Various degrees of intensity and locations of epilepsy are associated with malformations of cortical development. Researchers suggest that approximately 40% of children diagnosed with drug-resistant epilepsy have some degree of cortical malformation.

Lissencephaly (to which pachygyria is most closely linked) is associated with severe mental retardation, epilepsy, and motor disability. Two characteristics of lissencephaly include its absence of convolutions (agyria) and decreased presence of convolutions (pachygyria). The types of seizures associated with lissencephaly include:

- persisting spasms

- focal seizures

- tonic seizures

- atypical seizures

- atonic seizures

Other possible symptoms of lissencephaly include telecanthus, estropia, hypertelorism, varying levels of mental retardation, cerebellar hypoplasia, corpus callosum aplasia, and decreased muscle tone and tendon reflexes. Over 90% of children affected with lissencephaly have seizures.

Patients with subcortical band heterotopia (another disorder associated with pachygyria) typically have milder symptoms and their cognitive function is closely linked to the thickness of the subcortical band and the degree of pachygyria present.

There are various symptoms of colpocephaly and patients can experience effects ranging from mild to severe. Some patients do not show most of the symptoms related to colpocephaly, such as psychomotor abnormalilities and agenesis of the corpus callosum. In some cases, signs appear later on in life and a significant number of children suffer only from minor disabilities.

The following list includes common symptoms of colpocephaly.

- partial or complete agenesis of the corpus callosum

- intellectual disability

- motor abnormalities

- visual defects such as, crossing of the eyes, missing visual fields, and optic nerve hypoplasia

- spasticity

- seizures

- cerebral palsy

Intracranial abnormalities include:

- Microcephaly

- Agenesis of the corpus callosum

- Meningomyelocele

- Lissencephaly

- Periventricular leukomalacia (PVL)

- Enlargement of the cisterna magna

- Cerebellar hypoplasia

The diagnosis of PMG is merely descriptive and is not a disease in itself, nor does it describe the underlying cause of the brain malformation.

Polymicrogyria may be just one piece of a syndrome of developmental abnormalities, because children born with it may suffer from a wide spectrum of other problems, including global developmental disabilities, mild to severe mental retardation, motor dysfunctions including speech and swallowing problems, respiratory problems, and seizures. Though it is difficult to make a predictable prognosis for children with the diagnosis of PMG, there are some generalized clinical findings according to the areas of the brain that are affected.

- Bilateral frontal polymicrogyria (BFP) – Cognitive and motor delay, spastic quadriparesis, epilepsy

- Bilateral frontoparietal polymicrogyria (BFPP) – Severe cognitive and motor delay, seizures, dysconjugate gaze, cerebellar dysfunction

- Bilateral perisylvian polymicrogyria (BPP) – Pseudobulbar signs, cognitive impairment, epilepsy, some with arthrogryposis or lower motor neuron disease

- Bilateral parasagittal parieto-occipital polymicrogyria (BPPP) – Partial seizures, some with mental retardation

- Bilateral generalized polymicrogyria (BGP) – Cognitive and motor delay of variable severity, seizures

The region in which unilateral polymicrogyria occurs has been generalized into different cortical areas. Features associated with this form of polymicrogyria are similar to the other forms and include spastic hemiparesis, mental retardation in variable degrees, and seizures. The features depend on the exact area and extent to which polymicrogyria has affected the cortex. Patients who have unilateral polymicrogyria have been reported to also have electrical status epilepticus during sleep (EPES), and all suffered from seizures.

Pachygyria (from the Greek "pachy" meaning "thick" or "fat" gyri) is a congenital malformation of the cerebral hemisphere. It results in unusually thick convolutions of the cerebral cortex. Typically, children have developmental delay and seizures, the onset and severity depending on the severity of the cortical malformation. Infantile spasms are common in affected children, as is intractable epilepsy.

Delayed motor development of infants affected by PVL has been demonstrated in multiple studies. One of the earliest markers of developmental delays can be seen in the leg movements of affected infants, as early as one month of age. Those with white matter injury often exhibit "tight coupling" of leg joints (all extending or all flexing) much longer than other infants (premature and full-term). Additionally, infants with PVL may not be able to assume the same positions for sleeping, playing, and feeding as premature or full-term children of the same age. These developmental delays can continue throughout infancy, childhood, and adulthood.

