A reader asks:

For the past few weeks my right hand has been completely numb. Should I be worried about this?

Simon says:

Numbness in the hands is most commonly caused by conditions that lead to nerve compression, such as arthritis in the neck, injuries or pressure on the nerves at any point from the armpit to the wrist. Some people are born with an extra rib - the so-called cervical rib - which may cause numbness when the hands are raised, and an operation is required to remove it. Less common causes include pernicious anaemia because of vitamin B12 deficiency and a range of rare neurological conditions likely to cause additional symptoms such as muscle weakness, headaches or blurred vision. In any event, it is worth getting things checked out by your doctor.