Multiple sclerosis (MS) is diagnosed through a combination of strategies, as there is no single definitive test. Diagnosis typically involves:

• A detailed medical history and neurological exam to evaluate symptoms like movement, coordination, vision, balance, and reflexes.
• Magnetic Resonance Imaging (MRI) to detect lesions or plaques in the brain and spinal cord characteristic of MS. MRI can show both old and new lesions indicative of disease spread over time and space.
• Lumbar puncture (spinal tap) to analyze cerebrospinal fluid for immune system changes linked to MS, including oligoclonal bands.
• Evoked potential tests that measure electrical activity in the nervous system in response to stimuli, helping detect nerve pathway damage.
• Blood tests to rule out other diseases with similar symptoms.
• Additional tests like optical coherence tomography to assess eye nerve damage and neuropsychological testing to evaluate cognitive function.

The diagnosis also involves ruling out other conditions that mimic MS symptoms, and it may take time with repeated testing and observation to confirm. The McDonald criteria are widely used to combine clinical findings and test results for diagnosis. MS diagnosis is often confirmed if the signs and test markers show damage in different areas of the central nervous system at different times, validating the disease's progression pattern.