ABE is an acute state of elevated bilirubin in the central nervous system. Clinically, it encompasses a wide range of symptoms. These include lethargy, decreased feeding, hypotonia or hypertonia, a high-pitched cry, spasmodic torticollis, opisthotonus, setting sun sign, fever, seizures, and even death. If the bilirubin is not rapidly reduced, ABE quickly progresses to chronic bilirubin encepalopathy.

CBE is a chronic state of severe bilirubin-induced neurological lesions. Reduction of bilirubin in this state will not reverse the sequelae. Clinically, manifestations of CBE include:

1. movement disorders - athetoid cerebral palsy and or dystonia, 60% have severe motor disability(unable to walk).

2. auditory dysfunction - auditory neuropathy (ANSD)

3. oculomotor impairments (nystagmus, strabismus, Impaired upward or downward gaze, and/or cortical visual impairment),

4. dental enamel hypoplasia/dysplasia of the deciduous teeth,

5. Gastroesophageal reflux,

6. impaired digestive function.

Intellectual disability occur in 25% of cases. But they are often look like intellectually disabled because their severe motor handicaps.

Epilepsy occur in 20% of cases.

These impairments are associated with lesions in the basal ganglia, auditory nuclei of the brain stem, and oculomotor nuclei of the brain stem. Cortex and white matter are mildly involved. Cerebellum may be involved.

The mildest form of hepatic encephalopathy is difficult to detect clinically, but may be demonstrated on neuropsychological testing. It is experienced as forgetfulness, mild confusion, and irritability. The first stage of hepatic encephalopathy is characterised by an inverted sleep-wake pattern (sleeping by day, being awake at night). The second stage is marked by lethargy and personality changes. The third stage is marked by worsened confusion. The fourth stage is marked by a progression to coma.

More severe forms of hepatic encephalopathy lead to a worsening level of consciousness, from lethargy to somnolence and eventually coma. In the intermediate stages, a characteristic jerking movement of the limbs is observed (asterixis, "liver flap" due to its flapping character); this disappears as the somnolence worsens. There is disorientation and amnesia, and uninhibited behaviour may occur. In the third stage, neurological examination may reveal clonus and positive Babinski sign. Coma and seizures represent the most advanced stage; cerebral oedema (swelling of the brain tissue) leads to death.

Encephalopathy often occurs together with other symptoms and signs of liver failure. These may include jaundice (yellow discolouration of the skin and the whites of the eyes), ascites (fluid accumulation in the abdominal cavity), and peripheral edema (swelling of the legs due to fluid build-up in the skin). The tendon reflexes may be exaggerated, and the plantar reflex may be abnormal, namely extending rather than flexing (Babinski's sign) in severe encephalopathy. A particular smell ("foetor hepaticus") may be detected.

The primary symptom is yellowish discoloration of the white part of the eyes and skin in a newborn baby. Other symptoms may include excess sleepiness or poor feeding.

A bilirubin level more than 34 μmol/l (2 mg/dL) may be visible. For the feet to be affected level generally must be over 255 μmol/l (15 mg/dL).

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

The severity of hepatic encephalopathy is graded with the West Haven Criteria; this is based on the level of impairment of autonomy, changes in consciousness, intellectual function, behavior, and the dependence on therapy.

- Grade 1 - Trivial lack of awareness; euphoria or anxiety; shortened attention span; impaired performance of addition or subtraction

- Grade 2 - Lethargy or apathy; minimal disorientation for time or place; subtle personality change; inappropriate behaviour

- Grade 3 - Somnolence to semistupor, but responsive to verbal stimuli; confusion; gross disorientation

- Grade 4 - Coma

In newborns, jaundice tends to develop because of two factors—the breakdown of fetal hemoglobin as it is replaced with adult hemoglobin and the relatively immature metabolic pathways of the liver, which are unable to conjugate and so excrete bilirubin as quickly as an adult. This causes an accumulation of bilirubin in the blood (hyperbilirubinemia), leading to the symptoms of jaundice.

If the neonatal jaundice does not clear up with simple phototherapy, other causes such as biliary atresia, Progressive familial intrahepatic cholestasis, bile duct paucity, Alagille syndrome, alpha 1-antitrypsin deficiency, and other pediatric liver diseases should be considered. The evaluation for these will include blood work and a variety of diagnostic tests. Prolonged neonatal jaundice is serious and should be followed up promptly.

Severe neonatal jaundice may indicate the presence of other conditions contributing to the elevated bilirubin levels, of which there are a large variety of possibilities (see below). These should be detected or excluded as part of the differential diagnosis to prevent the development of complications. They can be grouped into the following categories:

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.

