Question about decorticate posture

[NontradCA]

Can someone tell me why, when someone gets knocked out they go into decorticate posture briefly? Is it because they're getting a lateral blow to the head, mimicking an uncal herniation, supratentorially?

Here's a sample, but I've seen this in a lot of sports and fights etc.




*I know this is X posted but no one responded in allo: not sure if they didn't know or if topic is too stupid to discuss 😀*

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[typhoonegator]

Hard to say. I've seen MMA KOs where the fighter goes decerebrate after a lateral load injury, or limp. Brainstem gets torqued, sudden coup-contrecoup, shear injury, all at once in different locations. Can happen in countless permutations, some of which result in varying posturing behaviors, some with flaccidity, and some with a combination. While you learn in school about these as distinct localizations, in real world trauma the presentations are remarkably varied. All posturing behaviors are "bad", and progression from decorticate to decerebrate tends to be worse, but in real time I don't think they've very reliable indicators of the localization of the trauma because there are multifocal injuries happening all at once and what you observe is just the summation of the long tract signals reaching the spinal cord, both inhibitory and excitatory.

Either way, getting knocked out is bad, regardless of whether you posture as you fall. The duration of his unresponsiveness is just as concerning as his initial posturing, and may be more suggestive of the severity of the injury, at least according to the usual rating scales (as long as his GCS improved, that is).

 

[NontradCA]

Hard to say. I've seen MMA KOs where the fighter goes decerebrate after a lateral load injury, or limp. Brainstem gets torqued, sudden coup-contrecoup, shear injury, all at once in different locations. Can happen in countless permutations, some of which result in varying posturing behaviors, some with flaccidity, and some with a combination. While you learn in school about these as distinct localizations, in real world trauma the presentations are remarkably varied. All posturing behaviors are "bad", and progression from decorticate to decerebrate tends to be worse, but in real time I don't think they've very reliable indicators of the localization of the trauma because there are multifocal injuries happening all at once and what you observe is just the summation of the long tract signals reaching the spinal cord, both inhibitory and excitatory.

Either way, getting knocked out is bad, regardless of whether you posture as you fall. The duration of his unresponsiveness is just as concerning as his initial posturing, and may be more suggestive of the severity of the injury, at least according to the usual rating scales (as long as his GCS improved, that is).

Thank you for the reply. It makes sense. Is the above true for other neurological injuries? I.e. Stroke, Toxics. Is there wide variability in the presenting symptoms? I'm about to start rotations now, so excuse my ignorance. I was under the impressions that exam findings could illicit good approximations of lesions.

 

[ProfMD]

Thank you for the reply. It makes sense. Is the above true for other neurological injuries? I.e. Stroke, Toxics. Is there wide variability in the presenting symptoms? I'm about to start rotations now, so excuse my ignorance. I was under the impressions that exam findings could illicit good approximations of lesions.

See if your school library has a copy of Plum and Posner's Diagnosis of Stupor and Coma.

It is the classic text and worth a read if you are interested in these things.

 

[kchan99]

Thank you for the reply. It makes sense. Is the above true for other neurological injuries? I.e. Stroke, Toxics. Is there wide variability in the presenting symptoms? I'm about to start rotations now, so excuse my ignorance. I was under the impressions that exam findings could illicit good approximations of lesions.

Strokes are more straight forward compared with toxic encephalopathies. Strokes are less diffuse unless they are embolic. Neurology used to be "one stroke at a time," but with embolic, it's >1 stroke at a time. I'm not even counting chronic strokes or microinfarcts (microscopic strokes).

Any way, I highly recommend Plum and Posner. If you go into neurology as a career, then at that point, i.e., during residency, read Localization in Clinical Neurology.