Causes of Dysarthria
The causes of dysarthria are rooted in damage to the nervous system that controls the muscles involved in speaking. This damage can occur in the brain, brainstem, spinal cord, or peripheral nerves. Any condition that disrupts the motor pathways responsible for speech may lead to dysarthria.
One of the leading causes is stroke. When blood flow to the brain is blocked or interrupted, the resulting brain damage can impair the muscles that control speech. Depending on the location and severity of the stroke, dysarthria may affect one side of the face, the tongue, or the respiratory muscles, making speech slow, weak, or imprecise.
Traumatic brain injury is another major cause. A blow to the head—such as from a car accident or fall—can damage the brain’s motor control centres, leading to slurred or difficult speech. In South Africa, road traffic accidents and violence are significant contributors to head injuries and, by extension, to dysarthria.
Progressive neurological diseases can also cause dysarthria. Conditions like Parkinson’s disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and Huntington’s disease gradually affect the brain and nervous system, leading to muscle weakness and speech difficulties over time. In these cases, dysarthria tends to worsen as the disease progresses.
Other causes include brain tumours, cerebral palsy, muscular dystrophy, and infections such as encephalitis or meningitis. Surgery involving the brain, face, or vocal cords may also lead to temporary or permanent dysarthria if nerves are damaged.
Medications can contribute as well. Sedatives, muscle relaxants, and drugs that affect the central nervous system may temporarily impair speech by relaxing the muscles too much or altering brain activity.
Some cases of dysarthria result from congenital conditions—those present at birth. Children with cerebral palsy, for example, may experience muscle coordination problems that affect their ability to produce speech clearly.
Causes of Dysarthria
Understanding the causes of dysarthria is essential for accurate diagnosis and effective treatment. A clear diagnosis helps guide therapy and manage expectations. In some cases, treating the underlying condition—such as improving blood sugar control in diabetic neuropathy or adjusting medication—can also improve speech.
Access to early intervention is vital. In rural parts of South Africa, limited resources can delay both diagnosis and therapy, leading to social isolation and reduced quality of life. Health awareness programmes, early screening, and speech-language services in local clinics can help address these challenges.
Identifying the cause allows healthcare professionals to create an appropriate, individualised care plan. Whether the goal is to improve intelligibility or provide alternative communication methods, recognising the origin of the condition is always the first step.
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