Patients who develop PSH after traumatic injury have longer hospitalization and longer durations in intensive care in cases where ICU treatment is necessary. Patients often are more vulnerable to infections and spend longer times on ventilators, which can lead to an increased risk of various lung diseases. PSH does not affect mortality rate, but it increases the amount of time it takes a patient to recover from injury, compared to patients with similar injuries who do not develop PSH episodes. It often takes patients who develop PSH longer to reach similar levels of the brain activity seen in patients who do not develop PSH, although PSH patients do eventually reach these same levels.

Diencephalic syndrome, diencephalic syndrome of emaciation or Russell's syndrome is a rare neurological disorder seen in infants and children and characterised by failure to thrive and severe emaciation despite normal or slightly decreased caloric intake. Classically there is also locomotor hyperactivity and euphoria. Less commonly diencephalic syndrome may involve skin pallor without anaemia, hypoglycaemia, and hypotension. The syndrome is a rare but potentially fatal cause of failure to thrive in children. Failure to thrive presents on average at 7 months of age. Of note the syndrome is not associated with developmental delay. There may be associated hydrocephalus.

Diencephalic syndrome was first described by Russell in 1951. It is usually caused by a brain tumor such as a low-grade glioma or astrocytoma located in the hypothalamic-optic chiasmatic region. It is not yet understood how diencephalic syndrome causes the effects on appetite and metabolism which are seen, though inappropriately high growth hormone release has been proposed, as has excessive β-lipotropin secretion and overall increased metabolic demand. It is treated with nutritional optimisation while the underlying lesion is treated with chemotherapy, surgery or radiotherapy.

Diagnosing PSH can be very difficult due to the lack of common terminology in circulation and a lack of diagnostic criteria. Different systems for diagnosis have been proposed, but a universal system has not been embraced. One example of a proposed system of diagnosis requires observation confirmation for four of the six following symptoms: fever greater than 38.3 degrees Celsius, tachycardia classified as a heart rate of 120 bpm or higher, hypertension classified as a systolic pressure higher than 160 mmHg or a pulse pressure higher than 80 mmHg, tachypnea classified as respiration rate higher than 30 breaths per minute, excess sweating, and severe dystonia. Ruling out other diseases or syndromes that show similar symptoms is imperative to diagnosis as well. Sepsis, encephalitis, neuroleptic malignant syndrome,

malignant hyperthermia, lethal catatonia, spinal cord injury (not associated with PSH), seizures, and hydrocephalus (this can be associated with PSH) are examples of diagnoses that should be considered due to the manifestation of similar symptoms before confirming a diagnosis of PSH. PSH has no simple radiological features that can be observed or detected on a scan.

KLS can be diagnosed when there is confusion, apathy, or derealization in addition to frequent bouts of extreme tiredness and prolonged sleep. The earliest it can be diagnosed is the second episode, this is not common. The condition is generally treated as a diagnosis of exclusion. Because KLS is rare, other conditions with similar symptoms are usually considered first.

MRIs can determine if the symptoms are caused by certain brain disorders, stroke, and multiple sclerosis. Lumbar puncture can determine if encephalitis is the cause. KLS must be differentiated from substance abuse by toxicology tests. The use of Electroencephalography (EEG) can exclude temporal status epilepticus from consideration. EEGs are normal in about 70% of KLS patients, but background slowing may sometimes be detected. In addition, low-frequency high-amplitude waves can be observed during waking hours.

Initially, KLS appears similar to bipolar depression. Patients with frontal-lobe syndromes and Klüver-Bucy syndrome also display similar symptoms, but these conditions can be differentiated by the presence of brain lesions. KLS should also be distinguished from very rare cases of menstruation-caused hypersomnia.

