The first symptom of compartment syndrome is pain. Loss of function and decreased pulses or pulselessness, however, are late signs. According to Shears, paresthesia in the distribution of the nerves transversing the affected compartment has also been described as relatively early sign of compartment syndrome, and later is followed by anesthesia (Shears, 2006).

- Pain is often reported early and almost universally. The description is usually of deep, constant, and poorly localized pain out of proportion with the findings on physical examination (often incorrectly described as pain out of proportion to the injury). The pain is aggravated by passively stretching the muscle group within the compartment or actively flexing it (though this finding is not specific to compartment syndrome alone) and is not relieved by analgesia up to and including morphine.

- Paresthesia (altered sensation e.g., "pins & needles") in the cutaneous nerves of the affected compartment is another typical sign.

- Paralysis of the limb is usually a late finding. The compartment may also feel very tense and firm (pressure). Some find that their feet and even legs fall asleep. This is because compartment syndrome prevents adequate blood flow to the rest of the leg.

- A lack of pulse rarely occurs in patients, as pressures that cause compartment syndrome are often well below arterial pressures and pulse is only affected if the relevant artery is contained within the affected compartment.

- Tense and swollen shiny skin, sometimes with obvious bruising of the skin.

- Congestion of the digits with prolonged capillary refill time.

The symptoms of chronic exertional compartment syndrome (CECS) are brought on by exercise and consist of a sensation of extreme tightness in the affected muscles followed by a painful burning sensation if exercise is continued. After exercise is ceased, the pressure in the compartment will decrease within a few minutes, relieving painful symptoms. Symptoms will occur at a certain threshold of exercise which varies from person to person but is rather consistent for a given individual and can range anywhere from 30 seconds of running to about 10–15 minutes of running. CECS most commonly occurs in the lower leg, with the anterior compartment being the most frequently affected compartment. Foot drop is a common symptom of CECS.

The ‘Harlequin Sign’ is unilateral flushing and sweating of the face, neck, and upper chest usually after exposure to heat or strenuous exertion. Horner syndrome, another problem associated with the sympathetic nervous system, is often seen in conjunction with harlequin syndrome.

Since Harlequin syndrome is associated with a dysfunction in the autonomic nervous system, main symptoms of this dysfunction are in the following: Absence of sweat(anhidrosis) and flushing on one side of the face, neck, or upper thoracic area. In addition, other symptoms include cluster headaches, tearing of the eyes, nasal discharge, abnormal contraction of the pupils, weakness in neck muscles, and drooping of on side of the upper eyelid.

Harlequin syndrome is a condition characterized by asymmetric sweating and flushing on the upper thoracic region of the chest, neck, and face. Harlequin syndrome is considered an injury to the autonomic nervous system (ANS). The ANS controls some of the body's natural processes such as sweating, skin flushing, and pupil response to stimuli. Such individuals with this syndrome have an absence of sweat skin flushing unilaterally; usually on the one side of the face, arms, and chest. It is an autonomic disorder that may occur at any age. Harlequin syndrome affects fewer than 200,000 people in the United States.

Symptoms associated with Harlequin syndrome are more likely to appear when a person has been in the following conditions: exercising, warm environment, and intense emotional situation. Since one side of the body sweats and flushes appropriately to the condition, the other side of the body will have an absence of such symptoms. This syndrome has also been called the "Harlequin sign," and thought to be one of the spectrum of diseases that may cause Harlequin syndrome.

It can also be the outcome of a one sided endoscopic thoracic sympathectomy (ETS) or endoscopic sympathetic blockade (ESB) surgery.

Harlequin syndrome can also be seen as a complication of VA (veno-arterial) extracorporeal membrane oxygenation (ECMO). This involves differential hypoxemia (low oxygen levels in the blood) of the upper body in comparison to the lower body.

Any fracture in elbow region or upper arm may lead to Volkmann's ischemic contracture, but it is especially associated with supracondylar fracture of the humerus.

Volkmann's contracture results from acute ischaemia and necrosis of the muscle fibres of the flexor group of muscles of the forearm, especially the flexor digitorum profundus and flexor pollicis longus. The muscles become fibrotic and shortened.

The condition is caused by obstruction on the brachial artery near the elbow, possibly from improper use of a tourniquet, improper use of a plaster cast, or compartment syndrome. It is also caused by fractures of the forearm bones if they cause bleeding from the major blood vessels of the forearm.

There is considerable variability in the phenotype of Loeys–Dietz syndrome, from mild features to severe systemic abnormalities. The primary manifestations of Loeys–Dietz syndrome are arterial tortuosity (winding course of blood vessels), widely spaced eyes (hypertelorism), wide or split uvula, and aneurysms at the aortic root. Other features may include cleft palate and a blue/gray appearance of the white of the eyes. Cardiac defects and club foot may be noted at birth.

