Human speech requires a coordinated effort of the lungs, the brain, and the larynx, the vocal apparatus in the upper throat. Most people take language and the ability to speak for granted, but communication through speech is a complex process that takes years to master.
Speech problems are usually temporary or can be overcome. For example, an upper respiratory infection often causes inflammation of the vocal cords (laryngitis), resulting in a temporary loss of voice. In some instances, however, speech problems signal an underlying disease affecting any of the organs used in talking.
Causes of speech problems
Persistent hoarseness is an early symptom of throat (pharynx) or larynx cancer. The hoarseness may be accompanied by difficulty in swallowing, a chronic cough, and increased production of sputum, which is often tinged with blood.
Alzheimer's and other diseases that affect the brain interfere with the ability to speak. Since memory is critical to speaking, the inability to remember and to think clearly hinder a person's speaking ability. Words may become jumbled, and as the dementia progresses, normal speech patterns are often replaced by muttering.
Since speech is developed by imitating sounds, babies who are born deaf are also mute. They may cry normally and make babbling sounds, but without special training, they will not learn how to put sounds together to form words. Because these babies fail to develop normal speech, they sometimes are mistakenly classified as mentally retarded.
Laryngitis is a temporary condition that is typically related to a cold or upper respiratory infection. The vocal cords become inflamed and lose some of their normal resilience, producing hoarseness or temporary loss of voice.
Babies born with Down's syndrome or other forms of mental retardation are slow to develop speech and, in severe
cases, may never advance beyond babbling. Others may develop a limited vocabulary, enabling them to make their basic wishes known. But since cognitive powers are limited, most retarded children have speech problems.
True mutism is rare. In most instances, it is due to deafness or severe mental retardation. Occasionally, however, a child persistently refuses to speak. This type of mutism is usually elective; for example, the child may speak at home but refuse to talk at school.
Nerve and muscle disorders
Slurred speech is a common symptom of many diseases affecting nerve and muscle function, including multiple sclerosis, Lou Gehrig's disease (amyotrophic lateral sclerosis), Guillain-Barre syndrome, and others. The speech problems usually are due to progressive disruption of the nerve pathways to the brain.
Increasing difficulty in speaking is one of the common symptoms of Parkinson's disease, a progressive disorder of the central nervous system. Other symptoms include tremors, difficulty walking, a fixed or staring facial expression, drooling, and slowed or sluggish responses.
Strokes and mini-strokes
Strokes are caused by an interruption of blood flow to the brain, resulting in death of the area of tissue that was supplied by the disrupted vessel. Most strokes are caused by a blood clot (cerebral thrombosis) blocking an artery to the brain. A mini-stroke is transient, but
is a warning of a possible impending stroke. Symptoms and aftereffects of a stroke depend upon the part of the brain that is damaged, with speech problems among the most common. In a mini-stroke, the speech problem or other symptoms will be temporary.
Stuttering is the unintentional repetition of certain words, sounds, or phrases. Many children stutter when they are learning how to talk, but in only a small percentage does stuttering become a permanent pattern of speech. In most cases, the cause of stuttering is unknown. It sometimes runs in families, indicating that stuttering may have a genetic basis.
Vocal cord problems
Nodules or polyps on the vocal cords often interfere with normal speech. Increasing hoarseness is the major symptom. The nodules and polyps, which are benign, occur most often in people who abuse their voices by excessive shouting or singing without proper training. In unusual cases, the cords may be paralyzed, which makes normal speech difficult if not impossible.
Advice about speech problems
- A speech therapist often can help a person overcome stuttering, lisping, and other common speech problems.
- Children learn to talk by imitating. Parents should talk to a baby, pronouncing words clearly and properly.
- Any persistent hoarseness or difficulty in speaking warrants prompt medical attention to rule out cancer.