Brief Answer:
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Detailed Answer:
Hello and welcome to HealthcareMagic!

I read your question carefully although I would have liked if you had provided some more detail on what you mean by temporary loss of leg strength such as:

-whether strength has completely returned to normal,
-was it only one leg or both involved,
-how long did the episode last,
-whether there was any abnormal uncontrolled movement of the limb,
-any signs on upper limb or face,
-any headache, back pain, limb pain (or any other symptom really),
-any other condition apart from the cervical stenosis

From only the current information I would say for a transitory episode the most likely cause is an transient ischemic attack (TIA), meaning a clot blocking a blood vessel which afterwards is spontaneously fragmented or dissolved soon, before leaving permanent damage, so the symptoms regress. It is a subtype of stroke, where fortunately the vessel is freed spontaneously but could herald a more serious event with residual damage so should be considered seriously. It usually happens in the brain, more commonly the upper limb, but depending on what brain area is supplied by that vessel lower limb can be involved as well. The same thing can happen in the spinal cord as well, but it is very very rare.

Another cause especially if the phenomenon happened during walking and was relieved by rest might be narrowing of a blood vessel supplying the limb, which can lead to insufficient blood supply to the limb itself. However apart from weakness usually there is cramp like pain, diminished pulse etc.

Other causes of limb weakness, especially if bilateral, would be cervical stenosis which you mention, or stenosis in thoracic spine as well, due most commonly to degenerative spinal changes, but also spinal tumors or infection. However if episode is transitory these are less likely because since it is a case of mechanical compression it doesn't regress spontaneously, the temporary factor indicates blood vessel causes mentioned above.

Compression of nerve roots or peripheral nerves in lumbar spine or more peripherally can also cause loss of strength, but usually pain is a predominant factor and again since mechanic compression does not regress in a rapid manner. There are other types of nerve damage like neuropathy, radiculopathy, but not temporary, if there is improvement it takes months.

I remain at your disposal for further questions, but possibly providing somme more info to the questions I mentioned at the beginning.

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