Speech Problems: Types and Causes

Types of speech problems

The difference between dysarthria and aphasia matters. In dysarthria, language is intact but speech sounds are poorly formed. In aphasia, the muscles work but the brain's language system is affected.

Sudden speech problems: stroke and TIA

A stroke occurs when blood flow to part of the brain is blocked or a vessel bleeds. Speech problems are one of the most common signs. Remember BE FAST: Balance, Eyes, Face drooping, Arm weakness, Speech difficulty, Time to call 911. A transient ischemic attack causes the same symptoms but they resolve within minutes to hours. It is still an emergency because a stroke may follow.

Other sudden causes:

• low blood sugar
• alcohol or drug intoxication, or medicine overdose
• seizures and the period after a seizure
• migraine with aura (rarely)
• head injury
• Bell's palsy (mild slurring from facial weakness, with no other neurological signs)
• brain infections

Gradual speech changes in adults

• Parkinson's disease: soft, monotone, rushed speech, often with tremor and slow movement.
• Amyotrophic lateral sclerosis: progressive slurring and nasal speech with swallowing problems and muscle wasting.
• Multiple sclerosis: "scanning" speech with irregular pauses, often with balance problems.
• Myasthenia gravis: speech that weakens with talking and becomes nasal, with drooping eyelids and double vision, worse late in the day.
• Dementia: word-finding problems and reduced speech, especially in primary progressive aphasia.
• Brain tumors: slowly worsening speech with headaches or seizures.
• Cerebellar ataxias: slurred, uncoordinated speech with unsteadiness.
• Mouth and throat causes: poorly fitting dentures, mouth ulcers, tongue problems.

Speech problems in children

Children develop speech at different rates, but some milestones matter:

• babbling by 6 to 9 months
• first words by about 12 months
• around 50 words and two-word phrases by 2 years
• understood by strangers most of the time by 4 years

Causes of delay include hearing loss (including from repeated ear infections), speech delay and developmental language disorder, childhood apraxia of speech, autism spectrum disorder, intellectual disability and cerebral palsy. Stuttering is common between ages 2 and 5 and most children outgrow it. Any concern should prompt a hearing test and speech-language evaluation, since early therapy improves outcomes.

How speech problems are diagnosed

For sudden changes, emergency teams check blood sugar and perform urgent brain imaging. For gradual changes, a doctor will take a history, examine the nerves of the face, tongue and throat, and test strength, coordination and memory. Tests may include:

• MRI or CT of the brain
• blood tests and specific antibody tests (for myasthenia gravis)
• electromyography (EMG) for nerve and muscle disease
• laryngoscopy (a camera view of the vocal cords) for voice problems
• hearing tests
• a detailed assessment by a speech-language pathologist

Treatment

• Treat the cause: emergency stroke treatment, medicines for Parkinson's or myasthenia gravis, managing MS.
• Speech-language therapy: exercises to strengthen muscles, slow speech, improve breathing support, and strategies for word-finding. Intensive programs such as LSVT LOUD help Parkinson's speech.
• Communication aids: alphabet boards, apps and speech-generating devices for severe impairment.
• Stuttering therapy: fluency techniques and support for confidence.
• Voice therapy and surgery for vocal cord problems.

Family members can help by giving extra time, reducing background noise, asking yes-or-no questions when needed, and not finishing sentences unless asked.

Frequently asked questions

What causes sudden slurred speech?

The most important cause is stroke or TIA. Other causes include low blood sugar, alcohol or drug intoxication, seizures, head injury and some infections. Any sudden slurred speech needs a 911 call, even if it improves.

What is the difference between dysarthria and aphasia?

Dysarthria is slurred or unclear speech caused by weakness or poor control of the speech muscles, while language is intact. Aphasia is difficulty with language itself: finding words, forming sentences or understanding, caused by damage to language areas of the brain.

Can anxiety cause speech problems?

Anxiety can cause a shaky voice, stumbling over words, a dry mouth and worsening of stuttering. It does not cause true slurred speech or aphasia. New slurred speech or word-finding problems should never be put down to anxiety without assessment.

When should I worry about my child's speech?

Talk to your pediatrician if your child is not babbling by 9 months, has no words by 16 months, is not combining words by 2 years, is hard for strangers to understand at 4 years, or loses words they previously used.