With due regard for the cause of the coma, and the rapidity of its onset, testing for the purpose of diagnosing death on brainstem death grounds may be delayed beyond the stage where brainstem reflexes may be absent only temporarily – because the cerebral blood flow is inadequate to support synaptic function although there is still sufficient blood flow to keep brain cells alive and capable of recovery. There has recently been renewed interest in the possibility of neuronal protection during this phase by use of moderate hypothermia and by correction of the neuroendocrine abnormalities commonly seen in this early stage.

Published studies of patients meeting the criteria for brainstem death or whole brain death – the American standard which includes brainstem death diagnosed by similar means – record that even if ventilation is continued after diagnosis, the heart stops beating within only a few hours or days. However, there have been some very long-term survivals and it is noteworthy that expert management can maintain the bodily functions of pregnant brain dead women for long enough to bring them to term.

The management of patients pronounced dead on meeting the brainstem death criteria depends upon the reason for diagnosing death on that basis. If the intent is to take organs from the body for transplantation, the ventilator is reconnected and life-support measures are continued, perhaps intensified, with the addition of procedures designed to protect the wanted organs until they can be removed. Otherwise, the ventilator is left disconnected on confirmation of the lack of respiratory centre response.

Lithium is the only drug that appears to have a preventive effect. In two studies of more than 100 patients, lithium helped prevent recurrence of symptoms in 20% to 40% of cases. The recommended blood level of lithium for KLS patients is 0.8-1.2 mEq/ml. It is not known if other mood stabilizers have an effect on the condition. Anti-depressants do not prevent recurrence.

In the UK, the formal rules for the diagnosis of brainstem death have undergone only minor modifications since they were first published in 1976. The most recent revision of the UK's Department of Health Code of Practice governing use of that procedure for the diagnosis of death reaffirms the preconditions for its consideration. These are:

1. There should be no doubt that the patient’s condition – deeply comatose, unresponsive and requiring artificial ventilation—is due to irreversible brain damage of known cause.

2. There should be no evidence that this state is due to depressant drugs.

3. Primary hypothermia as the cause of unconsciousness must have been excluded, and

4. Potentially reversible circulatory, metabolic and endocrine disturbances likewise.

5. Potentially reversible causes of apnoea (dependence on the ventilator), such as muscle relaxants and cervical cord injury, must be excluded.

With these pre-conditions satisfied, the definitive criteria are:

1. Fixed pupils which do not respond to sharp changes in the intensity of incident light.

2. No corneal reflex.

3. Absent oculovestibular reflexes – no eye movements following the slow injection of at least 50ml of ice-cold water into each ear in turn (the caloric reflex test).

4. No response to supraorbital pressure.

5. No cough reflex to bronchial stimulation or gagging response to pharyngeal stimulation.

6. No observed respiratory effort in response to disconnection of the ventilator for long enough (typically 5 minutes) to ensure elevation of the arterial partial pressure of carbon dioxide to at least 6.0 kPa (6.5 kPa in patients with chronic carbon dioxide retention). Adequate oxygenation is ensured by pre-oxygenation and diffusion oxygenation during the disconnection (so the brainstem respiratory centre is not challenged by the ultimate, anoxic, drive stimulus). This test—the apnoea test—is dangerous – and may prove lethal.

Two doctors, of specified status and experience, are required to act together to diagnose death on these criteria and the tests must be repeated after “a short period of time ... to allow return of the patient’s arterial blood gases and baseline parameters to the pre-test state”. These criteria for the diagnosis of death are not applicable to infants below the age of two months.

The most effective method of preventing Korsakoff's syndrome is to avoid B vitamin/thiamine deficiency. In Western nations, the most common causes of such a deficiency are alcoholism and eating disorders. Because these are behavioral-induced causes, Korsakoff's syndrome is essentially considered a preventable disease. Thus, fortifying foods with thiamine, or requiring companies that sell alcoholic beverages to supplement them with B vitamins in general or thiamine in particular, could avert many cases of Korsakoff's Syndrome.

