White matter, MS, & disconnection syndromes Flashcards
What is the most prominent artery supplying the cerebral white matter?
Lenticulostriate
Factors of MS that are related to cognitive impairment
Duration of illness, atrophy, total lesion volume, physical impairment, enlarged cerebral ventricles, CC atrophy, cerebral hypometabolism
Corona radiata
Rich mass of white matter within each hemisphere above the internal capsule
Central pontine myelinolysis (CPM)
Related to too rapid correction of sodium deficiency; leads to longstanding dementia or death
Psychiatric symptoms of white matter dementia
Irritability, depression, apathy, psychosis
Adrenoleukodystrophy
Generalized loss of myelin in the brain & adrenal insufficiency; posterior pattern of affected white matter
White matter disease is associated with what type of memory disturbance?
Poor retrieval but intact encoding
What type of aphasia is most closely associated with white matter disease?
Conduction aphasia
How has white matter damage been implicated in schizophrenia?
Research suggests that schizophrenia may result from disrupted frontal lobe connectivity related to oligodendriaglial dysfx and death resulting in abnormalities in myelin laying down & maintainence
Relapsing/remitting course of MS
Specific periods of relapse followed by periods of remission; most common type in the early years
Secondary progressive course of MS
Initially relapsing/remitting course followed by progression with or without occasional relapses, minor remissions, & plateaus
Typical areas of preserved functioning in MS
Memory storage, encoding, recognition, simple auditory span, motor skill & implicit learning, language skills (other than fluency), basic visuospatial functions
Lhermitte’s sign
Electrical sensation radiating down extremities or back upon cervical flexion; seen in MS
How are MS lesions related to cognition?
Extent of plaques & total lesion area is related to cognitive function, but, in general, location of plaques is not predictive
What toxin is associated with 2-3 weeks delayed demyelination?
Carbon monoxide
Impairments associated with white matter dementia (Filley)
Slowness of cognition, poor sustained attention/vigilance, visual-spatial deficits, memory retrieval deficits, exec dysfx
Factors associated with better MS prognosis
Young age (
Metachromatic leukodystrophy
Disorder of myelin metabolism that usually begins in infancy
White matter is most prominent in which lobe of the brain?
Frontal lobe
Sympathetic apraxia in Broca’s aphasia
Apraxia of command mvmts of the LH, due to disconnection of L language area & motor assoc. cortices from R motor association cortices
Cognitive impact of commissurotomy
L neglect, right-ear dominancy in dichotomous listening tasks, inability to name objects in L hand but can pick up with L hand if named, R constructional apraxia, spatial acalculia, cannot cross-replicate hand postures, difficulty naming points touched on L side of body, R-sided verbal anosmia, double hemianopia, hemialexia
What cognitive domains are spared in white matter dementia?
Language (word finding deficits but not aphasic), no extrapyramidal symptoms, normal procedural memory
Primary progressive course of MS
Continued decline
What are the symptoms of Hallervorden-Spatz syndrome?
Progressive rigidity beginning in the legs, choreathetoid movements, dysarthria, dystonia, emotional & mental deterioration (visuospatial & memory)
Marchiafava-Bignami disease
Rapidly progressing degeneration/demylination of CC that is associated with cognitive deterioration, emotional disturbances, confusion, hallucinations, tremor, rigidity, & seizures Associated with excessive consumption of red wine
Progressive relapsing course of MS
Progressive disease from onset with clear acute relapses, periods between relapses are characterized by continuing progression
What is the most common & debilitating complaint among patients with MS?
Fatigue - affects up to 90%
Charcot’s triad
Nystagmus, dysarthria, tremor (associated with cerebellar dysfx)
Pathology of MS
Multifocal areas of CNS white matter inflammation, demyelination with loss of oligodendrocytes & astrogliosis
Pure word mutism
Lose capacity to speak but oral & reading comprehension & writing intact; due to separation of Broca’s area from subcortical motor centers
Risk factors for central pontine myelinolysis
Alcoholism, liver disease, malnutrition
3 major groups of white matter pathways
Projection, commissural, association
1st degree relatives of patients with MS are ____x more at risk than the general population?
6-8x
Transsynaptic degeneration
Neuronal loss & reactive gliosis in neurons deprived of synaptic input by lesions in adjacent neurons
Common affective/behavioral problems in MS
Depression, personality changes, anxiety
Most common cognitive deficits in MS
Memory, complex attention/speed of info processing, exec fx, verbal fluency
Disconnection syndrome (Geschwind)
Any disorder in which cortical areas that normally work in conjunction become isolated, involving interruption of info transfer
Outcomes in childhood-onset MS
Increased risk of having deficits in at least 1 area of cognition, increased rate of need for educational assistance, 1/2 had psych diagnosis, little evidence of physical disability
Proposed explanations for MS
Slow-acting virus, delayed reaction to a common virus, autoimmune reaction in which body attacks its own tissues
How does MS risk vary by race/ethnicity?
Predilection for whites; Asian & black populations have low risk
Transverse myelitis
Acutely evolving inflammatory-demyelinative lesion of the spinal cord, often an expression of MS
Visual changes seen in MS
Optic neuritis, intranuclear ophthalmoplegia, Marcus Gunn pupil
Which hemisphere has a greater proportion of white matter?
Right
Overall prevalence of cognitive impairment in MS
40-70%; of those with impairment, 80% are mild
How does immigration from a high-risk to a low-risk latitude affect MS risk?
Individuals carry with them some of the risk from their place of origin if they move after age 15
How does childhood-onset MS differ from adult-onset?
Higher lesion burden on initial MRI, esp. in brainstem & cerebellum; however, T2-bright foci in younger children can vanish with repeat scans
Describe the steps of myelogenesis (i.e., which areas of the brain are myelinated 1st, 2nd, etc.)
1) Primordial (‘premature’) fields are myelinated before birth (somesthetic cortex, primary visual, primary auditory) 2) Intermediate (‘postmature’) fields myelinate during first 3 monts (secondary association areas) 3) Terminal fields myelinate b/t 4th month and 14 yrs of age (classical association areas)
Multiple sclerosis
Multifocal demyelinating disease that causes destruction of myelin sheath of nerve fibers along with sclerotic plaques that form in areas where demyelination has occurred & block or distort the normal transmission of nerve impulses
Retrobulbar neuritis
Optic neuritis that occurs far enough behind the optic disk that no early changes of the optic disk are visible by ophthalmascope
How do prevalence rates of MS change relative to the Equator?
Prevalence decreases systematically as latitude of habitation nears Equator
