Multiple sclerosis (MS) is a chronic disease that affects the central nervous system. It damages the myelin sheath that surrounds and protects the nerve fibers in the brain, spinal cord and optic nerves. This damage slows down or blocks messages between the brain and body, leading to symptoms such as numbness, weakness, balance and vision problems, fatigue and difficulty with coordination and walking.
There is no single test available to diagnose MS. Instead, physicians use several tests and criteria to rule out other conditions and narrow down to a definitive MS diagnosis. The key to treating MS effectively is detecting it early and beginning treatment as soon as possible. Early treatment helps slow the progression of disability and permanent nerve damage caused by MS.
What are the Symptoms of MS?
Some common symptoms of MS include:
- Numbness or weakness in one or more limbs that typically occurs on one side of the body at a time
- Electric-shock sensations with certain neck movements, especially bending the neck forward (Lhermitte sign)
- Tremor, lack of coordination or unsteady gait
- Vision problems like partial or complete vision loss, eye pain, double vision, blurry vision etc.
- Slurred speech, fatigue, dizziness, tingling, muscle spasms etc.
These symptoms may be mild initially but can worsen over time and lead to serious disability. The symptoms of MS are highly variable and depend on which areas of the central nervous system are affected. A combination of symptoms is evaluated to diagnose MS early.
Who is at Risk of Developing MS?
MS affects women more than men with a ratio of nearly 3 to 1. Most people are diagnosed between age 20 and 40 years but the disease can occur at any age. Certain risk factors that can increase a person’s chance of developing MS include:
- Genetics – MS is not directly inherited but people with a close family member with MS have higher risk.
- Environmental factors like low Vitamin D levels, smoking etc.
- Obesity during early adolescence
- Gender being female increases risk of MS
- Certain infections like Epstein-Barr virus may play a role
- Geography – MS is more common in colder climates farther from the equator
Doctors may evaluate for these risk factors while determining possibility of MS.
How is MS Diagnosed?
MS diagnosis involves multiple steps:
- Neurological exam – Neurological assessment involves checking major functions like vision, strength, coordination and reflexes. The physician looks for objective signs of neurological dysfunction.
- Medical history – Detailed history about the exact symptoms experienced and when they began is obtained.
- MRI – Magnetic resonance imaging (MRI) of the brain and spine can detect areas of damage and inflammation in white matter indicated by lesions.
- Spinal fluid analysis – Cerebrospinal fluid is obtained by lumbar puncture and analyzed for inflammatory markers typical of MS.
- Evoked potential tests – Visual, auditory and sensory evoked potentials check nerve signal pathways for areas of damage.
- Rule out other conditions – Numerous other disorders can mimic MS symptoms so they are excluded by blood tests and clinical evaluation.
These test results are put together to determine if the central nervous system damage matches MS diagnostic criteria. The updated McDonald criteria from 2017 is commonly used to diagnose MS.
McDonald Diagnostic Criteria for MS
This criteria requires objective proof of damage in the CNS based on clinical presentation plus:
- 2 or more separate lesions or areas of damage in the central nervous system white matter seen on MRI scan OR
- 2 or more clinically evident episodes involving different areas of CNS damage. AND
- Positive CSF lab findings with presence of specific antibodies or proteins OR
- 2 or more lesions on MRI scan along with reasonable historical account of previous episodes although not documented.
These guidelines allow MS diagnosis in some cases without requiring a second clinical attack. This enables earlier diagnosis and treatment.
Role of MRI in Early MS Diagnosis
Magnetic resonance imaging (MRI) is one of the most important tests for MS diagnosis and detecting it at the earliest. It can show areas of inflammation, demyelination and nerve damage in the brain and spinal cord even before major symptoms begin. MRI has the ability to:
- Detect multiple asymptomatic lesions in the CNS white matter
- Demonstrate lesions in characteristic locations like periventricular, juxtacortical, infratentorial or spinal cord
- Show active lesions and blood-brain barrier breakdown indicative of ongoing damage
- Identify changes over time with follow-up scans
High-resolution 3 Tesla MRI is more powerful at picking up small or subtle lesions compared to 1.5 Tesla machines. Using intravenous contrast dye like gadolinium can also improve detection of active inflammatory lesions. MRI spinal cord screening along with brain imaging is recommended for proper MS diagnosis. Certain imaging features and lesion patterns are highly specific for MS diagnosis.
