Multiple sclerosis
Multiple sclerosis is an autoimmune, demyelinating CNS disorder causing optic neuritis, myelitis, and brainstem/cerebellar syndromes separated in space and time. Diagnosis uses the McDonald MRI-based criteria; acute relapses are treated with high-dose glucocorticoids, and disease-modifying therapy (interferon beta, glatiramer, or a higher-efficacy agent such as ocrelizumab or natalizumab) is started early to prevent relapse and disability accumulation.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
Autoimmune demyelinating CNS disorder: multiple sclerosis (MS) causes inflammatory damage to the brain, spinal cord, and optic nerve, with most overt clinical symptoms resulting directly from…
- Epidemiology
Female predominance: female-to-male ratio is about 2:1.
- Risk factors
Genetic susceptibility: MS is associated with the HLA-DRB1 locus, with higher risk given a family history of autoimmune disease.
- Pathophysiology
Immune-mediated demyelination: MS is an autoimmune disorder in which inflammatory attack on CNS myelin interrupts axonal conduction, producing the clinical relapse; relapses evolve over hours to days and typically peak over days to weeks.
- Clinical features
Optic neuritis: subacute unilateral visual loss, sometimes with pain on eye movement or flashing lights (photopsia); examination shows reduced acuity, a scotoma or visual field deficit, impaired…
- Differential diagnosis
Neuromyelitis optica spectrum disorder: longitudinally extensive spinal cord lesions (=3 vertebral segments) and severe, often bilateral optic neuritis with aquaporin-4 antibody positivity, unlike…
- Diagnosis
The McDonald criteria establish the diagnosis by requiring symptoms of CNS demyelination separated in space and time, demonstrated through a combination of clinical relapses or progression…
- Management
First, confirm a true relapse (new or worsening neurologic symptoms lasting more than 24 hours) and exclude a pseudorelapse by evaluating for infection or another Uhthoff trigger before starting treatment.
- Complications
Secondary progressive MS: gradual disability accumulation independent of relapses, though disease-modifying therapy has reduced conversion rates.
- Prognosis
Course varies widely: relapsing-remitting MS carries the most favorable prognosis, while primary and secondary progressive forms carry a higher burden of accumulating disability.
- Prevention
No primary prevention exists once genetic and environmental risk (latitude, EBV exposure) has occurred, so efforts focus on relapse and disability prevention after diagnosis.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Transverse myelitis
Transverse myelitis is inflammation across one or more contiguous spinal cord segments causing subacute weakness, a sensory level, and bladder or bowel dysfunction; diagnosis requires spinal MRI showing cord enhancement or CSF inflammation with exclusion of compressive and infectious causes, and idiopathic disease is treated with high-dose intravenous methylprednisolone.
- Progressive multifocal leukoencephalopathy
Progressive multifocal leukoencephalopathy is an opportunistic demyelinating brain infection caused by reactivation of JC virus in significantly immunosuppressed patients, most often with AIDS or on natalizumab, rituximab, or other immunomodulators. Diagnosis rests on MRI white matter lesions plus CSF JC virus PCR; there is no antiviral treatment, so management is restoring immune function.
- Vertigo
The false sensation of self or environmental movement, classified as peripheral (inner ear or vestibular nerve) or central (brainstem or cerebellum) based on history, nystagmus pattern, and the bedside HINTS exam. Peripheral vertigo is managed with repositioning maneuvers or vestibular suppressants; central vertigo requires urgent stroke evaluation, since it can be the sole presenting symptom of a posterior circulation stroke.