Titel | Think metabolic! Biotidinase deficiency mimicking neuromyelitis optica |
Doel | Neuromyelitis 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. |
Methodes | A full ophthalmic and neurological workup |
Resultaten | A 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. |
Conclusie | Adult-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. |
Belangenverstrengeling | Nee |
Naam | IMSCHOOT |
Initialen | J |
Instituut | UZ Gent, Dpt of Ophthalmology |
Stad | Gent |
Naam | Van Iseghem |
Initialen | V |
Instituut | UZ Gent, Dpt of Neurology |
Naam | Sprengers |
Initialen | M |
Instituut | UZ Gent, Dpt of Neurology |
Naam | Sindic |
Initialen | CJM |
Instituut | UCL |
Stad | Louvain |
Naam | Willekens |
Initialen | B |
Naam | Hemelsoet |
Initialen | D |
Instituut | UZ Gent, Dpt of Neurology |
Naam | Laureys |
Initialen | G |
Instituut | UZ Gent, Dpt of Neurology |
Naam | De Zaeytijd |
Initialen | J |
Instituut | UZ Gent, Dpt of Ophthalmology |
Stad | Gent |