Diagnosis is the process of identifying a particular disease in a systematic manner. Differential diagnosis is the method of identifying all possible etiological factors related to all clinical signs and symptoms and thus accurately differentiating the diagnosis until an accurate conclusion is reached. Differential diagnosis is essential, especially in the field of neurology, where many diseases share similar characteristics but are not subject to any precise neurological examination or test: Parkinsonism, migraine, amyotrophic sclerosis and also multiple sclerosis. The differential diagnosis of multiple sclerosis is very broad in nature. Around a hundred pathologies can imitate multiple sclerosis; this figure is rather underestimated. However, it is impractical and tedious to systematically perform such differential diagnosis to exclude multiple sclerosis. Instead, the key characteristics of each patient allow for rational consideration of a relevant alternative diagnosis. Potential multiple sclerosis “imitators” can be easily distinguished from other patients, as most patients with relapsing onset suffer from either optic neuritis or myelitic syndromes.1. Monosymptomatic demyelinationThis is a single attack of optic neuritis, horizontal myelitis or any other lesion limited to one anatomical location at a given time. This was the first incident of multiple sclerosis. It shares similar symptoms and covers a wide range of other neurological disorders. More than half of cases have abnormalities on MRI, as well as other subclinical lesions in other parts of the central nervous system. The time factor differentiates this disease from multiple sclerosis. The presence of another lesion after an MRI performed one month later will imply multiple sclerosis.2. Schilder's diseaseThis is demyel...... middle of paper ......d can be increased. Meningeal abnormalities are often observed on MRI. Biopsies of the skin, lungs and lymph nodes are definitive.15. Anterior Ischemic Optic Neuropathy (AION) This is the arrest of the second cranial nerve due to a vascular disorder, either vasculitic or artherosclerotic. Subacute or sudden loss of monocular vision may resemble optic neuritis as in multiple sclerosis. The disease frequently affects elderly patients (over 50 years) with risk factors for lipid plaques. However, no other symptoms of multiple sclerosis are observed. Normal spinal fluid and MRI are evident.16. Cogan syndromeThis is the disease of interstitial keratitis with deafness and attacks of dizziness. Ataxic incidents may occasionally be reported. Abnormal MRIs are rare complaints. Deafness is a very rare incidence in multiple sclerosis. Additionally, cerebrospinal fluid readings are normal.