Progressive supranuclear palsy frequently misdiagnosed
A retrospective study of Chinese patients in Hong Kong highlights the high misdiagnosis rate of progressive supranuclear palsy (PSP) and identifies important clinical milestones for guiding advanced care planning (ACP) for patients with the condition.
Study authors retrospectively reviewed clinical records of all patients who presented to the geriatric clinics of Queen Mary Hospital and Tuen Mun Hospital between January 2008 and December 2017. Of the 21 patients (mean age at presentation, 67.6 years; 76.2 percent male) included in the final analysis, 19 had Richardson syndrome variant, one had PSP-corticobasal syndrome, and one had PSP with language impairment. [Hong Kong Med J 2019, doi: 10.12809/hkmj198101]
“An accurate diagnosis of PSP is important for management of affected patients, but only 43 percent of patients in this study received a correct diagnosis at the time of initial presentation,” wrote the researchers.
At the time of presentation to the geriatric clinic, 12 patients (57 percent) received another diagnosis, most commonly, Parkinson’s disease (nine patients), as well as Lewy body dementia, cervical myelopathy, and myasthenia gravis (one patient each).
Motor manifestations were among the earliest clinical features observed in patients with PSP. Gait impairment, falls and limb stiffness were most prevalent during initial presentation, affecting up to a third of patients. All motor features showed increased prevalence over time, with final prevalence rates ranging from 47.6 percent to 100 percent.
While rarely existent at presentation, aspiration pneumonia, dysarthria and dysphagia requiring Ryle’s tube insertion reached 100 percent prevalence over time. The degree of caregiver stress also increased with disease progression, reaching approximately 40 percent within 5 years after initial presentation.
Vertical gaze palsy (VGP) was present in 19 percent of patients at the time of presentation, but eventually affected all patients. According to the authors of the study, low prevalence of VGP at presentation could be the reason for original misdiagnosis of PSP. “Clinicians should regularly assess patients with parkinsonism for the presence of any VGP or poor response to levodopa, in order to correctly identify patients with PSP,” they recommended. “Earlier development of VGP [hazard ratio (HR), 4.4; 95 percent confidence interval (CI), 1.4 to 13.9; p=0.01] was predictive of mortality from disease onset,” they noted.
Memory impairment (33.3 percent) and apathy (23.8 percent) were the two most frequent cognitive symptoms at presentation. Apathy, along with dysphagia, Ryle’s tube feeding, pneumonia and pressure injuries, was predictive of mortality from both disease onset and presentation. “The finding of apathy as a time-dependent covariate for prediction of mortality is notable. Future clinical trials may consider the use of therapeutic measures to address apathy,” wrote the researchers.
“Because there is currently no disease-modifying treatment for patients with PSP, symptomatic care plays an important role,” noted the researchers. “Relevant symptoms include dystonia, drooling, reduced blinking, constipation, and apathy, which can be managed by the administration of sublingual atropine drops, frequent application of lubricating eyedrops, use of prisms or audiobooks, and use of eyeglasses or hearing aids, respectively,” they suggested.
“Important clinical milestones, including the development of dysphagia, VGP, significant caregiver stress, pressure injuries, and pneumonia, may be used to guide discussions of ACP with patients and caregivers in order to facilitate long-term care,” they concluded.