ICP correlates with intraocular pressure (IOP) but seems to lack the accuracy necessary for close management of intracranial pressure in the acute posttraumatic period.Papilledema, or the swelling of the optic disc, can be a reliable sign that ICP is elevated. Unlike other conditions that may result in the swelling of the optic disc, it is in the case of papilledema that vision may go largely unaffected. Causes of abnormal intracranial pressure
Increased ICP
Causes of increased intracranial pressure can be classified by the mechanism in which ICP is increased:

Mass effect such as brain tumor, infarction with edema, contusions, subdural or epidural hematoma, or abscesses all tend to deform the adjacent brain. Generalized brain swelling can occur in ischemic-anoxia states, acute liver failure, hypertensive encephalopathy, hypercarbia (hypercapnia), and Reye hepatocerebral syndrome. These conditions tend to decrease the cerebral perfusion pressure but with minimal tissue shifts. Increase in venous pressure can be due to venous sinus thrombosis, heart failure, or obstruction of superior mediastinal or jugular veins. Obstruction to CSF flow and/or absorption can occur in hydrocephalus (blockage in ventricles or subarachnoid space at base of brain, e.g., by Arnold–Chiari malformation), extensive meningeal disease (e.g., infection, carcinoma, granuloma, or hemorrhage), or obstruction in cerebral convexities and superior sagittal sinus (decreased absorption). Increased CSF production can occur in meningitis, subarachnoid hemorrhage, or choroid plexus tumor.
It is not a life-threatening disease, and it is not contagious.Dermographism may occur in mastocytosis (systemic mast cell proliferation). Diagnosis
This condition is diagnosed by a health care provider writing or drawing on the patients skin with a tongue depressor or other implement, to see whether a red wheal appears soon afterwards. Treatment
Dermographism can be treated by substances which prevent histamine from causing the reaction (i.e. an antihistamine). These may need to be given as a combination of H1 antagonists, or possibly with an H2-receptor antagonist such as cimetidine. Over-the-counter vitamin C, 1000 mg daily, increases histamine degradation and removal.Refraining from taking hot baths or showers may help if the condition is generalized (i.e. all over), as well as possibly for localized cases (i.e. in a specific area). If taking hot showers helps, it may be a condition called shower eczema. If it affects mainly the head, it may be psoriasis. In rare cases, allergy tests may uncover substances the patient is allergic to.While cromoglycate, which prevents histamine from being released from mast cells, is used topically in rhinitis and asthma, it is not effective orally for treating chronic urticaria. See also
Triple response of Lewis

References


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