Background

Measles Inclusion Body Encephalitis (MIBE) is a rare complication of measles infection or vaccination only described in immunodeficient patients. It occurs within a year of measles exposure. Diagnosis reached by clinical features, CSF anti measles antibody/measles RNA protein, MRI brain/EEG and brain biopsy alongwith underlying immunodeficiency.

Objectives

To describe 2 case reports of MIBE without evidence of immunodeficiency

Methods

We reviewed case notes of 2 patients with MIBE

Results

Case 1: 14 month boy presented with rapid neuroregression of motor-cognitive skillls / frequent seizures/ periodic asymmetric jerks.Clinical exome sequencing (CES) did not identify genetic immunodeficiency.

Case 2: 3 year boy/ consanguinity presented with neuroregression/periodic jerks/ dystonia/ partial seizures over 3 months. He was subsequently diagnosed with MIBE- brain biopsy not done. He required PICU care for aspiration pneumonia. CES awaited.

In both cases

No history of clinical measles

Measles vaccine at 10 months

EEG showed periodic jerks; CSF high titres of anti measles IgG

Extensive testing (immunonlogist consult) did not demonstrate immunodeficiency

Brain biopsy in case 1 did not show viral inclusion bodies.

Conclusion

MIBE has been described only in immunodeficient children- our cases had no evidence of immunodeficiency.

The diagnosis is suspected by typical clinical/ lab profile but also lesser time lag between exposure and presentation. SSPE- which presents 6-15 years post exposure - is a differential.

A limitation here is nonavailability of measles PCRs on brain biopsy.

We have 2 hypotheses:

Can MIBE occur in immunocompetent children OR Are MIBE and SSPE on the same clinical continuum with overlapping timelines?