Demyelinating Diseases

Question 1

myelin

Answer 1

*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

Question 2

order of the process of myelination

Answer 2

PNS myelinates first, followed by the spinal cord, and the brain last

Question 3

dysmyelination

Answer 3

*characterized by the gradual loss of function (pertains to poorly created myelin)
*most dysmyelination disorders are inherited
*most have onset at an early age

Question 4

etiologies of demyelination

Answer 4

-hereditary
-hypoxia and ischemia
-carbon monoxide toxicity
-nutritional deficiency
-direct viral invasion of CNS
-primary demyelinating disorders (MS, etc)

Question 5

multiple sclerosis - epidemiology

Answer 5

*more common in women than in men
*commonly diagnosed between ages 20 and 40
*more common in regions far from the equator

Question 6

multiple sclerosis - pathophysiology

Answer 6

*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

Question 7

multiple sclerosis - clinical patterns

Answer 7

*relapsing-remitting (most common)
*progressive-relapsing
*secondary-progressive
*primary-progressive

Question 8

multiple sclerosis - examples of demyelinating events

Answer 8

-optic neuritis
-transverse myelitis
-brainstem syndrome
-cerebellar syndrome

Question 9

optic neuritis

Answer 9

*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

Question 10

transverse myelitis

Answer 10

*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

Question 11

brainstem syndrome

Answer 11

*can be a demyelinating event of multiple sclerosis
*eye movement problems, intranuclear opthalmoplegia

Question 12

cerebellar syndrome

Answer 12

*can be a demyelinating event of multiple sclerosis
*ataxia
*vertigo

Question 13

multiple sclerosis - primary progressive clinical pattern

Answer 13

*asymmetrical myelopathy (gradual onset of weakness, typically in one leg, with findings on exam of spasticity and/or hyperreflexia)

Question 14

common, chronic symptoms of multiple sclerosis (outside of relapses)

Answer 14

*fatigue
*depression
*cognitive changes
-pain
-numbness
-dizziness
-spasticity
-bladder/bowel
-sexual dysfunction

Question 15

multiple sclerosis - diagnostic criteria

Answer 15

*more than one demyelinating event with separation in time and space with no better explanation

Question 16

multiple sclerosis - MRI findings

Answer 16

*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)

Question 17

clinically isolated syndrome

Answer 17

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)

Question 18

multiple sclerosis - treatment of relapses

Answer 18

*definition of a relapse/new neurologic event: new event in new area of CNS lasting more than 24 hours
*treat with STEROIDS

Question 19

multiple sclerosis - prevention of relapses

Answer 19

*disease modifying therapies
-older platform therapies (injectable)
-oral therapies
-monoclonal antibodies (IV or injectable)

Question 20

multiple sclerosis - prevention of disability

Answer 20

*Vitamin D
*monoclonal antibody therapy?
*health maintenance (physical therapy; general medical care, such as smoking cessation)

Question 21

correlation between Vitamin D and multiple sclerosis

Answer 21

*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

Question 22

multiple sclerosis - symptom management

Answer 22

-sleep hygiene
-moderate daily physical activity
-counseling
-social support
-organization
-safety
-energy conservation

Question 23

multidisciplinary care & multiple sclerosis

Answer 23

-neurology
-urology
-ophthalmology
-physical therapy
-occupational therapy
-speech therapy
-social work
-psychology

Question 24

neuromyelitis optica

Answer 24

*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

Question 25

progressive multifocal leukoencephalopathy (PML)

Answer 25

*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

Question 26

acute disseminated encephalomyelitis (ADEM)

Answer 26

*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

Question 27

central pontine myelinolysis

Answer 27

*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