MRI Features Suggestive of MS
| MRI Finding | Description |
|---|---|
| Periventricular lesions | Lesions located around fluid-filled ventricles in brain |
| Dawson’s fingers | Lesions extending perpendicular from ventricles |
| Juxtacortical lesions | Lesions adjacent to cortical gray matter of brain |
| Ovoid/round lesions | Distinct lesions with oval shape |
| Spinal cord lesions | Lesions within cervical spinal cord |
| Gadolinium enhancing lesions | Active inflammatory lesions detected after contrast injection |
| T2 hyperintensities | High signal on T2 sequences indicating myelin damage |
MRI is critical for MS diagnosis but lacks specificity as some other neurological conditions can also have similar findings. However, certain lesion patterns together with clinical findings point strongly towards MS. MRI along with spinal fluid testing improves diagnostic reliability.
Role of Spinal Fluid Testing
Cerebrospinal fluid (CSF) is tested to detect inflammation and immune system activity in the central nervous system. A lumbar puncture is done to obtain CSF from the lower spinal canal. Presence of specific proteins and antibodies called oligoclonal bands (OCBs) in the CSF indicate autoimmune inflammation and demyelination characteristic of MS. CSF testing can support MS diagnosis when:
- Oligoclonal IgG bands are detected
- Increased IgG antibodies or proteins are seen
- The IgG-index or Link’s index is elevated
CSF may be normal in early stages of MS. Repeat testing is done after few months if initial CSF profile is negative but suspicion remains high. Spinal fluid analysis is especially useful in clinically ambiguous situations or when patient has atypical symptoms.
Role of Evoked Potential Tests
Evoked potential (EP) tests assess signal transmission in sensory pathways of the CNS. Small electrodes placed on the skin pickup electrical signals generated in response to specific stimuli like visual input or sensory stimulation. Delayed response on EP tests implies demyelination or nerve damage in areas related to vision, hearing or sensory function. Common EP tests used are:
- Visual evoked potentials (VEP) – To check optic nerve damage
- Brainstem auditory evoked response (BAER) – Checks hearing pathways
- Somatosensory evoked potentials (SSEP) – Assesses spinal cord sensory function
EP testing serves as an objective measure of neurological dysfunction in MS. Conduction delays link clinical findings with corresponding CNS lesions. EP abnormalities may be present even without obvious symptoms. Serial EP studies help demonstrate worsening of nerve deficits. EPs are especially useful when MRI testing is inconclusive or unavailable.
Importance of Early MS Treatment
Initiating disease-modifying treatment (DMTs) soon after an MS diagnosis provides the best protection against irreversible disability and progression. Early treatment helps in the following ways:
- Reduces future relapses and new MRI lesion development
- Slows build up of disability and neurological decline
- Improves or stabilizes existing symptoms
- Enhances quality of life
- Delays secondary progression of MS
- Lowers MS morbidity and long-term costs
Treatment is most effective if begun within 5 years of symptom onset. Modern injectable, oral and intravenous DMTs control MS progression and lower relapse rates by almost 70%.
Guidelines for Early MS Treatment
Recent guidelines recommend early initiating treatment meeting the below criteria:
- Diagnosis of relapsing-remitting MS (RRMS) with 2 or more clinical attacks
- MRI findings consistent with MS based on spatial dissemination
- Positive CSF markers of immune activity
- Significant changes on evoked potential testing
- Worsening neurologic status suggestive of underlying disease activity
Treatment is tailored to individual circumstances like age, pregnancy plans, disease activity, tolerance for risks etc. Most guidelines advise against delaying treatment for extended periods of time.
Conclusion
Early recognition and treatment of MS leads to better health outcomes and prognosis. A combination approach using clinical evaluation, MRI scans, lumbar puncture and EP tests establishes an MS diagnosis quickly and reliably. Detecting the disease in the initial stages provides a critical window for treatment to prevent cumulative neurological disability. Recent diagnostic criteria and imaging techniques now allow earlier diagnosis even before full MS develops. Patients with suspected symptoms indicative of MS should seek prompt assessment for appropriate testing and treatment.