Abstract Details

Title Juvenile ALS Masquerading as an Acquired Inflammatory Neuropathy

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P11 - Poster Session 11 (8:00 AM-9:00 AM)

Poster/Presentation
Number 11-006

Objective To describe a unique clinical presentation of juvenile ALS that initially demonstrated features suggestive of an acquired inflammatory neuropathy.

Background NA

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.

Authors/Disclosures
Whitney Franklin, MD, PhD PRESENTER	Dr. Franklin has nothing to disclose.
Christina Massrey, MD (Baylor College of Medicine)	Dr. Massrey has nothing to disclose.
Abhijit R. Das, MD (Baylor college of medicine)	Dr. Das has nothing to disclose.
Ameya S. Walimbe, MD, PhD (Ameya Walimbe)	Dr. Walimbe has nothing to disclose.
Brooke Evans, MD (Baylor College of Medicine)	Dr. Evans has nothing to disclose.
Jamie Solis, MD	Dr. Solis has nothing to disclose.
Kristen Fisher, DO (Baylor College of Medicine)	Dr. Fisher has nothing to disclose.
Sreenivas Avula, MD (OSF Medical Center)	Dr. Avula has nothing to disclose.
Timothy E. Lotze, MD, FAAN (Texas Children's Hospital)	Dr. Lotze has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Department of Justice VICP. The institution of Dr. Lotze has received research support from NIH. The institution of Dr. Lotze has received research support from National MS Society. The institution of Dr. Lotze has received research support from Sarepta Therapeutics. The institution of Dr. Lotze has received research support from PTC THERAPEUTICS. The institution of Dr. Lotze has received research support from Avexis. Dr. Lotze has received publishing royalties from a publication relating to health care. Dr. Lotze has received publishing royalties from a publication relating to health care.

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