As previously noted, there are often few signs of white matter injury in newborns. Occasionally, physicians can make the initial observations of extreme stiffness or poor ability to suckle. The preliminary diagnosis of PVL is often made using imaging technologies. In most hospitals, premature infants are examined with ultrasound soon after birth to check for brain damage. Severe white matter injury can be seen with a head ultrasound; however, the low sensitivity of this technology allows for some white matter damage to be missed. Magnetic resonance imaging (MRI) is much more effective at identifying PVL, but it is unusual for preterm infants to receive an MRI unless they have had a particularly difficult course of development (including repeated or severe infection, or known hypoxic events during or immediately after birth). No agencies or regulatory bodies have established protocols or guidelines for screening of at-risk populations, so each hospital or doctor generally makes decisions regarding which patients should be screened with a more sensitive MRI instead of the basic head ultrasound.

PVL is overdiagnosed by neuroimaging studies and the other white matter lesions of the brain are underestimated. It is important to differentiate PVL from the following major white matter lesions in the cerebral hemispheres: edematous hemorrhagic leukoencephalopathy (OGL), telentsefalny gliosis (TG), diffuse leukomalacia (DFL), subcortical leukomalacia (SL), periventricular hemorrhagic infarction (PHI), intracerebral hemorrhage ( ICH), multicystic encephalomalacia (ME), subendymal pseudocyst. Diffuse white matter lesions of the cerebral hemispheres of the brain, accompanied by softening and spreading to the central and subcortical areas are more likely DFL, PHI and ME.

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.

Current clinical research ranges from studies aimed at understanding the progression and pathology of PVL to developing protocols for the prevention of PVL development. Many studies examine the trends in outcomes of individuals with PVL: a recent study by Hamrick, et al., considered the role of cystic periventricular leukomalacia (a particularly severe form of PVL, involving development of cysts) in the developmental outcome of the infant.

Other ongoing clinical studies are aimed at the prevention and treatment of PVL: clinical trials testing neuroprotectants, prevention of premature births, and examining potential medications for the attenuation of white matter damage are all currently supported by NIH funding.

Cases of cerebral softening in infancy versus in adulthood are much more severe due to an infant's inability to sufficiently recover brain tissue loss or compensate the loss with other parts of the brain. Adults can more easily compensate and correct for the loss of tissue use and therefore the mortality likelihood in an adult with cerebral softening is less than in an infant.

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.

In medicine, cerebral softening (encephalomalacia) is a localized softening of the brain substance, due to hemorrhage or inflammation. Three varieties, distinguished by their color and representing different stages of the morbid process, are known respectively as red, yellow, and white softening.

An AVM diagnosis is established by neuroimaging studies after a complete neurological and physical examination. Three main techniques are used to visualize the brain and search for AVM: computed tomography (CT), magnetic resonance imaging (MRI), and cerebral angiography. A CT scan of the head is usually performed first when the subject is symptomatic. It can suggest the approximate site of the bleed. MRI is more sensitive than CT in the diagnosis of AVMs and provides better information about the exact location of the malformation. More detailed pictures of the tangle of blood vessels that compose an AVM can be obtained by using radioactive agents injected into the blood stream. If a CT is used in conjunctiangiogram, this is called a computerized tomography angiogram; while, if MRI is used it is called magnetic resonance angiogram. The best images of an AVM are obtained through cerebral angiography. This procedure involves using a catheter, threaded through an artery up to the head, to deliver a contrast agent into the AVM. As the contrast agent flows through the AVM structure, a sequence of X-ray images are obtained.

A limitation of the Spetzler-Martin Grading system is that it does not include the following factors: Patient age, hemorrhage, diffuseness of nidus, and arterial supply. In 2010 a new supplemented Spetzler-Martin system (SM-supp, Lawton-Young) was devised adding these variables to the SM system. Under this new system AVMs are classified from grades 1 - 10. It has since been determined to have greater predictive accuracy that Spetzler-Martin grades alone.

Mild and moderate cerebral hypoxia generally has no impact beyond the episode of hypoxia; on the other hand, the outcome of severe cerebral hypoxia will depend on the success of damage control, amount of brain tissue deprived of oxygen, and the speed with which oxygen was restored.

