Progressive supranuclear palsy (Steele-Richardson-Olszewski)

Diagnosis

Clinical criteria; all core diagnostic features and no exclusion features must be present 113

1) Core diagnostic features of probable PSP

a. Gradually progressive disorder

b. Onset at age 40 or later

c. Vertical supranuclear palsy (upward or downward gaze) and prominent postural instability with fall in the first year of disease onset

d. No evidence of other diseases that could explain the above features

2) Core diagnostic features of possible PSP

a. At least one of the following must be present:

i. Vertical supranuclear palsy (upward or downward gaze)

ii. Both slowing of vertical saccades and prominent postural instability with falls in the first year of disease onset

3) Supportive diagnostic features of PSP

a. Symmetric akinesia or rigidity, proximal > distal

b. Abnormal neck posture

c. Early dysphagia and dysarthria

d. Poor or absent response of Parkinsonism to levodopa

e. Early onset of cognitive impairment (about 20% of PSP patients initially present with features of FTD such as behavioral changes or language impairments and up to 30% of PSP patients will meet criteria for bvFTD 95) including at least two of the following:

i. Apathy

ii. Impairment of abstract thought

iii. Decreased verbal fluency

iv. Utilization or imitation behavior

v. Frontal release signs

f. Neuropsychological pattern of performance with executive dysfunction and relatively preserved memory with good recognition

4) Exclusion criteria for PSP

a. Recent history of encephalitis

b. Alien limb syndrome, cortical sensory deficits, focal frontal or temporoparietal atrophy

c. Hallucinations or delusions

d. Cortical dementia of Alzheimer’s type (severe amnesia and aphasia or agnosia)

e. Prominent, early cerebellar symptoms or prominent, early unexplained dysautonomia (marked hypotension and urinary disturbance)

f. Severe, asymmetric Parkinsonism (e.g., bradykinesia)

g. Whipple’s disease

Golbe et al created a clinical rating scale for PSP with good interrater reliability 114. Based on patient scores it was also a good independent predictor of survival. It comprised of 28 items across six categories, scored 0 to 100. Examples include

• Daily activities (by history): withdrawal, irritability, dysphagia for solids, using a knife and fork / buttoning clothes / washing hands and face, falls, urinary incontinence, sleep difficulty
• Mentation / behavior: disorientation, bradyphrenia, emotional incontinence, grasping/imitative/utilizing behavior
• Bulbar: dysarthria, dysphagia
• Ocular motor: voluntary upward, downward, left, and right command movements, eyelid dysfunction,
• Limb motor: limb rigidity, limb dystonia, finger tapping, toe tapping, apraxia of hand movement, tremor in any part
• Gait / midline: neck rigidity or dystonia, arising from chair, gait, postural stability, sitting down

Examination

- Neurological examination will generally show axial rigidity, narrow-based gait (despite history of falls), slowed vertical saccades, dysarthria, apathy/depression, slowed speech and thought process. As the disease progresses, the patient develops akinetic/rigid Parkinsonism, dystonia, ophthalmoplegia of the vertical gaze, verbal apraxia, pseudobulbar palsy, and frontal release signs 95

- Neuropsychological testing demonstrates slowed processing speed, especially on executive function and verbal fluency; comprehension and memory are relatively spared.

Imaging

T1 MRI of 71-year-old patient with PSP (Ljubenkov and Miller 2016) - Sagittal view shows “hummingbird sign” including atrophic midbrain tegmentum (dashed arrow) resembling humminbird’s head and a relatively preserved basis pontis (solid arrow) that resembles the hummingbird’s belly).

Pathology

- Pathology is generally 4R tau (PSP > CBD) (Ljubenkov and Miller 2016)

References

Ljubenkov, P. A. & Miller, B. L. A Clinical Guide to Frontotemporal Dementias. FOCUS 14, 448–464 (2016). https://pubmed.ncbi.nlm.nih.gov/31975825/