It was once assumed that anyone suffering from Korsakoff's syndrome would eventually need full-time care. This is still often the case, but rehabilitation can help regain some, albeit often limited, level of independence. Treatment involves the replacement or supplementation of thiamine by intravenous (IV) or intramuscular (IM) injection, together with proper nutrition and hydration. However, the amnesia and brain damage caused by the disease does not always respond to thiamine replacement therapy. In some cases, drug therapy is recommended. Treatment of the patient typically requires taking thiamine orally for 3 to 12 months, though only about 20 percent of cases are reversible. If treatment is successful, improvement will become apparent within two years, although recovery is slow and often incomplete.

As an immediate form of treatment, a pairing of IV or IM thiamine with a high concentration of B-complex vitamins can be administered three times daily for period of 2–3 days. In most cases, an effective response from patients will be observed. A dose of 1 gram of thiamine can also be administered to achieve a clinical response. In patients who are seriously malnourished, the sudden availability of glucose without proper bodily levels of thiamine to metabolize is thought to cause damage to cells. Thus, the administration of thiamine along with an intravenous form of glucose is often good practice.

Treatment for the memory aspect of Korsakoff's syndrome can also include domain-specific learning, which when used for rehabilitation is called the method of vanishing cues. Such treatments aim to use patients' intact memory processes as the basis for rehabilitation. Patients who used the method of vanishing cues in therapy were found to learn and retain information more easily.

People diagnosed with Korsakoff's are reported to have a normal life expectancy, presuming that they abstain from alcohol and follow a balanced diet. Empirical research has suggested that good health practices have beneficial effects in Korsakoff's syndrome.

FACES syndrome is a syndrome of unique facial features, anorexia, cachexia, eye and skin anomalies.

It is a rare disease and estimated to occur in less than 1 in 1 million people.

Usually there are brief, arrhythmic interruptions of sustained voluntary muscle contraction causing brief lapses of posture, with a frequency of 3–5 Hz. It is bilateral, but may be asymmetric. Unilateral asterixis may occur with structural brain disease.

- It can be a sign of hepatic encephalopathy, damage to brain cells presumably due to the inability of the liver to metabolize ammonia to urea. The cause is thought to be predominantly related to abnormal ammonia metabolism.

- Asterixis is seen most often in drowsy or stuporous patients with metabolic encephalopathies, especially in decompensated cirrhosis or acute liver failure.

- It is also seen in some patients with kidney failure and azotemia, and in carbon dioxide toxicity.

- It can also be a feature of Wilson's disease.

- Asterixis is also seen in respiratory failure.

- Some drugs are known to cause asterixis, particularly phenytoin (when it is known as phenytoin flap). Other drugs implicated include benzodiazepines, barbiturates, valproate, gabapentin, lithium, ceftazidime, and metoclopramide.

Asterixis (also called the flapping tremor, or liver flap) is a tremor of the hand when the wrist is extended, sometimes said to resemble a bird flapping its wings. This motor disorder is characterized by an inability to maintain a position, which is demonstrated by jerking movements of the outstretched hands when bent upward at the wrist. The tremor is caused by abnormal function of the diencephalic motor centers in the brain, which regulate the muscles involved in maintaining position. Asterixis is associated with various encephalopathies due especially to faulty metabolism. The term derives from the Greek "a", "not" and "stērixis", "fixed position".

Asterixis is the inability to maintain posture due to a metabolic encephalopathy. This can be elicited on physical exam by having the patient extend their arms and bend their hands back.

With a metabolic encephalopathy, the patient is unable to hold their hands back resulting in a “flapping” motion consistent with asterixis. It can be seen in any metabolic encephalopathy e.g. chronic renal failure, severe congestive heart failure, acute respiratory failure and commonly in decompensated liver failure.

