Low-pressure hydrocephalus (LPH) is a condition whereby ventricles are enlarged and the individual experiences severe dementia, inability to walk, and incontinence - despite very low intracranial pressure (ICP). Low pressure hydrocephalus appears to be a more acute form of normal pressure hydrocephalus. If not diagnosed in a timely fashion, the individual runs the risk of remaining in the low pressure hydrocephalic state or LPHS. Shunt revisions, even when they are set to drain at a low ICP, are not always effective. The pressure in the brain does not get high enough to allow the cerebrospinal fluid to drain in a shunt system, therefore the shunt is open, but malfunctioning in LPH. In cases of LPH, chronic infarcts can also develop along the corona radiata in response to the tension in the brain as the ventricles increase in size. Certain causes of LPH include trauma, tumor, bleeding, inflammation of the lining of the brain, whole brain radiation, as well as other brain pathology that affects the compliance of the brain parenchyma. One treatment for the LPHS is an external ventricular drain (EVD) set at negative pressures. According to Pang & Altschuler et al., a controlled, steady, negative pressure siphoning with EVD, carefully monitored with partial computer tomography scans is a safe and effective way of treating LPH. In their experience, this approach helps restore the brain mantle. They caution against dropping or raising the pressure of the EVD too quickly as it increases risk and also destabilizes the ventricles. Getting the ventricles smaller, is the initial step, stabilising them is the second step before placing a shunt – which is the final step in therapy. Any variation from this formula can lead to an ineffective, yet patent shunt system, despite a low-pressure setting. Care should be taken with EVD therapy, as mismanagement of the EVD can lead to long-term permanent complications and brain injury.

The best-studied medical treatment for intracranial hypertension is acetazolamide (Diamox), which acts by inhibiting the enzyme carbonic anhydrase, and it reduces CSF production by six to 57 percent. It can cause the symptoms of hypokalemia (low blood potassium levels), which include muscle weakness and tingling in the fingers. Acetazolamide cannot be used in pregnancy, since it has been shown to cause embryonic abnormalities in animal studies. Also, in human beings it has been shown to cause metabolic acidosis as well as disruptions in the blood electrolyte levels of newborn babies. The diuretic furosemide is sometimes used for a treatment if acetazolamide is not tolerated, but this drug sometimes has little effect on the ICP.

Various analgesics (painkillers) may be used in controlling the headaches of intracranial hypertension. In addition to conventional agents such as paracetamol, a low dose of the antidepressant amitriptyline or the anticonvulsant topiramate have shown some additional benefit for pain relief.

The use of steroids in the attempt to reduce the ICP is controversial. These may be used in severe papilledema, but otherwise their use is discouraged.

The primary goal in treatment of IIH is the prevention of visual loss and blindness, as well as symptom control. IIH is treated mainly through the reduction of CSF pressure and, where applicable, weight loss. IIH may resolve after initial treatment, may go into spontaneous remission (although it can still relapse at a later stage), or may continue chronically.

Treatment approaches can include osmotherapy using mannitol, diuretics to decrease fluid volume, corticosteroids to suppress the immune system, hypertonic saline, and surgical decompression to allow the brain tissue room to swell without compressive injury.

Treatment focuses on monitoring and should be accomplished with inpatient floor service for individuals responsive to commands or neurological ICU observation for those with impaired levels of consciousness. Extra attention should be placed on intracranial pressure (ICP) monitoring via an intraventricular catheter and medications to maintain ICP, blood pressure, and coagulation. In more severe cases an external ventricular drain may be required to maintain ICP and evacuate the hemorrhage, and in extreme cases an open craniotomy may be required. In cases of unilateral IVH with small intraparenchymal hemorrhage the combined method of stereotaxy and open craniotomy has produced promising results.

Because the shunt systems are too expensive for most people in developing countries, such people often die without getting a shunt. Worse, the rate of revision in shunt systems adds to the cost of shunting many times. Looking at this point, a study compares shunt systems and highlights the role of low-cost shunt systems in most of the developing countries. It compares the Chhabra shunt system to shunt systems from developed countries.

Hydrocephalus can be successfully treated by placing a drainage tube (shunt) between the brain ventricles and abdominal cavity. There is some risk of infection being introduced into the brain through these shunts, however, and the shunts must be replaced as the person grows. A subarachnoid hemorrhage may block the return of CSF to the circulation.

