Hypertonicity vs spasticity

Clinical evaluation and management of spasticity,  Jeffery et. al.2002

 1-hypertonicity or spastic dystonia is a continues increase in the muscle tension without regarding to the movement and is dependent upon afferent information from feedback following movements of stretch , decorticat and decerbrate rigidity are a form of spastic dystonia, spastic dystonia is considered to be a form of sustained efferent muscular hyperactivity , dependent on continues supraspinal derive to the alpha motor neuron

2- spasticity is a velocity dependent increase in muscle tone in regarding to passive movement, 

-neural component of spasticity: pyramidal tract lesion , pyramidal tract injury doesn't give raise to spasticity (BURKE),

the main symptoms are weakness and loss of dexterity which is greater in distal than in the proximal muscles, 

- pyramidal tract is the system which balance the muscle tone.-the key tracts are :

1-DRT : Has inhibitory effect on MRT &VST

2-MRT & 3- VST : they have facilitatory effect on the extensor tone,

- all the three systems are though to inhibit flexor reflex afferents responsible for flexor spasm. (BROWN 1994)