If cerebral hypoxia was localized to a specific part of the brain, brain damage will be localized to that region. A general consequence may be epilepsy. The long-term effects will depend on the purpose of that portion of the brain. Damage to the Broca's area and the Wernicke's area of the brain (left side) typically causes problems with speech and language. Damage to the right side of the brain may interfere with the ability to express emotions or interpret what one sees. Damage on either side can cause paralysis of the opposite side of the body.

The effects of certain kinds of severe generalized hypoxias may take time to develop. For example, the long-term effects of serious carbon monoxide poisoning usually may take several weeks to appear. Recent research suggests this may be due to an autoimmune response caused by carbon monoxide-induced changes in the myelin sheath surrounding neurons.

If hypoxia results in coma, the length of unconsciousness is often indicative of long-term damage. In some cases coma can give the brain an opportunity to heal and regenerate, but, in general, the longer a coma, the greater the likelihood that the person will remain in a vegetative state until death. Even if the patient wakes up, brain damage is likely to be significant enough to prevent a return to normal functioning.

Long-term comas can have a significant impact on a patient's families. Families of coma victims often have idealized images of the outcome based on Hollywood movie depictions of coma. Adjusting to the realities of ventilators, feeding tubes, bedsores, and muscle wasting may be difficult. Treatment decision often involve complex ethical choices and can strain family dynamics.

CT and MRI are most commonly used to observe the brain for cerebral atrophy. A CT scan takes cross sectional images of the brain using X-rays, while an MRI uses a magnetic field. With both measures, multiple images can be compared to see if there is a loss in brain volume over time.

Cerebral atrophy can be hard to distinguish from hydrocephalus because both cerebral atrophy and hydrocephalus involve an increase in cerebrospinal fluid (CSF) volume. In cerebral atrophy, this increase in CSF volume comes as a result of the decrease in cortical volume. In hydrocephalus, the increase in volume happens due to the CSF itself.

Although the mechanism is not entirely understood, the likelihood of a watershed stroke increases after cardiac surgery. An experiment conducted in a five-year span studied the diagnosis, etiology, and outcome of these postoperative strokes. It was observed that intraoperative decrease in blood pressure may lead to these strokes and patients who have undergone aortic procedures are more likely to have bilateral watershed infarcts. Furthermore, bilateral watershed strokes are associated with poor short-term outcomes and are most reliably observed by diffusion-weighted imaging MRI. Thus future clinical research and practice should focus on the identification of bilateral stroke characteristics. This identification can help discover affected areas and increase correct diagnosis.

For newborn infants starved of oxygen during birth there is now evidence that hypothermia therapy for neonatal encephalopathy applied within 6 hours of cerebral hypoxia effectively improves survival and neurological outcome. In adults, however, the evidence is less convincing and the first goal of treatment is to restore oxygen to the brain. The method of restoration depends on the cause of the hypoxia. For mild-to-moderate cases of hypoxia, removal of the cause of hypoxia may be sufficient. Inhaled oxygen may also be provided. In severe cases treatment may also involve life support and damage control measures.

A deep coma will interfere with body's breathing reflexes even after the initial cause of hypoxia has been dealt with; mechanical ventilation may be required. Additionally, severe cerebral hypoxia causes an elevated heart rate, and in extreme cases the heart may tire and stop pumping. CPR, defibrilation, epinephrine, and atropine may all be tried in an effort to get the heart to resume pumping. Severe cerebral hypoxia can also cause seizures, which put the patient at risk of self-injury, and various anti-convulsant drugs may need to be administered before treatment.

There has long been a debate over whether newborn infants with cerebral hypoxia should be resuscitated with 100% oxygen or normal air. It has been demonstrated that high concentrations of oxygen lead to generation of oxygen free radicals, which have a role in reperfusion injury after asphyxia. Research by Ola Didrik Saugstad and others led to new international guidelines on newborn resuscitation in 2010, recommending the use of normal air instead of 100% oxygen.

