General
- AKA
- Steele-Richardson-Olszewski syndrome.
- Primary supranuclear palsy
- Downward gaze paresis
- Nuchal rigidity
- Progressive dementia
Triad
- Progressive supranuclear ophthalmoplegia (chiefly vertical gaze-downward gaze palsy):
- Paresis of voluntary vertical eye movement, but still moves to vertical doll’s eyes maneuver
- Only a minority of patients present with gaze palsy.
- Symptomatic eye movement abnormalities begin at a median of 4 years after disease onset
- Early signs
- The first ocular motility abnormality noted impairment of vertical saccades.
- Eventually, most patients with progressive supranuclear palsy show slow or absent vertical saccades.
- Downgaze is affected before the upgaze.
- Later signs
- Saccadic intrusions into fixation ("square wave jerks"), loss of optokinetic nystagmus (particularly in the vertical direction), loss of convergence, blepharospasm, and eyelid-opening apraxia.
- The patient is often unable to suppress the horizontal vestibulo-ocular reflex.
- End stage signs
- The vestibulo-ocular reflex is present until late in the disease, but with disease progression and brainstem involvement, vestibulo-ocular reflexes may be lost.
- Eventually, supranuclear gaze palsy may be present in all directions, and toward the end of the disease, the eyes may be virtually immobile.
- Pseudobulbar palsy
- Mask-like facies with marked dysarthria and dysphagia, hyperactive jaw jerk, emotional incontinence usually mild
Axial dystonia (especially of neck and upper trunk)
- Falls back wards
Associated findings
- Subcortical dementia (inconstant),
- Motor findings of pyramidal, extrapyramidal and cerebellar systems.
Pathophysiology
- Defining histopathologic feature
- Intracerebral aggregation of the microtubule-associated protein tau with preferential involvement of the subthalamic nucleus, pallidum, striatum, red nucleus, substantia nigra, pontine tegmentum, oculomotor nucleus, medulla, and dentate nucleus.
- The aggregates predominantly contain tau isoforms with four microtubule-binding repeats (4R-tau) in neurofibrillary tangles, oligodendrocytic coils, and astrocytic tufts.
- Normally, tau is phosphorylated on a series of serine and threonine residues, regulated by numerous kinases and phosphatases.
- In progressive supranuclear palsy and other tauopathies, the tau protein is hyperphosphorylated, which causes it to lose its affinity for microtubules and become resistant to proteolysis. This results in the accumulation of tau and the formation of neurofibrillary tangles.
Numbers
- Average age of onset: 60 yrs.
- Males comprise 60%.
- Average survival after diagnosis: 5.7 yrs.
Clinical features
- Early
- Many falls
- Due to dysequilibrium + downgaze palsy (can’t see floor)
- Falls backwards (unlike parkinsons which falls forward)
- Eye findings
- Initially normal
- Later develop
- Difficulty looking down (especially to command, less to following)
- Calorics have normal tonic component but absent nystagmus (cortical component)
- Slurred speech
- Personality changes
- Difficulty eating
- Due to pseudobulbar palsy + inability to look down at food on plate
- Late
- Eyes fixed centrally (no response to oculocephalics or oculovestibulars): ocular immotility is due to frontal lobe lesions
- Neck stiffens in extension (retrocollis)
Treatment
- None
- Response to anti-parkinson drugs is usually very short lived.
Outcome
- Average survival after diagnosis: 5.7 yrs.
Differentiating from Parkinson’s disease
- Patients with PSNP have a pseudo-parkinsonism.
- Have mask facies (same as parkinsons)
- Do not walk bent forward (they walk erect)
- Do not have a tremor (parkinsons have tremour)
- Fall backwards (parkinsons fall foward)
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