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ULY CLINIC
ULY CLINIC
6 Julai 2025, 09:05:18
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 |
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