Dengue Fever in Myasthenic Crisis

Aims: To investigate the possibility of a difference in late response towards intravenous immunoglobulin and its efficacy in myasthenic crisis when given during an acute dengue infection.

Presentation of Case: We report a 29-year old lady with myasthenia gravis diagnosed two years prior based on clinical presentation and positive anti-cholinesterase receptor antibody (AChR Ab) titre of > 20.98 nmol/L. Dengue infection was confirmed with positive SD® Dengue NS1 (Non Specific-1) antigen test. Muscle strength graded with the Medical Research Council (MRC) scale as well as hematological tests and arterial blood gases were done with chest X-rays to investigate for a concurrent chest infection. The patient was given IVIg) 0.4 g/kg/day for five days on the fifth day during the febrile phase of dengue fever after being ventilated in ICU for severe type 2 respiratory failure.

Discussion: The patient showed neurological improvement only after twenty five days post-IVIg administration due to ventilator associated pneumonia and Stenotrophomonas maltophilia bacteraemia as post viral complications, as compared to five days during her previous uncomplicated myasthenic crisis. From a muscle power of 4/5 bilaterally of upper and lower limb extremities it had improved to 5/5 bilaterally together with improving hematological blood counts which coincides with the resolution of dengue and bacterial infections.

Conclusion: The delay in response towards IVIg in this myasthenic crisis is multifactorial – including the patient’s non-compliance to therapy, the dengue viraemia as well as the concomitant pneumonia which occurred during the later stage of the dengue infection. A future alternative option of plasma exchange should be looked into detail.