Colpocephaly is characterized by disproportionately large occipital horns of the lateral ventricles (also frontal and temporal ventricles in some cases). MRI and CT scans of patients demonstrate abnormally thick gray matter with thin poorly myelinated white matter. This happens as a result of partial or complete absence of the corpus callosum. Corpus callosum is the band of white matter connecting the two cerebral hemispheres. The corpus callosum plays an extremely important role in interhemispheric communication, thus lack of or absence of these neural fibers results in a number of disabilities.

The lemon sign on CT scans of patients refers to the shape of the fetal skull when the frontal bones lose their normal convex contour and appear flattened or inwardly scalloped. This gives the skull a shape similar to that of a lemon. The sign is seen on transverse sonograms of the fetal cranium obtained at the level of the ventricles.

A special case is found in literature where lissencephaly, colpocephaly, and septal agenesis are all present together. The CT scans of the patient shows the ventricular system having a unique appearance of a crown of a king. This is referred to as the 'CROWN SIGN'.

Subcortical heterotopia form as distinct nodes in the white matter, "focal" indicating specific area. In general, patients present fixed neurologic deficits and develop partial epilepsy between the ages of 6 and 10. The more extensive the subcortical heterotopia, the greater the deficit; bilateral heterotopia are almost invariably associated with severe developmental delay or mental retardation. The cortex itself often suffers from an absence of gray matter and may be unusually thin or lack deep sulci. Subependymal heterotopia are frequently accompanied by other structural abnormalities, including an overall decrease in cortical mass. Patients with focal subcortical heterotopia have a variable motor and intellectual disturbance depending on the size and site of the heterotopion.

It is often impossible to identify PVL based on the patient’s physical or behavioral characteristics. The white matter in the periventricular regions is involved heavily in motor control, and so individuals with PVL often exhibit motor problems. However, since healthy newborns (especially premature infants) can perform very few specific motor tasks, early deficits are very difficult to identify. As the individual develops, the areas and extent of problems caused by PVL can begin to be identified; however, these problems are usually found after an initial diagnosis has been made.

The extent of signs is strongly dependent on the extent of white matter damage: minor damage leads to only minor deficits or delays, while significant white matter damage can cause severe problems with motor coordination or organ function. Some of the most frequent signs include delayed motor development, vision deficits, apneas, low heart rates, and seizures.

Periventricular means beside the ventricle, while subependymal (also spelled subepydymal) means beneath the ependyma; because the ependyma is the thin epithelial sheet lining the ventricles of the brain, these two terms are used to define heterotopia occurring directly next to a ventricle. This is by far the most common location for heterotopia. Patients with isolated subependymal heterotopia usually present with a seizure disorder in the second decade of life.

Subependymal heterotopia present in a wide array of variations. They can be a small single node or a large number of nodes, can exist on either or both sides of the brain at any point along the higher ventricle margins, can be small or large, single or multiple, and can form a small node or a large wavy or curved mass.

Symptomatic women with subependymal heterotopia typically present with partial epilepsy during the second decade of life; development and neurologic examinations up to that point are typically normal. Symptoms in men with subependymal heterotopia vary, depending on whether their disease is linked to their X-chromosome. Men with the X-linked form more commonly have associated anomalies, which can be neurological or more widespread, and they usually suffer from developmental problems. Otherwise (i.e., in non-X-linked cases) the symptomology is similar in both genders.

Patients come to clinical attention early in life (usually at birth or within the first few months), with a firm subcutaneous nodule at bridge of nose, or as a polypoid mass within the nasal cavity, or somewhere along the upper border of the nasal bow. If the patient presents with an intranasal mass, there may be obstruction, chronic rhinosinusitis, or nasal drainage. If there is a concurrent cerebrospinal fluid (CSF) leak, then an encephalocele is much more likely.