The hallmark of encephalopathy is an altered mental state. Characteristic of the altered mental state is impairment of the cognition, attention, orientation, sleep–wake cycle and consciousness. An altered state of consciousness may range from failure of selective attention to drowsiness. Hypervigilance may be present; with or without: congnitive deficits, headache, epileptic seizures, myoclonus (involuntary twitching of a muscle or group of muscles) or asterixis ("flapping tremor" of the hand when wrist is extended).

Depending on the type and severity of encephalopathy, common neurological symptoms are loss of cognitive function, subtle personality changes, inability to concentrate. Other neurological signs may include dysarthria, hypomimia, problems with movements (they can be clumsy or slow), ataxia, tremor. Another neurological signs may include involuntary grasping and sucking motions, nystagmus (rapid, involuntary eye movement), jactitation (restless picking at things characteristic of severe infection), and respiratory abnormalities such as Cheyne-Stokes respiration (cyclic waxing and waning of tidal volume), apneustic respirations and post-hypercapnic apnea. Focal neurological deficits are less common.

Encephalopathies exhibits both neurologic and psychopathologic symptoms.

Wernicke encephalopathy (alcoholic encephalopathy) also develop Korsakoff's syndrome, characterized by amnestic-confabulatory syndrome: retrograde amnesia, anterograde amnesia, confabulations (invented memories), poor recall and disorientation.

Anti-NMDA receptor encephalitis is the most common autoimmune encephalitis. It can cause paranoid and grandiose delusions, agitation, hallucinations (visual and auditory), bizarre behavior, fear, short-term memory loss, confusion.

HIV encephalopathy develop dementia ( †).

There are several different forms of glycine encephalopathy, which can be distinguished by the age of onset, as well as the types and severity of symptoms. All forms of glycine encephalopathy present with only neurological symptoms, including mental retardation (IQ scores below 20 are common), hypotonia, apneic seizures, and brain malformations.

With the classical, or neonatal presentation of glycine encephalopathy, the infant is born after an unremarkable pregnancy, but presents with lethargy, hypotonia, apneic seizures and myoclonic jerks, which can progress to apnea requiring artificial ventilation, and often death. Apneic patients can regain spontaneous respiration in their second to third week of life. After recovery from the initial episode, patients have intractable seizures and profound mental retardation, remaining developmentally delayed. Some mothers comment retrospectively that they noticed fetal rhythmic "hiccuping" episodes during pregnancy, most likely reflecting seizure episodes in utero. Patients with the infantile form of glycine encephalopathy do not show lethargy and coma in the neonatal period, but often have a history of hypotonia. They often have seizures, which can range in severity and responsiveness to treatment, and they are typically developmentally delayed. Glycine encephalopathy can also present as a milder form with episodic seizures, ataxia, movement disorders, and gaze palsy during febrile illness. These patients are also developmentally delayed, to varying degrees. In the later onset form, patients typically have normal intellectual function, but present with spastic diplegia and optic atrophy.

Transient neonatal hyperglycinemia has been described in a very small number of cases. Initially, these patients present with the same symptoms and laboratory results that are seen in the classical presentation. However, levels of glycine in plasma and cerebrospinal fluid typically normalize within eight weeks, and in five of six cases there were no neurological issues detected at follow-up times up to thirteen years. A single patient was severely retarded at nine months. The suspected cause of transient neonatal hyperglicinemia is attributed to low activity of the glycine cleavage system in the immature brain and liver of the neonate.

It typically presents as a severe encephalopathy with myoclonic seizures, is rapidly progressive and eventually results in respiratory arrest.Standard evaluation for inborn errors of metabolism and other causes of this presentation does not reveal any abnormality (no acidosis, no hypoglycaemia, or hyperammonaemia and no other organ affected). Pronounced and sustained hiccups in an encephalopathic infant have been described as a typical observation in non-ketotic hyperglycinaemia.

Hyperbilirubinemia, more precisely hyperbilirubinemia due to the unconjugated fraction, may cause bilirubin to accumulate in the gray matter of the central nervous system, potentially causing irreversible neurological damage leading to a condition known as kernicterus. Depending on the level of exposure, the effects range from clinically unnoticeable to severe brain damage and even death. Newborns are especially vulnerable to hyperbilirubinemia-induced neurological damage and therefore must be carefully monitored for alterations in their serum bilirubin levels.

The main sign of jaundice is a yellowish discoloration of the white area of the eye and the skin. Urine is dark in colour.

Slight increases in serum bilirubin are best detected by examining the sclerae, which have a particular affinity for bilirubin due to their high elastin content. The presence of scleral icterus indicates a serum bilirubin of at least 3 mg/dL.

The conjunctiva of the eye are one of the first tissues to change color as bilirubin levels rise in jaundice. This is sometimes referred to as "scleral icterus". However, the sclera themselves are not "icteric" (stained with bile pigment) but rather the conjunctival membranes that overlie them. The yellowing of the "white of the eye" is thus more properly termed "conjunctival icterus". The term "icterus" itself is sometimes incorrectly used to refer to jaundice that is noted in the sclera of the eyes; however, its more common and more correct meaning is entirely synonymous with jaundice.

