Accuracy and inter-observer variation in the classification of dysarthria from speech recordings

Dysarthria may be classified as flaccid, spastic, ataxic, hypokinetic, choreatic, dystonic, or mixed. We hypothesized that in routine neurological practice the reliability and accuracy of perceptual analysis alone in the classification of dysarthria is low and that this classification is mainly based on the clinical context rather than on the perception of speech. We therefore studied the accuracy and the inter- observer agreement in the classification of dysarthrias on the basis of perceptual analysis alone. Seventy two neurologists and neurological trainees classified recorded speech samples of 100 patients as flaccid, spastic, ataxic, extrapyramidal, or mixed dysarthria, or as not dysarthric. All observers were blinded to the patients' final diagnosis, which was based on all clinical features and investigations. In the analysis the observers were arranged in eight groups of nine observers, or four paired groups with similar levels of clinical experience. Together, the observers in a given group rated all 100 recordings. The accuracy of the classification was poor (35 % were classified correctly) and the inter-observer agreement between paired groups low (kappa 0.16 to 0.32). The level of experience in neurology did not have a significant influence. Neurological trainees as well as experienced neurologists have great difficulty in identifying specific types of dysarthria on the basis of perceptual analysis alone. In clinical practice this probably means that most neurologists will classify dysarthria in the context of other features from neurological examination or ancillary investigations.