This lesion is separated into two types based on the anatomic site of presentation:

1. Extranasal (60%): Subcutaneous bridge of nose

2. Intranasal (30%): Superior nasal cavity

3. Mixed (10%): Subcutaneous tissues and nasal cavity (larger lesions)

While nasal glial heterotopia (NGH) is the preferred term, synonyms have included nasal glioma. However, this term is to be discouraged, as it implies a neoplasm or tumor, which it is not. By definition, nasal glial heterotopia is a specific type of choristoma. It is not a teratoma, however, which is a neoplasm comprising all three germ cell layers (ectoderm, endoderm, mesoderm). As a congenital malformation or ectopia, it is distinctly different from the trauma or iatrogenic development of an encephalocele.

Choristomas, forms of heterotopia, are closely related benign tumors, found in abnormal locations.

It is different from hamartoma. The two can be differentiated as follows: a hamartoma is disorganized overgrowth of tissues in their normal location, (eg, Peutz-Jeghers polyps) while a choristoma is normal tissue growth in an abnormal location (e.g., gastric tissue located in distal ileum in Meckel diverticulum).

NPH may exhibit a classic triad of clinical findings (known as the Adams triad or Hakim's triad) of urinary incontinence, gait disturbance, and dementia (commonly referred to as "wet, wacky and wobbly" or "weird walking water").

- Gait disturbance is typically the initial and most prominent symptom of the triad and may be progressive, due to expansion of the ventricular system, particularly at the level of the lateral ventricles, leading to traction on the corticospinal tract motor fibers descending to the lumbosacral spinal cord. The gait disturbance can be classified as mild (cautious gait or difficulty with tandem gait), marked (evident difficulty walking or considerable unstable gait) or severe (unaided gait not possible) In the early stages, most often this gait disturbance occurs in the form of unsteadiness and impaired balance, especially when encountering stairs and curbs. Weakness and tiredness of the legs may also be part of the complaint, although examination discloses no paresis or ataxia. Often a mobility aid is used for added stability, once the patient has reached the mild to marked stage. Such aids may include a quad cane or wheeled walker. The patient's gait at the marked stage will often show a decrease in step height and foot-floor clearance, as well as a decrease in walking speed. This style is often referred to as a magnetic gait, in which the feet appear to be stuck to the walking surface, and is considered the characteristic gait disturbance of NPH. The gait may begin to mimic a Parkinsonian gait, with short shuffling steps and stooped, forward-leaning posture, but there is no rigidity or tremor. An increased tendency to fall backwards is also seen, and a broad-based gait may be employed by the patient in order to increase their base of support and thereby their stability. In the very late stages, the patient can progress from an inability to walk, to an inability to stand, sit, rise from a chair or turn over in bed; this advanced stage is referred to as "hydrocephalic astasia-abasia".

- Dementia is predominantly frontal lobe in nature and of the subcortical type of dementia. It presents in the form of abulia, forgetfulness, inertia, inattention, decreased speed of complex information procession (also described as a dullness in thinking and actions), and disturbed manipulation of acquired knowledge, which is reflective of the loss of integrity of the frontal lobes. Memory problems are usually a component of the overall problem and have been predominant in some cases, which can lead to the misdiagnosis of Alzheimer's disease. However, in NPH there may be an obvious discrepancy between (often severely) impaired recall and intact or much less impaired recognition. The dementia is thought to result from traction on frontal and limbic fibers that also run in the periventricular region.

- Urinary incontinence appears late in the illness, and is found to be of the spastic hyperreflexic, increased-urgency type associated with decreased inhibition of bladder contractions and detrusor instability. In the most severe cases, bladder hyperreflexia is associated with a lack of concern for micturition due to the severe frontal lobe cognitive impairment. This is also known as "frontal lobe incontinence", where the patient becomes indifferent to their recurrent urinary symptoms.

In neonates born at or beyond 35 weeks, neonatal encephalopathy may present itself as the following symptoms:

- Reduced level of consciousness

- Seizures (which peak at 48 hours)

- Difficulty initiating and maintaining respiration

- Depression of tone and reflexes

If a cause presents itself, the syndrome is referred to as "symptomatic" West syndrome, as the attacks manifest as a symptom of another problem. Almost any cause of brain damage could be associated, and these are divided into prenatal, perinatal, and post-natal. The following is a partial list:

- In around one third of the children, there is evidence of a profound organic disorder of the brain. This includes:

- microcephaly

- cortical dysplasia

- cerebral atrophy

- lissencephaly

- bacterial meningitis

- phakomatoses (e.g. tuberous sclerosis)

- Aicardi syndrome

- cephalhematoma and

- vascular malformation.

