The presence of porencephalic cysts or cavities can be detected using trans-illumination of the skull of infant patients. Porencephaly is usually diagnosed clinically using the patients and families history, clinical observations, or based on the presence of certain characteristic neurological and physiological features of porencephaly. Advanced medical imaging with computed tomography (CT), magnetic resonance imaging (MRI), or with ultrasonography can be used as a method to exclude other possible neurological disorders. The diagnosis can be made antenatally with ultrasound. Other assessments include memory, speech, or intellect testing to help further determine the exact diagnose of the disorder.

Diagnosis may be delayed for several months because the infant's early behavior appears to be relatively normal. Transillumination, an examination in which light is passed through body tissues, can be used to diagnose hydranencephaly. An accurate, confirmed diagnosis is generally impossible until after birth, though prenatal diagnosis using fetal ultrasonography (ultrasound) can identify characteristic physical abnormalities that exist. Through thorough clinical evaluation, via physical findings, detailed patient history, and advanced imaging techniques, such as angiogram, computerized tomography (CT scan), magnetic resonance imaging (MRI), or more rarely transillumination after birth are the most accurate diagnostic techniques. However, diagnostic literature fails to provide a clear distinction between severe obstructive hydrocephalus and hydranencephaly, leaving some children with an unsettled diagnosis.

Preliminary diagnosis may be made in utero via standard ultrasound, and can be confirmed with a standard anatomy ultrasound. This sometimes proves to provide a misdiagnosis of differential diagnoses including bilaterally symmetric schizencephaly (a less destructive developmental process on the brain), severe hydrocephalus (cerebrospinal fluid excess within the skull), and alobar holoprosencephaly (a neurological developmental anomaly). Once destruction of the brain is complete, the cerebellum, midbrain, thalami, basal ganglia, choroid plexus, and portions of the occipital lobes typically remain preserved to varying degrees. Though the cerebral cortex is absent, in most cases the fetal head remains enlarged due to the continued production by the choroid plexus of cerebrospinal fluid that is inadequately reabsorbed causing increased intracranial pressure.

The prognosis for individuals with schizencephaly varies depending on the size of the clefts and the degree of neurological deficit.

Under the United States federal government, the National Institute of Neurological Disorders and Stroke and National Institute of Health are involved in conducting and supporting research related to normal and abnormal brain and nervous system development. Information gained from the research is used to develop understanding of the mechanism of porencephaly and used to offer new methods of treatment and prevention for developmental brain disorders such as porencephaly.

In some cases, the defect is linked to mutations of the EMX2, SIX3, and Collagen, type IV, alpha 1 genes. Because having a sibling with schizencephaly has been statistically shown to increase risk of the disorder, it is possible that there is a heritable genetic component to the disease.

The prognosis for children with NMDs varies depending on the specific disorder and the degree of brain abnormality and subsequent neurological signs and symptoms.

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.

Treatment is symptomatic, and may include anti-seizure medication and special or supplemental education consisting of physical, occupational, and speech therapies.

Though it is only definitively diagnosed by a genetic test, autosomal dominant porencephaly type I can be suspected if the disease is known to run in the family or if someone shows symptoms. CT scanning or MRI may be useful in indicating a diagnosis. COL4A1 may be mutated in other diseases that need to be distinguished, including brain small vessel disease with hemorrhage and HANAC syndrome. CADASIL syndrome is caused by a mutation in a different gene, but may cause similar symptoms. Sporadic porencephaly is another disorder that can appear similar.

Cephalic disorders (from the Greek word "κεφάλι", meaning "head") are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. Cephalic means "head" or "head end of the body."

Cephalic disorders are not necessarily caused by a single factor, but may be influenced by hereditary or genetic conditions, nutritional deficiencies, or by environmental exposures during pregnancy, such as medication taken by the mother, maternal infection, or exposure to radiation. Some cephalic disorders occur when the cranial sutures (the fibrous joints that connect the bones of the skull) join prematurely. Most cephalic disorders are caused by a disturbance that occurs very early in the development of the fetal nervous system.

The human nervous system develops from a small, specialized plate of cells on the surface of the embryo. Early in development, this plate of cells forms the neural tube, a narrow sheath that closes between the third and fourth weeks of pregnancy to form the brain and spinal cord of the embryo. Four main processes are responsible for the development of the nervous system: cell proliferation, the process in which nerve cells divide to form new generations of cells; cell migration, the process in which nerve cells move from their place of origin to the place where they will remain for life; cell differentiation, the process during which cells acquire individual characteristics; and cell death, a natural process in which cells die.

Damage to the developing nervous system is a major cause of chronic, disabling disorders and, sometimes, death in infants, children, and even adults. The degree to which damage to the developing nervous system harms the mind and body varies enormously. Many disabilities are mild enough to allow those afflicted to eventually function independently in society. Others are not. Some infants, children, and adults die, others remain totally disabled, and an even larger population is partially disabled, functioning well below normal capacity throughout life.

The National Institute of Neurological Disorders and Stroke (NINDS) is currently "conducting and supporting research on normal and abnormal brain and nervous system development."

