What is primary lateral sclerosis (PLS)?

Updated: Apr 28, 2014
  • Author: Hidehiro Takei, MD; Chief Editor: Adekunle M Adesina, MD, PhD  more...
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PLS is a rare, idiopathic neurodegenerative disorder that primarily involves the UMNs, resulting in progressive spinobulbar spasticity. Because substantial numbers of cases initially diagnosed as PLS would be reclassified as ALS as the disease progresses, Pringle et al suggest that a disease duration of at least 3 years is required to render this diagnosis clinically. [1] There is still debate regarding whether PLS is a distinct pathologic entity or whether it represents one end of a clinical spectrum of ALS.

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