Cushing's triad is a clinical triad

Triad (anatomy)

In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum known as the terminal cisterna on either side. Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally...

 variably defined as either hypertension, bradycardia, and
irregular respiration , or less commonly as widened pulse pressure (with elevated systolic and a either elevated or normal diastolic BP), irregular respiration, and bradycardia

Bradycardia

Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...

. It is sign of increased intracranial pressure, and it occurs as a result of the Cushing reflex

Cushing reflex

Cushing reflex is a physiological nervous system response to increased intracranial pressure that results in Cushing's triad of widening pulse pressure, irregular breathing, and a reduction of the...

.

It should not be confused with Cushing's syndrome

Cushing's syndrome

Cushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone or CRH...

, a disease state resulting from the elevated levels of blood cortisol

Cortisol

Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...

.

Significance

Identification of the triad is important in emergency medicine

Emergency medicine

Emergency medicine is a medical specialty in which physicians care for patients with acute illnesses or injuries which require immediate medical attention. While not usually providing long-term or continuing care, emergency medicine physicians diagnose a variety of illnesses and undertake acute...

 because it suggests severe pressure within the cranial vault. This can be the result of cerebral hemorrhage, possibly due to a ruptured aneurysm or other cerebrovascular accident

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

 (a hemorrhagic stroke

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

) or head trauma

Physical trauma

Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...

 resulting in concussion and associated intracranial bleeding either within or outside the meninges

Meninges

The meninges is the system of membranes which envelopes the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.-Dura...

 (a subdural

Subdural hematoma

A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...

 or epidural

Epidural hematoma

Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...

 hemorrhage). It can also be due to an enlarging space-occupying lesion (a brain tumor

Brain tumor

A brain tumor is an intracranial solid neoplasm, a tumor within the brain or the central spinal canal.Brain tumors include all tumors inside the cranium or in the central spinal canal...

). All of these events lead to the possibility of brain herniation

Brain herniation

Brain herniation, also known as cistern obliteration, is a deadly side effect of very high intracranial pressure that occurs when the brain shifts across structures within the skull...

, which can be rapidly fatal

Brain death

Brain death is the irreversible end of all brain activity due to total necrosis of the cerebral neurons following loss of brain oxygenation. It should not be confused with a persistent vegetative state...

.

Eponym

It is named after Harvey Williams Cushing (1869-1939), an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 neurosurgeon.