Involuntary flexion or extension of the limbs indicate severe brain injury, and occur where one set of muscles is incapacitated (while the opposing set is not). The presence of abnormal posturing indicates a severe medical emergency requiring immediate attention. For example, near-drowning victims that display decerebrate or decorticate posturing have worse outcomes than those that do not. There are three types of abnormal posturing: 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.
Although the posturing may occur without a stimulus, an external stimulus, such as pain, may provoke the muscular contraction, with any imbalance between flexors and extensors then immediately apparent. Posturing is an important indicator of the amount of damage that has occurred to the brain, often a guide to the severity of a coma: the Glasgow Coma Scale (adults); and Pediatric Glasgow Coma Scale (infants).
Decorticate posturing is abnormal rigid bodily posturing characterized by tight clenching of the fists on the chest with the arms turned inward. Decerebrate posturing is rigid and abnormal bodily posturing characterized by extension and arching backward of the client’s head, while the arms and legs are extended and the toes are point upward. Abnormal posturing can be either unilateral or bilateral. Decerebrate and decorticate posturing can indicate that brain herniation is occurring, or is imminent. Changes in the overall condition of the patient, moreover, such as an impending brain herniation, may cause the patient to alternate between different types of posturing. Brain herniation syndrome is characterised by a decorticate, progressing to a decerebrate, posturing, if intracranial pressure is not rapidly relieved.
In general, posturing can be caused by conditions that lead to large increases in intracranial pressure:
- traumatic brain injury
- stroke
- intracranial hemorrhage
- brain tumors and brain abscess
- encephalopathy
- Creutzfeldt–Jakob disease
- diffuse cerebral hypoxia
- malaria
Post-acute care
The term “posturing” is often reserved for this acute setting, to reflect a recent and significant alteration in CNS function. In the post-acute setting, posturing may be caused by any imbalance in motor unit stimulation between flexor and opposing extensor muscles, often related to an upper motor neuron (UMN) lesion with characteristic bodily distribution according to site of the (brain) lesion. Posturing due to stroke, a spastic hemiplegia in cortical stroke, usually only occurs on one side of the body.
Spasticity is the velocity-dependent increase in muscle tone due to to an exaggerated stretch reflex, one of the hallmarks of an upper motor neuron syndrome, from the reduction of descending inhibition to the alpha motor neuron, such as occurs after a stroke.1
In the subacute and chronic stages of spastic paresis, such as that after a stroke, stretch‐sensitive (spastic) muscle overactivity emerges as a third fundamental mechanism of motor impairment, along with paresis and soft tissue contracture. Muscle contracture is thought to cause excessive responsiveness to stretch, which in turn aggravates contracture. But because the three mechanisms of impairment—paresis, contracture, and spastic overactivity— are each asymmetrically distributed between agonist and antagonist muscles, this generates torque imbalance around joints and consequent limb deformities.2
Children
The nervous system of children younger than age two has not yet developed, such that in younger children posturing may not necessarily be a reliable finding. Yet posturing can be pathological in children: children with (severe) malaria, for instance, frequently exhibit decorticate, decerebrate, and opisthotonic posturing because of a cerebral oedema.
Primitive reflexes are brainstem-mediated, complex, automatic movement patterns that commence as early as
the twenty-fifth week of gestation, are fully present at birth in term infants, and with central nervous system maturation become more and more difficult to elicit after the first half of the first year of life, when voluntary motor activity and, with it, cortical inhibition, emerges and subdues reflexivity. Primitive reflexes are considered part of the motor repertoire of the specific age: highly stereotypical patterns elicited by specific sensory stimuli.3
Special emphasis here should be placed on the plantar response of the infant, a polysynaptic response
elicited by stroking along the lateral aspect of the foot from heel to toe. Different types of responses elicited in infants vary from flexor to extensor, according to the intensity of stimulus applied. Nevertheless, it is generally accepted that extensor plantar response mature to flexor by the end of the first year in most normal infants.3
A number of postural reactions (i.e., motor patterns) in children have been identified and repeatedly described as diagnostically relevant. Most literature emphasises the distinction between the primitive reflexes and these postural reactions. In the 1960s, Czech neurologist Václav Vojta described the theory that postural reactions are present at birth and follow the stages of postural ontogenesis. Their mature equivalents (responses) were later delineated by Capute et al.3 Limited data is available regarding the evolution of postural reactions in early infancy; and it pertains mostly to the three righting reflexes in prone position: the tonic labyrinthine reflex, symmetric tonic neck righting, and the Landau reaction (vertical suspension).3
| Reaction | Position | Method |
| Traction | Supine | Placing the examiner’s index finger in the infant’s hand and pulling the infant at a 45° angle with the examination bed. |
| Horizontal suspension | Prone | Suspending the infant by placing the hands around the infant’s thorax without providing support for the head or legs. |
| Vertical suspension | Vertical | Placing both hands in the axillae, without grasping the thorax and lifting the infant straight up facing the examiner. |
| Vojta response | Vertical | Suspension from the vertical to the horizontal position facing the examiner by placing both hands around the infant’s thorax. |
| Collis horizontal suspension | Prone | Placing one hand around the upper arm and the other around the upper leg and suspending the infant in the horizontal position parallel to the examination bed. |
| Collis vertical suspension | Prone | Placing one hand around the upper leg and suspending the infant in the vertical position with head directed downwards. |
| Peiper-Isbert vertical suspension | Prone | Placing the examiner’s hands around each upper leg of the infant and suspending the infant in the vertical position with head directed downwards. |
References
- Gracies JM. Pathophysiology of spastic paresis. I: Paresis and soft tissue changes. Muscle Nerve. 2005 May;31(5):535-51. doi: 10.1002/mus.20284. PMID: 15714510.
- Gracies, J. “Pathophysiology of spastic paresis. II: Emergence of muscle overactivity.” Muscle & Nerve 31 (2005).
- Zafeiriou, Dimitrios, I. “Primitive Reflexes and Postural Reactions in the Neurodevelopmental Examination.” Paed Neurol 31(1); 2004, 3. doi:10.1016/j.pediatrneurol.2004.01.012.
- Decerebrate posturing | Project Gutenberg Self-Publishing – eBooks | Read eBooks online
Further:
Epple, Corina et al. “Vojta therapy improves postural control in very early stroke rehabilitation: a randomised controlled pilot trial.” Neurological research and practice vol. 2 23. 20 Aug. 2020, doi:10.1186/s42466-020-00070-4.
Idro, R., Otieno, G., White, S. et al. “Decorticate, decerebrate and opisthotonic posturing and seizures in Kenyan children with cerebral malaria.” Malar J 4(57); 2005. https://doi.org/10.1186/1475-2875-4-57.
Mitchell, R.G. (1962), The Landau Reaction (Reflex). Developmental Medicine & Child Neurology, 4: 65-70. https://doi.org/10.1111/j.1469-8749.1962.tb03099.x.
