Multiple Sclerosis Flashcards
MS pathology
Focal demyelination within the brain and spinal cord. Discrete areas of damaged myelin, termed plaques, are embedded within normal-appearing tissue
Within these plaques, damaged myelin is associated with inflammatory infiltrates of lymphocytes and macrophages, antibody and complement deposition, activated microglia, and oligodendroglial cell loss
Early studies showed that disease progression is linked to CD4+ effector cells infiltrating the BBB and expressing pro-inflammatory cytokines that help to activate microglia and other immune cells.
Now, interleukin 17 producing T helper 17 cells, B cells, CD8 T cells, and both CD4/CD8 positive T-reg cells may all play roles
Benign MS
20% of cases
Least severe type. Includes a few mild early attacks with complete clearing of symptoms. There is minimal or no disability in this condition
Relapsing-remitting MS
25%
Sudden onset (over hrs or days) of neuro symptoms that usually last several weeks and then resolve often leaving few or no deficits
The frequencies of these relapses are highly variable but averages about 1 every 2 years. Some degree of disability is usually present
Secondary progressive MS
40% of diagnosed cases.
Initial relapsing-remitting course followed by increasing attacks with fewer and less complete remissions after each one. The MS can continue to worsen for many years and then level off with moderate to severe disability
Primary progressive MS
15%
Most disabling form of MS.
Onset is quite severe and the course is slowly progressive without any clearing of symptoms. Fortunately, it is the least common type
Progressive relapsing MS
Rare and characterized by progressive disease punctuated by acute relapses
Clinically isolated syndrome
characterized by the first demyelinating event that is suggestive of MS
It places the patient at risk for further relapses. Some patients will go on to develop relapsing-remitting MS and suffer from multiple attacks
Others will have no further evidence of demyelinating disease
Tough to predict whether a given individual will develop MS following symptom onset, but the risk of having second attack after 14yrs of follow up is 88% if any lesions are present on initial brain MRI and 19% if MRI is normal
Lhermitte sign
sensation of electricity running down their spine, sometimes extending into the limbs
Often aggravated by flexing cervical spine and should raise suspicion of MS or other compromise of the upper cervical spinal cord
Are symptoms worse in heat or cold?
Heat - fever, increased exertion, hot bath
Same for Myasthenia gravis (ice can improve ptosis)
Charcot’s triad
Intention tremor
Dysarthria
Nystagmus
Brainstem signs
Optic neuritis (presenting complaint in 14-23% of cases) Retrobulbar neuritis
Diplopia (12-22% of patients)
Trigeminal neuralgia - always suspect MS in young patient with TN
Facial myokymia - wormlike movement of muscles that patient feels but is tough to see. Involves orbicularis oculi muscles
Vertigo
Dx of MS
If a patient has symptoms reflecting 2 or more separate brain lesions over time and this is confirmed on MRI then suspect MS
Typical MS lesions are bright lesions on T2 especially in corpus callosum and periventricular regions. Usually linear or ovoid and perpendicular to ventricular surface (Dawson fingers). MRI lesions larger than 5mm or lesions inferior to the tentorium (esp cereballar peduncle) help confirm MS
FLAIR is even more sensitive
N-acetylaspartate (NAA) can also be used with MR Spec to detect MS - NAA levels are lower in MS plaques and can also be lower in seemingly unaffected areas of white matter suggesting axonal damage
CSF analysis also helps. It is indicated when MRI is normal or shows a pattern consistent with other disease processes like microvascular ischemia or infection.
CSF is abnormal in 85-90% of patients with MS. Elevated IgG index, presence of 2 or more oligoclonal bands occur in 90% of MS but also in 30% of CNS inflammatory neuro diseases. Might see high CSF white count
Visual evoked response - prolongation of P100 wave is seen in more than 75% of MS patients. This shows compromise between optic nerve and brain
What other conditions have oligoclonal bands?
1) SLE
2) Neurosarcoid
3) Subacute sclerosing panencephalitis
4) SAH
5) Syphilis
6) CNS lymphoma
MS treatment
IV steroids, primarily during acute attacks. Steroids have not been shown to lower the risk of future attacks or change the natural history of disease though. They do hasten recovery of acute attack.
Immunomodulating agents or disease-modifying agents can be used to modify the course of MS and are used on a chronic, ongoing basis. Interferon B-1a, Interferon B-1b, Glatiramer acetate (synethetic polypeptide of myelin basic protein), Natalizumab (prevents autoreactive T cells from crossing BBB), and Fingolimod (structural analogue of sphingosine which targets receptors for sphingosine-1-phosphate and hinders migration of lymphocytes from secondary lymphoid organs to the periphery). These disease modifying agents slow progression of disability, impact relapse rate, and prevent accumulation of burden of MRI lesions
Vitamin D insufficiency can increase susceptibility to MS. Vitamin D may reduce severity of disease
IV Mitoxantrone - an antineoplastic immunomodulatory agent may also improve neuro disability and delayed progression of MS in patients with worsening relapsing-remitting or secondary progressive disease. Its role is limited by cardiotoxic and myelosuppressive effects.
Interferons
Work by altering T cells and sealing the BBB against their entry into CNS
Interferons are injected subQ or IM
Side effects: Flu-like symptoms and injection site reactions