Treatment for autosomal dominant porencephaly type I is based on the symptoms that an individual is experiencing - for example, treatment of seizures with anticonvulsants. It is particularly important for individuals with this disorder and hypertension to control their blood pressure, as they are at higher risk of stroke. Other stroke prevention treatments include avoiding anticoagulants, smoking, and situations that may lead to head trauma.

Where known, the ICD-10 code is listed below.

- Anencephaly (Q00.0)

- Colpocephaly (ICD10 unknown)

- Holoprosencephaly (Q04.2)

- Ethmocephaly (ICD10 unknown)

- Hydranencephaly (Q04.3)

- Iniencephaly (Q00.2)

- Lissencephaly (Q04.3)

- Megalencephaly (Q04.5)

- Microcephaly (Q02)

- Porencephaly (Q04.6)

- Schizencephaly (Q04.6)

Because the causes of CP are varied, a broad range of preventative interventions have been investigated.

Electronic fetal monitoring has not helped to prevent CP, and in 2014 the American College of Obstetricians and Gynecologists, the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, and the Society of Obstetricians and Gynaecologists of Canada have acknowledged that there are no long-term benefits of electronic fetal monitoring. Prior to this, electronic fetal monitoring was widely used to prop up obstetric litigation.

In those at risk of an early delivery, magnesium sulphate appears to decrease the risk of cerebral palsy. It is unclear if it helps those who are born at term. In those at high risk of preterm labor a review found that moderate to severe CP was reduced by the administration of magnesium sulphate, and that adverse effects on the babies from the magnesium sulphate were not significant. Mothers who received magnesium sulphate could experience side effects such as respiratory depression and nausea. Caffeine is used to treat apnea of prematurity and reduces the risk of cerebral palsy in premature babies, but there are also concerns of long term negative effects. A moderate level of evidence has been shown for giving women antibiotics during preterm labour when their waters had not broken was associated with an increased risk of cerebral palsy in the child. Additionally, allowing a preterm birth to proceed rather than trying to delay the birth also had a moderate level of evidence for increased risk of cerebral palsy in the child.

Cooling high-risk full-term babies shortly after birth may reduce disability, but this may only be useful for some forms of the brain damage that causes CP.

Over time, the approach to CP management has shifted away from narrow attempts to fix individual physical problems such as spasticity in a particular limb to making such treatments part of a larger goal of maximizing the person's independence and community engagement. Much of childhood therapy is aimed at improving gait and walking. Approximately 60% of people with CP are able to walk independently or with aids at adulthood. However, the evidence base for the effectiveness of intervention programs reflecting the philosophy of independence has not yet caught up: effective interventions for body structures and functions have a strong evidence base, but evidence is lacking for effective interventions targeted toward participation, environment, or personal factors. There is also no good evidence to show that an intervention that is effective at the body-specific level will result in an improvement at the activity level, or vice versa. Although such cross-over benefit might happen, not enough high-quality studies have been done to demonstrate it.

Because cerebral palsy has "varying severity and complexity" across the lifespan, it can be considered a collection of conditions for management purposes. A multidisciplinary approach for cerebral palsy management is recommended, focusing on "maximising individual function, choice and independence" in line with the International Classification of Functioning, Disability and Health's goals. The team may include a paediatrician, a health visitor, a social worker, a physiotherapist, an orthotist, a speech and language therapist, an occupational therapist, a teacher specialising in helping children with visual impairment, an educational psychologist, an orthopaedic surgeon, a neurologist and a neurosurgeon.

Various forms of therapy are available to people living with cerebral palsy as well as caregivers and parents. Treatment may include one or more of the following: physical therapy; occupational therapy; speech therapy; water therapy; drugs to control seizures, alleviate pain, or relax muscle spasms (e.g. benzodiazepines); surgery to correct anatomical abnormalities or release tight muscles; braces and other orthotic devices; rolling walkers; and communication aids such as computers with attached voice synthesisers. A Cochrane review published in 2004 found a trend toward benefit of speech and language therapy for children with cerebral palsy, but noted the need for high quality research. A 2013 systematic review found that many of the therapies used to treat CP have no good evidence base; the treatments with the best evidence are medications (anticonvulsants, botulinum toxin, bisphosphonates, diazepam), therapy (bimanual training, casting, constraint-induced movement therapy, context-focused therapy, fitness training, goal-directed training, hip surveillance, home programmes, occupational therapy after botulinum toxin, pressure care) and surgery (selective dorsal rhizotomy).

For many adopted or adults and children in foster care, records or other reliable sources may not be available for review. Reporting alcohol use during pregnancy can also be stigmatizing to birth mothers, especially if alcohol use is ongoing. In these cases, all diagnostic systems use an unknown prenatal alcohol exposure designation. A diagnosis of FAS is still possible with an unknown exposure level if other key features of FASD are present at clinical levels.

Confirmed absence of exposure would apply to planned pregnancies in which no alcohol was used or pregnancies of women who do not use alcohol or report no use during the pregnancy. This designation is relatively rare, as most people presenting for an FASD evaluation are at least "suspected" to have had a prenatal alcohol exposure due to presence of other key features of FASD.

Oculocerebrocutaneous syndrome (also known as Delleman–Oorthuys syndrome) is a condition characterized by orbital cysts, microphthalmia, porencephaly, agenesis of the corpus callosum, and facial skin tags.