Difficulty Speaking: Causes and When to Worry

What does difficulty speaking mean?

Speaking needs three systems to work: the brain areas that form language, the nerves and muscles that move the lips, tongue and palate, and the voice box (larynx) that makes sound. A problem in any of them makes it hard to speak, but each sounds different.

Someone with aphasia may also struggle to read and write. Someone with pure slurred speech understands and writes normally.

What causes sudden difficulty speaking?

Stroke and TIA

A stroke cuts off blood to part of the brain. Speech problems are among its commonest signs, together with face drooping and arm weakness. A transient ischemic attack (TIA, or mini-stroke) causes the same symptoms for minutes to hours and then clears. It is a warning: the risk of a full stroke is highest in the next few days.

Use BE FAST to spot it:

• Balance: sudden loss of balance
• Eyes: sudden loss of vision
• Face: one side droops when smiling
• Arm: one arm drifts down when both are raised
• Speech: slurred or strange speech
• Time: call 911 and note when symptoms started

Clot-busting and clot-removal treatments work only within hours, so never wait to see if it passes.

Other sudden causes

• Alcohol, sedatives and drug toxicity: slurred speech with drowsiness and unsteadiness. Some medicines, including antiseizure drugs, lithium and benzodiazepines, cause slurring at high levels.
• Low blood sugar: confusion, slurred speech, sweating and shaking in someone with diabetes. Give sugar if they can swallow safely.
• Migraine with aura: speech can briefly become garbled before or during a migraine, usually spreading over several minutes and settling within an hour. A first episode must still be treated as a possible stroke.
• Seizures: some seizures stop speech or cause garbled words, and speech can be muddled for a while afterward.
• Bell's palsy: sudden weakness of one whole side of the face, including the forehead, makes lip sounds hard to say. Speech is otherwise normal.
• Head injury, brain infection or bleeding: speech problems with headache, vomiting or drowsiness.
• Panic attacks: can cause a feeling of being unable to get words out, with breathlessness and tingling, but true slurring or word errors point elsewhere.

Sudden and temporary difficulty speaking

Speech trouble that comes and goes within minutes is most often a TIA, a migraine aura, a seizure or low blood sugar. These are hard to tell apart without tests, so anyone who has had even a brief episode should be seen the same day, ideally in an ER.

Causes that develop gradually

Nerve and muscle diseases

• Myasthenia gravis: speech becomes nasal and slurred as you keep talking and recovers with rest, often with drooping eyelids and double vision.
• Parkinson's disease: a quiet, monotone, rushed voice, with tremor and slow movement.
• Multiple sclerosis: slurred or "scanning" speech that breaks words into syllables.
• Amyotrophic lateral sclerosis (ALS): steadily worsening slurring and swallowing problems, with muscle wasting and twitching.
• Dementia: word-finding trouble and shrinking vocabulary, as in aphasia from Alzheimer's disease or primary progressive aphasia.
• Brain tumor: speech or language problems that build over weeks, often with headaches or seizures.

Voice box problems

• Laryngitis: hoarseness from a cold, overuse or acid reflux. Usually settles within 2 weeks.
• Vocal cord nodules or polyps: a husky voice in people who use their voice heavily.
• Vocal cord paralysis: a weak, breathy voice after neck or chest surgery, or from a tumor pressing on the nerve.
• Laryngeal cancer: persistent hoarseness, especially in smokers, sometimes with pain or a neck lump.

Mouth and other causes

Dental problems, poorly fitting dentures, mouth ulcers, a very dry mouth, tongue swelling and hearing loss can all make speech unclear. Stuttering usually begins in childhood. New stuttering in adults can follow a stroke, head injury or medication change.

Accompanying symptoms and what they suggest

How doctors find the cause

A doctor will ask exactly when the problem started, whether it was sudden, whether it comes and goes, and what other symptoms you had. Witnesses help, because people with aphasia may not realize their speech is wrong. Expect:

• A neurological exam: face, tongue, limb strength, coordination, and tests of naming, repetition and understanding.
• Blood sugar check: at once, in any sudden case.
• Brain imaging: an urgent CT or MRI scan for suspected stroke. MRI shows MS, tumors and small strokes.
• Blood tests: for infection, thyroid problems, vitamin B12 and medicine levels.
• Laryngoscopy: a thin camera looks at the vocal cords when the voice is the problem.
• Specialist tests: nerve conduction studies, antibody tests for myasthenia gravis, or a swallowing study.

Treatment and speech therapy

Treatment targets the cause: clot-busting or clot-removal for stroke, sugar for hypoglycemia, voice rest for laryngitis, medicines for myasthenia gravis or Parkinson's disease, and surgery for some vocal cord problems.

A speech-language pathologist (speech therapist) helps in almost every lasting speech problem. Therapy can include exercises to strengthen and coordinate the mouth muscles, slowing the rate of speech, techniques for word-finding, voice training such as the LSVT LOUD program for Parkinson's disease, and communication aids or apps when speech is very limited.

Helping someone with speech difficulty

• Give them time to finish. Do not speak for them.
• Ask yes-or-no questions and use gestures, writing or pictures.
• Reduce background noise.
• Speak normally, not loudly, unless they also have hearing loss.

Frequently asked questions

What causes sudden difficulty speaking?

The most important cause is a stroke or TIA, which needs 911 immediately. Other sudden causes include low blood sugar, alcohol or medicine effects, migraine aura, seizures, head injury and Bell's palsy. Only tests in the ER can safely rule out a stroke.

What does it mean if I have sudden and temporary difficulty speaking?

Speech that goes wrong for a few minutes and then returns to normal is often a transient ischemic attack (mini-stroke). It can also be a migraine aura, seizure or low blood sugar. A TIA greatly raises the short-term risk of a major stroke, so get emergency assessment the same day.

Can anxiety cause difficulty speaking?

Anxiety and panic can make your mouth dry, your voice shaky and words hard to get out, and can worsen stammering. Anxiety does not cause true slurring, one-sided weakness or using the wrong words. If those happen, assume a medical cause and seek urgent help.

What is the difference between aphasia and dysarthria?

Aphasia is a language problem: the brain cannot find, form or understand words, so speech may be fluent but make no sense. Dysarthria is a muscle-control problem: the words are correct but sound slurred or mumbled. Both can result from a stroke.

Can a vitamin deficiency cause slurred speech?

Rarely. Severe vitamin B12 deficiency and thiamine (B1) deficiency in heavy drinkers can affect the nerves and brain and cause unsteadiness and slurred speech. These are uncommon causes and should be considered only after more urgent problems have been ruled out.