This should be distinguished from external hydrocephalus. This is a condition generally seen in infants and involving enlarged fluid spaces or subarachnoid spaces around the outside of the brain. This is generally a benign condition that resolves spontaneously by 2 years of age. (Greenberg, Handbook of Neurosurgery, 5th Edition, pg 174). Imaging studies and a good medical history can help to differentiate external hydrocephalus from subdural hemorrhages or symptomatic chronic extra-axial fluid collections which are accompanied by vomiting, headaches and seizures.

Hydrocephalus treatment is surgical, creating a way for the excess fluid to drain away. In the short term, an external ventricular drain (EVD), also known as an extraventricular drain or ventriculostomy, provides relief. In the long term, some patients will need any of various types of cerebral shunt. It involves the placement of a ventricular catheter (a tube made of silastic) into the cerebral ventricles to bypass the flow obstruction/malfunctioning arachnoidal granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the peritoneal cavity (ventriculo-peritoneal shunt), but alternative sites include the right atrium (ventriculo-atrial shunt), pleural cavity (ventriculo-pleural shunt), and gallbladder. A shunt system can also be placed in the lumbar space of the spine and have the CSF redirected to the peritoneal cavity (Lumbar-peritoneal shunt). An alternative treatment for obstructive hydrocephalus in selected patients is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis. This may or may not be appropriate based on individual anatomy. For infants, ETV is sometimes combined with choroid plexus cauterization, which reduces the amount of cerebrospinal fluid produced by the brain. The technique, known as ETV/CPC was pioneered in Uganda by neurosurgeon Ben Warf and is now in use in several U.S. hospitals.

Intraventricular hemorrhage (IVH), also known as intraventricular bleeding, is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space. It can result from physical trauma or from hemorrhaging in stroke.

30% of intraventricular hemorrhage (IVH) are primary, confined to the ventricular system and typically caused by intraventricular trauma, aneurysm, vascular malformations, or tumors, particularly of the choroid plexus. However 70% of IVH are secondary in nature, resulting from an expansion of an existing intraparenchymal or subarachnoid hemorrhage. Intraventricular hemorrhage has been found to occur in 35% of moderate to severe traumatic brain injuries. Thus the hemorrhage usually does not occur without extensive associated damage, and so the outcome is rarely good.

Many studies of the mechanical properties of brain edema were conducted in the 2010, most of them based on finite element analysis (FEA), a widely used numerical method in solid mechanics. For example, Gao and Ang used the finite element method to study changes in intracranial pressure during craniotomy operations. A second line of research on the condition looks at thermal conductivity, which is related to tissue water content.

Patients with dementia who are confined to a nursing home and may have undiagnosed NPH can possibly become independent again once treated. So far only one study was able to evaluate the prevalence of NPH, both diagnosed and undiagnosed, among residents of assisted-living facilities, showing a prevalence in 9 to 14% of the residents.

NPH may be relieved by surgically implanting a ventriculoperitoneal shunt to drain excess cerebrospinal fluid to the abdomen where it is absorbed. Once the shunt is in place, the ventricles usually diminish in size in 3 to 4 days, regardless of the duration of the hydrocephalus. Even though the ventricular swelling diminishes, only 21% of patients show a marked improvement in symptoms. The most likely patients to show improvement are those that show only gait disturbance, mild or no incontinence, and mild dementia. A more recent study (2004) found better outcomes, concluding that if patients with idiopathic normal pressure hydrocephalus are correctly identified, shunt insertion yielded beneficial outcomes in 86% of patients, in either gait disturbance (81%), improved continence (70%), or both. They also observed that measurements in the diagnostic clinical triad, the cortical sulci size, and periventricular lucencies were related to outcome. However, other factors such as age of the patient, symptom duration, dilation of ventricles, and the degree of presurgical dementia were unrelated to outcome.

The general purpose of the following treatment methods is to divert the flow of CSF from the blocked aqueduct, which is causing the buildup of CSF, and allow the flow to continue. Another goal of these treatments is to reduce the stress within the ventricles. Studies have not shown that either of the following treatments results in a higher IQ of the patient, and there is not statistical difference in a patient's quality of life based on treatment method. The following treatment methods are not used for aqueductal stenosis caused by tumor compression; if the obstruction is a direct result of tumor compression, CSF flow may be normalized by the surgical removal of the tumor.

