Accurate Diagnosis of Functional Motor Disorders in Elders Critical to Long-Term Care, Management

Michele Tinazzi, MD, PhD

A recently published, Italian-based registry study described the clinical manifestations of functional motor disorders (FMD) among elders, with results suggesting that an accurate diagnosis is crucial for effectively managing FMD symptoms and addressing neurological comorbidities. Investigators noted that an incorrect diagnosis can have “serious” consequences, including initiation of unnecessary and potentially harmful therapies for an alternative neurological diagnosis.¹

Published in Movement Disorders, the analysis included 410 patients with a “clinically definite” diagnosis of FMD from the Italian Registry of Functional Motor Disorders (IRFMD). Of these, 34 (8.2%) were included in the elderly FMD onset group, considered at least 65 years of age. The elderly cohort was mostly comprised of females (79.4%), with a mean age of 74.3 (±5.2) years and mean age at FMD onset of 70.9 (±5.1) years. All told, the most frequent phenotype was tremor (47.1%), followed by gait disorders (29.4%), weakness (23.5%), and dystonia (14.7%).

Senior author Michele Tinazzi, MD, PhD, a professor of neurology at the University of Verona, and colleagues, aimed to assess the prevalence of FMD in a large cohort and describe the clinical manifestations of FMD in individuals with elderly and younger onset. Patients were further stratified into 4 groups: group 1, FMD with ages between 2 and 18 years old (pediatric); group 2, FMD with ages between 19 and 39 years old (adulthood); group 3, FMD with ages between 40 to 64 years old (late adulthood); and group 4, FMD with ages between 65 and 83 years old (elderly).

When compared with the younger FMD onset group, elderly patients with FMD reported less weakness (P = .012), panic attacks (P = .026), fatigue (P = .003), and sensory functional symptoms (P = .021). Moreover, elderly FMD onset patients reported more neurological and non-neurological comorbidities like parkinsonism (P = .017), cerebrovascular diseases (P = .005), hypertension (P = .001), dyslipidemia (P = .009) than younger FMD onset. Overall, when pooling non-motor and other FNDs, symptoms occurred more frequently in the younger group (335 of 376; 89.1%) compared with the elderly group (25 of 34; 73.5%).

"In our sample, we did not identify a distinct phenotype or risk factor for a specific group of FMD, suggesting that the clinical signs may not differ significantly across lifespan," the study authors wrote. "Therefore, our findings support the importance of establishing a comprehensive diagnosis in elderly people with FMD, rather than relying solely on phenotype or other clinical characteristics." Additionally, the explorative analysis suggested that patients with elderly FMD onset may have a shorter disease duration likely because of a delayed diagnosis.

When comparing groups, it was evident that neurological and non-neurological comorbidities were more prevalent in older patients with FMDs (28 of 34; 82.4%) as opposed to the younger group (123 of 376; P <.001). Onset of FMD in elders was linked with less use of painkillers (P = .006) and non-steroidal anti-inflammatory drugs (P = .034). In the elderly, 11 patients had a combined phenomenology: 9 patients had 2 phenotypes while 2 patients had 3 phenotypes.

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Logistic regression models were used to estimate the adjusted odds ratio (aOR) of elderly FMD onset in relation to sociodemographic and clinical characteristics. After mutually adjusting for such variables, the model confirmed the association between elderly age at FMD onset and the following variables: fatigue (aOR, 0.27; 95% CI, 0.11-0.68), parkinsonism (aOR, 6.73; 95% CI, 1.63-27.73), cerebrovascular diseases (aOR, 5.48; 95% CI, 1.48-20.25), and hypertension (aOR, 6.79; 95% CI, 3.12-14.80).

In the elderly, FMD appeared after the diagnosis of parkinsonism (100%; n = 4) and cerebrovascular diseases (100%; n = 5) at a mean latency of 1.7 (±2.4) and 1.2 (±0.8) years, respectively. When stratified by the 4 groups, elderly patients with FMD demonstrated several age-related comorbidities, including parkinsonism, cerebrovascular diseases, hypertension, and dyslipidemia. Of note, weakness as a functional symptom was less frequent in older patients while the other functional symptoms were equally distributed in the various age groups.

The study was limited by the fact that there was no control, as well as the cross-sectional design and reliance on clinical records and patient self-reports, which may have introduced recall bias. Investigators were also unable to assess the severity of recorded symptoms because of a lack of rating instrument for them, as well as evaluate the effects of treatments such as botulinum toxin, physiotherapy, and others. “Longitudinal studies are needed to investigate the long-term outcome of elderly FMD onset, including its impact in terms of disease severity, functional disability, and therapeutical interventions.

REFERENCE
1. Geroin C, Petracca M, Di Tella S, et al. Elderly onset of functional motor disorders: clinical correlates from the Italian registry. Mov Disord. Published online November 2, 2023. doi:10.1002/mdc3.13916