Brief Answer:
Seizure or panic attacks....would favor seizure possibility.

Detailed Answer:
I read your question carefully and I understand your concern.

Judging from your description and that MRI report I would say that the two main possibilities in your case would be either seizures for which you may have a predisposition given the hippocampal atrophy or simply a case of panic attacks as it was suggested to you.

Perhaps you are more familiar with the concept of seizures as episodes where you lose consciousness and have convulsions. However there are many types of seizures depending on where do the electrical discharges happen, they may be focal and cause only partial seizures without losing consciousness, manifesting even with anxiety as this case. Actually temporal lobe seizures (where the hippocampus is found) may manifest precisely that way and the hippocampus is a region very commonly associated with seizures.

How to differentiate between those possibilities....an EEG may help at times. It has value only when confirming epileptiform activity though, it doesn't exclude the diagnosis as between episodes EEG may be normal in half of the patients. Repeat EEGs have a greater chance of detecting something, but still do not exclude epilepsy.
Apart from the EEG the distinction lies mainly in the clinical manifestations of the episodes. As I said the distinction is difficult because seizures may manifest with anxiety but in your case I am more in favor of the seizure possibility. That is because you mention that spasm in your left hand only which would coincide with that right hippocampal finding. If it was anxiety spasms would have been on both sides. However I would repeat EEG before starting treatment.

I remain at your disposal for other questions.

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Brief Answer:
Can happen

Detailed Answer:
The fact that it happens only during sleep is actually a common finding in epilepsy, it is a well known phenomenon in many patients to have seizures only in sleep. The mechanism is not well understood, it is thought to be due to being more predisposed to seizures during changes in sleep phases (in sleep we undergo cycles which are separated in phases where brain activity changes from one phase to the other).
So it is not an argument against seizures at all, actually would be something to sway balance more in the direction of a seizure (though panic attacks may happen at night as well, is not a differentiating factor).

Let me know if I can further assist you.

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Brief Answer:
Hope things work out for the best.

Detailed Answer:
Glad to have been of help. Hope things work out for the best.

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