Observational Study on "Functional Overlay" in Patients With Movement Disorders

Last updated: September 23, 2025
Sponsor: Medical University of Graz
Overall Status: Active - Recruiting

Phase

N/A

Condition

Tardive Dyskinesia

Anxiety Disorders

Tic Disorders

Treatment

Neurological examination

Anamnesis

Tremor recording

Clinical Study ID

NCT05943652
34-509 ex 21/22
  • Ages 18-18
  • All Genders

Study Summary

The goal of this observational study is to learn about functional neurological disorders in patients with common non-functional movement disorders ("functional overlay"). The main questions it aims to answer are:

  • What is the frequency of functional neurological disorders in patients with non-functional movement disorders (functional overlay)?

  • What are the characteristics of functional neurological disorders in patients with non-functional movement disorders?

Participants will be examined clinically and electrophysiologically, the examinations consist of:

  • a neurological examination

  • neuropsychological testing

  • electrophysiological tremor diagnostic

  • questionnaires about psychological, biological and social risk factors

Researchers will compare patients with functional motor disorders to patients wit non-functional movement disorders to see if they differ from each other regarding the functional symptoms.

Eligibility Criteria

Inclusion

Inclusion Criteria:

  • Functional or non-functional movement disorder

  • 18 to 80 years

Exclusion

Exclusion Criteria:

  • Patient is not able to consent

  • Patient is not able to understand / speak German fluently (questionnaires areavailable only in German)

Study Design

Total Participants: 216
Treatment Group(s): 5
Primary Treatment: Neurological examination
Phase:
Study Start date:
January 01, 2023
Estimated Completion Date:
June 30, 2026

Study Description

Functional neurological disorders (FND) are common neurological disorders that are present in up to 16% of patients in neurological outpatient clinics. They are associated with a significant reduction in quality of life, can lead to permanent impairment, and have a poor prognosis, especially if the diagnosis is delayed.

FND have multifactorial causes and risk factors, including psychological stressors, childhood trauma, female gender, psychiatric disorders such as depression, anxiety disorder, or post-traumatic stress disorder, and other functional disorders such as irritable bowel syndrome or chronic pain syndrome. Patients with FND often report additional cognitive complaints ("cognitive fog").

A mismatch of various regulatory mechanisms, a disruption of sensory processing and motor output is assumed to be a central part of the pathogenesis. A characteristic feature of FND is a variability of symptoms according to attention. FND can be intensified by increased attention and weakened by distraction. Positive diagnostic criteria for FND have been established recently, so that by definition FND are no longer a diagnosis of exclusion.

The clinical presentations of FND are diverse and include impaired limb movement control, disturbances in vigilance that may be associated with seizures, and non-motor symptoms. FND often coincide and often coexist with pain, fatigue, sleep disorders, and cognitive disorders. Particularly non-motor functional symptoms are highly debilitating for patients.

The coincidence of "organic" neurological disorders and FND in the same patients ("functional overlay") is probably not uncommon, but has been investigated primarily in patients with Parkinson's Disease and epilepsy, so far. However, it is important to recognize FND in patients with movement disorders in order to treat them adequately and to protect them from incorrect treatment (surgery, unnecessary medication, etc.). However, the basic prerequisite for this is an exploration of the frequency and characteristics of the functional symptoms in movement disorders.

Connect with a study center

  • Medical University of graz

    Graz, Styria 8010
    Austria

    Site Not Available

  • Medical University of graz

    Graz 2778067, Styria 2764581 8010
    Austria

    Active - Recruiting

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