Functional (psychogenic) symptoms in Parkinson's disease

Abstract

It has been reported that patients who have Parkinson's disease have a high prevalence of somatisation (functional neurological symptoms) compared with patients who have other neurodegenerative conditions. Numerous explanations have been advanced for this phenomenon. Here, with illustrative cases, we discuss this topic, including its clinical importance, and suggest a link between the pathophysiology of Parkinson's disease and the proposed propensity to develop functional symptoms.

Functional neurological disorders in Parkinson disease

“…Year of symptom onset and clinical diagnosis for PD and FND were recorded. Neurological and psychiatric comorbidities and FND symptom onset were analysed in relation to timing of PD diagnosis 6. Dosage of dopaminergic therapy, history of DBS and outcome of [(123)I]FP-CIT SPECT (DATscan) were also recorded, when available.…”

“…Some features such as gastric symptoms, anxiety and pain are difficult to correctly classify as FND3–5 and may instead represent non-motor features of PD. Nevertheless, in a series of 11 patients with PD and FND, 4 exhibited functional manifestations predating PD diagnosis 6. Most of these functional symptoms led to significant disability and escalation of PD treatment, including requests for consideration of deep brain stimulation (DBS).…”

Functional (Psychogenic) Cognitive Disorders: A Perspective from the Neurology Clinic

“…Neurological or medical disorders may also be complicated by additional functional symptoms. [36,37] The discovery of such symptoms (for instance through internal inconsistencies) should not stop the clinician from considering consider whether another disease process is also present [38]. Patients may also develop functional symptoms such as paralysis as part of a prodrome of dementia.…”

A role for accelerometry in the differential diagnosis of tremor syndromes

“…It must also be underlined that the criteria pertaining to PD-T apply only to patients with classic PD-T (Type I), and not to variants of PD or other tremors. Some patients with PD may display isolated postural and kinetic tremor (Type III) (Deuschl et al, 1998), dystonic tremor due to focal dystonia (Deuschl, 2003), or functional tremor as coexistent features with PD (Parees et al, 2013). In such instances, clinical evaluation should guide instrumental analysis and interpretation of metrics generated.…”