Down & Out

[chbare]

On the right track. Why would a GABA deficiency cause seizures and why would benzodiazepines possibly not work?

[DartmouthDave]

Hello,

A GABA deficiency will cause an elevation of the resting membrane potential. In effect, they will be less refractory and more prone to deploarization. In this case the status epilepticus.

In this case, I think an RSI and deep sedation may be in order. I would keep going with the benzodiazipines. I would also ensure a good minute ventilation because odds are the patient is quite acidotic. That temperature is a worry as well.

If I recall, INH theapy causes a vitamine deficiency. I don't know which one. Needless to say it won't be on an ambulance.

Good case. Excellent brain gym.

Cheers

[chbare]

I think you guys pretty much got this. INH leads (by complex mechanisms) to decreased GABA synthesis by decreasing levels of pyridoxine. Therefore, benzodiazepines may not be effective. Basically, GABA acts as a ligand for an ionotropic receptor that when activated, allows Chloride ions to enter the neuron. The changes the resting potential and makes it much harder for the cell to depolarise as much more stimulus is required to meet the threshold. This in essence, depresses the neuron.

As stated earlier, pyridoxone can be administer but it is not something commonly carried outside of the hospital. Additionally, other agents such as Diprivan may be effective alternatives until pyridoxone therapy can be administered. A good rule of thumb is administering 1 gram of pyridoxine for every suspected gram of INH ingested.