Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent over-activity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug and/or physical therapy. Presentation
Symptoms associated with central nervous systems disorders are classified into positive and negative categories. Positive symptoms include those that increase muscle activity through hyper-excitability of the stretch reflex (i.e., rigidity and spasticity) where negative symptoms include those of insufficient muscle activity (i.e. weakness) and reduced motor function. Often the two classifications are thought to be separate entities of a disorder; however, some authors propose that they may be closely related. Pathophysiology
Hypertonia is caused by upper motor neuron lesions which may result from injury, disease, or conditions that involve damage to the central nervous system. The lack of or decrease in upper motor neuron function leads to loss of inhibition with resultant hyperactivity of lower motor neurons.
Thromboangiitis obliterans, also known as Buerger disease (English ; German: [ˈbʏʁɡɐ]), is a recurring progressive inflammation and thrombosis (clotting) of small and medium arteries and veins of the hands and feet. It is strongly associated with use of tobacco products, primarily from smoking, but is also associated with smokeless tobacco. Signs and symptoms
There is a recurrent acute and chronic inflammation and thrombosis of arteries and veins of the hands and feet. The main symptom is pain in the affected areas, at rest and while walking (claudication). The impaired circulation increases sensitivity to cold. Peripheral pulses are diminished or absent. There are color changes in the extremities. The colour may range from cyanotic blue to reddish blue. Skin becomes thin and shiny. Hair growth is reduced. Ulcerations and gangrene in the extremities are common complications, often resulting in the need for amputation of the involved extremity. Pathophysiology
There are characteristic pathologic findings of acute inflammation and thrombosis (clotting) of arteries and veins of the hands and feet (the lower limbs being more common). The mechanisms underlying Buergers disease are still largely unknown, but smoking and tobacco consumption are major factors associated with it. It has been suggested that the tobacco may trigger an immune response in susceptible persons or it may unmask a clotting defect, either of which could incite an inflammatory reaction of the vessel wall. This eventually leads to vasculitis and ischemic changes in distal parts of limbs.A possible role for Rickettsia in this disease has been proposed.