There is overlap in the manifestations of Loeys–Dietz and Marfan syndromes, including increased risk of ascending aortic aneurysm and aortic dissection, abnormally long limbs and fingers, and dural ectasia (a gradual stretching and weakening of the dura mater that can cause abdominal and leg pain). Findings of hypertelorism (widely spaced eyes), bifrid or split uvula, and skin findings such as easy bruising or abnormal scars may distinguish Loys-Dietz from Marfan syndrome.

Findings of Loys-Dietz syndrome may include:

- Skeletal/spinal malformations: craniosynositosis, Scoliosis, spinal instability and spondylolisthesis, Kyphosis

- Sternal abnormalities: pectus excavatum, pectus carinatum

- Contractures of fingers and toes (camptodactyly)

- Long fingers and lax joints

- Weakened or missing eye muscles (strabismus)

- Club foot

- Premature fusion of the skull bones (craniosynostosis)

- Joint hypermobility

- Congenital heart problems including patent ductus arteriosus (connection between the aorta and the lung circulation) and atrial septal defect (connection between heart chambers)

- Translucency of the skin with velvety texture

- Abnormal junction of the brain and medulla (Arnold-Chiari malformation)

- Bicuspid aortic valves

- Criss-crossed pulmonary arteries

Volkmann's contracture is a permanent flexion contracture of the hand at the wrist, resulting in a claw-like deformity of the hand and fingers. Passive extension of fingers is restricted and painful.

All people with this disorder have at least one limb abnormality that affects bones in the wrist (carpal bones). Often, these wrist bone abnormalities can be detected only by X-ray. Affected individuals may have additional bone abnormalities that can include polydactyly, a hypoplastic thumb or a Triphalangeal thumb, partial or complete absence of bones in the forearm, an underdeveloped Humerus, and abnormalities that affect the Clavicle and Scapula. Bone abnormalities may affect each arm differently, and the left side can be affected more than the right side. In some cases, only one arm and/or hand is affected.

About 75 percent of individuals with Holt–Oram syndrome have heart problems. The most common problem is a defect in the muscular wall, or septum, that separates the right and left sides of the heart (atria). Atrial septal defects (ASD) are caused by a hole in the septum between the left and right upper chambers of the heart (atria), and ventricular septal defects (VSD) are caused by a hole in the septum between the left and right lower chambers of the heart (ventricles). Sometimes people with Holt–Oram syndrome have cardiac conduction disease, which is caused by abnormalities in the electrical system that coordinates contractions of the heart chambers. Cardiac conduction disease can lead to problems such as a slow heart rate (bradycardia) or a rapid and ineffective contraction of the heart muscles (fibrillation). Cardiac conduction disease can occur along with other heart defects (such as septal defects) or as the only heart problem in people with Holt–Oram syndrome.

Loeys–Dietz syndrome (LDS) is an autosomal dominant genetic connective tissue disorder. It has features similar to Marfan syndrome and Ehlers–Danlos syndrome. The disorder is marked by aneurysms in the aorta, often in children, and the aorta may also undergo sudden dissection in the weakened layers of the wall of aorta. Aneurysms and dissections also can occur in arteries other than the aorta. Because aneurysms in children tend to rupture early, children are at greater risk for dying if the syndrome is not identified. Surgery to repair aortic aneurysms is essential for treatment.

There are four types of the syndrome, labelled types I through IV, which are distinguished by their genetic cause. Type 1, Type 2, Type 3, and Type 4 are caused by mutations in "TGFBR1", "TGFBR2", "SMAD3", and "TGFB2" respectively. These four genes encoding transforming growth factors play a role in cell signaling that promotes growth and development of the body's tissues. Mutations of these genes cause production of proteins without function. Although the disorder has an autosomal pattern of inheritance, this disorder results from a new gene mutation in 75% of cases and occurs in people with no history of the disorder in their family.

Loeys-Dietz syndrome was identified and characterized by pediatric geneticists Bart Loeys and Harry Dietz at Johns Hopkins University in 2005.

