Fluid is produced within the brain that serves many functions, including cushioning the brain, and aiding in removing waste materials from the tissue. This fluid is normally drained away naturally, but some people produce too much or can't drain it away quickly enough. This leads to high pressures as the fluid builds up, and high pressures can result in headaches, blurred vision and nausea.
The standard way to treat this is to implant a tube (known as a shunt) to drain the fluid away into the gut or a blood vessel, where it is harmlessly absorbed into the bloodstream, and pressures in the skull are kept low. These shunts are safe and remain implanted for years without complications. To aid the doctor to decide whether a patient needs an operation to implant, remove or change a shunt, we monitor the pressures in the skull overnight at the James Cook University Hospital (JCUH). This requires a very small device to be placed through a small hole in the skull, and onto the surface of the brain. The patient remains in bed whilst specialist equipment records the pressures measured by this small device in the skull.
Pressures in the skull are higher when patients are lying down than when sitting or standing, and there is strong evidence that this difference between pressures when lying and sitting is higher in patients with a working shunt, and lower in patients without a shunt. We would ask patients to move between lying and sitting whilst the pressure in their skull is being measured. This might provide a very simple means of identifying whether a shunt is working correctly. It could also help the doctor to decide whether a patient who doesn't have a shunt could benefit from having one implanted.
FAQs
Positional changes in intracranial pressure (ICP) have been described in humans when measured over minutes or hours in a static posture, with ICP higher when lying supine than when sitting or standing upright.
What is the best position for intracranial pressure? ›
In most patients with intracranial hypertension, head and trunk elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of at least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat.
What is a normal intracranial pressure for a supine person? ›
It is normally 7-15 mm Hg in adults who are supine, with pressures over 20 mm Hg considered pathological and pressures over 15 mm Hg considered abnormal. Note that ICP is positional, with elevation of the head resulting in lower values. A standing adult generally has an ICP of -10 mm Hg but never less than -15 mm Hg.
How does posture affect intracranial pressure? ›
It has been shown that ICP (i.e., CSF pressure in the ventricles) is reduced when moving from a supine to an upright position, whereas CSF pressure at the lumbar level of the spinal subarachnoid space increases, and it has been hypothesized that there exists a hydrostatic indifference point in the CSF system as well ( ...
Does laying down make intracranial hypertension worse? ›
Symptoms of IIH include headache that worsens on lying down, diplopia, transient visual obscuration, scotomas, pulsatile tinnitus, and vertigo, as well as retro-orbital, cervical, or facial pain.
What are the physiological changes from supine to standing? ›
The transition from supine to standing causes a drop in arterial blood pressure. A fall in systolic blood pressure (SBP) of at least 20 mm Hg, or 10 mm Hg in diastolic blood pressure (DBP), within 3 minutes of standing is defined as orthostatic hypotension.
What is the fastest way to decrease intracranial pressure? ›
- Decompressive Craniectomy (DC) DC involves removal of a portion of the skull vault resulting in immediate decrease of the ICP. ...
- Hyperventilation. ...
- Antiseizure Therapy. ...
- Therapeutic Hypothermia.
Increased ICP can result from bleeding in the brain, a tumor, stroke, aneurysm, high blood pressure, or brain infection. Treatment focuses on lowering increased intracranial pressure around the brain.
Does walking lower intracranial pressure? ›
In patients with normal ICP, passive range of motion decreased mean ICP by 1 mm Hg in the supine position but not in the head-up position. In patients with high ICP, it decreased ICP by 2 mm Hg. Limb exercises left the mean ICP essentially unchanged in both the patients with normal ICP and the patients with high ICP.
What are signs of increased intracranial pressure? ›
What are the symptoms of ICP?
- Headache.
- Blurred vision.
- Feeling less alert than usual.
- Vomiting.
- Changes in your behavior.
- Weakness or problems with moving or talking.
- Lack of energy or sleepiness.
Oxidative stress is an important pathophysiological mechanism that causes intracranial hypertension, rendering oxidative stress as a potential target for the treatment of intracranial hypertension.
What drugs increase intracranial pressure? ›
Causes
- Amiodarone.
- Birth control pills such as levonorgestrel (Norplant)
- Cyclosporine.
- Cytarabine.
- Growth hormone.
- Isotretinoin.
- Levothyroxine (children)
- Lithium carbonate.
Pressures in the skull are higher when patients are lying down than when sitting or standing, and there is strong evidence that this difference between pressures when lying and sitting is higher in patients with a working shunt, and lower in patients without a shunt.
What position relieves intracranial pressure? ›
ICP can also be lowered by raising the head of the bed, improving venous drainage. A side effect of this is that it could lower pressure of blood to the head, resulting in a reduced and possibly inadequate blood supply to the brain.
Does sitting increase intracranial pressure? ›
Positional changes in intracranial pressure (ICP) have been described in humans when measured over minutes or hours in a static posture, with ICP higher when lying supine than when sitting or standing upright.
Why does fluid pressure change when someone goes from supine to standing? ›
When standing up, gravity moves blood from the upper body to the lower limbs. As a result, there is a temporary reduction in the amount of blood in the upper body for the heart to pump (cardiac output), which decreases blood pressure.
How does blood pressure change from supine to sitting? ›
Pickering et al state that it is widely accepted, that the diastolic blood pressure (DBP) when measured in a seated position is higher than when measured supine (by 5 mm Hg), although there is less agreement about the systolic blood pressure (SBP).
Does elevating head of bed decrease ICP? ›
Several authors have documented the beneficial effects on ICP of elevating the head. Feldman et al demonstrated among 22 patients with severe traumatic brain injury (TBI) that head elevation to 30° reduced ICP significantly without affecting CPP or cerebral blood flow (CBF).
What is the best position for a head injury patient? ›
The injured person should lie down with the head and shoulders slightly elevated. Don't move the person unless necessary. Avoid moving the person's neck. If the person is wearing a helmet, don't remove it.
