Dermographism is a reaction of skin vessels to mechanical irritation. There are local and reflex dermographism (Fig. 5-8).
Fig. 3. White dermographism.
Fig. 4. Red dermographism.
Fig. 5. Sublime dermographism.
Fig. 6. Reflex dermographism.
The first is the local reaction of the vessels; cause it a stroke skin irritation blunt object. With weak pressure, a white band appears, with strong pressure - a red one. White dermographism occurs when a spasm, and red - with the expansion of the capillaries of the skin. Sometimes red dermographism turns into sublime dermographism. If white dermographism occurs with weak and strong pressure, this means that the sympathetic innervation tone prevails, if red dermographism occurs, the parasympathetic innervation tone prevails. Changes in dermographism can be observed in vegetative dystonia, meningitis, thyrotoxicosis and other diseases. The absence of dermographism is often noted with severe intoxications of the nervous system, exhaustion of the body and other pathological conditions.
Reflex dermographism is a spinal reflex; cause it to stroke the skin on the tip of the needle. The arc of this reflex passes through the corresponding spinal segments. Reflex dermographism is absent in the defeat of the posterior and anterior roots of the spinal cord , its lateral horns, as well as in the defeat of the peripheral nerve (inflammatory processes, injuries, tumors).Go