Coagulopathy is another cardinal feature of ALF. The liver has the central role in the synthesis of almost all coagulation factors and some inhibitors of coagulation and fibrinolysis. Hepatocellular necrosis leads to impaired synthesis of many coagulation factors and their inhibitors. The former produces a prolongation in prothrombin time which is widely used to monitor the severity of hepatic injury. There is significant platelet dysfunction (with both quantitative and qualitative platelet defects). Progressive thrombocytopenia with the loss of larger and more active platelets is almost universal. Thrombocytopenia with or without DIC increases risk of intracerebral bleeding.

Depending on the location of the brain lesion different symptoms are more frequent:

- Brainstem tegmentum. - Ocular: pupillary changes. Extraocular muscle palsy; gaze palsy: nystagmus.

- Hypothalamus. Medulla: dorsal nuc. of vagus. - Autonomic dysfunct.: temperature; cardiocirculatory; respiratory.

- Medulla: vestibular region. Cerebellum. - Ataxia.

- Dorsomedial nuc. of thalamus. Mammillary bodies. - Amnestic syndrome for recent memory.

Mamillary lesion are characteristic-small petechial hemorrhages are found.

- Diffuse cerebral dysfunction.- Altered cognition: global confusional state.

- Brainstem: periaqueductal gray.- Reduction of consciousness

- Hypothalamic lesions may also affect the immune system, which is known in alcohol abusers, causing dysplasias and infections.

Kidney failure is common, present in more than 50% of ALF patients, either due to original insult such as paracetamol resulting in acute tubular necrosis or from hyperdynamic circulation leading to hepatorenal syndrome or functional kidney failure. Because of impaired production of urea, blood urea does not represent the degree of kidney impairment.

Neonatal cholestasis defines persisting conjugated hyperbilirubinemia in the newborn with conjugated bilirubin levels exceeding 15% (5.0 mg/dL) of total bilirubin level. The disease is either due to defects in bile excretion from hepatocytes or impaired bile flow.

General presentations in neonates include abdominal pain and general GI upset. Physical examination may show palpable liver and enlarged spleen. Differential diagnosis typically presents with a host of possibilities, many of them not treatable. Histopathology shows dilated bile duct system at all levels and bile duct proliferation in response to back pressure. The incidence has been found to be about 1:2,500 live births.

The classic triad of symptoms found in Wernicke's encephalopathy is:

- ophthalmoplegia (later expanded to other eye movement abnormalities, most commonly affecting the lateral rectus or any eye sign. Lateral nystagmus is most commonly seen although lateral rectus palsy, usually bilateral, may be seen).

- ataxia (later expanded to imbalance or any cerebellar signs)

- confusion (later expanded to other mental changes. Has 82% incidence in diagnosis cases)

However, in actuality, only a small percentage of patients experience all three symptoms, and the full triad occurs more frequently among those who have overused alcohol.

Also a much more diverse range of symptoms has been found in patients with this condition, including:

- pupillary changes, retinal hemorrhage, papilledema, impaired vision and hearing, vision loss

- hearing loss,

- fatigability, apathy, irritability, drowsiness, psycho and/or motor slowing

- dysphagia, blush, sleep apnea, epilepsy and stupor

- lactic acidosis

- memory impairment, amnesia, depression, psychosis

- hypothermia, polyneuropathy, hyperhidrosis.

Although hypothermia is usually diagnosed with a body temperature of 35 °C / 95° Fahrenheit, or less, incipient cooling caused by deregulation in the CNS needs to be monitored because it can promote the development of an infection. The patient may report feeling cold, followed by mild chills, cold skin, moderate pallor, tachycardia, hypertension, tremor or piloerection. External warming techniques are advised to prevent hypothermia.

Among the frequently altered functions are the cardio circulatory. There may be tachycardia, dyspnea, chest pain, orthostatic hypotension, changes in heart rate and blood pressure. The lack of thiamine sometimes affects other major energy consumers, the myocardium, and also patients may have developed cardiomegaly. Heart failure with lactic acidosis syndrome has been observed. Cardiac abnormalities are an aspect of the WE, which was not included in the traditional approach, and are not classified as a separate disease.

Infections have been pointed out as one of the most frequent triggers of death in WE. Furthermore, infections are usually present in pediatric cases.

In the last stage others symptoms may occur: hyperthermia, increased muscle tone, spastic paralysis, choreic dyskinesias and coma.

Because of the frequent involvement of heart, eyes and peripheral nervous system, several authors prefer to call it Wernicke disease rather than simply encephalopathy.

