Paraphasia is a type of language output error commonly associated with aphasia and characterized by the production of unintended syllables, words, or phrases during the effort to speak. Paraphasic errors are most common in patients with fluent forms of aphasia, and come in three forms: phonemic or literal, neologistic, and verbal. Paraphasias can affect metrical information, segmental information, number of syllables, or both. Some paraphasias preserve the meter without segmentation, and some do the opposite. However, most paraphasias partially have both affects. The term was apparently introduced in 1877 by the German-English physician Julius Althaus in his book on Diseases of the Nervous System, in a sentence reading, "In some cases there is a perfect chorea or delirium of words, which may be called paraphasia".
Causes Paraphasia is associated with fluent aphasias, characterized by "fluent spontaneous speech, long grammatically shaped sentences and preserved prosody abilities." Examples of these fluent aphasias include receptive or Wernicke's aphasia, anomic aphasia, conduction aphasia, and transcortical sensory aphasia, among others. All of these lead to a difference in processing efficiency, which is often caused by damage to a cortical region in the brain (in receptive aphasia, for example, the lesion is in or near Wernicke's area); lesion location is the most important determining factor for all aphasic disorders, including paraphasia – the location of the lesion can be used to hypothesize the type of aphasic symptoms the patient will display. This lesion can be caused by a variety of different methods: malfunctioning blood vessels (caused, for example, by a stroke) in the brain are the cause of 80% of aphasias in adults, as compared to head injuries, dementia and degenerative diseases, poisoning, metabolic disorders, infectious diseases, and demyelinating diseases. Lesions involving the posterior superior temporal lobe are often associated with fluent aphasias.
Damage to the brain's language centers Two areas of the brain, Broca's area and Wernicke's area, are responsible for various disruptions in speech when damaged. Each is defined by their distinct characteristics. Broca's aphasia is characterized by non-fluent or telegraphic-type speech - where articles, conjunctions, prepositions, auxiliary verbs, pronouns and morphological inflections (plurals, past tense) are omitted. The word substitutions are infrequent and distortion of consonants and simplification of consonant clusters is frequent. Content words such as nouns, verbs and adjectives may be preserved. Subjects of this aphasia are aware of their errors in speech. Damage to the Broca's area does not affect comprehension of speech. Wernicke's aphasia is characterized by fluent language with made up or unnecessary words with little or no meaning to speech. Those who suffer from this type of aphasia have difficulty understanding others' speech and are unaware of their own mistakes. When corrected they will repeat their verbal paraphasias and have trouble finding the correct word. Wernicke's area is found in the dominant hemisphere of the posterior gyrus of the first temporal convolution of the brain, whereas Broca's area is found anterior to the Wernicke's area.
Symptoms
Phonemic paraphasia Phonemic paraphasia, also referred to as phonological paraphasia or literal paraphasia, refers to the substitution of a word with a nonword that preserves at least half of the segments and/or number of syllables of the intended word. This can lead to a variety of errors, including formal ones, in which one word is replaced with another phonologically related to the intended word; phonemic ones, in which one word is replaced with a nonword phonologically related to the intended word; and approximations, an attempt to find the word without producing either a word or nonword. These types of errors are associated with Wernicke's aphasia, among others. Phonemic paraphasias are often caused by lesions to the external capsule, extending to the posterior part of the temporal lobe or internal capsule. This type of paraphasia also occurs in other languages as well. For example, case studies have been performed with German speakers, which demonstrated that 30.8% of paraphasias occurred at the beginning of the word in patients with Wernicke's aphasia and 22.6% for patients with Broca's aphasia. In English speakers this tendency to create errors at the beginning of the word remained.
Neologistic paraphasia Neologistic paraphasias, a substitution with a non-English or gibberish word, follow pauses indicating word-finding difficulty. They can affect any part of speech, and the previously mentioned pause can be used to indicate the relative severity of the neologism; less severe neologistic paraphasias can be recognized as a distortion of a real word, and more severe ones cannot. The hypothesized source for these neologisms is “a device which quasirandomly combines English phonemes in a phonotactically regular way.” A neologistic paraphasia can be thought of as a neologism resulting from aphasia, rather than any other of the sources with which they are associated. Neologistic paraphasia is often associated with receptive aphasia and jargon aphasia. There are various types of neologistic paraphasias. They can be phonologically related to a prior word, a following word, the intended word, or another neologism. The neologistic paraphasia shares phonemes or the position of phonemes with the related word. This most often occurs when the word and neologistic paraphasia are in the same clause. Neologistic paraphasias have a less stringent relationship with the target word than phonological paraphasias – where a phonological paraphasia has more than half of the target word’s phonemes, a neologistic paraphasia has less than half.
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