441 - Rare presentation of a progressive motor neuron disease with characteristics of both PLS and ALS

Thursday, February 22, 2024

5:00 PM – 6:30 PM EDT

Presenting Author(s)

DW

Daniel Weng, MD

Medical Resident
Mount Sinai Hospital
New York City, New York, United States

Corresponding Author(s)

VH

Vincent Huang, MD

Associate Professor
Mount Sinai Hospital
New York City, New York, United States

Case Diagnosis: An unclassified motor neuron disease with characteristics of both PLS and ALS

Case Description: A 58 year-old-male was admitted to neurology with rapid progression of bilateral leg and arm weakness, increased tone, inability to speak, and dysphagia over two years. Outpatient NCS showed mild distal sensory greater than motor neuropathy polyneuropathy and grossly normal EMG with no evidence of motor neuron disease. MRI spine showed patchy cord hyperintensities. Further work-up was negative for malignancy, infections, or metabolic causes, leading to a working diagnosis of Primary Lateral Sclerosis (PLS), however inconsistent with the time course. He was admitted to acute rehab where he remained moderate to max assist with severe communication barriers. After discharge, the patient's Amyotrophic Lateral Sclerosis (ALS) panel was negative for known genetic variants. The patient continued to decompensate at home and was admitted into hospice care.

Discussions: Motor neuron diseases such as ALS and PLS exist on a spectrum and a patient’s presentation may not fit into a specific diagnosis. In this case, the patient had EMG findings inconsistent with ALS as there was no evidence of lower motor neuron disease and his genetic testing did not show any known variants. PLS is primarily an upper motor neuron disease (consistent with this patient’s EMG and MRI) that typically progresses over a longer period of time and has a more benign survival prognosis compared to ALS. For a patient with inconsistent findings, prognosis for functional recovery and life expectancy can be challenging. This patient case warrants further research involving those who lie on the spectrum of motor neuron disease to aid in prognostication for rehabilitation and survival.

Conclusions: We describe a patient case looking at an unclassified motor neuron disease that presents as rapidly progressive, upper motor neuron predominant, with poor functional prognosis and short life expectancy after onset.