In human development, muteness or mutism is defined as an absence of speech, with or without an ability to hear the speech of others. Mutism is typically understood as a person's inability to speak, and commonly observed by their family members, caregivers, teachers, doctors or speech and language pathologists. It may not be a permanent condition, as muteness can be caused or manifest due to several different phenomena, such as physiological injury, illness, medical side effects,

psychological trauma Psychological trauma (also known as mental trauma, psychiatric trauma, emotional damage, or psychotrauma) is an emotional response caused by severe distressing events, such as Major trauma, bodily injury, Sexual assault, sexual violence, or ot ...

developmental disorders Developmental disorders comprise a group of psychiatric conditions originating in childhood that involve serious impairment in different areas. There are several ways of using this term. The most narrow concept is used in the category "Specific D ...

, or

neurological disorders Neurological disorders represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These Disorder of consciousness, disorders affect the brain, spinal cord, and nerve networks, presenting unique ...

. A specific

physical disability A physical disability is a limitation on a person's physical functioning, mobility, dexterity or stamina. Other physical disabilities include impairments which limit other facets of daily living, such as respiratory disorders, blindness, epilepsy ...

communication disorder A communication disorder is any disorder that affects an individual's ability to Speech perception, comprehend, detect, or apply language and speech to engage in dialogue effectively with others. This also encompasses deficiencies in verbal and N ...

can be more easily diagnosed. Loss of previously normal speech (

aphasia Aphasia, also known as dysphasia, is an impairment in a person's ability to comprehend or formulate language because of dysfunction in specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aph ...

) can be due to accidents, disease, or surgical complication; it is rarely for

psychological Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...

reasons. Treatment or management also varies by cause and this can often be determined after a speech assessment. Treatment can sometimes restore speech. If not, a range of assistive and augmentative communication devices are available.

Biological causes

Biological causes of mutism may stem from several different sources. One cause of muteness may be problems with the physiology involved in speech, for example, the mouth or tongue. Mutism may be due to

apraxia Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex or corpus callosum), which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the di ...

, that is, problems with coordination of muscles involved in speech. Another cause may be a medical condition impacting the physical structures involved in speech, for example, loss of voice due to the injury, paralysis, or illness of the

larynx The larynx (), commonly called the voice box, is an organ (anatomy), organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal ...

. Anarthria is a severe form of

dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. It is a condition in which problems effectively occur with the ...

, in which the coordination of movements of the mouth and tongue or the conscious coordination of the lungs are damaged. Neurological damage due to

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

may cause loss or impairment of speech, termed

. Neurological damage or problems with development of the area of the brain involved in speech production,

Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant Cerebral hemisphere, hemisphere, usually the left, of the Human brain, brain with functions linked to speech production. Language processing in the brai ...

, may cause muteness. Trauma or injury to Broca's area, located in the left inferior

frontal cortex The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betw ...

of the brain, can cause muteness. Muteness may follow brain surgery. For example, there is a spectrum of possible neurobehavioural deficits in the posterior fossa syndrome in children following

cerebellar The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or e ...

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

surgery.

Psychological causes

When children do not speak, psychological problems or

emotional stress In psychology, stress is a feeling of emotional strain and pressure. Stress is a form of psychological and mental discomfort. Small amounts of stress may be beneficial, as it can improve athletic performance, motivation and reaction to the env ...

, such as

anxiety Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...

, may be involved. Children may not speak due to

selective mutism Selective mutism (SM) is an anxiety disorder in which a person who is otherwise capable of speech becomes unable to speak when exposed to specific situations, specific places, or to specific people, one or multiple of which serve as triggers. Se ...

. Selective mutism is a condition in which the child speaks only in certain situations or with certain people, such as close family members. Assessment is needed to rule out possible illness or other conditions and to determine treatment. Prevalence is low, but not as rare as once thought. Selective mutism should not be confused with a child who does not speak and cannot speak due to physical disabilities. It is common for symptoms to occur before the age of five. Not all children express the same symptoms. Selective mutism may occur in conjunction with

autism spectrum disorder Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing di ...

or other diagnoses.