- Furthermore, other causes increasingly being named in the literature are:

- Incontinentia pigmenti

- Foix-Chavany-Marie syndrome

- Patau syndrome (trisomy 13)

- Sturge-Weber syndrome

- neurometabolic diseases

- congential infections (e.g. Cytomegalovirus)

- hypoglycemia

- brain damage due to asphyxiation or hypoxia (lack of oxygen, e.g. during birth), periventricular leukomalacia, cephalhematoma, cerebrovascular accident or brain damage of various types as well as that caused by premature birth.

The features of this syndrome affect the face, skin, brain and the body.

Face:

- downslanting palpebral fissures

- pointed chin

- prominent forehead

- proptosis

- thin upper lip

- wide nasal bridge

Skin:

- fragile

- hyperelastic

Brain:

- Low IQ

- Periventricular white matter lesions

Body:

The height, lower-segment, hand, and foot length are all greater than usual.

Neonatal encephalopathy (NE), also known as neonatal hypoxic-ischemic encephalopathy (neonatal HIE or NHIE), is defined by signs and symptoms of abnormal neurological function in the first few days of life in an infant born at term. In this condition there is difficulty initiating and maintaining respirations, a subnormal level of consciousness, and associated depression of tone, reflexes, and possibly seizures. Encephalopathy is a nonspecific response of the brain to injury which may occur via multiple methods, but is commonly caused by birth asphyxia.

Normal pressure hydrocephalus (NPH), also termed Hakim's syndrome and symptomatic hydrocephalus, is a type of brain malfunction caused by expansion of the lateral cerebral ventricles and distortion of the fibers in the corona radiata. Its typical symptoms are urinary incontinence, dementia, and gait disturbance. CSF pressure is usually normal. Ventricles are chronically dilated.

The name “normal pressure” came out of a 1965 medical paper describing cases of hydrocephalus where the symptoms occurred in the presence of supposedly normal cerebrospinal-fluid pressure. The paper was published before continuous pressure-recording techniques were available. We now know that “normal pressure” is a misnomer.

The usual treatment is surgical installation of a ventriculoperitoneal shunt to drain excess CSF into the lining of the abdomen where the CSF will eventually be absorbed.

West syndrome appears in 1% to 5% of infants with Down syndrome. This form of epilepsy is relatively difficult to treat in children who do not have the chromosomal abnormalities involved in Down syndrome. However, in children with Down syndrome, the syndrome is often far more mild, and the children often react better to medication. The German Down Syndrom InfoCenter noted in 2003 that what was normally a serious epilepsy was in such cases often a relatively benign one.

EEG records for children with Down syndrome are often more symmetrical with fewer unusual findings. Although not all children can become entirely free from attacks with medication, children with Down syndrome are less likely to go on to develop Lennox-Gastaut syndrome or other forms of epilepsy than those without additional hereditary material on the 21st chromosome. The reason why it is easier to treat children with Down syndrome is not known.

If, however, a child with Down syndrome has seizures that are difficult to control, the child should be accessed for autistic spectrum disorder.

Athetoid cerebral palsy or dyskinetic cerebral palsy (sometimes abbreviated ADCP) is a type of cerebral palsy primarily associated with damage, like other forms of CP, to the basal ganglia in the form of lesions that occur during brain development due to bilirubin encephalopathy and hypoxic-ischemic brain injury. Unlike spastic or ataxic cerebral palsies, ADCP is characterized by both hypertonia and hypotonia, due to the affected individual's inability to control muscle tone. Clinical diagnosis of ADCP typically occurs within 18 months of birth and is primarily based upon motor function and neuroimaging techniques. While there are no cures for ADCP, some drug therapies as well as speech, occupational therapy, and physical therapy have shown capacity for treating the symptoms.

