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Differential Diagnosis


A differential diagnosis for a disease is another disease that has clinical or other similarities with it. Before making a firm diagnosis for any disease, it is important to rule out the differential diagnoses.

Because there is no specific test for multiple sclerosis, diagnosing it relies on the old Sherlock Holmes maxim that when you have ruled out all the possible alternatives, whatever remains, however improbable, must be the truth. Since there are so many potential symptoms associated with MS, there are a large number conditions that clinically resemble it in one way or another. Thus there are a large number of diffential diagnoses for it.

The differential diagnoses can be ruled out by blood tests, MRI scans, CT-scans, spinal taps etc.

Here is a list of some of the differential diagnoses for multiple sclerosis (in no particular order) - some of these are less severe than MS and some are more so, many are very rare:

Here is a table of how a few different central nervous system conditions show up differently in MRI scans:
MRI White Matter Abnormalities
Condition MRI Features
Multiple Sclerosis Multifocal, asymmetrical, periventricular lesions
ADEM Can be identical to MS. Symmetrical cerebral, basal ganglia or cerebral lesions in some
Ageing Usually less extensive than MS. Discrete lesions. Little posteria fossa involvement
Behcet's syndrome Prominent brain stem involvement
Cerebrovascular involvement Large lesions of arterial territories involving cortex as well as small lesions. Smooth periventricular lesions
Decompression sickness Focal sub-cortical lesions? Any difference from healthy controls
Fat embolism High signal lesions on T1-weighted images, high or low signal on T2-weighted
HIV encephalitis Patchy or punctate white matter lesions, commonly involving basal ganglia. Diffuse pattern in AIDS dementia complex
HTLV-1 associated myelopathy Usually few supratentorial lesions only
Hydrocephalus Diffuse smooth periventricular, high signal
Irradiation Diffuse periventricular and sub-cortical lesions
Leucodystrophies Various patterns of extensive symmetrical white matter abnormalities; atrophy
Migraine A few more discrete lesions than age-matched controls
Mitochondrial encephalopathy Diffuse abnormalities as well as stroke-like lesions
Motor neuron disease Symmetrical high signal involving pyramidal tracts, especially internal capsules
Neurosarcoidosis Can be identical to MS but also large parenchymal lesions, prominent basal involvement and diffuse menigeal enhancement
Phenylketonuria Periventricular and sub-cortical changes
Progressive multifocal leucoencephalopathy Large focal lesions
Subacute sclerosing panencephalitis Few scattered white matter lesions
Systemic lupus erythmatosus Many sub-cortical lesions; lesions involving arterial territories
Trauma Variable

Differential Diagnosis links:
Multiple Sclerosis: Differential Diagnosis
Multiple Sclerosis - NeuroHaven

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