Differential diagnosis In healthcare, a differential diagnosis (DDx) is a method of analysis that distinguishes a particular disease or condition from others that present with similar clinical features. Differential diagnostic procedures are used by clinicians to di ...

between selective mutism and language delay associated with autism or other disorders is needed to determine appropriate treatment. Adults who previously had speech and subsequently ceased talking may not speak for psychological or emotional reasons, though this is rare as a cause for adults. Absence or paucity of speech in adults may also be associated with specific psychiatric disorders.

Developmental and neurological causes

Absence of speech in children may involve

s or language delays. Communication disorders or developmental language delays may occur for several different reasons. Language delays may be associated with other developmental delays. For example, children with Down syndrome often have impaired language and speech. Children with

autism Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing d ...

, categorized as a

neurodevelopmental disorder Neurodevelopmental disorders are a group of mental conditions negatively affecting the development of the nervous system, which includes the brain and spinal cord. According to the American Psychiatric Association Diagnostic and Statistical Manu ...

in the

DSM-5 The ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition'' (DSM-5), is the 2013 update to the '' Diagnostic and Statistical Manual of Mental Disorders'', the taxonomic and diagnostic tool published by the American Psychiat ...

, often demonstrate language delays.

Treatment

Evaluation of children with language delays is necessary to determine whether the language delay was caused by another condition. Examples of such conditions are

, hearing loss and

. The manner of treatment depends on the diagnosed condition. Language delays may impact expressive language, receptive language, or both. Communication disorders may impact articulation, fluency (

stuttering Stuttering, also known as stammering, is a speech disorder characterized externally by involuntary repetitions and prolongations of sounds, syllables, words, or phrases as well as involuntary silent pauses called blocks in which the person who ...

) and other specified and unspecified communication disorders. For example, speech and language services may focus on the production of speech sounds for children with

phonological Phonology (formerly also phonemics or phonematics: "phonemics ''n.'' 'obsolescent''1. Any procedure for identifying the phonemes of a language from a corpus of data. 2. (formerly also phonematics) A former synonym for phonology, often prefer ...

challenges. Intervention services and treatment programs have been specifically developed for autistic children with language delays. For example, pivotal response treatment is a well-established and researched intervention that includes family participation. Mark Sundberg's verbal behavior framework is another well-established assessment and treatment modality that is incorporated into many

applied behavior analysis Applied behavior analysis (ABA), also referred to as behavioral engineering, is a behavior modification system based on the principles of respondent and operant conditioning. ABA is the applied form of behavior analysis; the other two are: ...

(ABA) early intervention treatment programs for young children with autism and communication challenges. Treatment for absence of speech due to apraxia, involves assessment, and, based on the assessment,

occupational therapy Occupational therapy (OT), also known as ergotherapy, is a healthcare profession. Ergotherapy is derived from the Greek wiktionary:ergon, ergon which is allied to work, to act and to be active. Occupational therapy is based on the assumption t ...

physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

, and/or

speech therapy Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, suc ...

. Treatment for selective mutism involves assessment, counseling, and positive supports. Treatment for absence of speech in adults who previously had speech involves assessment to determine cause, including medical and surgery related causes, followed by appropriate treatment or management. Treatment may involve counseling, or rehabilitation services, depending upon cause of loss of speech.

Management

Management involves the use of appropriate assistive devices, called alternative and augmentative communications. Suitability and appropriateness of modality will depend on users' physical abilities and cognitive functioning. Augmentative and alternative communication technology ranges from elaborated software for tablets to enable complex communication with an auditory component to less technologically involved strategies. For example, a common method involves the use of pictures that can be attached to velcro strips to create an accessible communication modality that does not require the cognitive or fine motor skills needed to manipulate a tablet. Speech-generating devices can help people with speech deficiencies associated with medical conditions that affect speech, communication disorders that impair speech, or surgeries that have impacted speech. Speech-generating devices continue to improve in ease of use.

References