ICL 10.2: Symptoms of Cortical Dysfunction Flashcards
what is agnosia?
the inability to recognize, or ascribe meaning to a sensory input
a failure of recognition that is not explained by impaired primary sensation—tactile, visual, and auditory—or cognitive impairment
what is aphasia?
failure of some part of speech or language
what is apraxia?
failure to execute learned patterns of behavior or movement, NOT due to weakness or other deficits
what is alexia?
inability to read
what is agraphia?
inability to write
what is achromatopsia?
inability to identify or name colors
what are the 6 functional segments of the frontal cortex?
- motor function/pre-central gyrus
- frontal eye fields –> turning the eyes and head contralaterally
- Broca’s area/expression
- limbic system components/projections (orbitofrontal cortex) –> respiration, BP, peristalsis, other autonomic functions
- prefrontal cortex –> involved in the initiation of planned action and executive control of all mental operations, including emotional expression
- micturition center
slide 6
what deficits would you see if there was a lesion in the posterior frontal lobe?
- weakness
- gait apraxia = loss of the ability to use the lower limbs in the act of walking that cannot be explained by weakness, loss of sensation, or ataxia
this is because this is where the motor cortex is located
what deficits would you see if there was a lesion in the lateral dominant frontal lobe?
Broca’s aphasia
so the patient would have decreased speech and repetition but comprehension is relatively preserved!
the patient will also have a right-sided hemiparesis
what deficits would you see if there was a lesion in the medial frontal lobe?
bladder incontinence
lesions in the posterior part of the superior frontal gyrus, the anterior cingulate gyrus, and the intervening white matter result in a loss of control of micturition and defecation
the medial frontal lobe is where the micturition cortex is located
what deficits would you see if there was a lesion in the anterior/prefrontal lobe?
- dysexecutive function
- apathy and abulia = lack of initiative and spontaneity
- disinhibition = lack of self control
the prefrontal cortex is responsible for executive function!
what deficits would you see if there was a lesion in the frontal eye fields?
gaze deviation towards the lesion
nasal vs. temporal eye field of each eye pushes your vision to the opposite side normally
what are the overall effects of a frontal lobe lesion?
lesions of the frontal lobes give rise to a loss of drive, impairment of consecutive planning, an inability to maintain serial relationships of events, and to shift easily from one mental activity to another
these are combined with sucking, grasping, and groping reflexes and other obligate behavior
in the emotional sphere, frontal lobe lesions may cause anhedonia (lack of pleasure), apathy, loss of self-control, disinhibited social behavior
what is dysexecutive syndrome?
the prefrontal cortex controls personality, character, motivation, abstract thinking, introspection and planning
so lesions of the frontal lobe would cause dysexecutive syndrome:
- abulia = loss of drive/willpower
- inability to shift attention
- anhedonia = lack of pleasure
- apathy
- disinhibition = no self control
what is Broca’s aphasia?
due to damage to Broca’s area in the frontal lobe of the dominant left hemisphere
signs of broca’s aphasia include:
- decreased fluency and phrase length; more nouns, fewer articles prepositions, agrammatism
- naming is impaired
- repetition impaired
- reading and writing are slow
- right sided weakness
comprehension is still intact though so the patients can understand you and what they’re saying makes sense even if it’s broken –> this leads to the patients often being frustrated
what are the functional segments of the temporal lobe?
- Heschl’s gyrus/audtory cortex @ the sylvan fissure
- auditory association cortex @ superior temporal lobe
- medial temporal lobe = gustation and olfaction
- arcuate fasciculus
- Meyer’s loop = visual pathway
- Wernicke’s area
- hippocampus
- visual association cortex
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what deficits would you see with lesions involving Wernicke’s area?
receptive aphasia
the patient literally doesn’t make any sense – poor comprehension and meaning is impaired but speech is effortless
decreased reptition as well – may be semi or quadrantanopia
Wernicke’s area = temporal lobe
what deficits would you see with lesions involving the auditory association cortex?
