Behavior, Cortical Function, and Dementia Flashcards
What is memory?
The ability to learn and then recall information after different periods of time
What is “immediate” memory?
The pre-requisite state of attentiveness required for learning something
How can you determine if “immediate” memory is intact? If it appears to not be intact, what are possible causes?
Patient should be alert and awake enough to immediately repeat or recite a sequence of 5 numbers spoken out loud
Excessive sleepiness
Sedation from medications
Systemic illness diffusely inhibiting cortical function
Lesions affecting the RAS more directly
Impaired ___ precludes any reliable testing of recent or remote memory as well as other cortical functions.
Attention
What is recent or “short-term” memory?
Ability to recall information after several minutes of retention
How is short-term memory tested?
Patient is given 3 items to repeat aloud and instructed to recall them 5 minutes later on command
What is remote or “long-term” memory?
Ability to recall past events hours, weeks, or even years afterward
How is long-term memory tested?
Ask a prior address or anniversary date for which the correct answer is known
Memory function depends on what pathways?
Bilateral pathways involving the temporal lobe and thalamus, specifically hippocampus -> fornix -> mammillary body -> anterior thalamic nucleus
What causes amnesia in Wernicke-Korsafoff syndrome?
Bilateral thalamic and mammillary body lesions; caused by thiamine deficiency in malnourished alcoholics
What are 2 other causes of bilateral hippocampal lesions causing amnesia?
Anoxia
Herpes simplex encephalitis
What is apraxia?
The inability to conceptualize and perform a skilled, learned, motor act on command
What kind of lesions may cause gait apraxia (inability to walk on command)?
Prefrontal lobe lesion
What kind of lesions may cause a constructional (cannot draw a house or copy a drawing) or dressing (cannot put on and button a shirt) apraxia?
Posterior cortical lesions, especially involving the parietal lobe
What is agnosia?
Impaired recognition of perceived stimuli caused by lesions of sensory association cortex
Lesions of particular lobes of the cerebral hemispheres often involve what 4 general etiologies?
Head trauma
Stroke
Tumor
Dementia
Presentation of patients with pre-frontal or frontal lobe syndrome?
Listless, apathetic, unconcerned
Poor hygiene, incontinence
Poor judgment and disinhibition -> outbursts, rude humor, inappropriate sexual behavior
Executive functions are impaired (poor planning and performance of multistep or novel tasks, lack of creative thinking, limited attention, motor perseveration)
Gait apraxia
Paratonia
Frontal lobe release signs
What is paratonia?
Increased limb tone or resistance is felt as the examiner moves the patient’s limb more rapidly
What are frontal lobe release signs?
Previously normal findings during infancy when myelination of descending inhibitory pathways was incomplete -> sucking reflex, rooting reflex, palmar and plantar grasps
Presentation of syndromes of the temporal lobes?
Amnesia (bilateral hippocampal lesions)
Cortical deafness (bilateral auditory cortex lesions)
Kluver-Bucy syndrome (limbic system)
Unilateral lesion of superior-posterior dominant temporal lobe -> Wernicke’s aphasia
Presentation of syndromes of the parietal lobes?
Asterognosis
Agraphesthesia
Extinction on double simultaneous stimulation
Impaired spatial relationships between the body and its surrounds if lesion of the non-dominant parietal lobe -> anosognosia (unaware of hemiparesis), hemispatial neglect
What is Gerstmann’s syndrome?
Agraphia
Right-left disorientation
Dyscalculia
Finger agnosia
What causes Gerstmann’s syndrome?
Lesion of the supramarginal or angular gyrus of the dominant parietal lobe
Presentation of occipital lobe syndromes?
If enough bilateral visual cortex is involved -> cortical blindness
What type of lesion causes visual agnosia?
Bilateral temporo-occipital lesions
Key features of delirium?
Fluctuating levels of attention and motor activity, with alternating agitation/hyperactivity and obtundation/stupor
Moods and emotions may vary
Hallucinations are often reported
Tremulousness, asterixis, myoclonus, ataxia, dysarthria
What is 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 the patient
Work-up for dementia?
Standardized cognitive testing such as the MMSE or neuropsych testing
Brain scan (preferably MRI) -> chronic subdural hematomas, brain tumors/abscesses, multiple infarctions or hemorrhages, NPH
LP if unexplained fever and headache (could be chronic meningitis)
HIV (younger patients)
All: CBC, CMP, B12, thyroid
Most common type of dementia in the US?
Alzheimer’s
Pathogenesis of Alzheimer’s?
Degenerative disease, where specific types of neurons are gradually destroyed by metabolic changes unrelated to infection, ischemia, or immune system abnormalities
Excessive accumulation of beta-amyloid in the form of extracellular amyloid or senile cortical plaques. Deposition leads to formation of intraneuronal neurofibrillary tangles, consisting of microtubule-associated tau protein
What is typically the earliest finding in Alzheimer’s?
Memory loss
What are the major tauopathies?
Alzheimer’s dementia
Progressive supranuclear palsy
Corticobasal degeneration
Frontotemporal lobar dementia
Manage Alzheimer’s?
Slow deteriorating coarse by enhancing the cholinergic system with ACEIs (donepezil, rivastigmine, or galantamine)
May add memantine later (NMDA antagonist that opposes the excitotoxic effects of glutamate in the CNS)
May need sedatives and antipsychotics to control behavioral symptoms
