Neuromodulation for the treatment of functional neurological disorder and somatic symptom disorder: a systematic review

Abstract

Functional neurological disorder and somatic symptom disorder are complex neuropsychiatric conditions that have been linked to circuit-based dysfunction of brain networks. Neuromodulation is a novel therapeutic strategy capable of modulating relevant brain networks, making it a promising potential candidate for the treatment of these patient populations. We conducted a systematic review of Medline, Embase and PsycINFO up to 4 March 2021. Trials investigating neuromodulation devices for the treatment of functional neurological disorder or somatic symptom disorder were selected. Extracted variables included study design, demographic and clinical characteristics, psychiatric comorbidity, neurostimulation protocols, clinical outcome measures and results. 404 studies were identified with 12 meeting inclusion criteria. 221 patients were treated in the included studies with mean study sample size of 18 (4–70). Five studies were randomised clinical trials. Functional motor symptoms (six weakness, four movement disorders) were the most studied subpopulations. Transcranial magnetic stimulation (TMS) was the most frequently used device (10 studies), followed by electroconvulsive therapy (one study) and direct-current stimulation (one study). Treatment protocols varied in intended therapeutic mechanism(s): eight studies aimed to modulate underlying network dysfunction, five aimed to demonstrate movement (one also leveraged the former) and three boosted their primary mechanism with enhanced suggestion/expectation. All but one study reported positive results; however, methodological/outcome heterogeneity, mixed study quality and small sample sizes precluded quantitative meta-analysis. Neuromodulation, particularly TMS for the treatment of functional motor symptoms, shows preliminary promise in a growing line of research. Larger, sham-controlled studies are needed to further establish efficacy and better understand therapeutic mechanisms.

Non-invasive neuromodulation of the right temporoparietal junction using theta-burst stimulation in functional neurological disorder

“…Although the presented sample is relatively large in comparison with other rTMS studies in the field, 17 18 we acknowledge the sample size of 23 patients and 19 HC as a major limitation. This furthermore prevented us from performing subgroup analyses to determine whether specific symptom types would be more responsive to neuromodulation.…”

“…Although an increasing amount of empirical work on NIBS in FND has emerged recently, reports on rTMS protocols are scarce and constraint with heterogeneity in methods and outcome measures 17 18. Only two studies investigated the potential of rTMS over the rTPJ: one case report on a single patient19 and one case series of seven patients20 with functional seizures reporting improved symptom severity after rTMS over the rTPJ.…”

“…Whereas NIBS has predominantly been used to improve symptom severity in FND,17 we set out to assess the effect on the SoA’s neural correlates. The rTPJ activity was previously found to be enhanced during an incongruence condition of an action-recognition task with manipulated visuomotor feedback in healthy controls (HC), and behavioural measures of SoA were successfully modulated by cTBS applied over this region 21.…”

Case report: New insights into persistent chronic pelvic pain syndrome with comorbid somatic symptom disorder

“…Furthermore, neuromodulation, which modulates relevant brain networks, may be a promising treatment option. In a systematic review, TMS was found to be the most frequently used treatment, followed by electroconvulsive therapy and tDCS (35). It may reduce opioid use when combined with exercise and other components of interdisciplinary rehabilitation.…”

Neurovisceral interactions within the brain-heart axis as the basis of neurocardiology

“…Кроме того, существует группа расстройств, при которых нарушение интероцепции является центральной проблемой -соматоформные расстройства по международной классификации болезней 10 пересмотра (МКБ-10) (расстройства с соматическими симптомами по МКБ 11 пересмотра). Применение нейромодуляции при данных расстройствах могло бы быть перспективным, однако систематический обзор [73] показывает, что нейромодуляция в основном применяется для лечения двигательных функциональных расстройств, а не соматоформных расстройств с преобладанием интероцептивных симптомов. Перспективным представляется выявить объективные показатели нарушений интероцепции при соматоформных расстройствах, чтобы повысить надежность диагностики и облегчить маршрутизацию пациентов с кардиологическими жалобами без выявляемой патологии сердца к психиатру.…”