Patient Information and Resources

Patient Information

What is a nerve study?

Electromyography (EMG), and nerve conduction studies (NCS) are performed to assess the integrity of your nerves and muscles. It is usually ordered to ascertain if a patient’s symptoms are due to a problem with a nerve or nerves. It is less commonly ordered to evaluate for the possibility of muscle disease.

How is the test performed?

You will be asked to lie on a treatment table. For the NCS exam, small metal electrodes will be placed on your hands, feet, arms or legs. The electrodes are connected to a small amplifier and oscilloscope. The nerve will then be stimulated at several sites with a small electric shock to measure the speed and volume that the nerve is able to carry an impulse. Several nerves will be evaluated in similar fashion.

The EMG component of the exam is usually performed next. With this exam, a small intramuscular electrode is inserted. The electrode is connected to an amplifier, sending signals to the oscilloscope. Muscle generated waveforms are observed on the oscilloscope with the muscle at rest, and then when the muscle is contracting.

Will the test hurt?

The test is not pain free, but only uncomfortable. A calm patient will experience less discomfort than a tense, anxious one.

Are there any side effects from the test?

There are no side effects from the NCS exam. Some bruising may occur on occasion with the EMG exam, but this is temporary. The intramuscular electrode used for the EMG exam is a very fine wire with teflon coating, much smaller in diameter than the hollow needle used for the drawing of blood or injections. The EMG electrode is used only once, then disposed.

How long will the test take?

Usually the test will take one half of an hour. More complicated cases may take longer.

How should I prepare for the test?

You may shower or bathe normally, using deodorant. Please do not use cream or lotion on your skin. If your arms are to be tested, a short sleeve shirt may be advisable. You may be asked to change into a gown.

What are nerves?

Nerves are made of soft tissue cables that exit the spinal cord as nerve roots, and travel to the extremity or trunk. They convey information to and from the brain. Sensory nerves carry information regarding sensation to the spinal cord and brain. Motor nerves carry electric impulses from the brain through the spinal cord, terminating in a muscle. Muscles contract as the result of chemical and electrical impulses generated through a peripheral nerve.

What are symptoms of nerve problems?

Depending on the nerve, symptoms of numbness, tingling, motor weakness, or clumsiness are suspicious of a nerve-related problem.

How do nerve become damaged?

The usual mechanism of damage is for the nerve to be constricted or compressed by various anatomic structures. Nerves can be cut during trauma. Various medical conditions such as Diabetes can cause nerve problems. Toxic effects from various medications, exposure to certain organic compounds, or excessive use of alcoholic beverages can affect the nerves. Lack of important nutritional elements can cause nerve disease.

What is carpal tunnel syndrome?

Carpal tunnel syndrome (CTS) implies the compression of the median nerve in the palm. Symptoms include numbness and tingling of the thumb, index and middle fingers. Motor weakness affecting the thumb may occur in more advanced cases. Symptoms are provoked by activities performed with a flexed wrist such as driving, holding a phone, reading, and sleeping.

What is cubital tunnel syndrome?

This condition implies a compression of the ulnar nerve at the inner elbow. This is the area called the “funny bone”. Symptoms include numbness and tingling of the little and ½ of the ring finger. Motor weakness of hand and forearm muscles will occur in more advanced cases. Symptoms are usually provoked by periods of positioning with a bent elbow, or when the inner aspect of the elbow is resting on a support.

What is guyon’s canal?

The ulnar nerve may become entrapped at the wrist. The symptoms may include numbness and tingling of the little and ½ of the ring finger, and weakness of the hand muscles. This condition can be brought about after a fall and fracture of the wrist, or by compression of the area of the palm used when biking, performing push-ups, or pushing heavy weights at the gym.

What is radiculopathy?

The spinal nerve roots exiting the spinal cord can become compressed by various structures, such as a bulging or ruptured disc, or arthritis. Cervical radiculopathy will cause numbess and tingling, possibly motor weakness of the upper extremity. Lower extremity numbness, tingling, motor weakness will be the result of lumbar or sacral radiculopathy.

What is tarsal tunnel syndrome?

The posterior tibial nerve may become constricted at the inner ankle. This condition is not as common as carpal tunnel syndrome. Symptoms of tarsal tunnel syndrome (TTS) include numbness and tingling of the sole of the foot, and motor weakness of the foot. The motor weakness of the foot may not be noticeable, except by a trained observer.

What is peroneal neuropathy?

	The peroneal nerve may be damaged where is lies at a superficial location on the outer aspect of the leg, just below the knee. This usually occurs due to external pressure from leg crossing, or from resting the leg against a support. Symptoms include motor weakness of the muscles that elevate the foot, resulting in a foot drop. Numbness and tingling may be felt in an area on top of the foot.
	The peroneal nerve may also be damaged over an area where it is superficial on the front of the ankle. This may occur from a bad ankle sprain or fracture, or from tight shoelaces. Symptoms will include numbness and tingling of the top of the foot. Minor motor weakness of the foot may not be noticeable, except by a trained observer.

What is peripheral polyneuropathy?

This condition implies damage of multiple nerves, usually affecting the lower extremities first, then the upper extremities. Symptoms will include numbness and tingling, usually first in the feet and legs, then hands and arms, in a so called “stocking-glove distribution”. Advanced cases will demonstrate motor weakness of the feet and hands, then in the more distal, possibly more proximal muscles of the arms and legs.

Causes of peripheral polyneuropathy include a relation to medical conditions such as Diabetes, after suffering from certain infectious diseases such as Guillen Barre syndrome, exposure to toxins such as lead, excessive alcohol intake, as a side effect from certain medications, or simply hereditary in nature. Many times the underlying cause of a patient’s peripheral polyneuropathy is unable to be determined.

Home