Inflammatory demyelinating diseases of the central nervous system in Niger

In sub-Saharan Africa (SSA), few studies have been reported on inflammatory demyelinating diseases of the central nervous system (CNS). Neuromyelitis optica spectrum disorders (NMOSD) seems to be the most frequent inflammatory demyelinating disease of CNS in sub-Saharan Africans or people of sub-Saharan African descent.

We report the observations of seven patients from Niger diagnosed with inflammatory demyelinating diseases of CNS over a period of 21 years (1996-2017).

They were four women and three men aged 19 to 66 years (mean age: 37 years), with no known past medical history. Four patients were diagnosed with NMOSD (2 men and 2 women) and the three other patients with multiple sclerosis (MS, 2 women and 1 man). The three patients diagnosed with MS had the relapsing-remitting form. The cerebrospinal fluid study revealed the presence of oligoclonal bands in the three patients. Of the patients diagnosed with NMOSD, two patients negative anti-aquaporin 4 antibodies (anti-MOG antibodies not done), one of whom had bilateral optic neuritis (ON) with longitudinally extensive transverse myelitis (LETM) and the other unilateral ON with LETM. Two patients with MS were treated with interferon beta-1a and the third patient with azathioprine. The Expanded Disability Status Scale ranged from 1 to 2 in these three patients at the time of initiation of background treatment. Azathioprine was the treatment prescribed in the four patients with NMOSD. We did not find any case of acute disseminated encephalomyelitis.

Our case series suggests the rarity of inflammatory demyelinating diseases of CNS in Niger, and NMOSD seems to be more frequent than MS.