The most likely diagnosis is relapsing-remitting multiple sclerosis.
1. Definition
Multiple sclerosis (MS) is a chronic immune-mediated inflammatory, demyelinating, and neurodegenerative disease of the central nervous system, involving the brain, optic nerves, and spinal cord.
2. Clinical Course
1. Relapsing-remitting multiple sclerosis (RRMS)
o Characterized by discrete neurologic relapses followed by partial or complete recovery
o Most common initial clinical course
2. Secondary progressive multiple sclerosis (SPMS)
o Progressive accumulation of disability following an initial relapsing course
3. Primary progressive multiple sclerosis (PPMS)
o Progressive neurologic disability from disease onset
Related diagnostic states include:
4. Clinically isolated syndrome (CIS)
5. Radiologically isolated syndrome (RIS)
o Under the 2024 McDonald criteria, some individuals previously classified as RIS may meet criteria for MS when sufficient imaging and biomarker evidence is present
3. Etiology and Risk Factors
1. Exact cause is multifactorial
2. Immune dysregulation involves T cells, B cells, macrophages, and microglia
3. Important environmental associations include:
1. Epstein-Barr virus infection
2. Low vitamin D exposure or status
3. Cigarette smoking
4. Strong genetic association with HLA-DRB1*15:01
4. Pathophysiology
1. Immune-mediated inflammation causes demyelination, oligodendrocyte injury, and neuroaxonal damage
2. Demyelinating plaques commonly occur in:
1. Periventricular regions
2. Cortical or juxtacortical regions
3. Infratentorial regions
4. Spinal cord
5. Optic nerve
3. Lesions characteristically have a perivenular distribution
4. Active inflammatory lesions may show gadolinium enhancement
5. Chronic disease leads to axonal loss, gliosis, and progressive neurodegeneration
5. Clinical Features
1. Sensory symptoms
o Numbness
o Paresthesia
o Impaired vibration or proprioception
2. Motor symptoms
o Weakness
o Spasticity
o Hyperreflexia
o Extensor plantar response
3. Optic neuritis
4. Brainstem and cerebellar manifestations
o Diplopia
o Vertigo
o Ataxia
5. Bladder dysfunction
o Urgency
o Frequency
o Incontinence
6. Fatigue
7. Cognitive and mood symptoms
Characteristic phenomena include:
1. Uhthoff phenomenon
o Transient worsening of preexisting neurologic symptoms with increased body temperature
o Represents a pseudoexacerbation, not a new inflammatory relapse
2. Lhermitte sign
o Electric shock-like sensation down the spine or limbs with neck flexion
6. Optic Neuritis
1. Subacute monocular visual loss
2. Pain with eye movement
3. Relative afferent pupillary defect
4. Reduced color vision and contrast sensitivity
5. Fundoscopy may be normal in retrobulbar optic neuritis
7. Diagnosis
Diagnosis is based on the 2024 revised McDonald criteria, together with exclusion of a better alternative diagnosis.
7.1 MRI and Dissemination in Space
1. Typical MS lesions occur in five characteristic CNS locations:
1. Periventricular
2. Cortical or juxtacortical
3. Infratentorial
4. Spinal cord
5. Optic nerve
2. Dissemination in space requires at least one typical T2-hyperintense lesion in at least two of the five characteristic locations
3. Periventricular lesions may form Dawson fingers
4. Active lesions may show gadolinium enhancement
5. Typical spinal cord lesions are usually short-segment
6. The central vein sign and paramagnetic rim lesions may provide additional diagnostic support in selected cases
7.2 Dissemination in Time and Substitutes for DIT
Dissemination in time may be demonstrated by:
1. A new clinical attack
2. A new T2 or gadolinium-enhancing lesion on follow-up MRI
3. Simultaneous presence of enhancing and nonenhancing lesions
Under the 2024 McDonald criteria, separate conventional evidence of dissemination in time is not required in every diagnostic pathway.