Treatment involves removal of the etiologic mass and decompressive craniectomy. Brain herniation can cause severe disability or death. In fact, when herniation is visible on a CT scan, the prognosis for a meaningful recovery of neurological function is poor. The patient may become paralyzed on the same side as the lesion causing the pressure, or damage to parts of the brain caused by herniation may cause paralysis on the side opposite the lesion. Damage to the midbrain, which contains the reticular activating network which regulates consciousness, will result in coma. Damage to the cardio-respiratory centers in the medulla oblongata will cause respiratory arrest and (secondarily) cardiac arrest. Current investigation is underway regarding the use of neuroprotective agents during the prolonged post-traumatic period of brain hypersensitivity associated with the syndrome.

Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the tentorium cerebelli, and even through the foramen magnum (the hole in the base of the skull through which the spinal cord connects with the brain). Herniation can be caused by a number of factors that cause a mass effect and increase intracranial pressure (ICP): these include traumatic brain injury, intracranial hemorrhage, or brain tumor.

Herniation can also occur in the absence of high ICP when mass lesions such as hematomas occur at the borders of brain compartments. In such cases local pressure is increased at the place where the herniation occurs, but this pressure is not transmitted to the rest of the brain, and therefore does not register as an increase in ICP.

Because herniation puts extreme pressure on parts of the brain and thereby cuts off the blood supply to various parts of the brain, it is often fatal. Therefore, extreme measures are taken in hospital settings to prevent the condition by reducing intracranial pressure, or decompressing (draining) a hematoma which is putting local pressure on a part of the brain.

An extracranial shunt is essentially a sturdy tube with a catheter on one end to drain the third ventricle. The shunt also has a valve which serves to maintain one-way flow of the CSF and regulates the flow rate. The end with the catheter is placed in the third ventricle to drain the excess CSF and the other end is placed in the peritoneal cavity or atrium of the heart (making it a ventriculoperitoneal or ventriculoatrial shunt, respectively). The excess CSF which is diverted to a cavity is then reabsorbed by the surrounding tissue where it is drained to.

The procedure to insert this device is a technically straightforward endoscopic surgery with a low mortality rate (essentially 0% mortality since the 1970s). If the shunt has an adjustable valve the current method of setting the valve pressure is to choose one setting, observe the patient to see if CSF flow improves and the symptoms lessen over time, and adjust the pressure setting as needed if improvement isn't seen. For example, if there is not enough CSF flow, another surgery is performed to lower the valve pressure so that less force needs to be applied to open the valve and thereby drain more CSF.

This treatment method has several possible problems with it (with a 50% failure rate in 2 years), and unfortunately shunt malfunctions and associated complications cause a death rate of 1.2% per year. Problems which can necessitate a secondary surgery to fix them include: mechanical failure, incorrect catheter size, inappropriate valve drainage pressure, and infection.

- Inappropriate valve pressure can lead to "overdraining" or "underdraining", both of which should be treated by adjusting the valve pressure. Overdraining occurs when the valve pressure is too low and CSF flows out of the third ventricle too quickly. The ventricle then collapses and blood vessles can be torn in the process. This in turn can lead to headache, hemorrhage, or slit ventricle syndrome. Underdraining occurs when the valve pressure is too high and CSF flows out too slowly. This results in symptoms of hydrocephalus as the CSF is still collecting rather than being absorbed or diverted.

- Risk of infection is due to the fact that a foreign object is being introduced into the body. Infection can have symptoms of fever and soreness of the neck and shoulders.

Management involves general measures to stabilize the person while also using specific investigations and treatments. These include the prevention of rebleeding by obliterating the bleeding source, prevention of a phenomenon known as vasospasm, and prevention and treatment of complications.

Stabilizing the person is the first priority. Those with a depressed level of consciousness may need to be intubated and mechanically ventilated. Blood pressure, pulse, respiratory rate, and Glasgow Coma Scale are monitored frequently. Once the diagnosis is confirmed, admission to an intensive care unit may be preferable, especially since 15 percent may have further bleeding soon after admission. Nutrition is an early priority, with by mouth or nasogastric tube feeding being preferable over parenteral routes. In general, pain control is restricted to less-sedating agents such as codeine, as sedation may impact on the mental status and thus interfere with the ability to monitor the level of consciousness. Deep vein thrombosis is prevented with compression stockings, intermittent pneumatic compression of the calves, or both. A bladder catheter is usually inserted to monitor fluid balance. Benzodiazepines may be administered to help relieve distress. Antiemetic drugs should be given to awake persons.

