Brief Answer:
Peroneal nerve damage more likely.

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

Since the symptoms are triggered by crossing the legs then the most likely cause is a nerve compression during that position, more specifically the peroneal nerve. It is a branch of the sciatic nerve supplying sensation to the lower leg, foot and toes. Therefore its compression may cause numbness, tingling and pain in the leg. Its damage may be caused by any type of trauma, among which also crossing the legs. Usually such mild trauma causes damage when there is a predisposition such as in people who suffer diabetes, use alcohol, are very thin etc.

The spinal MRI you seem to refer to doesn't provide much information about peroneal damage which is further downwards. The more appropriate test to confirm diagnosis would be nerve conduction studies.

I remain at your disposal for other questions.

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Brief Answer:
Unlikely

Detailed Answer:
Thank you for the update. Scoliosis doesn't justify those symptoms. It would be a possible candidate if it led to nerve compression, but that would be evidenced by the MRI. Also there is no reason it would be triggered by crossing the legs. The same applies for spondylosis. Scoliosis and spondylosis may cause local pain, but unless they lead to nerve compression there is no reason for them to cause symptoms in the legs.

Let me know if I can further assist you.

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Brief Answer:
Read below.

Detailed Answer:
Hello again. Thank you for the additional information.

I still believe that the most likely cause is peripheral nerve compression given the relationship with the leg crossing. It is good that the nerve conduction studies were normal which shows that there was no structural damage to the nerve, but that still does not exclude temporary dysfunction of the nerve due to compression. As the trigger factor is removed in time once you uncross the legs there is no permanent damage detectable by nerve studies.

What other possibilities could there be apart from peripheral neuropathy....since central nervous system issues have been ruled out by MRI then a vascular condition, an issue of the blood vessels may be considered. For that purpose a Doppler ultrasound may be scheduled. I wouldn't consider vessel issues to be likely at your young age though.

I hope to have been of help.

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Brief Answer:
No, I wouldn't.

Detailed Answer:
As long as symptoms remain limited only to when crossing the legs I wouldn't go out and do unnecessary tests. There is nothing to indicate any threatening issue. Would try to strengthen lower limb muscles so that nerves are best protected.

Wishing you good health.

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