Early symptoms are nonspecific, and it has been stated that WE may present nonspecific findings. In Wernicke Korsakoff’s syndrome some single symptoms are present in about one-third.

Toxic encephalopathy is often irreversible. If the source of the problem is treated by removing the toxic chemical from the system, further damage can be prevented, but prolonged exposure to toxic chemicals can quickly destroy the brain. Long term studies have demonstrated residual cognitive impairment (primarily attention and information-processing impairment resulting in dysfunction in working memory) up to 10 years following cessation of exposure. Severe cases of toxic encephalopathy can be life-threatening.

"Encephalopathy" is a general term describing brain malfunctions and "toxic" asserts that the malfunction is caused by toxins on the brain. The most prominent characteristic of toxic encephalopathy is an altered mental status. Acute intoxication is a reversible symptom of exposure to many synthetic chemical neurotoxicants. Acute intoxication symptoms include lightheadedness, dizziness, headache and nausea, and regular cumulative exposure to these toxic solvents over a number of years puts the individual at high risk for developing toxic encephalopathy. Chronic exposure to low levels of neurotoxic chemicals can also cause reversible changes in mood and affect which resolve with cessation of exposure. Acute and chronic toxic encephalopathy on the other hand, are persistent changes in neurological function that typically occur with exposure to higher concentrations and longer durations respectively. The symptoms of acute and chronic toxic encephalopathy do not resolve with cessation of exposure and can include memory loss, small personality changes/increased irritability, insidious onset of concentration difficulties, involuntary movements (parkinsonism), fatigue, seizures, arm strength problems, and depression. Neurobehavioral effects of occupational exposure to organic solvents exists among painters. The condition may also be referred to as substance-induced persistent dementia.

Magnetic Resonance Imaging (MRI) analyses have also demonstrated increased rates of dopamine synthesis in the putamen, reduced anterior and total corpus callosum volume, demyelination in the parietal white matter, basal ganglia, and thalamus, as well as atypical activation of frontal areas of the brain due to neural compensation. A thorough and standard diagnostic process is paramount with toxic encephalopathy, including a careful occupational history, medical history, and standardized imaging/neurobehavioral testing.

Neurologic signs and symptoms include progressively delayed development, weak muscle tone (hypotonia), seizures, and abnormal movements. The body's network of blood vessels is also affected. Children with this disorder may experience rashes of tiny red spots (petechiae) caused by bleeding under the skin and blue discoloration in the hands and feet due to reduced oxygen in the blood (acrocyanosis). Chronic diarrhea is another common feature of ethylmalonic encephalopathy. EE is often identified by urine organic acid analysis, the excretion of ethylmalonic acid, methylsuccinic acid, isobutyrylglycine and isovalerylglucine. Patients will also often have elevated thiosulphate concentration in their urine.

The signs and symptoms of ethylmalonic encephalopathy are apparent at birth or begin in the first few months of life. Problems with the nervous system typically worsen over time, and most affected individuals survive only into early childhood. A few children with a milder, chronic form of this disorder have been reported, and there can be considerable phenotypic variation, even within families. The life expectancy of individuals with EE is less than ten years.

Acute fatty liver of pregnancy (or hepatic lipidosis of pregnancy) usually manifests in the third trimester of pregnancy, but may occur any time in the second half of pregnancy, or in the puerperium, the period immediately after delivery. On average, the disease presents during the 35th or 36th week of pregnancy. The usual symptoms in the mother are non-specific including nausea, vomiting, anorexia (or lack of desire to eat) and abdominal pain; excessive thirst may be the earliest symptom without overlap with otherwise considered normal pregnancy symptoms; however, jaundice and fever may occur in as many as 70% of patients.

In patients with more severe disease, pre-eclampsia may occur, which involves elevation of blood pressure and accumulation of fluid (termed oedema). This may progress to involvement of additional systems, including acute renal failure, hepatic encephalopathy, and pancreatitis. There have also been reports of diabetes insipidus complicating this condition.

Many laboratory abnormalities are seen in acute fatty liver of pregnancy. Liver enzymes are elevated, with the AST and ALT enzymes ranging from minimal elevation to 1000 IU/L, but usually staying in the 300-500 range. Bilirubin is almost universally elevated. Alkaline phosphatase is often elevated in pregnancy due to production from the placenta, but may be additionally elevated. Other abnormalities may include an elevated white blood cell count, hypoglycemia, elevated coagulation parameters, including the international normalized ratio, and decreased fibrinogen. Frank disseminated intravascular coagulation, or DIC, may occur in as many as 70% of people.

Abdominal ultrasound may show fat deposition in the liver, but, as the hallmark of this condition is microvesicular steatosis (see pathology below), this is not seen on ultrasound. Rarely, the condition can be complicated by rupture or necrosis of the liver, which may be identified by ultrasound.

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.

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).