If an individual is missing an arm, why do they sometimes have sensations in their missing limb? (e.g an itch)

Question: If an individual is missing an arm, why do they sometimes have sensations in their missing limb? (e.g an itch)
- Keywords:
  brain,
  limb,
  phantom limb
Asked by Zealousy to Rebecca on 19 Jun 2015.
- Rebecca Dewey answered on 19 Jun 2015:
  
  The nervous system (nerves and brain) is still active all the time, even when it has no messages to transmit. If there are no messages coming from a part of the body (i.e. after amputation) the nerves will still keep working and sending random low-level noise messages. I think this is the leading theory at the moment on these sensations. Alternatively, it is the same sort of idea, but just occurring in the brain and not in the nerves in the body. Either way, it’s just the body and the brain “filling the silence”.

Question: If an individual is missing an arm, why do they sometimes have sensations in their missing limb? (e.g an itch)