When and why

These examine the function of peripheral nerves and detect whether there has been any damage either to the nerves or to the muscles they supply. They are therefore usually undertaken when someone complains of numbness, pins and needles or weakness in their legs or arms.

The test measures the speed of an electrical impulse travelling down a particular peripheral nerve. Some people find this procedure uncomfortable but it is not normally painful and is routinely carried out as an outpatient procedure.

How it will help

The test helps to detect or define the presence and severity of damage to the peripheral nerves (peripheral neuropathy) and can give clues to their cause. An EMG test can be used to detect myopathy.