Table 2

Positive clinical features of functional communication and swallowing disorders

Positive clinical signs of FNDGeneral examples in functional communication and swallowing disorders
Symptoms are inconsistent with clinical examination and laboratory/imaging findings
  • Severity of speech deficit is disproportionate to severity of injury or locus of lesion (eg, single lacunar stroke; mild traumatic brain injury).

  • Total or partial loss of voice despite normal structure and function of vocal folds during laryngoscopy.

Symptoms are internally inconsistent
  • Resolution or reduced severity during small talk or other spontaneous discussion, when attention is diverted, or during natural automatic functions, preverbal and/or automatic utterances, playful, emotionally expressive activities, during laryngeal manipulation (voice disorders).*

  • Suggestibility—for example, the symptom becomes much more prominent when it is being discussed.

Symptoms are associated with inefficient and non-ergonomic patterns of movement
  • When weakness is major complaint, speech, voice, swallowing fatigues in the direction of muscle hyperfunction.

  • Struggle behaviours—overmouthing, eye blinking, facial contortions, excessive effort in breathing, neck, shoulders, strap muscles, shifts in body posture—including during non-speech oromotor tasks.

  • *Note that many structural/neurological communication disorders can show symptom fluctuations. The core difference is that in structural/neurological cases one can discern plausible predictability in how/when/where symptoms vary—for example, in relation to fatigue, time in medication cycle, cognitive load and language variables such as word frequency, syllable complexity, stress placement in word/sentence. These underlying regularities tend not to be present in functional communication and swallowing disorders.

  • FND, functional neurological disorder.