Classification of cerebral palsy can be based on severity, topographic distribution, or motor function. Severity is typically assessed via the Gross Motor Function Classification System (GMFCS) or the International Classification of Functioning, Disability and Health (described further below). Classification based on motor characteristics classifies CP as occurring from damage to either the corticospinal pathway or extrapyramidal regions. Athetoid dyskinetic cerebral palsy is a non-spastic, extrapyramidal form of cerebral palsy (spastic cerebral palsy, in contrast, results from damage to the brain’s corticospinal pathways). Non-spastic cerebral palsy is divided into two groups, ataxic and dyskinetic. Dyskinetic cerebral palsy is separated further into two different groups; choreoathetoid and dystonic. Choreo-athetotic CP is characterized by involuntary movements most predominantly found in the face and extremities. Dystonic ADCP is characterized by slow, strong contractions, which may occur locally or encompass the whole body.

Clinically, physicians have also classified cerebral palsy according to the topographic distribution of muscle spasticity. This method classifies children as diplegic, (bilateral involvement with leg involvement greater than arm involvement), hemiplegic (unilateral involvement), or quadriplegic (bilateral involvement with arm involvement equal to or greater than leg involvement).

ADCP is often characterized by slow, uncontrolled movements of the extremities and trunk. Small, rapid, random and repetitive, uncontrolled movements known as chorea may also occur. Involuntary movements often increase during periods of emotional stress or excitement and disappear when the patient is sleeping or distracted. Patients experience difficulty in maintaining posture and balance when sitting, standing, and walking due to these involuntary movements and fluctuations in muscle tone. Coordinated activities such as reaching and grasping may also be challenging. Muscles of the face and tongue can be affected, causing involuntary facial grimaces, expressions, and drooling. Speech and language disorders, known as dysarthria, are common in athetoid CP patients. In addition, ADCP patients may have trouble eating. Hearing loss is a common co-occurring condition, and visual disabilities can be associated with Athetoid Cerebral Palsy. Squinting and uncontrollable eye movements may be initial signs and symptoms. Children with these disabilities rely heavily on visual stimulation, especially those who are also affected by sensory deafness.

Cognitive impairment occur in 30% of cases.

Epilepsy occur in 25% of cases.

Spastic quadriplegia can be detected by the abnormal development of motor skills in children. Symptoms can present themselves as early as three months but are generally seen before the child reaches two years of age. Some warning signs include: a child of more than two months who has stiff legs that scissor and is unable to control his or her head, and a child of more than twelve months who has not developed the ability to crawl or stand.

Spastic quadriplegia also presents a range of symptoms that affect the musculature. Many experience contractures, which are defined as joints that cannot be stretched or moved. Clonus is another symptom that is characterized by alternating, rapid muscle contraction and relaxation. This presents itself as tremors and scissoring of the limbs. Distonia, or lasting muscle contractions and tightness, is also often experienced by those affected by spastic quadriplegia. These involuntary muscle contractions may affect the development of structural muscle around the hip and lead to hip dysplasia and dislocation, making it difficult to sit. The combination of these symptoms often makes it difficult for the patients to walk as well. Although the arms and legs of patients are often stiff, the neck is usually limp due to the lack of voluntary muscle control. Some adults have issues with sexual organs such as the ones that control the sphincter (anus) as well and bladder control. These can sometimes be treated with training and stimulation even if the problems have presented for years, some issues can be corrected in many cases with nutrition modification in 90 percent of cases, especially B12. Stimulation of the muscles involved can treat some forms of nerve damage, depending on what the issue is. Sexual issues can be difficult for those with this, and sexual acts and stimulation can correct most of the sexual issues.

Kosaki overgrowth syndrome (KOGS) is a rare (27 cases reported by 2017) syndrome caused by mutations in the PDGFRB gene.

One of the most troublesome hamartomas occurs on the hypothalamus. Unlike most such growths, a hypothalamic hamartoma is symptomatic; it most often causes gelastic seizures, and can cause visual problems, other seizures, rage disorders associated with hypothalamic diseases, and early onset of puberty. The symptoms typically begin in early infancy and are progressive, often into general cognitive and/or functional disability. Moreover, resection is usually difficult, as the growths are generally adjacent to, or even intertwined with, the optic nerve. Symptoms tend to be resistant to medical control; however, surgical techniques are improving and can result in immense improvement of prognosis.