Romano–Ward syndrome presents the following in an affected individual:

- Ventricular fibrillation

- Syncope

- Torsade de pointes

- Abnormality of ear

Romano–Ward syndrome is the major variant of "long QT syndrome". It is a condition that causes a disruption of the heart's normal rhythm. This disorder is a form of long QT syndrome, which is a heart condition that causes the cardiac muscle to take longer than usual to recharge between beats; if untreated, the irregular heartbeats can lead to fainting, seizures, or sudden death

Holt–Oram syndrome (also called Heart and Hand Syndrome, atrio-digital syndrome, atriodigital dysplasia, cardiac-limb syndrome, heart-hand syndrome type 1, HOS, ventriculo-radial syndrome) is an autosomal dominant disorder that affects bones in the arms and hands (the upper limbs) and may also cause heart problems. The syndrome includes an absent radial bone in the arms, an atrial septal defect, and a first degree heart block. Thalidomide syndrome can produce similar morphology to Holt–Oram syndrome, sufficient to be considered a phenocopy.

The syndrome is a rare clinical disorder.

- Physical

- Overgrowth

- Accelerated skeletal maturation

- Dysmorphic facial features

- Prominent eyes

- Bluish sclerae

- Coarse eyebrows

- Upturned nose

- Radiologic examination

- Accelerated osseous maturation

- Phalangeal abnormalities

- Tubular thinning of the long bones

- Skull abnormalities

- Mental

- Often associated with intellectual disability (of variable degree)

Heerfordt syndrome, also referred to as uveoparotid fever, Heerfordt–Mylius syndrome, Heerfordt–Waldenström syndrome, and Waldenström's uveoparotitis, is a rare manifestation of sarcoidosis. The symptoms include inflammation of the eye (uveitis), swelling of the parotid gland, chronic fever, and in some cases, of the facial nerves.

The main sign of metabolic syndrome is central obesity (also known as visceral, male-pattern or apple-shaped adiposity), overweight with adipose tissue accumulation particularly around the waist and trunk.

Other signs of metabolic syndrome include high blood pressure, decreased fasting serum HDL cholesterol, elevated fasting serum triglyceride level (VLDL triglyceride), impaired fasting glucose, insulin resistance, or prediabetes.

Associated conditions include hyperuricemia, fatty liver (especially in concurrent obesity) progressing to nonalcoholic fatty liver disease, polycystic ovarian syndrome (in women), erectile dysfunction (in men), and acanthosis nigricans.

The Kocher–Debré–Semelaigne syndrome is hypothyroidism in infancy or childhood characterised by lower extremity or generalized muscular hypertrophy, myxoedema, short stature and cretinism. The absence of painful spasms and pseudomyotonia differentiates this syndrome from its adult form, which is Hoffmann syndrome.

The syndrome is named after Emil Theodor Kocher, Robert Debré and Georges Semelaigne.

Also known as Debre–Semelaigne syndrome or cretinism-muscular hypertrophy, hypothyroid myopathy, hypothyroidism-large muscle syndrome, hypothyreotic muscular hypertrophy in children, infantile myxoedema-muscular hypertrophy, myopathy-myxoedema syndrome, myxoedema-muscular hypertrophy syndrome, myxoedema-myotonic dystrophy syndrome.

Kocher-Debre-Semelaigne syndrome gives infant a Hercules appearance.

In patients that have already been diagnosed with sarcoidosis, Heerfordt syndrome can be inferred from the major symptoms of the syndrome, which include parotitis, fever, and facial nerve palsy. In cases of parotitis, ultrasound-guided biopsy is used to exclude the possibility of lymphoma. There are many possible causes of facial nerve palsy, including Lyme disease, HIV, Melkersson–Rosenthal syndrome, schwannoma, and Bell's palsy. Heerfordt syndrome exhibits spontaneous remission. Treatments for sarcoidosis include corticosteroids and immunosuppressive drugs.

Reye syndrome progresses through five stages:

- Stage I

- Rash on palms of hands and feet

- Persistent, heavy vomiting that is not relieved by not eating

- Generalized lethargy

- Confusion

- Nightmares

- No fever usually present

- Headaches

- Stage II

- Stupor

- Hyperventilation

- Fatty liver (found by biopsy)

- Hyperactive reflexes

- Stage III

- Continuation of Stage I and II symptoms

- Possible coma

- Possible cerebral edema

- Rarely, respiratory arrest

- Stage IV

- Deepening coma

- Dilated pupils with minimal response to light

- Minimal but still present liver dysfunction

- Stage V

- Very rapid onset following stage IV

- Deep coma

- Seizures

- Multiple organ failure

- Flaccidity

- Hyperammonemia (above 300 mg/dL of blood)

- Death

Metabolic syndrome, sometimes known by other names, is a clustering of at least three of the five following medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides and low high-density lipoprotein (HDL) levels.

Metabolic syndrome is associated with the risk of developing cardiovascular disease and type 2 diabetes. In the USA, about a quarter of the adult population have metabolic syndrome, and the prevalence increases with age, with racial and ethnic minorities being particularly affected.

