Speech Difficulties: Causes and When to Get Help

Types of speech difficulties

A useful distinction: in dysarthria the words are right but poorly pronounced, while in aphasia the words themselves come out wrong or are hard to find or understand.

Sudden speech difficulties

Stroke and TIA

A stroke is the most important cause of sudden speech problems. Left-sided brain strokes usually cause aphasia, and strokes in many locations can cause dysarthria. A transient ischemic attack causes the same symptoms that go away within minutes to hours. It still needs urgent assessment, because the risk of a major stroke is highest in the following days.

Other sudden causes

• Bell's palsy: sudden weakness of one side of the face, causing slurring of lip sounds. The forehead is also weak, unlike in stroke, but it should be checked urgently to be sure.
• Alcohol, sedatives, opioids and some anti-seizure medicines.
• Low blood sugar in people with diabetes.
• Migraine with aura: temporary speech disturbance is possible.
• Seizures and the period after them.
• Head injury.
• Infections such as encephalitis, and severe infections causing confusion in older adults.

Gradual speech difficulties

• Parkinson's disease: a soft, monotone, fast or mumbled voice that people often fail to notice in themselves.
• Amyotrophic lateral sclerosis (ALS): progressive slurring, often with swallowing problems, tongue wasting and limb weakness.
• Myasthenia gravis: speech becomes slurred or nasal with use and improves with rest, often with drooping eyelids and double vision.
• Multiple sclerosis: slow, scanning, or slurred speech.
• Dementia: word-finding difficulty and reduced vocabulary. Primary progressive aphasia is a type of dementia that starts with language.
• Brain tumors.
• Vocal cord problems: nodules, polyps, paralysis, reflux and laryngeal cancer cause hoarseness rather than slurring.
• Mouth problems: poorly fitting dentures, mouth ulcers, dry mouth and tongue swelling.

Speech difficulties in children

Children learn speech gradually, and many variations are normal. Seek an assessment if a child:

• is not babbling by 12 months, has no words by 16 to 18 months, or no two-word phrases by 2 years
• is hard for family to understand at age 3, or for strangers at age 4
• loses words or skills they had before
• stutters for more than 6 months, starts after age 3½, or struggles, avoids talking or seems distressed

Common causes include speech sound disorders, developmental language disorder, childhood apraxia of speech, hearing loss (often from repeated ear infections with fluid), autism spectrum disorder, cerebral palsy and cleft palate. A hearing test is always part of the evaluation.

How doctors assess speech difficulties

For sudden symptoms, an ER team will do a rapid stroke assessment, check blood sugar, and arrange an urgent CT or MRI scan of the brain.

For gradual problems, a doctor will ask when it started, whether it fluctuates, and about swallowing, weakness, memory and other symptoms. They will examine the face, tongue, palate and nervous system. Tests may include:

• MRI of the brain
• blood tests, including for myasthenia gravis antibodies
• nerve and muscle studies (EMG) if ALS or myasthenia is suspected
• laryngoscopy to look at the vocal cords for persistent hoarseness
• formal assessment by a speech-language pathologist

Treatment

• Emergency stroke treatment: clot-dissolving medicine or clot removal, which can reverse speech loss if given quickly.
• Speech and language therapy: the main treatment for aphasia, dysarthria, apraxia and stuttering. Therapists teach exercises, strategies and alternative communication methods, such as communication boards and speech-generating apps.
• Treating the cause: medicines for Parkinson's or myasthenia gravis, voice therapy or surgery for vocal cord problems, and adjusting medicines.
• Voice amplifiers and programs such as LSVT LOUD for Parkinson's disease.
• Early intervention for children, often through school or early childhood services.

Tips for communicating with someone who has speech difficulties

• Reduce background noise and face the person.
• Give them time and do not finish their sentences unless asked.
• Ask yes-or-no questions when they are struggling.
• Use gestures, writing, pictures or apps to support conversation.
• Check understanding by repeating back what you heard.

Frequently asked questions

What causes sudden slurred speech?

The most important cause is a stroke or TIA, which needs emergency care. Other causes include alcohol or drug intoxication, low blood sugar, Bell's palsy, seizures and head injury. Call 911 or your local emergency number for sudden slurred speech.

What is the difference between aphasia and dysarthria?

Aphasia is a language problem: the brain has trouble finding, forming or understanding words. Dysarthria is a muscle problem: the words are correct but sound slurred, slow or mumbled because the speech muscles are weak or uncoordinated.

Can anxiety cause speech difficulties?

Anxiety can make you stumble over words, speak quickly, or have a shaky voice, and it worsens stuttering. It does not cause true slurring or aphasia. Sudden slurred speech should never be assumed to be anxiety until a stroke has been ruled out.

Can speech difficulties be cured?

It depends on the cause. Speech often improves a lot after a stroke with therapy, especially in the first months. Problems from medicines, low blood sugar or Bell's palsy usually resolve. Progressive conditions cannot be cured, but therapy helps people communicate for longer.

When should a child see someone about speech problems?

See a doctor or speech-language pathologist if a child has no words by 16 to 18 months, no phrases by 2 years, is hard for strangers to understand by age 4, loses skills, or stutters with distress. Early help gives the best results.