Behavior, Cortical Function, and Dementia Flashcards
what is memory?
the ability to learn and then recall information
what bilateral circuits or pathways does memory function depend on?
b/l circuits or pathways involving the TEMPORAL LOBE and THALAMUS.
specifically the hippocampus–> fornix –> mammillary body–> anterior thalamic nucleus
Wernicke-Korsakoff syndrome
a. what is it caused by
b. what is it
a. amnesia 2/2 b/l thalamic and mammillary body lesions
b. state of thiamine (B1) deficiency seen in malnourished alcoholics
Anoxia (cardiac arrest survivors) and Herpes simplex encephalitis sequelae
b/l hippocampal lesions cause amnesia
apraxia
inability to conceptualize and perform a skilled, learned, motor act on command, but may spontaneously carry them out at another time
gait apraxia
feet stuck in the mud/glued to the floor; 2/2 prefrontal lobe lesion
constructional apraxia
2/2 posterior cortical lesions, especially involving the parietal lobe; cant draw house or copy simple drawing
dressing apraxia
cannot put on and button a shirt; 2/2 posterior cortical lesions, especially involving the parietal lobe
agnosia
impaired recognition of perceived stimuli caused by lesions of the sensory association cortex
visual agnosia
pt cant id a bell by seeing it, but can recognize it by hearing it rung or touching it
tactile agnosia
inability to recognize objects solely fe feel or with eyes closed. severe degree of astereogenesis (lesion of parietal lobe or dorsal column-inability to id an object by touch sans sight)
prefrontal or frontal lobe syndrome
- listless, apathetic, unconcerned
- poor hygiene, incontinence
- poor judgement, disinhibition (=impolite outbursts, rude humor, inappropriate sexual jokes)
- exec function impaired=poor planning, cant do multistep tasks, aimless repetition of simple motor acts
may be noted on examination of someone with prefrontal or frontal lobe syndrome
- gegenhalten or paratonia: increased limb tone or resistance
- frontal lobe release sign: suck, snout and root; palmar and plantar grasp responses (all previously nml findings d/r infancy)
syndromes of temporal lobes may include:
- amnesia (b/l hippocampal lesions)
- cortical deafness (b/l auditory cortex lesions)
- KLuver-Bucy syndrome
What type of lesion causes Wernicke’s aphasia?
a unilateral lesion of the superior-posterior dominant TEMPORAL lobe
Parietal lobe syndromes
-affect sensory cortex=astereognosis, agraphesthesia, and extinction on dbl simultaneous stimulation
what do lesions of the nondominant parietal lobe cause?
impairment of spatial relationships between the body and its surroundings.
describe a pt with anosognosia
unaware of her hemiparesis, which in extreme form consists of denial of that half of the body=hemispatial neglect
Gerstmann’s syndrome
- 2/2 lesion of supramarginal or angular gyrus of the dominant parietal lobe
- consists of: agraphia, R-L disorientation, dyscalculia, and finger agnosia
occipital lobe syndromes
-may involved b/l visual cortex and cause cortical blindness
Anton’s syndrome
denial or unawareness of visual loss
b/l temporal occipital lesions may produce…
visual agnosia, a subtype of which is prosopagnosia=inability to recognize previously known faces
dominant temporo-occipital lobe lesion may cause
color anomia
define Delirium
=acute confusional state
- fluctuating levels of attn and motor activity
- moods, emotions may vary, hallucinations common
- also: tremulousness, asterixis, myoclonus, ataxia, dysarthria
causes of delirium
- viral encephalitis (brain directly involved)
- post-ictal state after a sz (brain directly involved)
- systemic illness: kidney failure, metabolic abnormalities, meds/illicit rx
define dementia
-general term for a diffuse impairment of cortical function which usually evolves less abruptly over a longer period of months to years and impedes the daily function of a pt
first deficit noticed in dementia
memory loss then personality change: suspicious, mistrust, paranoia
as dementia progresses what happens to the pt
- pt gets disoriented to time and place
- fails to recognize family and friends
- becomes unable to perform basic tasks
how is dementia diagnosed
depends heavily on family and friends observations
**always screen for depression
what should evaluation of dementia include?
MMSE-some standardized cognitive testing to be used as a baseline
what type of imaging can be useful in dementia pts
brain scan, preferably MRI to determine if dementia is d/t chronic SDH, brain tumors or abscesses, multiple infarctions, or hemorrhages, or NPH
what should you suspect in a younger pt with dementia
HIV
what should be checked in all pts with memory or cognitive impairment?
- CBC
- chemistry profile
- B12
- thyroid
Alzheimer’s Disease
- m/c type of dementia in the US
- diagnosis of exclusion
- most cases are sporadic
what is AD
- degenerative dz
- earliest/most prominent deficit: MEMORY LOSS 2/2 pathological changes int he medial temporal lobes and hippocampi
pathophys of AD
- xs accumulation of protein BETA-AMYLOID in the form of extracellular amyloid OR senile cortical plaques.
- BETA AMYLOID is a part of larger transmembrane BETA-APP (beta amyloid precursor protein) on chrom 21
- BETA AMYLOID deposition=formation of intraneuronal neurofibrillary tangles
- tangles consist of microtubule-associated TAU PROTEIN
PET scans and AD
-PET scans utilizing Pittsburg Compound B (PIB), which selectively binds to beta amyloid, apparently show the typical AD uptake (in the prefrontal, temporal, and sensory association cortex)
Slow down deteriorating course of AD by?
- enhancing the cholinergic system with central acetylcholinesterase inhibiiors (AChE-I): DoNEpezil, Rivastigmine, or Galantamine
- as dementia worsens, MEMANTINE can be added or used in place of AChE-I
- MEMANTINE is an NMDA antagonist which opposed the excitotoxic effects of glutamate in the CNS
Differential diagnosis of dementia subtypes
- Alzheimer
- vascular dementia
- frontotemporal dementia
- dementia with lewy bodies
- NPH
- Prion disease
Alzheimer disease
- early insidious short-term memory loss
- language deficits and spatial disorientation
- later personality changes
Vascular dementia
- stepwise decline
- early executive dysfunction
- cerebral infarction and or deep white matter changes on neuroimaging
frontotemporal dementia
- early personality changes
- apathy, disinhibition and compulsive behavior
- frontotemporal atrophy on neuroimaging
dementia with Lewy bodies
- visual hallucinations
- spontaneous parkinsonism
- fluctuating cognition
NPH
- ataxia early in dz
- urinary incontinence
- dilated ventricles on neuroimaging
prion dz
- behavioral changes
- rapid progression
- myoclonus and or seizures
cholinesterase inhibitors (Rivastigmine, Galantamine, Donepezil)
may provide moderate symptomatic relief of cognitive symptoms and temporarily improve functioning in Alzheimers (but do not alter dz course)
early findings in Alzheimers
- anterograde memory loss (immediate recall affected, distant memories preserved)
- visuospatial deficits (lost in own neighborhood)
- language difficulties (difficulty finding words)
- cognitive impairment with progressive decline
late findings in Alzheimers
- neuropsych (hallucinations, wandering)
- dyspraxia (difficulty performing learned motor tasks)
- lack of insight regarding deficits
- noncognitive neurologic deficits (pyramidal and extrapyramidal motor, myoclonus, seizures)
- urinary incontinence
trihexyphenidyl
anticholinergic med sometimes used in tx of PD, generally in younger pts where tremor is the primary symptom
pronator drift
- sn and sp for UMN or pyramidal tract disease affecting the upper extremities
- in pts with pyramidal lesions, the affected arm drifts downward and palm pronates toward the floor
