Electromyogram (EMG)

An EMG (electromyography) is a test used to study nerve and muscle function. There are two parts to EMG testing; a nerve conduction study and a needle exam for muscle testing. The nerve conduction study involves stimulating the nerves at different points with small electric stimulation so their function can be measured. The needle exam involves inserting very fine needles into several muscles. These needles pick up both normal and abnormal electrical signals given off by a muscle.

The EMG can provide information about the extent of nerve and/or muscle injury and can give some indication as to whether the damage is reversible. An EMG may be performed when patient’s have unexplained muscle weakness to distinguish if the problem is in the muscle or if it due to nerve disorders. The EMG can detect abnormal electrical activity of muscles and nerves that can occur in many diseases and conditions, including muscular dystrophy, muscle inflammation, pinched nerves, damage to nerves in the arms and legs (peripheral nerve damage), multiple sclerosis and carpal tunnel syndrome.

 An EMG is a well tolerated procedure with minimal discomfort and patients rarely need pain medication before or after the test. Although uncommon, risks include infection, bleeding and nerve damage.