Demyelinating Diseases Flashcards
myelin
*increases the speed at which nerve impulses propagate along the nerve fiber (saltatory conduction)
*provides electrical insulation to nerves in both the CNS and PNS
order of the process of myelination
PNS myelinates first, followed by the spinal cord, and the brain last
dysmyelination
*characterized by the gradual loss of function (pertains to poorly created myelin)
*most dysmyelination disorders are inherited
*most have onset at an early age
etiologies of demyelination
-hereditary
-hypoxia and ischemia
-carbon monoxide toxicity
-nutritional deficiency
-direct viral invasion of CNS
-primary demyelinating disorders (MS, etc)
multiple sclerosis - epidemiology
*more common in women than in men
*commonly diagnosed between ages 20 and 40
*more common in regions far from the equator
multiple sclerosis - pathophysiology
*demyelinating disease of the CNS
*immune-mediated attack on myelin
*cells of the immune system are programmed to recognize myelin as foreign
*results in “relapses” marked by intermittent, recurrent neurologic symptoms and “progression” involving a gradual decline of function
multiple sclerosis - clinical patterns
*relapsing-remitting (most common)
*progressive-relapsing
*secondary-progressive
*primary-progressive
multiple sclerosis - examples of demyelinating events
-optic neuritis
-transverse myelitis
-brainstem syndrome
-cerebellar syndrome
optic neuritis
*can be a demyelinating event of multiple sclerosis
*a “film” over the eye
*gradual onset over a few days
*presenting event in 20% of MS patients
*some pain with eye movement
transverse myelitis
*can be a demyelinating event of multiple sclerosis
*ascending numbness/weakness
*results from demyelination in the spinal cord
*usually, you can find a sensory level somewhere on the trunk
brainstem syndrome
*can be a demyelinating event of multiple sclerosis
*eye movement problems, intranuclear opthalmoplegia
cerebellar syndrome
*can be a demyelinating event of multiple sclerosis
*ataxia
*vertigo
multiple sclerosis - primary progressive clinical pattern
*asymmetrical myelopathy (gradual onset of weakness, typically in one leg, with findings on exam of spasticity and/or hyperreflexia)
common, chronic symptoms of multiple sclerosis (outside of relapses)
*fatigue
*depression
*cognitive changes
-pain
-numbness
-dizziness
-spasticity
-bladder/bowel
-sexual dysfunction
multiple sclerosis - diagnostic criteria
*more than one demyelinating event with separation in time and space with no better explanation
multiple sclerosis - MRI findings
* Dawson’s fingers (oval shaped lesions sticking up perpendicularly away from corpus callosum)
* demyelinating lesions (often near the ventricles)
* lesions on spinal cord (2 vertebral segments long or shorter)
clinically isolated syndrome
when someone does not yet meet the criteria for multiple sclerosis because they have not had multiple events (we adopt a watch and wait approach)
multiple sclerosis - treatment of relapses
*definition of a relapse/new neurologic event: new event in new area of CNS lasting more than 24 hours
*treat with STEROIDS
multiple sclerosis - prevention of relapses
*disease modifying therapies
-older platform therapies (injectable)
-oral therapies
-monoclonal antibodies (IV or injectable)
multiple sclerosis - prevention of disability
*Vitamin D
*monoclonal antibody therapy?
*health maintenance (physical therapy; general medical care, such as smoking cessation)
correlation between Vitamin D and multiple sclerosis
*greater prevalence of MS as distance from equator increases
*exposure to sunlight increases Vitamin D levels (body makes vitamin D when exposed to UV light from sun)
*higher levels of vitamin D in adolescence is correlated with a lower risk of MS
*higher vitamin D levels in individuals with MS is correlated with lower rate of disability
multiple sclerosis - symptom management
-sleep hygiene
-moderate daily physical activity
-counseling
-social support
-organization
-safety
-energy conservation
multidisciplinary care & multiple sclerosis
-neurology
-urology
-ophthalmology
-physical therapy
-occupational therapy
-speech therapy
-social work
-psychology
neuromyelitis optica
*mutation in the aquaporin-4 gene
*results in abnormal transport of water in and out of cells
*demyelination occurs in areas highly populated with these water channels (optic nerves and spinal cord)
*dx: lesions in spinal cord greater than 3 vertebral segments in length, along with optic neuritis
*tx with immunoSUPPRESSANT agents (Imuran, Rituximab, etc)
*can worsen with interferons/common MS meds
progressive multifocal leukoencephalopathy (PML)
*caused by JC virus
*presents like a stroke (acute onset, affects behavior, usually affects one hemisphere)
*seen most often in immunocompromised pts
*causes progressive disability, often death
*can be caused by Natalizumab (monoclonal antibody used to treat MS)
*therefore, we must test MS patients for the antibody against JC so that we do not put them on this med
acute disseminated encephalomyelitis (ADEM)
*most often in pediatric populations, usually post-infectious
*sudden onset of focal motor symptoms accompanied by ALTERED MENTAL STATUS
*resolves with no sequelae and typically does not recur
*treated with steroids
central pontine myelinolysis
*a result of electrolyte correction
*seen in patients who have had low sodium that was corrected too rapidly
*results in difficulty speaking, difficulty swallowing, and weakness (because it impacts the brainstem, usually the pons)
*usually permanent damage
