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Wed Sep 6 22:58:56 BST 2006

Dean,

A most interesting case. I'm on board with the GHB theory only if the patient arrived with a GCS of 3 then got better. If he deteriorated in the ED, it is not likely GHB unless a nurse gave it to him. The stuff is rapidly absorbed, rapidly metabolized, and the effects generally last less than 4-6 hours. The negative head CT leads one to suspect this patient's decline was not from diffuse axonal injury. Even though studies have shown that focal axonal injury can exist in seemingly minor head injury, these are not comatose patients. But Tim may be partially right: small mild focal axonal injury (cerebral neuropraxia) may explain this patient's course. However, Rob is correct in stating ("long-time badness") that diffuse axonal injury - as a cause for coma in a patient presenting to the ED - would not be considered to be reversible in the time frame described, if at all. The CT could show blurred or poor gray/white matter interface, but MRI would be a better imaging option. DAI - when
 the patient arrives in coma - has the worst outcome of all, including traumatic SAH, SDH, and EDH, and is not know to reverse itself, especially in the time frame you describe.

Other theories: Transient hypoglycemia (certainly a reasonable phenomenon in a patient with alcohol intoxication). Cerebral arterial vasospasm, which accounts for the deterioration often seen day 2 - 3 after closed head injury (especially if there is subarachnoid hemorrhage, no matter how large or small), may occur at any time in head injury and is self-reversed if conditions are favorable. Reperfusion "no-reflow" phenomenon, which is know to occur in profoundly hypotensive or arrested victims, occurs 90 minutes or so after the re-establishment of perfusion pressure, is also potentially self-reversible; but now I'm stretching it. 

My money is on either focal cerebral edema or the modified-Harcastle theory. Small, well placed foci of brain edema or axonal injury (the fornices or especially the brainstem) can result in coma and has the potential for self-reversal, especially with the expert supportive care you provided this victim.

In summary, you may never know what happened, but it was not diffuse axonal injury.

DB

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