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What is Pseudoclonus?

Clonus (from the Greek for "violent, confused motion") is a series of involuntary, rhythmic, muscular contractions and relaxations. Clonus is a sign of certain neurological conditions, particularly associated with upper motor neuron lesions affecting the descending motor pathways, and in most cases is, accompanied by spasticity (another form of hyperexcitability).
The clonus is  sustained inspite of a steady pressure,this is seen in pseudoclonus
It is irregular in rate (usually less than 6 at a time) and rhythm.
It is commonly seen in anxiety, in tense persons, often in hysteria and thyrotoxicosis.
Plantar response is always flexor.
Many a time, the boundary between true and pseudoclonus is not very clear.