Abnormal posturing

Source: Wikipedia, the free encyclopedia.
Abnormal posturing
SpecialtyNeurology
Differential diagnosisTraumatic brain injury, Stroke, Intracranial hemorrhage, Brain tumors, and Encephalopathy.

Abnormal posturing is an involuntary

Pediatric Glasgow Coma Scale
(for infants).

The presence of abnormal posturing indicates a severe medical emergency requiring immediate medical attention. Decerebrate and decorticate posturing are strongly associated with poor outcome in a variety of conditions. For example, near-drowning patients that display decerebrate or decorticate posturing have worse outcomes than those that do not.[3] Changes in the condition of the patient may cause alternation between different types of posturing.[4]

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.[citation needed]

Decorticate

Decorticate posturing, with elbows, wrists and fingers flexed, and legs extended and rotated inward

Decorticate posturing is also called decorticate response, decorticate rigidity, flexor posturing, or, colloquially, "mummy baby".[5] 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.[6]

There are two parts to decorticate posturing.

  • The first is the disinhibition of the
    pontine reticulospinal tract
    biased extension in the upper extremities.
  • The second component of decorticate posturing is the disruption of the lateral corticospinal tract 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.[citation needed]

Decorticate posturing indicates that there may be damage to areas including the

midbrain. While decorticate posturing is still an ominous sign of severe brain damage, 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.[citation needed
]

Decerebrate

Decerebrate rigidity or abnormal extensor posturing.

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.[8] A hallmark of decerebrate posturing is extended elbows.[7] The arms and legs are extended and rotated internally.[9] The patient is rigid, with the teeth clenched.[9] 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.[9]

A person displaying decerebrate posturing in response to pain receives a score of two in the motor section of the

Pediatric Glasgow Coma Scale (for infants), due to the muscles extending because of the neuro-muscular response to the trauma.[6]

Decerebrate posturing indicates

brain stem damage, specifically damage below the level of the red nucleus (e.g. mid-collicular lesion). It is exhibited by people with lesions or compression in the midbrain and lesions in the cerebellum.[7] 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.[1] Progression from decorticate posturing to decerebrate posturing is often indicative of uncal (transtentorial) or tonsilar brain herniation. Activation of gamma motor neurons is thought to be important in decerebrate rigidity due to studies in animals showing that dorsal-root transection eliminates decerebrate rigidity symptoms.[10]
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.[11] Such conditions include traumatic brain injury, stroke, intracranial hemorrhage, brain tumors, brain abscesses and encephalopathy.[8][failed verification] Posturing due to stroke usually only occurs on one side of the body and may also be referred to as spastic hemiplegia.[2] Diseases such as malaria are also known to cause the brain to swell and cause this posturing effect.[citation needed]

Decerebrate and decorticate posturing can indicate that brain herniation is occurring[12] or is about to occur.[11] 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.[12]

Posturing has also been displayed by patients with Creutzfeldt–Jakob disease,[13] diffuse cerebral hypoxia,[14] and brain abscesses.[2]

It has also been observed in cases of hanging.[15]

Children

In children younger than age two, posturing is not a reliable finding because their nervous systems are not yet developed.

Reye's syndrome and traumatic brain injury can both cause decorticate posturing in children.[2]

For reasons that are poorly understood, but which may be related to high intracranial pressure, children with malaria frequently exhibit decorticate, decerebrate, and opisthotonic posturing.[16]

Prognosis

Normally people displaying decerebrate or decorticate posturing are in a

cardiac arrhythmia or arrest and respiratory failure.[9]

History

Sir

brain stems of cats and monkeys, causing them to exhibit the posturing.[7]

See also

References

  1. ^ a b AllRefer.com. 2003 "Decorticate Posture"[failed verification] Archived October 3, 2005, at the Wayback Machine. Retrieved January 15, 2007.
  2. ^ a b c d e WrongDiagnosis.com, Decorticate posture: Decorticate rigidity, abnormal flexor response (Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series). Retrieved on September 15, 2007.
  3. PMID 2218768
    .
  4. ^ ADAM. Medical Encyclopedia: Abnormal posturing. Archived September 11, 2007, at the Wayback Machine Retrieved on September 3, 2007.
  5. .
  6. ^ .
  7. ^ a b c d Elovic E, Edgardo B, Cuccurullo S (2004). "Traumatic brain injury". In Cuccurullo SJ (ed.). Physical Medicine and Rehabilitation Board Review. Demos Medical Publishing. pp. 54–55. .
  8. ^ a b ADAM. 2005. "Decorticate Posture" Archived 2008-10-14 at the Wayback Machine. Retrieved January 15, 2007.
  9. ^ .
  10. ^ Berne and Levy principles of physiology/[editors] Matthew N. Levy, Bruce M. Koeppen, Bruce A. Stanton.-4th ed. Philadelphia, PA: Elsevier Mosby, 2006.
  11. ^ a b Yamamoto, Loren G. (1996). "Intracranial Hypertension and Brain Herniation Syndromes". Radiology Cases in Pediatric Emergency Medicine. 5 (6). Kapiolani Medical Center for Women and Children; University of Hawaii; John A. Burns School of Medicine. Retrieved January 24, 2007.
  12. ^
    PMID 12224233
    .
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  16. .