title: Progression in primary lateral sclerosis: a prospective analysis.
abstract: OBJECTIVE
  To determine whether rates and patterns of progression differ among primary lateral sclerosis (PLS) patients.
  
  
  METHODS
  Fifty patients fulfilling clinical criteria for PLS were classified on initial presentation into three subtypes: ascending, multifocal, and sporadic paraparesis (PLS-A, PLS-M or PLS-SP). Patients were surveyed annually. Measures of movement speed, clinical rating scales, and transcranial magnetic stimulation were re-assessed at 1-5 year intervals for spread to additional body regions and progression of severity within affected regions.
  
  
  RESULTS
  Forty-seven patients continued to fulfill criteria for PLS over a mean follow-up of 6.6 years, with a mean disease duration > 14 years. PLS-A patients had more predictable progression to additional body regions. Severity progressed faster in newly affected regions followed by stabilization in PLS-A or PLS-M subtypes.
  
  
  CONCLUSIONS
  Clinical progression in PLS does not occur steadily, but has periods of faster decline upon spreading to a newly affected region. Classification of PLS patients by subtype is more relevant to predicting the spread of disease, but not progression of severity.
authors.affiliation: Electromyography Section, National Institutes of Neurological Disorders and Stroke, 10 Center Drive, Bethesda, Maryland 20892, USA. floeterm@ninds.nih.gov
authors.forename: Mary Kay
authors.initials: MK
authors.lastname: Floeter
authors.forename: Reversa
authors.initials: R
authors.lastname: Mills
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D018450:Disease Progression; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology; D012720:Severity of Illness Index