Behavioral Neurology
Joel Salinas
Jesse Mez
APHASIA
Aphasia: Abnormalities of symbolic communication (language). Inability to translate nonverbal images (thought) into language and/or inability to translate language into nonverbal thoughts (lexical-semantic) and/or inability to sequence words & word endings to convey relationships among words (syntactic). Affects written code in auditorily based languages (e.g., English) or written code in ideogram-based languages (e.g., Chinese).
Fluency: Free-flowing quality & rate of speech, from spontaneous speech, phrases >4 words.
Prosody: Cadence & intonation of syntactic speech, typically a nondominant hemisphere finding.
Circumlocution: Use of many unnecessary words to express an idea.
Paraphasia: Word substitution. Phonemic paraphasia: Substituted word w/similar sound (e.g., ben for pen). Semantic paraphasia: Substituted word w/similar meaning (e.g., pencil for pen).
Neologism: New word only understood by speaker.
Jargon: Strings of neologisms or improperly combined real words.
Phonemes: Smallest meaning-carrying sounds.
Lexicon/semantic: Word availability (i.e., the internal dictionary).
Syntax: Grammatical construction of phrases & sentences.
Discourse: Organized & logical expression of thoughts.
Epidemiology: US prevalence: 1 million. 1-yr incidence in the United States: 200,000 secondary to head trauma; 100,000 secondary to stroke. About 20% of strokes produce aphasia.
DIFFERENTIAL DIAGNOSIS OF APHASIA
Motor speech d/os (i.e., abnlities of articulation): Examples: Dysarthria, speech apraxia, & stuttering. Intact comprehension of spoken & written language.
Psych thought d/os (i.e., abnlities of thought content): Usually seen in psychosis, mania. Bizarre, illogical lang that is fluent & syntactically/grammatically intact.
Muteness: Absence of speech output in an alert pt. Common etiologies: Frontal lobe synd (e.g., abulia), basal ganglia synd (e.g., Parkinson), psych synd (e.g., catatonia), severe dysarthria (e.g., mech d/o of the larynx). May be present in aphasia. Mute aphasics (“global aphasia”) usually have severe comprehension, reading, & writing deficits also. Exception is pts w/severe motor speech d/o (as can be seen in primary progressive aphasia) in which pt may be mute 2/2 motor speech d/o but w/significantly less abnlities in other aspects of language.
Aphemia: Nonfluent syndrome initially presenting w/muteness & progressing to speaking w/phoneme substitutions & pauses. Not a true aphasia as all other language functions, including writing, are intact. Rare & usually transitory. Due to small lesions in the Broca area or inferior precentral gyrus. May be considered a speech apraxia.
Pure word deafness: Inability to understand or repeat spoken language, in the absence of deafness for nonverbal sounds. Not a true aphasia as the deficit can be bypassed w/reading. Speaking, naming, reading, & writing are intact. Classic localization: b/l temporal lesions that disconnect Wernicke area from both aud cortical areas (also reported in lesions of left temporal white matter tracts). Better defined as verbal auditory agnosia.
APHASIA EXAMINATION
Spontaneous speech: Listen for fluency, paraphasias, neologisms, circumlocution, & jargon (see definitions above).
Constrained speech: Have pt describe picture such as “cookie theft picture” & listen for word-finding (lexical retrieval difficulties), paraphasias, word/sound substitutions, syntactic constructions.
Repetition: Test small grammatical words (“no ifs, ands, or buts”) initially as they are most diff for Broca aphasics. Keep sentence length short to avoid simultaneously testing for attentional deficits. Multisyllabic words (hippopotamus) can be helpful to diagnose apraxia of speech, dysarthria, or other motor speech d/os.
Naming: Test low frequency words (“lapel, lens, band”) first as they are most diff. Listen for circumlocutions, paraphasias, neologisms, perceptual misidentifications. Use cue for perceptual misidentifications (e.g., if “mushroom” called “umbrella,” cue w/“something you eat”). When visual identification is intact, use phonemic cue for name retrieval errors (e.g., for “mushroom” cue w/“mu” or “mush”). Test for one-way errors (pt cannot name, but recog name from choices) & two-way errors (pt cannot name or recog name from choices; e.g., “point to the picture of the penguin”).
Comprehension: Test both oral & written comprehension (e.g., state “stick out your tongue,” then write “close your eyes”). Test for semantic errors (e.g., “Does a cork float?”). Test for syntactic errors: (e.g., “If the lion were eaten by the tiger, which animal is still alive?”)