- auditory agnosia
- amusia
lesions have no effect on the perception of sounds and pure tones however, the appreciation of complex combinations of sounds is severely impaired
this impairment, or auditory agnosia, takes several forms: inability to recognize sounds, different musical notes (amusia), or words
auditory association cortex = temporal lobe
what deficits would you see with lesions involving the visual association cortex?
visual agnosia
this is a condition in which a person can see but cannot recognize or interpret visual information –> an inability to name or describe the use for an object placed in front of you when just looking at it
visual association area = temporal lobe
what deficits would you see with lesions involving Heschl’s gyrus?
aka the auditory cortex in the temporal lobe!
the patient will experience cortical deafness ONLY if the lesion is bilateral
what is paraphasia?
inappropriate word substitutions
it can either be semantic substitutions like water for jacuzzi or it can be phonemic substitutions like trap for flap
what is global aphasia?
impaired fluency, comprehension and repetition
patient might also be hemiplegic
it’s a full middle cerebral artery infarct so frontal and temporal lobes will be effected
what is conduction aphasia?
impaired repetition but normal fluency and comprehension
due to a lesion of the arcuate fasciculus
what is transcortical motor aphasia?
decreased speech but comprehension and repetition are fine!
usually due to a stroke anterior to Broca’s area
what is transcortical sensory aphasia?
speech and repetition are normally but there is decreased comprehension
usually due to a stroke around Wernicke’s area
what is aprosodosia?
flat speech
usually due to a lesion of the non-dominant inferior frontal lobe
what are the functional segments of the parietal cortex?
- somatosensory cortex
- somatosensory association cortex
- most of the angular gyrus
- supramarginal gyrus
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what deficits would you see with a lesion involving the somatosensory cortex?
contralateral sensory loss including spacial orientation, 2 point discrimination and asterognosis
somatosensory cortex = parietal lobe
what deficits would you see with a lesion involving the somatosensory association cortex in the dominant hemisphere?
- motor apraxia = individual has difficulty with the motor planning to perform tasks or movements when asked, provided that the request or command is understood and the individual is willing to perform the task
- dyslexia
- tactile agnosia
- Gerstmann’s syndrome
what is tactile agnosia?
the lack of ability to recognize objects through touch
the weight and texture of an object may be perceived, but the person can neither describe it by name nor comprehend its significance or meaning
associated with a lesion to the dominant somatosensory association area
what is Gerstmann’s syndrome?
it’s due to an angular gyrus lesion in the parietal lobe of the dominant hemisphere
damage may impair one or more of the below functions:
- dysgraphia/agraphia: deficiency in the ability to write
- dyscalculia/acalculia: difficulty in learning or comprehending mathematics
- finger agnosia: inability to distinguish the fingers on the hand
- left-right disorientation
what deficits would you see with a lesion involving the somatosensory association cortex in the non-dominant hemisphere?
- dressing apraxia
- neglect
- constructional apraxia
what are the 2 types of apraxia associated with the dominant hemisphere?
- ideational apraxia
- ideomotor apraxia
these are associated with parietal lobe lesions; specifically the somatosensory association cortex in the dominant hemisphere
what is ideational apraxia?
failure to conceive or formulate an action to command
not knowing “what to do”
associated with parietal lobe lesions; specifically the somatosensory association cortex in the dominant hemisphere
what is ideomotor apraxia?
the inability to carry out actions in response to verbal commands; patient is unable to correctly sequence movements
the patient may know and remember the planned action, but cannot actually execute it with either hand
not knowing “how to do”
associated with parietal lobe lesions; specifically the somatosensory association cortex in the dominant hemisphere
what are the 3 types of apraxia associated with the non-dominant hemisphere?
- dressing apraxia
- constructional apraxia = inability to copy
- eyelid apraxia = disinclination to open the eyes, or even opposition to passive eyelid opening
what are the functional segments of the occipital cortex?
