Sunday, 28 September 2014

Progressive Supranuclear Palsy MRI

Progressive Supranuclear Palsy (PSP)

Also known as the Steele-Richardson-Olszewski syndrome, a neuro degenerative disease with no treatment.

PSP typically becomes clinically apparent in the 6th decade of life, and progresses to death usually within next 2 decades from diagnosis.

Clinically characterized by decreased cognition, abnormal eye movements, vertical gaze palsy, postural instability and falls. Parkinsonian features and speech disturbances.

Investigation of choice is MRI.
Imaging features
Mid brain atrophy is must.
Hummingbird sign also known as the penguin sign on mid sagittal sections as in our case. The key is a flattening or concave outline to the superior aspect of the midbrain which should be upwardly convex.
Reduction of antero posterior mid line mid brain diameter, at the level of the superior colliculi on axial imaging (from interpeduncular fossa, to the inter colicular groove: < 12mm, give a mickey mouse appearance.
Reduced area of the midbrain on midline sagittal and  reduced midbrain to pons area ratio: approx 0.12  (normal approx 0.24) on midline sagittal.
Loss of the lateral convex margin of the tegmentum of midbrain has been described as the morning glory sign.
T2w images may show diffuse high-signal lesions in pontine tegmentum,tectum of the midbrain, inferior olivary nucleus.

Differential diagnosis especially when features are not typical.
1. Parkinson disease, spares the midbrain and superior cerebellar peduncles.
2. Multiple system atrophy (MSA), predominantly affects middle cerebellar peduncles and pons with a hot cross bun sign click here on T2w images.
3. Corticobasal degeneration (CBD), cortical atrophy is prominent.

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