Paroxysmal hypertension is episodic and volatile high blood pressure, which may be due to stress of any sort, or from a pheochromocytoma, a type of tumor involving the adrenal medulla. Patients with paroxysmal hypertension who test negative for pheochromocytoma are said to be suffering from a clinical entity called "pseudopheochromocytoma." This disorder is due to episodic dopamine discharge and has been observed predominantly in hypertensive women, that had episodes that shared similar characteristics of pheochromocytoma but testing proved negative and had ruled out the tumor. In patients with pseudopheochromocytoma dopamine was found to be significantly increased post-paroxysm. The paroxysm is said to be similar to the hypertensive episodes described by Page. These episodes commonly occur after diencephalic stimulation. Therefore, pseudopheochromocytoma, shares many characteristics of "Page's syndrome."

Pseudopheochromocytoma, colloquially known as page's syndrome, is caused predominantly by episodic dopamine discharge, stressors including pain or anxiety, or possibly repressed emotions caused by prior emotional trauma and commonly, a repressive way of coping emotionally. Therefore, treatment of pseudopheochromocytoma is aimed at psychological support and intervention with antidepressants, but also treatment with alpha and then beta blockers in resistant cases.

Diagnosis is very difficult, and usually one of exclusion. SMA syndrome is thus considered only after patients have undergone an extensive evaluation of their gastrointestinal tract including upper endoscopy, and evaluation for various malabsorptive, ulcerative and inflammatory instestinal conditions with a higher diagnostic frequency. Diagnosis may follow x-ray examination revealing duodenal dilation followed by abrupt constriction proximal to the overlying SMA, as well as a delay in transit of four to six hours through the gastroduodenal region. Standard diagnostic exams include abdominal and pelvic computed tomography (CT) scan with oral and IV contrast, upper gastrointestinal series (UGI), and, for equivocal cases, hypotonic duodenography. In addition, vascular imaging studies such as ultrasound and contrast angiography may be used to indicate increased bloodflow velocity through the SMA or a narrowed SMA angle.

Despite multiple case reports, there has been controversy surrounding the diagnosis and even the existence of SMA syndrome since symptoms do not always correlate well with radiologic findings, and may not always improve following surgical correction. However, the reason for the persistence of gastrointestinal symptoms even after surgical correction in some cases has been traced to the remaining prominence of reversed peristalsis in contrast to direct peristalsis.

Since females between the ages of 10 and 30 are most frequently afflicted, it is not uncommon for physicians to initially and incorrectly assume that emaciation is a choice of the patient instead of a consequence of SMA syndrome. Patients in the earlier stages of SMA syndrome often remain unaware that they are ill until substantial damage to their health is done, since they may attempt to adapt to the condition by gradually decreasing their food intake or naturally gravitating toward a lighter and more digestible diet.

Craniopharyngiomas are usually successfully managed with a combination of adjuvant chemotherapy and neurosurgery. Recent research describes the rare occurrence of malignant transformations of these normally benign tumors. Malignant craniopharyngiomas can occur at any age, are slightly more common in females, and are usually of the adamantinomatous type.

The malignant transformations can take years to occur (although 1 in 5 of the diagnosed cases were de novo transformations), hence the need for lengthier follow up in patients diagnosed with the more common benign forms.

There was no link found between malignancy and initial chemo-radiotherapy treatment, and the overall survival rate was very poor with median survival being 6 months post diagnosis of malignancy.

Delay in the diagnosis of SMA syndrome can result in fatal catabolysis (advanced malnutrition), dehydration, electrolyte abnormalities, hypokalemia, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia), gastric distention, spontaneous upper gastrointestinal bleeding, hypovolemic shock, and aspiration pneumonia.

A 1-in-3 mortality rate for Superior Mesenteric Artery syndrome has been quoted by a small number of sources. However, after extensive research, original data establishing this mortality rate has not been found, indicating that the number is likely to be unreliable. While research establishing an official mortality rate may not exist, two recent studies of SMA syndrome patients, one published in 2006 looking at 22 cases and one in 2012 looking at 80 cases, show mortality rates of 0% and 6.3%, respectively. According to the doctors in one of these studies, the expected outcome for SMA syndrome treatment is generally considered to be excellent.

