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Issue: Issue 5 – 2018

Case Report

More than meets the eye: an unusual Parkinson’s disease mimic

Verónica Cabreira, Eva Brandão, and João Massano
Introduction: Fragile X-associated tremor/ataxia syndrome (FXTAS) is a rare, X-linked adult-onset neurodegenerative disorder affecting carriers of the fragile X mental retardation 1 (FMR1) gene premutation, a 55-200 cytosine-guanine-guanine [CGG] repeat expansion in the 5' untranslated region of the gene. Intention tremor and ataxia are usually the core features of the syndrome, while parkinsonism has also been described, but less frequently seen. FXTAS probably remains underdiagnosed, possibly mistaken for essential tremor, various degenerative ataxias, and atypical parkinsonian syndromes. Hyperintensity of the middle cerebellar peduncle (MCP) detected in T2 or FLAIR MRI, a highly specific sign of this disorder, is present in approximately 60% of men with FXTAS. 
Case report: We present the unusual case of a patient with previously undiagnosed FXTAS who was referred for deep brain stimulation (DBS) surgery, as the phenotype resembled Parkinson’s disease (PD). An MRI scan requested in 2006 had revealed symmetrical T2 hyperintensity in the middle cerebellar peduncles. Genetic testing disclosed FMR1 premutation with 90 CGG repeats expansion confirming the diagnosis of FXTAS. 
Discussion: This case highlights the relevance of considering FXTAS as a possible diagnosis in these cases, even if the clinical picture resembles PD. MCP hyperintensity seen on MRI should therefore trigger genetic testing and subsequent appropriate management.

Keywords: Parkinsonism, Parkinson’s disease, Fragile X-associated Tremor/Ataxia Syndrome, differential diagnosis, FMR1.

International Journal of Clinical Neurosciences and Mental Health 2018; 5:8
DOI: https://doi.org/10.21035/ijcnmh.2018.5.8
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