Stuttering Severity Instrument–Fourth Edition

Normal disfluency (ages 2–4): whole-word or phrase repetitions (smooth, effortless, e.g., 'I I I want'), <1% syllables, minimal or no visible struggle, no awareness or frustration, no family concern. Stuttering: syllable or sound repetition (e.g., 's-s-see'), ≥1% syllables stuttered, visible tension/effort/struggle, awareness and frustration, family concern. SSI-4 with low frequency (<1%), no physical tension scores indicates disfluency; scores with higher frequency + tension indicate stuttering. When in doubt, repeat SSI-4 after 2–4 weeks; persistent stuttering (not brief disfluency fluctuation) warrants monitoring and possible early intervention.

No fixed score mandates therapy; clinical judgment considers: (1) SSI-4 severity (Mild+ typically warrants therapy consideration); (2) age (preschool with even Mild stuttering is candidate for early intervention, maximizing responsiveness; school-age with Mild may monitor if no family concern); (3) impact (child's awareness, frustration, communication avoidance; parent concern); (4) trajectory (SSI-4 increasing over 2–4 weeks suggests persistence, warranting intervention; stable/improving scores suggest monitoring). Most consensus guidelines recommend treatment evaluation for any child with consistent stuttering (SSI-4 Mild or higher, or >1% syllables) for ≥3 months.

Meaningful improvement: ≥3 percentile-rank points or shift to next milder Severity category (e.g., Moderate → Mild). Minimal improvement: <1 percentile change or no category shift. Modest improvement: 1–2 percentile points or subtle category shift. Measure SSI-4 at baseline and every 4–8 weeks; if no improvement after 8–12 weeks of treatment, modify approach (different fluency strategy, reduce frequency of sessions, refer to specialized stuttering clinic).

SSI-4 can be administered to document current stuttering severity in adults with acquired stuttering, but interpretation is limited because SSI-4 norms are based on developmental stuttering. Use SSI-4 as a change measure (compare post-stroke SSI-4 to baseline pre-event score if available) or as a descriptive severity measure (frequency, duration, concomitants) rather than age-normed percentile. Acquired stuttering often has different underlying mechanism (neurological) than developmental stuttering; consult neurogenic speech-language pathology literature for outcome expectations and intervention.