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TitreThink metabolic! Biotidinase deficiency mimicking neuromyelitis optica
ButNeuromyelitis optica spectrum disorders (NMOSDs) and biotidinase deficiency (BD) both involve optic atrophy and spinal cord lesions. However, BD starts in early childhood and only very rarely presents in adulthood.
MéthodesA full ophthalmic and neurological workup
RésultatsA 19-year-old male patient was referred for further investigation of profound, painless, binocular visual loss evolving over 2 months, exacerbated by physical activity. Best-corrected visual acuity was 0.16 in the right eye and 0.1 in the left eye. Fundoscopy revealed a pale and atrophic temporal side of the optic disc confirmed by nerve fibre layer loss on OCT. Otherwise, he was in general good health. Brain MRI directed towards a NMOSD diagnosis. However spinal cord MRI, chest CT, cerebrospinal fluid examination and biochemical tests for other auto-immune, infectious, toxic and genetic causes (LHON) were all found to be negative. During the workup he developed spastic paraparesis. Urgent treatment with methylprednisolone followed by plasmapheresis did not relieve symptoms. Further exhaustive biochemical screening showed a reduced biotidinase serum activity (<5%). Biotin substitution was started with slow visual improvement up to 0.8 but normal gait and reflexes.
ConclusionAdult-onset BD may mimic inflammatory disorders such as the NMOSD or other genetic disorders such as spastic paraplegia type 7 or LHON. When confronted with patients with a similar clinical course, the absence of laboratory confirmation of the former disorders should guide towards low-cost enzymatic screening.
Conflit d'intérêtNon
Auteur 1
NomIMSCHOOT
InitialesJ
InstitutUZ Gent, Dpt of Ophthalmology
VilleGent
Auteur 2
NomVan Iseghem
InitialesV
InstitutUZ Gent, Dpt of Neurology
Auteur 3
NomSprengers
InitialesM
InstitutUZ Gent, Dpt of Neurology
Auteur 4
NomSindic
InitialesCJM
InstitutUCL
VilleLouvain
Auteur 5
NomWillekens
InitialesB
Auteur 6
NomHemelsoet
InitialesD
InstitutUZ Gent, Dpt of Neurology
Auteur 7
NomLaureys
InitialesG
InstitutUZ Gent, Dpt of Neurology
Auteur 8
NomDe Zaeytijd
InitialesJ
InstitutUZ Gent, Dpt of Ophthalmology
VilleGent
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