People with poor clinical grade on admission, acute neurologic deterioration, or progressive enlargement of ventricles on CT scan are, in general, indications for the placement of an external ventricular drain by a neurosurgeon. The external ventricular drain may be inserted at the bedside or in the operating room. In either case, strict aseptic technique must be maintained during insertion. In people with aneurysmal subarachnoid hemorrhage the EVD is used to remove cerebrospinal fluid, blood, and blood byproducts that increase intracranial pressure and may increase the risk for cerebral vasospasm.

Vasospasm, in which the blood vessels constrict and thus restrict blood flow, is a serious complication of SAH. It can cause ischemic brain injury (referred to as "delayed ischemia") and permanent brain damage due to lack of oxygen in parts of the brain. It can be fatal if severe. Delayed ischemia is characterized by new neurological symptoms, and can be confirmed by transcranial doppler or cerebral angiography. About one third of people admitted with subarachnoid hemorrhage will have delayed ischemia, and half of those have permanent damage as a result. It is possible to screen for the development of vasospasm with transcranial Doppler every 24–48 hours. A blood flow velocity of more than 120 centimeters per second is suggestive of vasospasm.

The use of calcium channel blockers, thought to be able to prevent the spasm of blood vessels by preventing calcium from entering smooth muscle cells, has been proposed for prevention. The calcium channel blocker nimodipine when taken by mouth improves outcome if given between the fourth and twenty-first day after the bleeding, even if it does not reduce the amount of vasospasm detected on angiography. It is the only Food and Drug Administration (FDA) approved drug for treating cerebral vasospasm. In "traumatic" subarachnoid hemorrhage, nimodipine does not affect long-term outcome, and is not recommended. Other calcium channel blockers and magnesium sulfate have been studied, but are not presently recommended; neither is there any evidence that shows benefit if nimodipine is given intravenously.

Some older studies have suggested that statin therapy might reduce vasospasm, but a subsequent meta-analysis including further trials did not demonstrate benefit on either vasospasm or outcomes. While corticosteroids with mineralocorticoid activity may help prevent vasospasm their use does not appear to change outcomes.

A protocol referred to as "triple H" is often used as a measure to treat vasospasm when it causes symptoms; this is the use of intravenous fluids to achieve a state of hypertension (high blood pressure), hypervolemia (excess fluid in the circulation), and hemodilution (mild dilution of the blood). Evidence for this approach is inconclusive; no randomized controlled trials have been undertaken to demonstrate its effect.

If the symptoms of delayed ischemia do not improve with medical treatment, angiography may be attempted to identify the sites of vasospasms and administer vasodilator medication (drugs that relax the blood vessel wall) directly into the artery. Angioplasty (opening the constricted area with a balloon) may also be performed.

Treatment depends substantially of the type of ICH. Rapid CT scan and other diagnostic measures are used to determine proper treatment, which may include both medication and surgery.

- Tracheal intubation is indicated in people with decreased level of consciousness or other risk of airway obstruction.

- IV fluids are given to maintain fluid balance, using isotonic rather than hypotonic fluids.

There are two types of normal pressure hydrocephalus: idiopathic and secondary. The secondary type of NPH can be due to a subarachnoid hemorrhage, head trauma, tumor, infection in the central nervous system, or a complication of cranial surgery.

Head circumference measurements should be obtained regularly and monitored carefully to detect hydrocephalus. Neurosurgical procedures to relieve hydrocephalus are important. A ventriculoperitoneal shunt may be required in some infants. A pediatric cardiologist should be consulted to manage high-output failure, if present. Often patients need to be intubated. In most cases, the fistulous arteries feeding into the Vein of Galen must be blocked, thereby reducing the blood flow into the vein. Open surgery has a high morbidity and mortality. Recent advances over the past few decades have made endovascular embolization the preferred method of treatment. These treatments are preferred because they offer little threat to the surrounding brain tissue. However, there have been several reported cases of arteriovenous malformations recurring. The young age of many patients, the complex vascular anatomy, and the sensitive location of the Vein of Galen offer considerable challenges to surgeons. Another treatment option is Radiotherapy. Radiotherapy, also called radiosurgery, involves the use of focused beams to damage the blood vessel. Radiotherapy is often not pursued as a treatment because the effects of the procedure can take months or years and there is risk of damaging adjacent brain tissue.