Brain damage can occur both during and after oxygen deprivation. During oxygen deprivation, cells die due to an increasing acidity in the brain tissue (acidosis). Additionally, during the period of oxygen deprivation, materials that can easily create free radicals build up. When oxygen enters the tissue these materials interact with oxygen to create high levels of oxidants. Oxidants interfere with the normal brain chemistry and cause further damage (this is known as "reperfusion injury").

Techniques for preventing damage to brain cells are an area of ongoing research. Hypothermia therapy for neonatal encephalopathy is the only evidence-supported therapy, but antioxidant drugs, control of blood glucose levels, and hemodilution (thinning of the blood) coupled with drug-induced hypertension are some treatment techniques currently under investigation. Hyperbaric oxygen therapy is being evaluated with the reduction in total and myocardial creatine phosphokinase levels showing a possible reduction in the overall systemic inflammatory process.

In severe cases it is extremely important to act quickly. Brain cells are very sensitive to reduced oxygen levels. Once deprived of oxygen they will begin to die off within five minutes.

Diagnosis of a cerebral vascular accident begins with a general neurological examination, used to identify specific areas of resulting injury. A CT scan of the brain is then used to identify any cerebral hemorrhaging. An MRI with special sequences called diffusion-weighted MR imaging (DWI), is very sensitive for locating areas of an ischemic based stroke, such as a watershed stroke.

Further diagnosis and evaluation of a stroke includes evaluation of the blood vessels in the neck using either Doppler ultrasound, MR-angiography or CT-angiography, or formal angiography. An echocardiogram may be performed looking for a cardiac source of emboli. Blood tests for risk factors also may be ordered, including cholesterol levels, triglyceride levels, homocysteine levels, and blood coagulation tests.

While there are no standard criteria for the diagnosis of Grinker's myelinopathy, neuroimaging can be an important diagnostic tool in ruling out other diagnoses. Magnetic resonance imaging (MRI) or computed tomography (CT) scans can be used to demonstrate a decrease in white matter density in the patient’s cerebral hemispheres, with the typical exception of overlying cortices. Unexplained, uniform demyelination of white matter can indicate acute onset Grinker's myelinopathy.

Diagnostic methods include:

- Angiogram

Due to positive remodeling the plaque build-up shown on angiogram may appear further downstream on the x-ray where the luminal diameter would look normal even though there is severe narrowing at the real site. Because angiograms require x-rays to be visualized the number of times an individual can have it done over a year is limited by the guidelines for the amount of radiation they can be exposed to in a one-year period.

- Magnetic resonance imaging (MRI)

Magnetic resonance imaging has the ability to quantify the plaque anatomy and composition. This allows physicians to determine certain characteristics of the plaque such as how likely it is to break away from the wall and become an embolus. MRI does not use ionizing radiation, so the number of times that it is used on a single person is not a concern; however since it uses strong electric fields those who have metal implants in cannot use this technique.

- Computed tomography (CT)

Multidirectional computed tomography (MDCT) is better than regular CT scans, because it can provide a higher spatial resolution and it has a shorter acquisition time. MDCT uses x-rays to obtain the image; however it can identify the composition of the plaque. Thus it can be determined whether the plaque is calcified plaque and lipid-rich plaque, so the inherent risks can be determined. Subjects are exposed to a substantial amount of radiation with this procedure, so their use is limited.

Since cerebral swelling presents a danger to the patient, treatment of cerebral contusion aims to prevent swelling. Measures to avoid swelling include prevention of hypotension (low blood pressure), hyponatremia (insufficient sodium), and hypercapnia (increased carbon dioxide in the blood). Due to the danger of increased intracranial pressure, surgery may be necessary to reduce it. People with cerebral contusion may require intensive care and close monitoring.

Computed tomography (CT) and MRI scanning will show damaged area in the brain, showing that the symptoms were not caused by a tumor, subdural hematoma or other brain disorder. The blockage will also appear on the angiogram.

Grinker's myelinopathy is diagnosed by establishing a clinical history of carbon monoxide poisoning, narcotic overdose, myocardial infarction, or other global cerebral hypoxic events. This diagnosis can then be supported by neuroimaging confirmation of broadcast cerebral hemisphere demyelination sparing cerebellar and brainstem tracts. The neuroimaging evidence can also be used to diagnose Grinker's myelinopathy through an elevation in the concentrations of a myelin basic protein in the cerebrospinal fluid .

