Progressive supranuclear palsy (PSP)
General description
Progressive supranuclear palsy (PSP) is a neurodegenerative disorder that typically manifests in middle or late adulthood. Pathologically, it is characterized by neuronal loss in the globus pallidus, subthalamic nucleus, dentate nucleus of the cerebellum, red nucleus, substantia nigra, and brainstem tegmentum, along with the accumulation of abnormally phosphorylated tau protein within neurons and glial cells.
Clinically, the disease is marked by early falls, supranuclear gaze palsy, parkinsonism, and cognitive impairment. The underlying cause remains unknown.
Initial symptoms may resemble those of Parkinson's disease, although resting tremor is uncommon. Instead, early manifestations often include frequent falls, stooped posture, and postural instability during gait. As the disease progresses, patients develop cervical retrocollis, a recumbent posture, and vertical supranuclear gaze palsy. Additional features include dysarthria, dysphagia, and cognitive impairment. Gradually, patients become immobile and bedridden, unable to maintain a standing position or ambulate independently.
Atrophy of midbrain tegmentum
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BrainstemMidbrainMidbrain tegmentum
On MRI, Progressive supranuclear palsy (PSP) is characterized by focal atrophy of the midbrain tegmentum, while the base of the pons is typically preserved. A key imaging finding is a reduced sagittal midbrain tegmentum area, typically measuring less than 70 square millimeters.
T2WI and FLAIR hyperintensity
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BrainstemMidbrainMidbrain tegmentum
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BrainstemPonsPontine tegmentum
In some cases of Progressive supranuclear palsy (PSP), hyperintense signal abnormalities may be observed along the midbrain and pontine tegmentum on FLAIR sequences.
Cerebral atrophy and decreased CBF
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CerebrumFrontal lobe
As Progressive supranuclear palsy (PSP) advances, neuroimaging studies demonstrate atrophic changes involving the frontal lobes. Additionally, cerebral blood flow single-photon emission computed tomography (CBF SPECT) reveals reduced perfusion in these regions as the disease progresses.
Atrophy of basal ganglia
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Subthalamic nucleus
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Globus pallidus
Neuroimaging studies in progressive supranuclear palsy (PSP) demonstrate symmetric atrophy of the subthalamic nuclei, which is a relatively specific finding in this condition. In advanced cases, bilateral atrophy of the globus pallidi is also noted.