Dysmetria is a medical term used to describe a condition that affects one’s ability to control and coordinate their movements accurately. In simpler terms, it is like having a glitch in the brain’s “motion control system”.
When someone experiences dysmetria, their movements, such as reaching for an object or touching a specific point, may be imprecise and often overshoot (where we call it hypermetria) or undershoot (where we call it hypometria) the intended target.
Imagine trying to throw a ball at a target, but your brain misjudges the force needed, and the ball either goes too far or does not reach the target at all. This is similar to what happens in dysmetria, where the brain’s signals to the muscles do not work as smoothly as they should, leading to inaccurate movements.
What Causes Dysmetria?
Most cases of dysmetria are caused by problems in the cerebellum, which is the part of the brain that coordinates and fine-tunes voluntary motor actions. Cerebellar diseases like cerebellar ataxia, multiple sclerosis, and cerebellar strokes can damage this important part of the brain, which can then cause dysmetria.
The cerebellum or its neural connections can also be damaged by head injuries, traumatic brain injuries, infections like encephalitis (inflammation of the brain) or meningitis (inflammation of the meninges, the protective membranes that surround the brain and spinal cord), and long-term use of alcohol or certain drugs. Even brain tumours, especially those located close to the cerebellum, may affect the way the brain works and cause dysmetria.
How to Diagnose and Treat Dysmetria?
Diagnosis of dysmetria typically starts with a thorough assessment, during which a doctor reviews the medical history and conducts physical examinations, assessing the motor skills and balance. To pinpoint the underlying causes, brain imaging tests like MRI (magnetic resonance imaging) or CT (computed tomography) scans may be requested to examine the brain’s structural issues. Specialized neurological tests might also be performed to evaluate the severity of dysmetria.
Treatment strategies for dysmetria might vary based on the cause; for instance, managing underlying conditions like multiple sclerosis or stroke is crucial. Physical and occupational therapy are also vital components of treatment, focusing on improving muscle control, coordination, and daily functioning. Medications may be prescribed to alleviate symptoms or address specific underlying conditions. In rare cases, surgical intervention may be necessary to correct structural problems or remove tumors contributing to dysmetria.
How is Dysmetria Related to Ataxia?
Dysmetria is a specific component of ataxia, but ataxia can involve a wider range of coordination problems beyond the dysmetria. Both conditions often involve dysfunction in the cerebellum or related brain regions, which are critical for coordinating movements and maintaining balance.
If you would like to learn more about dysmetria, take a look at these resources by Osmosis and the Cleveland Clinic.
Snapshot Written by: Lin Dong
Edited by: Priscila Pereira Sena
References
Alusi, S. H., Macerollo, A., MacKinnon, C. D., Rothwell, J. C., & Bain, P. G. (2021). Tremor and Dysmetria in Multiple Sclerosis: A Neurophysiological Study. Tremor and other hyperkinetic movements (New York, N.Y.), 11, 30. https://doi.org/10.5334/tohm.598
Cabaraux, P., Gandini, J., Kakei, S., Manto, M., Mitoma, H., & Tanaka, H. (2020). Dysmetria and Errors in Predictions: The Role of Internal Forward Model. International journal of molecular sciences, 21(18), 6900. https://doi.org/10.3390/ijms21186900
Manto M. (2009). Mechanisms of human cerebellar dysmetria: experimental evidence and current conceptual bases. Journal of neuroengineering and rehabilitation, 6, 10. https://doi.org/10.1186/1743-0003-6-10
Kornegay J. N. (1991). Ataxia, dysmetria, tremor. Cerebellar diseases. Problems in veterinary medicine, 3(3), 409–416.
Scarratt W. K. (2004). Cerebellar disease and disease characterized by dysmetria or tremors. The Veterinary clinics of North America. Food animal practice, 20(2), 275–vi. https://doi.org/10.1016/j.cvfa.2004.02.010
Schmahmann J. D. (2004). Disorders of the cerebellum: ataxia, dysmetria of thought, and the cerebellar cognitive affective syndrome. The Journal of neuropsychiatry and clinical neurosciences, 16(3), 367–378. https://doi.org/10.1176/jnp.16.3.367
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