A new instrument for measuring stuttering severity has been standardized on 109 children and 28 adults. The instrument attempted to meet the criteria of simplicity, objectivity, sensitivity to fluency changes of clinical significance, reliability, validity, and usability with children and adults. The frequency, duration, and associated physical concomitants of prolongations or repetitions of short speech segments are described. Procedures have been devised for scoring so that a range of 0 to 45 is possible. The statistical reliability and validity appear to qualify the instrument for clinical and research uses.

Position emission tomography using 6-FDOPA as a marker of presynaptic dopaminergic activity was used to investigate the role of the dopamine system in stuttering. Three patients with moderate to severe developmental stuttering were compared with six normal controls. Stuttering subjects showed significantly higher 6-FDOPA uptake than normal controls in medial prefrontal cortex, deep orbital cortex, insular cortex, extended amygdala, auditory cortex and caudate tail. Elevated 6-FDOPA uptake in ventral limbic cortical and subcortical regions is compatible with the hypothesis that stuttering is associated with an overactive presynaptic dopamine system in brain regions that modulate verbalization.

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