There are a few scans and tests that the physician can conduct in order to diagnose a person with craniopharyngioma. Your doctor may order a high-resolution magnetic resonance imaging (MRI) scan. This test is valuable because it allows the neuroradiologist to view the tumor from different angles.

In some cases, a powerful 3T (Tesla) MRI scanner can help define the location of critical brain structures affected by the tumor.The histologic pattern consists of nesting of squamous epithelium bordered by radially arranged cells. It is frequently accompanied by calcium deposition and may have a microscopic papillary architecture.A computed tomography (CT) scan is also a good diagnostic tool as it detects calcification in the tumor.

Two distinct types are recognized:

- Adamantinomatous craniopharyngiomas, which resemble ameloblastomas (the most common type of odontogenic tumor), are characterized by activating CTNNB1 mutations; and,

- Papillary craniopharyngiomas are characterized by BRAFv600E mutations.

In the adamantinomatous type, calcifications are visible on neuroimaging and are helpful in diagnosis.

The papillary type rarely calcifies. A vast majority of craniopharyngiomas in children are adamantiomatous whereas both subtypes are common in adults. Mixed type tumors also occur.

On macroscopic examination, craniopharyngiomas are cystic or partially cystic with solid areas. On light microscopy, the cysts are seen to be lined by stratified squamous epithelium. Keratin pearls may also be seen. The cysts are usually filled with a yellow, viscous fluid which is rich in cholesterol crystals. Of a long list of possible symptoms, the most common presentations include: headaches, growth failure, and bitemporal hemianopsia.

If one of these tests shows a deficiency of hormones produced by the pituitary, magnetic resonance imaging (MRI) scan of the pituitary is the first step in identifying an underlying cause. MRI may show various tumors and may assist in delineating other causes. Tumors smaller than 1 cm are referred to as "microadenomas", and larger lesions are called "macroadenomas". Computed tomography with radiocontrast may be used if MRI is not available. Formal visual field testing by perimetry is recommended, as this would show evidence of optic nerve compression by a tumor.

Other tests that may assist in the diagnosis of hypopituitarism, especially if no tumor is found on the MRI scan, are ferritin (elevated in hemochromatosis), angiotensin converting enzyme (ACE) levels (often elevated in sarcoidosis), and human chorionic gonadotropin (often elevated in tumor of germ cell origin). If a genetic cause is suspected, genetic testing may be performed.

Physical examination to examine muscle wasting, laboratory investigations.

According to the 2007 AHRQ National Inpatient Sample, in a projected 129,164 hospital encounters in the United States, cachexia was listed as at least one of up to 14 recorded diagnosis codes based on a sample of 26,325 unweighted encounters. A sample of 32,778 unweighted US outpatient visits collected by the CDC's National Ambulatory Medical Care Survey did not list any visits where cachexia was one of up to three recorded diagnoses treated during the visit.

However, diagnosis can be difficult due to the comprehensive measurements used in research that are not always practical in healthcare settings. Hand grip strength alone has also been advocated as a clinical marker of sarcopenia that is simple and cost effective and has good predictive power, although it does not provide comprehensive information.

Exercise remains the intervention of choice for sarcopenia but translation of findings into clinical practice is challenging. The type, duration and intensity of exercise are variable between studies, so an ‘off the shelf’ exercise prescription for sarcopenia remains an aspiration.

The role of nutrition in preventing and treating sarcopenia is less clear. Large, well-designed studies of nutrition particularly in combination with exercise are needed, ideally across healthcare settings. For now, basing nutritional guidance on the evidence available from the wider health context is probably the best approach with little contention in the goals of replacing vitamin D where deficient, and ensuring an adequate intake of calories and protein, although there is debate about whether currently recommended protein intake levels are optimal.

A working definition for diagnosis was proposed in 1998 by Baumgartner "et al" which uses a measure of lean body mass as determined by dual energy X-ray absorptiometry (DEXA) compared to a normal reference population. His working definition uses a cut point of 2 standard deviations below the mean of lean mass for gender specific healthy young adults.

