Myasthenia Gravis at Presentation: A 14 Year Institutional Review of a Rare Disorder in Calabar, Southern Nigeria

Aim: Spurred on by the prevailing dearth of data from Nigeria and West Africa, in the context of reports suggesting racially influenced phenotypic variation in the manifestation of myasthenia gravis, this study explored the clinical presentation of patients with myasthenia gravis at a tertiary health facility in Calabar, Nigeria.

Study Design: We employed a cross-sectional study design.

Place and Duration of Study: This study was conducted at the University of Calabar Teaching Hospital, Nigeria. The period under review spanned from January 2006 to December 2019.

Methods: We obtained relevant demographic and clinical data from those who presented with myasthenia gravis from June 2017 to December 2019, and retrospectively extracted demographic and clinical information at presentation, from the records of patients diagnosed with myasthenia gravis at the outpatient neurology and ophthalmology clinics of the hospital from January 2006 to May 2017. Data analysis was done with version 22 of the statistical package for social sciences software.

Results: 26 patients with myasthenia gravis comprising 11 males and 15 females, with an overall mean age of 36.7 ± 18.79 years, presented at the clinics over 14 years; giving a male: female ratio of 1:1.4, and a prevalence of 26.3 per 100,000. Ocular and generalized forms of myasthenia gravis each constituted half of the number of cases.18.4%, 65.4% and 19.2% of the patients presented with juvenile-onset, early-onset, and late-onset myasthenia gravis, respectively. Ptosis (88.5%), diplopia (84.6%) and limb weakness (42.3%) were the top three presenting features. None of the patients had co-existing thymic enlargement at the time of the first presentation.

Conclusion: The majority of the cases had early-onset myasthenia gravis, with females more affected than males. Ocular symptoms comprise the predominant clinical features at initial presentation and there was no co-existing thymic enlargement.