Abstract
Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are clinical syndromes classified as atypical parkinsonism. Due to their overlapping symptomatology, recent research shows the necessity of finding new methods of examination of these clinical entities. PSP is a heterogenic disease. PSP Richardson-Steele Syndrome (PSP-RS) and parkinsonism predominant (PSP-P) are the most common clinical variants of progressive supranuclear palsy syndrome. The different clinical course and life expectancy of PSP-RS and PSP-P stress the need of efficient examination in the early stages. The aim of the study was to evaluate the possible feasibility of the combined use of frontal assessment battery (FAB) and single-photon emission computed tomography (SPECT) in the differentiation of PSP-RS, PSP-P, and CBS. The findings show that FAB may be interpreted as a possible supplementary tool in the differential diagnosis of PSP-P and PSP-RS. The differences in SPECT are less pronounced. The study does not show any advantages of performing combined frontal SPECT and FAB in the differential examination of PSP and CBS. Moreover, PSP-RS and CBS, in a detailed evaluation of the frontal lobe, do not show any significant differences. This is a relatively small study which, however, highlights the relevant features of clinical examination of these rare entities.
Highlights
The examination of tauopathic atypical parkinsonism remains a difficult issue
In the case of Progressive supranuclear palsy (PSP)-RS, only the frontal assessment battery (FAB) turned out to be a significant parameter differentiating this subgroup from the others with area under the ROC curve (AUC) of 0.691 and cutoff of 12, with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and ACC at 72.2, 65.2, 61.9, 75, and 68.3%, respectively (Table 2 and Figure 1)
The best overall performance revealed frontal lobe (AAL) L with AUC = 0.71 and with cutoff value equal to −2.2 and sensitivity, specificity, PPV, NPV, and ACC at 75, 95.7, 90, 88, and 88.6%, respectively (Figure 3B)
Summary
The examination of tauopathic atypical parkinsonism remains a difficult issue. The differentiation of progressive supranuclear palsy syndrome and corticobasal syndrome (CBS) is affected by significant overlaps in the diseases’ symptomatology. Previous studies with SPECT-99mTc-HMPAO conducted on patients with tauopathic atypical parkinsonism showed thalamic hypoperfusion in PSP which, did not confirm any significant differences of perfusion between PSP and CBS [6, 7]. A combined assessment using dopamine transporter and perfusion SPECT was evaluated in a paper by Van Laere et al where the authors attempted to define the role of this assessment in the differential diagnosis of parkinsonism [8]. Another work presented the differentiation of parkinsonism using technetium-99m ethyl cysteinate dimer It confirmed a potentially beneficial role in the differential diagnosis of MSA and idiopathic Parkinson’s disease (PD) [10]. A study evaluating Tc-99m ethylene cysteinate in the SPECT examination of PD and MSA showed elevated perfusion in the lentiform, cerebellum, and thalamus among patients with PD [11]
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