4. CSF-specific oligoclonal IgG bands, defined as at least two CSF-restricted bands, may substitute for dissemination in time in appropriate pathways
5. A validated kappa free light-chain index meeting the accepted diagnostic threshold may also substitute for dissemination in time
6. In a typical clinical presentation, characteristic lesions involving four or five of the five diagnostic locations may permit diagnosis without separate evidence of dissemination in time
7. A qualifying Select 6 central vein sign pattern may also serve as a substitute for dissemination in time in appropriate diagnostic pathways
7.3 Cerebrospinal Fluid
1. CSF-specific oligoclonal IgG bands
2. Increased IgG index may provide supportive evidence
3. Kappa free light-chain index may serve as an alternative CSF biomarker in appropriate settings
7.4 Optic Nerve Assessment
Optic nerve involvement can be demonstrated using:
1. Orbital MRI
2. Optical coherence tomography
3. Visual evoked potentials
o Delayed visual evoked potential latency supports demyelinating optic nerve injury
7.5 Additional Evaluation
Alternative diagnoses should be investigated when clinically indicated. Testing may include:
1. Vitamin B12
2. Thyroid function
3. Selected autoimmune, infectious, or metabolic investigations
4. AQP4-IgG when neuromyelitis optica spectrum disorder is suspected
5. MOG-IgG when MOG antibody-associated disease is suspected
8. Disease Course
8.1 Relapsing-Remitting MS
1. Characterized by clearly defined neurologic relapses
2. A relapse consists of new or worsening neurologic symptoms lasting at least 24 hours, occurring in the absence of fever, infection, or another explanation
3. A distinct new relapse generally begins at least 30 days after the onset of the preceding relapse
4. Symptoms usually evolve over hours to days and may persist for days to weeks
5. Relapses are followed by partial or complete recovery
6. Transient worsening caused by heat, infection, or metabolic stress without new inflammatory activity is a pseudoexacerbation
8.2 Secondary Progressive MS
1. Gradual accumulation of disability following an initial relapsing-remitting course
2. Progression may occur with or without superimposed relapses
8.3 Primary Progressive MS
1. Progressive neurologic disability from disease onset
2. Relapses are absent or uncommon
9. Management
9.1 Acute Relapse
1. Treat functionally significant relapses with high-dose corticosteroids
2. Accepted regimens include:
o Oral methylprednisolone 500 mg daily for 5 days
o Alternative high-dose oral regimens, such as 1 g daily for 3 to 5 days, according to local practice
o IV methylprednisolone 1 g daily for 3 to 5 days for severe attacks, intolerance or inadequate response to oral therapy, or when hospitalization is required
3. Corticosteroids accelerate recovery but do not alter long-term disease progression
4. Mild sensory relapses that do not significantly impair function may not require corticosteroid treatment
5. Plasma exchange is considered for severe corticosteroid-refractory demyelinating relapses
9.2 Disease-Modifying Therapy
1. Disease-modifying therapy should be considered early after a confident diagnosis of relapsing MS
2. Treatment is individualized according to:
o Clinical and MRI disease activity
o Prognostic features
o Treatment efficacy
o Safety profile
o Comorbidities
o Reproductive plans
o Patient preferences
3. High-efficacy therapy may be considered from disease onset in appropriately selected patients rather than using a rigid treatment-escalation approach
4. Examples of disease-modifying therapies include:
o Interferon beta
o Glatiramer acetate
o Fumarates
o Teriflunomide
o Sphingosine-1-phosphate receptor modulators
o Natalizumab
o Anti-CD20 therapies
o Cladribine
o Other agents selected according to disease activity and individual patient factors
9.3 Symptomatic Treatment
1. Baclofen or other antispasticity therapy for troublesome spasticity
2. Gabapentin or other neuropathic pain therapies when indicated
3. Bladder-directed treatment, including antimuscarinic therapy, after appropriate evaluation
4. Individualized management of fatigue, pain, mood symptoms, sexual dysfunction, and cognitive impairment
9.4 Supportive Care
1. Exercise, physiotherapy, and rehabilitation
2. Management of heat sensitivity when it triggers symptoms
3. Smoking cessation
4. Correct vitamin D deficiency when present
5. Regular monitoring of neurologic function, MRI activity, treatment efficacy, and treatment-related adverse effects
10. Key Clinical Insight
Recurrent neurologic attacks separated in time and affecting different CNS regions, together with painful monocular optic neuritis, upper motor neuron signs, characteristic MRI lesions, and CSF-specific oligoclonal bands, establish a highly characteristic presentation of relapsing multiple sclerosis.
References
1. Montalban X, Lebrun-Frénay C, Oh J, et al. Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria. Lancet Neurol. 2025;24(10):850-865. doi:10.1016/S1474-4422(25)00270-4.
2. Ramo-Tello C, Blanco Y, Brieva L, et al. Recommendations for the diagnosis and treatment of multiple sclerosis relapses. J Pers Med. 2022;12(1):6. doi:10.3390/jpm12010006.
3. Meca-Lallana JE, Martínez Yélamos S, Eichau S, et al. Consensus statement of the Spanish Society of Neurology on the treatment of multiple sclerosis and holistic patient management in 2023. Neurologia (Engl Ed). 2024;39(2):196-208. doi:10.1016/j.nrleng.2024.01.003.