Since Baumgartner's working definition first appeared, some consensus groups have refined the definition, including the European Working Group on Sarcopenia in Older People (EWGSOP). Their consensus definition is:

- Low muscle mass, (e.g. >2 standard deviations below that mean measured in young adults [aged 18–39 years in the 3rd NHANES population] of the same sex and ethnic background).

And either:

- Low gait speed (e.g. a walking speed below 0.8 m/s in the 4-m walking test)

Or:

- Low muscular strength (e.g. grip strength: <30 kg in males, <20 kg in females)

Severe sarcopenia requires the presence of all three conditions.

Growth hormone deficiency is almost certain if all other pituitary tests are also abnormal, and insulin-like growth factor 1 (IGF-1) levels are decreased. If this is not the case, IGF-1 levels are poorly predictive of the presence of GH deficiency; stimulation testing with the insulin tolerance test is then required. This is performed by administering insulin to lower the blood sugar to a level below 2.2 mmol/l. Once this occurs, growth hormone levels are measured. If they are low despite the stimulatory effect of the low blood sugars, growth hormone deficiency is confirmed. The test is not without risks, especially in those prone to seizures or are known to have heart disease, and causes the unpleasant symptoms of hypoglycemia. Alternative tests (such as the growth hormone releasing hormone stimulation test) are less useful, although a stimulation test with arginine may be used for diagnosis, especially in situations where an insulin tolerance test is thought to be too dangerous. If GH deficiency is suspected, and all other pituitary hormones are normal, two different stimulation tests are needed for confirmation.

If morning cortisol levels are over 500 nmol/l, ACTH deficiency is unlikely, whereas a level less than 100 is indicative. Levels between 100-500 require a stimulation test. This, too, is done with the insulin tolerance test. A cortisol level above 500 after achieving a low blood sugar rules out ACTH deficiency, while lower levels confirm the diagnosis. A similar stimulation test using corticotropin-releasing hormone (CRH) is not sensitive enough for the purposes of the investigation. If the insulin tolerance test yields an abnormal result, a further test measuring the response of the adrenal glands to synthetic ACTH (the ACTH stimulation test) can be performed to confirm the diagnosis. Stimulation testing with metyrapone is an alternative. Some suggest that an ACTH stimulation test is sufficient as first-line investigation, and that an insulin tolerance test is only needed if the ACTH test is equivocal. The insulin tolerance test is discouraged in children. None of the tests for ACTH deficiency are perfect, and further tests after a period of time may be needed if initial results are not conclusive.

Symptoms of diabetes insipidus should prompt a formal fluid deprivation test to assess the body's response to dehydration, which normally causes concentration of the urine and increasing osmolarity of the blood. If these parameters are unchanged, desmopressin (an ADH analogue) is administered. If the urine then becomes concentrated and the blood osmolarity falls, there is a lack of ADH due to lack of pituitary function ("cranial diabetes insipidus"). In contrast, there is no change if the kidneys are unresponsive to ADH due to a different problem ("nephrogenic diabetes insipidus").

Malnutrition–inflammation complex (syndrome), abbreviated as "MICS" and also known as "malnutrition–inflammation–cachexia syndrome", is a common condition in chronic disease states such as chronic kidney disease (where it is also known as uremic malnutrition or protein–energy malnutrition) and chronic heart failure.

The MICS is believed to be a cause of survival paradoxes seen in these distinct patient populations, also known as reverse epidemiology populations.

Because LAL deficiency is inherited, each sibling of an affected individual has a 25% chance of having pathological mutations in LAL genes from both their mother and their father, a 50% chance of having a pathological mutation in only one gene, and a 25% chance of having no pathological mutations. Genetic testing for family members and genetic prenatal diagnosis of pregnancies for women who are at increased risk are possible if family members carrying pathological mutations have been identified.