Abnormal posturing is an involuntary

flexion Motion, the process of movement, is described using specific anatomical terminology, anatomical terms. Motion includes movement of Organ (anatomy), organs, joints, Limb (anatomy), limbs, and specific sections of the body. The terminology used de ...

or extension of the arms and legs, indicating severe

brain injury Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...

. It occurs when one set of

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

s becomes incapacitated while the opposing set is not, and an external stimulus such as

pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

causes the working set of muscles to contract.AllRefer.com. 200
"Decorticate Posture"
. Retrieved January 15, 2007. The posturing may also occur without a stimulus.WrongDiagnosis.com

(Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series). Retrieved on September 15, 2007. Since posturing is an important indicator of the amount of damage that has occurred to the brain, it is used by medical professionals to measure the severity of a

coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to Nociception, respond normally to Pain, painful stimuli, light, or sound, lacks a normal Circadian rhythm, sleep-wake cycle and does not initiate ...

with the Glasgow Coma Scale (for adults) and the Pediatric Glasgow Coma Scale (for infants). The presence of abnormal posturing indicates a severe

medical emergency A medical emergency is an acute injury or illness that poses an immediate risk to a person's life or long-term health, sometimes referred to as a situation risking "life or limb". These emergencies may require assistance from another, qualified ...

requiring immediate medical attention. Decerebrate and decorticate posturing are strongly associated with poor outcome in a variety of conditions. For example, near-

drowning Drowning is a type of Asphyxia, suffocation induced by the submersion of the mouth and nose in a liquid. Submersion injury refers to both drowning and near-miss incidents. Most instances of fatal drowning occur alone or in situations where othe ...

patients who display decerebrate or decorticate posturing have worse outcomes than those who do not. Changes in the condition of the patient may cause alternation between different types of posturing.

Types

Three types of abnormal posturing are decorticate posturing, with the arms flexed over the chest; decerebrate posturing, with the arms extended at the sides; and opisthotonus, in which the head and back are arched backward.

Decorticate

Decorticate posturing is also called decorticate response, decorticate rigidity, flexor posturing, or, colloquially, "mummy baby". Patients with decorticate posturing present with the arms flexed, or bent inward on the chest, the hands are clenched into fists, and the legs extended and feet turned inward. A person displaying decorticate posturing in response to pain gets a score of three in the motor section of the Glasgow Coma Scale, caused by the flexion of muscles due to the neuro-muscular response to the trauma. There are two parts to decorticate posturing. * The first is the disinhibition of the

red nucleus The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. ...

with facilitation of the rubrospinal tract due to severment of the

corticospinal tract The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk. There are more than one million neu ...

. The rubrospinal tract facilitates

motor neuron A motor neuron (or motoneuron), also known as efferent neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly o ...

s in the cervical spinal cord supplying the flexor muscles of the upper extremities. The rubrospinal tract and medullary reticulospinal tract biased flexion outweighs the medial and lateral vestibulospinal and pontine reticulospinal tract biased extension in the upper extremities. * The second component of decorticate posturing is the disruption of the lateral

which facilitates motor neurons in the lower spinal cord supplying flexor muscles of the lower extremities. Since the corticospinal tract is interrupted, the pontine reticulospinal and the medial and lateral vestibulospinal biased extension tracts greatly overwhelm the medullary reticulospinal biased flexion tract. The effects on these two tracts (corticospinal and rubrospinal) by lesions above the red nucleus is what leads to the characteristic flexion posturing of the upper extremities and extensor posturing of the lower extremities. Decorticate posturing indicates that there may be damage to areas including the

cerebral hemisphere The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...

s, the

internal capsule The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...

, and the

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

. It may also indicate damage to the

midbrain The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

. While decorticate posturing is still an ominous sign of severe

brain damage Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...

, decerebrate posturing is usually indicative of more severe damage at the rubrospinal tract, and hence, the red nucleus is also involved, indicating a lesion lower in the brainstem.

