “why” behind your symptoms and build a personalized road map to help you move through the world with confidence.

Talk to Your Doctor About Ataxia and Dysmetria

If you have questions about dysmetria or how it’s affecting your life or your child’s life, take them to your care team. They understand the details of your condition and can help you find the answers you need.

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