Clinimetric Analysis of the Motor Section of the Progressive Supranuclear Palsy Rating Scale: Reliability and Factor Analysis. Permalink

Introduction: PSP is a rare degenerative disorder associated with significant morbidity. Recently, investigations of the etiology and treatment of PSP have been initiated. The aim of the present study was to validate the motor domain of the Progressive Supranuclear Palsy Rating Scale (PSPRS) as part of a larger epidemiological study. Methods: Fifty videos of patients with PSP were rated by four trained movement disorder neurologists using the PSPRS. Reliability and construct validity of the scale were evaluated using standard methods. Results: Inter-rater reliability for the total scale score was good. Internal consistency of the scale improved with the removal of three items. Four factors accounted for the majority of the variance of the scale as determined by principal components analysis. Discussion: This study shows that the motor domain of the PSPRS is a reliable scale, with a factor structure that suggests construct validity, for the assessment of motor signs of the disease. Removal or modification of items may improve the clinimetric features of the motor domain of the scale. PSP is a rare neurodegenerative disorder characterized by postural instability with falls, axial rigidity, oculomotor deficits, spastic/ataxic dysarthria, and frontal-type dysfunction. The PSP Rating Scale (PSPRS), developed by Golbe and Ohman-Strickland, has 28 items with total scores ranging from 0 to 100. The scale is divided into interview and examination sections and assesses five domains: history, mentation, bulbar, ocular motor, and limb motor functions. The history items (n = 7) include questions regarding activities of daily living (ADLs) and subjective measures of symptoms. The mentation items (n = 4) are scored by the examiner based on the interference of the sign with ADLs. Bulbar items (n = 2) address dysarthria and dysphagia, and ocular motor items (n = 4) allow the examiner to assess saccades and eyelid function. The largest domain, limb motor (n = 11), includes items for evaluation of bradykinesia, apraxia, tremor, rigidity, and gait. The aim of this study was to validate the motor domain of the PSPRS, as part of a larger study investigating environmental and genetic risk factors for PSP (R01 AG024040). Materials and Methods A structured videotape protocol was developed to capture the PSPRS motor domain, including bulbar, ocular motor, limb motor, and gait/midline items (16 items total). Only the motor items of the PSPRS were included owing to the fact that the other sections of the scale are more difficult to capture with video. The limb rigidity item was not videotaped. The following items did not have instructions on the PSPRS, so the score of the worse of the two sides was used, with the worse score counted as one item: voluntary left and right command movement (ocular motor); apraxia of hand movement; and tremor in any part. Neck rigidity/dystonia was scored, with the caveat that rigidity may not be assessable by video. Video recordings were divided into individual PSPRS items for scoring review. Four movement disorder neurologists, who were trained in person by the principal investigator (PI; I.L.) of this study to use the scale, rated videos of 50 subjects consisting of 44 PSP patients, 5 Parkinson’s disease (PD) patients, and 1 patient with Department of Neurological Sciences, Rush University, Chicago, Illinois, USA; Department of Neurosciences, University of California San Diego, Sand Diego, California, USA; Department of Neurology, University of California Los Angeles, Los Angeles, California, USA; Department of Neurology, Case Western Reserve University, Cleveland, Ohio, USA; Department of Neurology, University of Washington, Seattle, Washington, USA; Department of Neurology, University of Alabama at Birmingham, Birmingham, Albama, USA *Correspondence to: Dr. Deborah A. Hall, Department of Neurological Sciences, Rush University, 1725 West Harrison Street, Suite 755, Chicago, IL 60611, USA; E-mail: deborah_a_hall@rush.edu