Reading aloud: Have pt read entire paragraph. Listen for subtle grammatical mistakes. Have pt read nonsense words. Have pt read irregular words (dough, height, pint).
Writing: Have pt write spontaneously. Write to dictation; copy; write nonsense words; write a description of “cookie theft” picture or other complex pictures.
CLASSICAL APHASIA TYPES
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Note that there is a Broca area (inferior frontal gyrus including operculum) & Wernicke area (posterior third of superior temporal gyrus) & there is a Broca aphasia & Wernicke aphasia. Lesions to the area do not always produce corresponding aphasia, & conversely, the aphasia can be produced by lesions outside of the corresponding area.
Additional findings in Broca aphasia: Lack of prepositions, conjunctions, & word order (e.g., “Go I home tomorrow”), difficulty w/comprehension & reading aloud related to agrammatism. Test: “The girl kisses the boy, who was kissed?”, phonemic paraphasias are common, tip of the tongue phenomenon (i.e., hesitation in getting words out); pt is typically aware of language deficit, often leading to frustration, assn w/right hemiparesis (proximity to motor strip).
Additional findings in Wernicke aphasia: Unintelligible speech content due paraphasias (both phonemic & semantic), circumlocutions, neologisms, & generic words (e.g., “thing” or “stuff”), pt often relatively unaware of language deficit, sometimes leading to anger & hostility, but not frustration, assn w/right hemianopsia (close proximity to temporal optic radiation).
Caveats to classical aphasia types: Classical aphasia types based on stroke/vascular territories. Tumors, other structural lesions, degenerative diseases often
don’t follow classic categorization. Automatic speech (e.g., expletives or counting or singing) usually localize to nondominant hemisphere & are preserved in most aphasias including global.
don’t follow classic categorization. Automatic speech (e.g., expletives or counting or singing) usually localize to nondominant hemisphere & are preserved in most aphasias including global.
Handedness, cerebral dominance, & aphasia: 99% of right-handers have left hemisphere language dominance, & 2/3 s of left-handers have left hemisphere language dominance. Anatomic asymmetry: dominant hemisphere is usually larger (esp temporal lobe). Crossed aphasia in right-handers (rare): aphasia from right hemisphere lesion in right-hander that cannot be explained (e.g., by forced right-handedness, known childhood central nervous system impairment), presumably 2/2 crossed or mixed dominance. Atypical syndromes in left-handers (rare): left-handers without left cerebral dominance may develop aphasia from lesion in either hemisphere; may be left hemisphere dominant for comprehension & right hemisphere dominant for speech production (or vice versa); recovery may be more complete 2/2 shared dominance.
Subcortical aphasias: Exaggerated fluent aphasia (w/mild deficits in comprehension & repetition): left anterolateral thalamic nuclei; assoc w/attentional & memory deficits. Defective comprehension w/or w/o repetition deficits: head of left caudate, anterior limb of left internal capsule; assoc w/dysarthria & right hemiparesis.
APROSODIA
Prosody: Syntactic > emotional aspects of language that convey info beyond that transmitted by word choice & word order. Acoustic features: Pitch, intonation, melody, cadence, loudness, timber, tempo, stress, accent, timing of pauses.
Kinesics: Limb, body, & facial mvmts that accompany discourse & modulate verbal message. Pantomime: mvmts to express mutually agreed upon symbols: (e.g., peace sign). Gestures: mvmts that color, emphasize, & embellish speech. Spontaneous kinesic mvmts during discourse are usually a mixture of pantomime & gesture.
Testing production of spontaneous prosody & gesturing: Observe spontaneous speech for prosody & gestures. Ask emotionally loaded questions.
Testing repetition of prosody: W/a happy tone, make a declarative sentence that lacks emotional words, ask pt to repeat w/the same affective intonation. Repeat process for sad, tearful, disinterested, angry, & surprised tones.
Testing comprehension of prosody: Stand behind pt to avoid giving clues from gestures. Again make a declarative sentence that lacks emotional words, in a happy tone. Either ask pt to name underlying emotion or, if unable, choose from a list of emotions. Repeat process for sad, disinterested, angry, & surprised tones. Determine if pt can differentiate between variably compounded lexemes (e.g., “lighthouse keeper” vs. “light housekeeper”)
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