Mutism in the Older Adult
Mutism in older adults is not uncommon. It is often confused with severe depression, locked-in syndrome, and persistent vegetative state, but it is important to distinguish among them as the management and prognosis are different. The family physician is the most consulted professional and so is the most helpful in making this distinction. Mutism is a neuropsychological disorder with marked heterogeneity among patients, raising the possibility of conditions such as advanced Alzheimer’s disease, Jacob-Creutzfeldt disease, frontotemporal dementias, and certain psychiatric and psychological conditions. It is both a symptom and a syndrome, and is often associated with akinesia when the term akinetic mutism is used. Akinetic mutism has a number of causes with varied pathology and is characterized by a marked reduction in motor function, including facial expression, gestures, and speech output, with awareness being preserved. All of the disease manifestations can be explained by damage to the frontal lobe or interruption of the complex frontal subcortical circuits and the frontal diencephalic brain stem system by focal lesions or diffuse brain damage.
Key words: mutism, akinetic mutism, frontal-subcortical circuitry, locked-in-syndrome, persistent vegetative state.
Introduction
By definition, mutism is the state or condition of being speechless. If speech occurs it is restricted to terse responses or monosyllables. Mutism is not uncommon in the older population. Since it is often caused by brain damage, mutism is considered a neurological disorder. However, it is also a psychological disorder and so can be more accurately termed a neuropsychological disorder. Mutism can be congenital or acquired when, as a result of damage to a part of the brain, the normally functioning psychological capability is altered. In mutism there is impairment of speech function and it is an articulatory disorder as opposed to aphasia, a disorder of linguistic processing (Figure 1).
The primary care physician must have a high degree of awareness or suspicion in patients presenting with varied clinical conditions that are often associated with mutism, and often erroneously diagnosed as depression, delirium, and locked-in-syndrome, amongst others.
Terminology and General Considerations
Terms such as apathy, abulia, and akinetic mutism (AM) are used to designate behavioural abnormalities relating to reduced activity and slowness. It is believed that these clinical disorders exist along a continuum of severity of reduced behaviour, and AM may be an extreme form.1 The term abulia was initially used by Auerbach2 and later called akinesia. Fischer3 used the term abulia to embrace the full spectrum of abnormalities, characterized by a reduction in speech, spontaneous activity, prolonged latency in responding to questions, and lack of persistence with tasks.
In 1865, Broca4 used the term aphemia to describe eight patients with loss of speech, which Trousseau later referred to as aphasia.5 Aphemia is now recognized as an articulatory disorder with normal propositional language. Aphemia has often been misdiagnosed as aphasia; this is partly due to confusion resulting from the numerous terms that have been used to describe this syndrome.6 In mutism, unlike in aphemia, the patient makes no attempt to communicate verbally or by gesture.7 Aphemia more often than not follows mutism.
Clinical Considerations
There is marked heterogeneity among patients with mutism, which raises the possibility of such varied conditions as advanced Alzheimer’s disease, Pick’s disease, and Creutzfeldt-Jakob Disease. It may also complicate certain psychiatric disorders including catatonic schizophrenia, severe depression, and conversion