Christina Massrey1, Abhijit Das3, Ameya Walimbe1, Brooke Evans2, Jamie Solis2, Whitney Franklin2, Kristen Fisher2, Sreenivas Avula4, Timothy Lotze2
1Neurology, Baylor College of Medicine, 2Baylor College of Medicine, 3Baylor college of medicine, 4OSF Medical Center
Objective:
To describe a unique clinical presentation of juvenile ALS that initially demonstrated features suggestive of an acquired inflammatory neuropathy.
Design/Methods:
Case report
Results:
A 16-year-old female with a learning disability initially presented with seven months of proximal muscle weakness. She had preserved reflexes, but cerebrospinal fluid (CSF) showed albumino-cytologic dissociation. Post-contrast MRI of the spine demonstrated peripheral nerve root enhancement, suggesting an acquired inflammatory neuropathy. There was little clinical improvement with IVIG, steroids, and PLEX. An EMG demonstrated fibrillation potentials, severely decreased motor amplitudes, and prolonged motor latencies –which was consistent with axonal neuropathy. A muscle biopsy corroborated these findings. Chromosomal Microarray (CMA) and duo-whole exome sequencing (WES) reported no pathogenic variants related to the described phenotype of chronic, progressive weakness with neuropathic features. With non-diagnostic genetic studies, inflammatory neuropathy remained a consideration, and rituximab and monthly IVIG were started. She presented to our institution with acute respiratory failure requiring tracheostomy, flaccid quadriplegia, areflexia, tongue atrophy, fasciculations, and polyminimyoclonus. WES re-analysis was performed with updates to the phenotype, including concern for motor neuron disease. This revealed de novo homozygous pathogenic variants in the FUS gene (c.1573C>T, p.P525S), consistent with juvenile Amyotrophic Lateral Sclerosis (ALS) Type 6.
Conclusions:
We demonstrate a clinical presentation of juvenile ALS that began with progressive weakness accompanied by CSF albumino-cytologic dissociation, nerve root enhancement on MRI, and an initially non-diagnostic genetic work-up mimicking an acquired inflammatory neuropathy. Our study highlights how features of juvenile ALS can mimic an inflammatory neuropathy and the benefit of WES re-analysis when the clinical phenotype has evolved.
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