Progressive Supranuclear Palsy—Parkinsonism Predominant (PSP-P)—A Clinical Challenge at the Boundaries of PSP and Parkinson's Disease (PD)

Abstract

Progressive Supranuclear Palsy (PSP) and Parkinson's Disease (PD), especially in their early stages, show overlapping clinical manifestations. The criteria for the diagnosis of PSP, released in 2017, indicate four basic features of the disease-postural instability (P), akinesia (A), oculomotor dysfunction (O) and cognitive and lingual disorders (C), which clarify the interpretation of the disease. There is growing interest in the second most common variant of PSP-parkinsonism predominant PSP-P. It is observed in up to 35% of cases. The diagnosis of PSP-P requires the presence of akinetic-rigid predominantly axial and levodopa resistant parkinsonism (A2) or parkinsonism with tremor and/or asymmetric and/or levodopa responsive (A3). The development of supplementary methods of examination added new insights to observations related to PSP-P. Among the methods recently analyzed are freezing of swallowing and speech breathing assessment, transcranial sonography, and various methods using magnetic resonance imaging, such as pons/midbrain area ratio and magnetic resonance parkinsonism index (MRPI), fractional anisotropy or mean diffusivity. The proper examination of overlapping parkinsonian syndromes, regardless of the development of the method of examination, remains an incompletely explored issue. The aim of this review is to elucidate which factors may be interpreted as influential in the differential diagnosis of PSP-P, PSP-RS and postural instability and gait difficulty (PIGD) subtype of Parkinson's disease (PD).

Fixel-Based Analysis of White Matter Degeneration in Patients With Progressive Supranuclear Palsy or Multiple System Atrophy, as Compared to Parkinson's Disease

“…Patients with PSP have a reduced FDC in both the corona radiata and internal capsules. Such alterations are in line with the higher severity of motor deficits observed in patients with PSP than in those with PD (Alster et al, 2020 ).…”

Clinical Features of Patients With Progressive Supranuclear Palsy in an US Insurance Claims Database

“…This study, therefore, reports primarily on PSP-RS, not other subtypes of PSP, and is likely an underestimation of the prevalence of all types of PSP. However, some of the patients in this study may also have PSP-P, which is the second most common variant of PSP and observed in up to 35% of cases ( 30 ). In the only epidemiologic study including PSP subtypes other than PSP-RS, conducted in Japan, the prevalence of PSP-RS only was 13.8 per 100,000, while the prevalence of all PSP was higher at 17.3 per 100,000 ( 21 ).…”

Diagnostic accuracy of MR planimetry in clinically unclassifiable parkinsonism

“…MSA patients had increased 3 rd V width, which is in accordance with a volumetric MRI study [12] reporting larger ventricular system (including lateral, third and fourth ventricles) in MSA and PSP compared to PD patients. In our CUP-cohort, diagnostic accuracy was better for PSP-RS than for PSP-P, most probably because PSP-P is associated with a less severe course of the disease and less severe atrophy of infratentorial brain structures [10] pathognomonic for PSP as assessed with MR planimetry.…”