Speech, language and swallowing impairments in functional neurological disorder: a scoping review

Background: Functional neurological disorder (FND) is common across healthcare settings. The Diagnostic and Statistical Manual of Mental Disorders states that speech and swallowing symptoms can be present in FND. Despite this, there is a dearth of guidelines for speech and language therapists (SLTs) for this client group.

Aims: To address the following question in order to identify gaps for further research: What is known about speech, language and swallowing symptoms in patients with FND?

Methods & procedures: A scoping review was conducted. Six healthcare databases were searched for relevant literature: CINAHL PLUS, MEDLINE, ProQuest Nursing and Allied Health Professionals, Science Citation Index, Scopus, and PsychINFO. The following symptoms were excluded from the review: dysphonia, globus pharyngeus, dysfluency, foreign accent syndrome and oesophageal dysphagia.

Main contribution: A total of 63 papers were included in the final review; they ranged in date from 1953 to 2018. Case studies were the most frequent research method (n = 23, 37%). 'Psychogenic' was the term used most frequently (n = 24, 38%), followed by 'functional' (n = 21, 33%). Speech symptoms were reported most frequently (n = 41, 65%), followed by language impairments (n = 35, 56%) and dysphagia (n = 13, 21%). Only 11 publications comment on the involvement of SLTs. Eight papers report direct speech and language therapy input; however, none studied the effectiveness of speech and language therapy.

Conclusions & implications: Speech, language and swallowing symptoms do occur in patients with FND, yet it is a highly under-researched area. Further research is required to create a set of positive diagnostic criteria, gather accurate data on numbers of patients with FND and speech, language or swallowing symptoms, and to evaluate the effectiveness of direct speech and language therapy involvement.