Decerebrate

Decerebrate posturing is also called decerebrate response, decerebrate rigidity, or extensor posturing. It describes the involuntary extension of the upper extremities in response to external stimuli. In decerebrate posturing, the head is arched back, the arms are extended by the sides, and the legs are extended. A hallmark of decerebrate posturing is extended elbows. The arms and legs are extended and rotated internally. The patient is rigid, with the teeth clenched. The signs can be present on only one side of the body or on both sides, and they may be present just in the arms, and they may be intermittent. A person displaying decerebrate posturing in response to pain receives a score of two in the motor section of the Glasgow Coma Scale (for adults) and the Pediatric Glasgow Coma Scale (for infants), due to the muscles extending because of the neuro-muscular response to the trauma. Decerebrate posturing indicates

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is co ...

damage, specifically damage below the level of the

(e.g. mid-collicular lesion). It is exhibited by people with lesions or compression in the

and lesions in the

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

. Decerebrate posturing is commonly seen in pontine strokes. A patient with decorticate posturing may begin to show decerebrate posturing, or may go from one form of posturing to the other. Progression from decorticate posturing to decerebrate posturing is often indicative of uncal (transtentorial) or tonsilar

brain herniation Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the human brain, brain is squeezed across structures within the human skull, skull. The brain can shift across such structures ...

. Activation of

gamma motor neuron A gamma motor neuron (γ motor neuron), also called gamma motoneuron, or fusimotor neuron, is a type of lower motor neuron that takes part in the process of muscle contraction, and represents about 30% of ( Aγ) fibers going to the muscle. Like ...

s is thought to be important in decerebrate rigidity due to studies in animals showing that dorsal-root transection eliminates decerebrate rigidity symptoms. Transection releases the centres below the site from higher inhibitory controls. In competitive contact sports, posturing (typically of the forearms) can occur with an impact to the head and is termed the fencing response.

Causes

Posturing can be caused by conditions that lead to large increases in

intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and at rest, is normally 7–15 mmHg for a supine adu ...

. Such conditions include

traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity ranging from mild traumatic brain injury (mTBI/concussion) to severe traumati ...

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

intracranial hemorrhage Intracranial hemorrhage (ICH) refers to any form of Hemorrhage, bleeding Internal bleeding, within the Human skull, skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized ...

brain tumor A brain tumor (sometimes referred to as brain cancer) occurs when a group of cells within the Human brain, brain turn cancerous and grow out of control, creating a mass. There are two main types of tumors: malignant (cancerous) tumors and benign ...

brain abscess The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special sense ...

es and

encephalopathy Encephalopathy (; ) means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of overall brain dysfunction; this syndrome ...

.ADAM. 2005
"Decorticate Posture"
. Retrieved January 15, 2007. Posturing due to stroke usually only occurs on one side of the body and may also be referred to as spastic hemiplegia. Diseases such as

malaria Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...

are also known to cause the brain to swell and cause this posturing effect. Decerebrate and decorticate posturing can indicate that

is occurring or is about to occur. Brain herniation is an extremely dangerous condition in which parts of the brain are pushed past hard structures within the skull. In herniation syndrome, which is indicative of brain herniation, decorticate posturing occurs, and, if the condition is left untreated, develops into decerebrate posturing. Posturing has also been displayed by patients with

Creutzfeldt–Jakob disease Creutzfeldt–Jakob disease (CJD) is an incurable, always fatal neurodegenerative disease belonging to the transmissible spongiform encephalopathy (TSE) group. Early symptoms include memory problems, behavioral changes, poor coordination, visu ...

, diffuse

cerebral hypoxia Cerebral hypoxia is a form of Hypoxia (medical), hypoxia (reduced supply of oxygen), specifically involving the human brain, brain; when the brain is completely deprived of oxygen, it is called ''cerebral anoxia''. There are four categories of c ...

, and

es. It has also been observed in cases of hanging.

Children

In children younger than age two, posturing is not a reliable finding because their nervous systems are not yet developed. However, Reye's syndrome and traumatic brain injury can both cause decorticate posturing in children. For reasons that are poorly understood, but which may be related to high intracranial pressure, children with

frequently exhibit decorticate, decerebrate, and opisthotonic posturing.

Prognosis

Normally people displaying decerebrate or decorticate posturing are in a

and have poor prognoses, with risks for

cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – above 100 beat ...

arrest An arrest is the act of apprehending and taking a person into custody (legal protection or control), usually because the person has been suspected of or observed committing a crime. After being taken into custody, the person can be question ...

and

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a r ...

History

Sir Charles Sherrington was first to describe decerebrate posturing after transecting the

s of cats and monkeys, causing them to exhibit the posturing.

References

{{Nervous and musculoskeletal system symptoms and signs Symptoms and signs: Nervous system