Insulin resistance, metabolic syndrome, and prediabetes are closely related to one another and have overlapping aspects.

The syndrome is thought to be caused by an underlying disorder of energy utilization and storage. The cause of the syndrome is an area of ongoing medical research.

Marshall-Smith Syndrome, discovered in 1971 (Marshall, Graham, Scott, Boner, & Smith), is characterized by unusual accelerated skeletal maturation (usually starting before birth) and symptoms like conspicuous physical characteristics, respiratory difficulties, and mental retardation. Cases described in the literature show a clinical variability regarding related symptoms. For instance, respiratory difficulties are ranging from absent to severe difficulties.

A syndrome is a set of medical signs and symptoms occurring together, constitutes a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". In some instances, a syndrome is so closely linked with a pathogenesis or cause that the words "syndrome", "disease", and "disorder" end up being used interchangeably for them. This is especially true of inherited syndromes. For example, Down syndrome, Wolf–Hirschhorn syndrome, and Andersen syndrome are disorders with known pathogeneses, so each is more than just a set of signs and symptoms, despite the "syndrome" nomenclature. In other instances, a syndrome is not specific to only one disease. For example, toxic shock syndrome can be caused by various toxins; premotor syndrome can be caused by various brain lesions; and premenstrual syndrome is not a disease but simply a set of symptoms.

If an underlying genetic cause is suspected but not known, a condition may be referred to as a genetic association (often just "association" in context). By definition, an association indicates that the collection of signs and symptoms occurs in combination more frequently than would be likely by chance alone.

Syndromes are often named after the physician or group of physicians that discovered them or initially described the full clinical picture. Such eponymous syndrome names are examples of medical eponyms. Recently, there has been a shift towards naming conditions descriptively (by symptoms or underlying cause) rather than eponymously, but the eponymous syndrome names often persist in common usage.

The predominant symptom of Pisa syndrome is dystonia. Dystonia is a neurological movement disorder characterized by sustained muscle contraction leading to abnormal posture, twisting, and repetitive movement. In Pisa Syndrome specifically there is commonly a tonic flexion of the trunk of the body to one side, leading to a slight lean (reminiscent of the Leaning Tower of Pisa, hence the name "Pisa syndrome"). This is usually associated with a backward axial rotation of the spine and indifferent to markedly abnormal posture. Patients diagnosed with Pisa Syndrome usually experience either acute dystonia or tardive dystonia, also known as tardive dyskinesia. Differential diagnosis between the two may be hard to accomplish without a complete patient history, since both types of dystonia may occur simultaneously in a patient. These symptoms generally disappear after discontinuation of the antipsychotic drug. The time of onset of symptoms may vary depending on drug being administered and the neurological characteristics of the patient in question.

Pleurothotonus, commonly known as Pisa syndrome, is a rare neurological disorder which occurs due to prolonged exposure to antipsychotic drugs (which may also be referred to as neuroleptics). It is characterized by dystonia, and abnormal and sustained involuntary muscle contraction. This may cause twisting or jerking movements of the body or a body part. Although Pisa syndrome develops most commonly in those undergoing long-term treatment with antipsychotics, it has been reported less frequently in patients receiving other medications, such as an acetylcholinesterase inhibitor. However, it has also been seen in those with other diseases causing neurodegeneration and in those who are not receiving any medication (idiopathic Pisa syndrome). The characteristic development of Pisa syndrome consists of two types of dystonia: acute dystonia and tardive dystonia (also known as tardive dyskinesia). The underlying pathology of drug-induced Pisa syndrome is very complex, and development may be due to an underlying dopaminergic-cholinergic imbalance, or serotonergic/noradrenergic dysfunction.

The joint changes include hyperextensibility (double-jointedness) and arthritis. Babies and young children with Stickler syndrome usually have very hyperextensible joints. As an affected child gets older, they may experience pain and stiffness from overuse of a joint. Osteoarthritis of the large joints often develops during the third or fourth decade. The joint changes in Marshall syndrome are of the same type but to a lesser degree. There also may be changes in the bones that show up on X-ray but generally are not a problem.

LGL syndrome is diagnosed on the basis of the surface EKG in a symptomatic individual with a PR interval less than or equal to 0.12 second (120 ms) with normal QRS complex configuration and duration. It can be distinguished from WPW syndrome because the delta waves seen in WPW syndrome are not seen in LGL syndrome. It is a clinical diagnosis that came about before the advent of electrophysiology studies. Be aware, however, that not all WPW EKG's have a delta wave; the absence of a delta wave does not conclusively rule out WPW.