Surgery is required if the hematoma is greater than , if there is a structural vascular lesion or lobar hemorrhage in a young patient.

- A catheter may be passed into the brain vasculature to close off or dilate blood vessels, avoiding invasive surgical procedures.

- Aspiration by stereotactic surgery or endoscopic drainage may be used in basal ganglia hemorrhages, although successful reports are limited.

Cerebellar stroke syndrome is a condition in which the circulation to the cerebellum is impaired due to a lesion of the superior cerebellar artery, anterior inferior cerebellar artery or the posterior inferior cerebellar artery.

Cardinal signs include vertigo, headache, vomiting, and ataxia.

Cerebellar strokes account for only 2-3% of the 600 000 strokes that occur each year in the United States. They are far less common than strokes which occur in the cerebral hemispheres. In recent years mortality rates have decreased due to advancements in health care which include earlier diagnosis through MRI and CT scanning. Advancements have also been made which allow earlier management for common complications of cerebellar stroke such as brainstem compression and hydrocephalus.

Research is still needed in the area of cerebellar stroke management; however, it has been proposed that several factors may lead to poor outcomes in individuals who suffer from cerebellar stroke. These factors include:

1. Declining levels of consciousness

2. New signs of brainstem involvement

3. Progressing Hydrocephalus

4. Stroke to the midline of the cerebellum (a.k.a. the vermis)

Vein of Galen malformations are devastating complications. Studies have shown that 77% of untreated cases result in mortality. Even after surgical treatment, the mortality rate remains as high as 39.4%. Most cases occur during infancy when the mortality rates are at their highest. Vein of Galen malformations are a relatively unknown affliction, attributed to the rareness of the malformations. Therefore, when a child is diagnosed with a faulty Great Cerebral Vein of Galen, most parents know little to nothing about what they are dealing with. To counteract this, support sites have been created which offer information, advice, and a community of support to the afflicted (, ).

There is no standard treatment for hydranencephaly. Treatment is symptomatic and supportive. Hydrocephalus may be treated with surgical treatment of a shunt, which often grants a much better prognosis and greater quality of life.

The prognosis for children with hydranencephaly is generally quite poor. Death often occurs in the first year of life, but other children may live several years.

Medical text identifies that hydranencephalic children simply have only their brain stem function remaining, thus leaving formal treatment options as symptomatic and supportive. Severe hydrocephalus causing macrocephaly, a larger than average head circumference, can easily be managed by placement of a shunt and often displays a misdiagnosis of another lesser variation of cephalic condition due to the blanketing nature of hydrocephalus. Plagiocephaly, the asymmetrical distortion of the skull, is another typical associated condition that is easily managed through positioning and strengthening exercises to prevent torticollis, a constant spasm or extreme tightening of the neck muscles.

The precise causes of syringomyelia are still unknown although blockage to the flow of cerebrospinal fluid has been known to be an important factor since the 1970s. Scientists in the UK and America continue to explore the mechanisms that lead to the formation of syrinxes in the spinal cord. It has been demonstrated a block to the free flow of cerebrospinal fluid is a contributory factor in the pathogenesis of the disease. Duke University in America and Warwick University are conducting research to explore genetic features of syringomyelia.

Surgical techniques are also being refined by the neurosurgical research community. Successful procedures expand the area around the cerebellum and spinal cord, thus improving the flow of cerebrospinal fluid thereby reducing the syrinx.

It is also important to understand the role of birth defects in the development of hindbrain malformations that can lead to syringomyelia as syringomyelia is a feature of intrauterine life and is also associated with spina bifida. Learning when these defects occur during the development of the fetus can help us understand this and similar disorders, and may lead to preventive treatment that can stop the formation of some birth abnormalities. Dietary supplements of folic acid prior to pregnancy have been found to reduce the number of cases of spina bifida and are also implicated in prevention of cleft palate and some cardiac defects.

Diagnostic technology is another area for continued research. MRI has enabled scientists to see conditions in the spine, including syringomyelia before symptoms appear. A new technology, known as dynamic MRI, allows investigators to view spinal fluid flow within the syrinx. CT scans allow physicians to see abnormalities in the brain, and other diagnostic tests have also improved greatly with the availability of new, non-toxic, contrast dyes.

In utero exposure to cocaine and other street drugs can lead to hydranencephaly.