Because this disease shares many of the symptoms with various forms of dementia or hysteria, these possibilities must be eliminated before a diagnosis for Grinker's myelinopathy can be made.

The clinician should first rule out conditions with similar symptoms, such as subarachnoid hemorrhage, ischemic stroke, pituitary apoplexy, cerebral artery dissection, meningitis, and spontaneous cerebrospinal fluid leak. This may involve a CT scan, lumbar puncture, MRI, and other tests. Posterior reversible encephalopathy syndrome has a similar presentation, and is found in 10–38% of RCVS patients.

RCVS is diagnosed by detecting diffuse reversible cerebral vasoconstriction. Catheter angiography is ideal, but computed tomography angiography and magnetic resonance angiography can identify about 70% of cases. Multiple angiographies may be necessary. Because other diseases (such as atherosclerosis) have similar angiographic presentations, it can only be conclusively diagnosed if vasoconstriction resolves within 12 weeks.

Cerebral angiography and magnetic resonance imaging, family medical history, symptoms, a complete physical examination, and ultimately biopsy of the brain, are often required for the diagnosis. Also, many lab tests must be done for the diagnosis; tests may reveal anemia (a shortage of red blood cells), a high white blood cell count, a high platelet count, allergic reactions, immune complexes, antibodies (tools the body uses to fight off threats) and elevation of inflammatory markers. Another crucial part in the diagnosis of cerebral vasculitis is the use of imaging techniques. Techniques such as conventional digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) are used to find and monitor cerebral involvement.

The aim in cerebral amyloid angiopathy is to treat the symptoms, as there is no current cure. Physical and/or speech therapy may be helpful in the management of this condition.

The most important initial investigation is computed tomography of the brain, which is very sensitive for subarachnoid hemorrhage. If this is normal, a lumbar puncture is performed, as a small proportion of SAH is missed on CT and can still be detected as xanthochromia.

If both investigations are normal, the specific description of the headache and the presence of other abnormalities may prompt further tests, usually involving magnetic resonance imaging (MRI). Magnetic resonance angiography (MRA) may be useful in identifying problems with the arteries (such as dissection), and magnetic resonance venography (MRV) identifies venous thrombosis. It is not usually necessary to proceed to cerebral angiography, a more precise but invasive investigation of the brain's blood vessels, if MRA and MRV are normal.

It is usually associated with amyloid beta.

However, there are other types:

- the "Icelandic type" is associated with Cystatin C

- the "British type" is associated with ITM2B

Research is currently being conducted to determine if there is a link between cerebral amyloid angiopathy and ingestion of excessive quantities of aluminum.

There are various neuroimaging investigations that may detect cerebral sinus thrombosis. Cerebral edema and venous infarction may be apparent on any modality, but for the detection of the thrombus itself, the most commonly used tests are computed tomography (CT) and magnetic resonance imaging (MRI), both using various types of radiocontrast to perform a venogram and visualise the veins around the brain.

Computed tomography, with radiocontrast in the venous phase ("CT venography" or CTV), has a detection rate that in some regards exceeds that of MRI. The test involves injection into a vein (usually in the arm) of a radioopaque substance, and time is allowed for the bloodstream to carry it to the cerebral veins - at which point the scan is performed. It has a sensitivity of 75-100% (it detects 75-100% of all clots present), and a specificity of 81-100% (it would be incorrectly positive in 0-19%). In the first two weeks, the "empty delta sign" may be observed (in later stages, this sign may disappear).

Magnetic resonance venography employs the same principles, but uses MRI as a scanning modality. MRI has the advantage of being better at detecting damage to the brain itself as a result of the increased pressure on the obstructed veins, but it is not readily available in many hospitals and the interpretation may be difficult.

Cerebral angiography may demonstrate smaller clots than CT or MRI, and obstructed veins may give the "corkscrew appearance". This, however, requires puncture of the femoral artery with a sheath and advancing a thin tube through the blood vessels to the brain where radiocontrast is injected before X-ray images are obtained. It is therefore only performed if all other tests give unclear results or when other treatments may be administered during the same procedure.