Developed nonsustained ankle clonus unilateral. 2 years ago had a neuro exam and this was not present. is developing it a bad sign?

Hyperreflexia: It suggests a condition of hyperreflexia which means that something is being irritated that is making your foot be overly active when doing a stretch reflex. That could be coming from something like a spinal canal stenosis in the back or neck. It could also be a sign of spasticity which is mediated by the brain such as from lack of oxygen, strokes, tumors, etc. See what doc wants to do now.

Clonus meaning ?: Sometimes it means something. Non sustained clonus sometimes does not hold up from exam to exam- some people are not good at detecting this. Clonus of any kind should indicate something happening in the spinal cord or the brain. If you have it on one side, it should be the brain. Sometimes the cause is not found however. If it was found in a new exam, a work up will be planned.