Prolonged immobilization seems to be an important predisposing factor for CRPS. Patients with fractures and limbs in cast for a long time can develop CRPS. Some studies suggest supplementation with vitamin C can prevent occurance of CRPS in such patients. Exercises of the fingers and hand of CRPS feed into this vicious circle to increase the friction and hence the repeated exacerbations. It is as if the limb affected by CRPS-1 experiences a trauma every time the patient attempts physical therapy and hence experiences an exacerbation of their symptoms when they do physiotherapy. It is also a common finding that patients have no symptoms of CRPS as long as their hand is immobilized in a plaster cast and the problems of pain and swelling start only during the mobilization phase after removal of plaster cast. They also complain that it is their fingers that hurt most and later swell, when they try to make a fist. Less movements mean more stiffness, deterioration and no improvement, and little more exercises and the patient deteriorates with exacerbations. Thus intense physiotherapy is usually counterproductive. But since USGDN directly and reliably reverses this worsening it makes intense physiotherapy actually productive. This predictable relief of pain makes the patients gain the confidence to work with the physiotherapist. This makes graded improvement an achievable goal.