- primary visual cortex
visual perception, color recognition, recognition of object movement, depth perception
- visual association areas
what are the 2 visual association areas of the occipital cortex?
- ventral stream = information to the temporal lobe
2. dorsal stream = information to the parietal lobe
what is the function of the ventral stream?
part of the visual association cortex of the occipital lobe that sends information to the temporal lobe
functions for recognition and discrimination of visual shapes and objects
visual object agnosia, prosopagnosia, alexia, and color agnosia. In this way, the ventral stream may be considered to represent the “what” of visual processing to identify objects
what is the function of the dorsal stream?
part of the visual association cortex of the occipital lobe that sends information to the to the parietal lobe
“vision-for-action” pathway = has been primarily associated with visually guided reaching and grasping based on the moment-to-moment analysis
dorsal stream syndromes are visual simultanagnosia, Balint syndrome and the earlier mentioned topographagnosia, that reflect disorders of “where” in visual behavior
what happens if there’s a lesion involving the primary visual cortex unilaterally?
contralateral homonymous hemianopia
a condition in which a person sees only one side―right or left―of the visual world of each eye
primary visual cortex = occipital lobe
what happens if there’s a lesion involving the primary visual cortex bilaterally?
cortical blindness or achromatopsia
primary visual cortex = occipital lobe
what happens if there’s a lesion involving the visual association areas?
visual object or word agnosias
visual association areas = occipital lobe
what happens if there’s a lesion involving the dominant visual cortex and selenium?
alexia without agraphia
what are the 7 visual agnosias associated with the occipital lobe?
- visual object agnosia
- prosopagnosia
- color agnosia
- alexia
- simultanagnosia
- Balint syndrome
- topographagnosia
what is visual object agnosia?
failure to name and indicate the use of a seen object by spoken or written word or by gesture not due to poor visual acuity or aphasia
object may be recognized by touch, smell or sound
isually associated with alexia
usually bilateral
what is prosopagnosia?
the inability to identify faces
may be unable to interpret the meaning of facial expressions or to judge the ages or distinguish the genders of faces
usually bilateral lesions of the ventromedial occipito-temporal regions
what is color agnosia?
aka central achromatopsia
unable to discriminate hues or name colors (color anomia)
caused by a cerebral lesion(s), with normal visual acuity
what alexia?
inability to read
may occur with or without agraphia
what is simultanagnosia?
inability to grasp the sense of the multiple components of a total visual scene despite retained ability to identify individual details
failure to perceive simultaneously all the elements of a scene and to properly interpret the scene
so if you showed someone a junk drawer, they wouldn’t be able to pick out all the separate things in the drawer it would just look like a big jumble to them
due to an occipital lobe problem
what is Balint syndrome?
- visual simultanagnosia
- difficulty in grasping or touching an object under visual guidance (optic ataxia)
- failure to properly direct oculomotor function in the exploration of space
due to lesions that span the occipital and parietal lobes
optic ataxia = to reach an object, the patient engages in a tactile search with the palm and fingers, presumably using somatosensory cues to compensate for a lack of visual information – in contrast, movements that do not require visual guidance, such as those directed to the body or movements of the body itself, are performed naturally
what is Anton syndrome?
Denial of cortical blindness – these patients act as though they could see, collide with objects when trying to walk, even to the point of injury
they may offer excuses for the difficulties—”I lost my glasses,” “The light is dim“
the lesions often extend beyond the visual cortex to involve the visual association areas
what causes visual hallucinations?
more frequent with right-sided than left-sided occipital lesions
usually lesions responsible for visual hallucinations are situated in the occipital lobe or posterior part of the temporal lobe
may be part of a seizure or seizure aura
what are the 2 types of visual hallucinations?
- elementary = shapes or flashes of light
- complex = people, objects or animals
elementary hallucinations usually arise in the occipital cortex, and complex ones in the temporal visual association cortex
