Idiopathic or unknown cause (idiopathic intracranial hypertension, a common cause in otherwise well people especially younger women)
CraniosynostosisOne of the most damaging aspects of brain trauma and other conditions, directly correlated with poor outcome, is an elevated intracranial pressure. ICP is very likely to cause severe harm if it rises too high. Very high intracranial pressures are usually fatal if prolonged, but children can tolerate higher pressures for longer periods. An increase in pressure, most commonly due to head injury leading to intracranial hematoma or cerebral edema, can crush brain tissue, shift brain structures, contribute to hydrocephalus, cause brain herniation, and restrict blood supply to the brain. It is a cause of reflex bradycardia. Low ICP
Spontaneous intracranial hypotension may occur as a result of an occult leak of CSF into another body cavity. More commonly, decreased ICP is the result of lumbar puncture or other medical procedures involving the brain or spinal cord. Various medical imaging technologies exist to assist in identifying the cause of decreased ICP. Often, the syndrome is self-limiting, especially if it is the result of a medical procedure.If persistent intracranial hypotension is the result of a lumbar puncture, a "blood patch" may be applied to seal the site of CSF leakage. Various medical treatments have been proposed; only the intravenous administration of caffeine and theophylline has shown to be particularly useful.
The cranium and its constituents (blood, CSF, and brain tissue) create a state of volume equilibrium, such that any increase in volume of one of the cranial constituents must be compensated by a decrease in volume of another. *This concept only applies to adults, as the presence of fontanelles and open suture lines in infants that have not yet fused means there is potential for a change in size and intracranial volume. The principal buffers for increased volumes include CSF and, to a lesser extent, blood volume. These buffers respond to increases in volume of the remaining intracranial constituents. For example, an increase in lesion volume (e.g., epidural hematoma) will be compensated by the downward displacement of CSF and venous blood.The Monro–Kellie hypothesis is named after Edinburgh doctors Alexander Monro and George Kellie. Diagnosis
The most definitive way of measuring the intracranial pressure is with transducers placed within the brain. A catheter can be surgically inserted into one of the brains lateral ventricles and can be used to drain CSF (cerebrospinal fluid) in order to decrease ICPs. This type of drain is known as an external ventricular drain (EVD). This is rarely required outside brain injury and brain surgery settings.In situations when only small amounts of CSF are to be drained to reduce ICPs (e.g. in IIH), drainage of CSF via lumbar puncture can be used as a treatment. Non-invasive measurement of intracranial pressure is being studied. Treatment
The treatment for ICP depends on the cause.