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ULY CLINIC

ULY CLINIC

6 Julai 2025, 09:05:18

Decerebrate Posture

Decerebrate Posture
Decerebrate Posture
Decerebrate Posture

Decerebrate Posture also Known as Decerebrate Rigidity or Abnormal Extensor Reflex is characterized by extension and adduction of the upper limbs, pronation of the wrists, and flexion of the fingers, with stiff extension of the lower limbs and plantar flexion of the feet. In severe cases, opisthotonos—acute arching of the back—may be observed.


Decerebrate posture may appear spontaneously or in response to noxious stimuli, and may present unilaterally or bilaterally. In some cases, one side of the body may display decerebrate posture and the other decorticate posture. These patterns may alternate depending on the progression of brain damage. Duration and persistence correlate with severity of injury.


Pathophysiology and causes

Decerebrate posture signifies damage to the upper brainstem, which disrupts descending inhibitory motor pathways and results in unopposed extensor muscle activity. Causes include:

  • Brainstem infarction, hemorrhage, or tumors

  • Metabolic encephalopathies (e.g., hepatic, hypoglycemic)

  • Severe head trauma

  • Increased intracranial pressure (ICP) leading to brainstem compression

  • Complications such as cerebral herniation post-lumbar puncture in patients with high ICP


Emergency Interventions

Airway Management

  • Ensure airway patency; prevent aspiration

  • Use artificial airway if necessary

  • Maintain spinal precautions if spinal injury suspected


Breathing

  • Assess spontaneous respirations

  • Provide supplemental oxygen

  • Prepare for manual ventilation or intubation as needed


Resuscitation Preparedness

  • Keep endotracheal intubation equipment and emergency resuscitation tools ready at bedside


History and Physical examination

  • Vital signs: Look for Cushing’s triad (bradycardia, hypertension with widened pulse pressure, and irregular respirations) indicating raised ICP.

  • Level of Consciousness: Assess using Glasgow Coma Scale (GCS).

  • Pupillary examination: Check size, symmetry, and light reactivity.

  • Reflexes: Assess deep tendon reflexes (DTRs), Babinski sign, cranial nerve reflexes (e.g., doll’s eye reflex).

  • Coma history: Evaluate for preceding trauma, metabolic illness, infections, drug use, or systemic disease.

  • Gather history from family about time course and any preceding symptoms or trauma.


Medical causes and key clinical findings

Condition

Key Findings

Brain Stem Infarction

Coma, cranial nerve palsies, ataxia, absent doll’s eye reflex, positive Babinski, flaccidity

Cerebral Lesion (Tumor, Trauma, Abscess, Infarct)

Late sign of raised ICP, abnormal pupil responses, Cushing’s triad

Hepatic Encephalopathy

Terminal coma, hyperreflexia, asterixis, fetor hepaticus, disorientation, tremors

Hypoglycemic Encephalopathy

Coma, seizures, bradycardia, twitching, flaccidity, slow respirations

Hypoxic Encephalopathy

Positive Babinski, absent doll’s eye reflex, hypoactive DTRs, respiratory arrest

Pontine Hemorrhage

Coma, pinpoint pupils, quadriplegia, positive Babinski, absent reflexes

Posterior Fossa Hemorrhage

Headache, vomiting, stiff neck, papilledema, cranial nerve palsy, coma, respiratory arrest

Lumbar Puncture (Complication)

Cerebral herniation with brainstem compression following CSF removal


Special considerations

  • Prepare urgent neuroimaging: CT scan, MRI, cerebral angiography as indicated.

  • Consider EEG or other functional brain studies if needed.

  • Frequent monitoring of neurological status and vital signs (e.g., every 30 minutes).

  • Observe for worsening signs of increased ICP.

  • Educate family that decerebrate posture is a reflexive, involuntary response and not a voluntary movement or reaction to pain.

  • Provide emotional support and counseling to family regarding prognosis and care plan.


Patient counseling

  • Explain that this posture reflects severe brain injury and is involuntary.

  • Prepare caregivers for intensive diagnostic evaluation and likely ICU-level care.

  • Discuss possible outcomes honestly and compassionately.


Pediatric considerations

  • Children <2 years may not show classic decerebrate posturing due to immature CNS.

  • Opisthotonos is more common and often a terminal sign in infants.

  • Common pediatric causes include head trauma, Reye’s syndrome, and raised ICP from infections or metabolic disturbances.


Comparison of decerebrate vs. decorticate postures

Feature

Decerebrate Posture

Decorticate Posture

Brain injury site

Upper brainstem

Corticospinal tract (above brainstem)

Arm position

Extended, adducted, pronated

Flexed at elbows and wrists

Leg position

Extended, plantar flexed

Extended, internally rotated

Severity

More severe injury

Less severe injury


References
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  2. Yildizdas D, Kendirli T, Arslanköylü AE, Horoz OO, Incecik F, Ince E. Neurological complications of H1N1 in children. Eur J Pediatr. 2011;170(6):779–788.

  3. Plum F, Posner JB. The Diagnosis of Stupor and Coma. 4th ed. Oxford University Press; 2007.

  4. Gennarelli TA, Graham DI. Textbook of Neuropathology. 2nd ed. Arnold; 2004.

  5. Guyton AC, Hall JE. Textbook of Medical Physiology. 13th ed. Elsevier; 2015.

  6. Smith SJ, Young GB. Coma and impaired consciousness. In: Daroff RB, et al. Bradley’s Neurology in Clinical Practice. 7th ed. Elsevier; 2016.

  7. Adams RD, Victor M, Ropper AH. Principles of Neurology. 9th ed. McGraw-Hill; 2009.

  8. Freeman WD. Management of intracranial hypertension. Neurol Clin. 2008;26(2):521–541.

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