Which conditions are included in the differential diagnoses of primary lateral sclerosis (PLS)?

Updated: Apr 28, 2014
  • Author: Hidehiro Takei, MD; Chief Editor: Adekunle M Adesina, MD, PhD  more...
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The major differential diagnosis for PLS is UMN-dominant ALS. According to Pringle et al, disease duration of at least 3 years is required to render this diagnosis [1] ; similarly, Gordon et al reported that clinically pure PLS can be defined by isolated UMN signs 4 years after symptom onset. [64] Differentiation between PLS and UMN-dominant ALS is reported to have prognostic significance. [64]

Other diseases that cause a slowly progressive pyramidal or pseudobulbar syndrome should be considered in the differential diagnosis of PLS. These include the following:

  • Structural spinal cord disorders (compressive lesions at the foramen magnum or cervical spinal cord), such as cervical spondylotic myelopathy, Arnold-Chiari malformation, or tumors

  • Pure (uncomplicated) HSP

  • Metabolic disorders, such as subacute combined degeneration of the cord (vitamin B-12 deficiency)

  • Viral infections, such as tropical spastic paraparesis (human T-lymphotropic virus type I) or HIV infection

  • Primary progressive multiple sclerosis (PPMS) – The most common presentation of PPMS (seen in 80% of patients) is progressive spastic paraparesis, mainly in the legs [66]

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