EMG's/Nerve Conduction Studies

Electromyography (EMG) and Nerve Conduction Tests are ordered to learn more about the health of peripheral nerves. These tests can establish if a nerve is pinched, and give a numeric value to how severely it is pinched and often where it is pinched. The test can last anywhere from a half an hour to an hour. The quality of the results is quite dependent on the skill of the person administering the test.

EMG's

The EMG portion of the test measures the electrical activity in muscles. Muscles normally receive constant electrical signals from healthy nerves, and in return "broadcast" their own healthy electrical signals. During the EMG portion of the test, the doctor places acupuncture like needles into the muscles to record the electrical signal from the various muscles in the arm. If a muscle doesn't receive adequate signals from a sick nerve, it broadcasts signals, which show the muscle is confused.

Nerve Conduction

During the Nerve Conduction portion of the test, electrodes much like EKG patches are placed along the known course of the nerve. The nerve is stimulated with a tiny electrical current at one point. The nerve must then transmit the signal along its course, and an electrode placed further down the arm captures the signal as it passes it. A healthy nerve will transmit the signal faster and stronger than a sick nerve.

*Discomfort and Risks

Some discomfort may occur as the needle electrodes are inserted. The muscle(s) tested may feel sore after the EMG. The risks are minimal. There may be some minor bleeding and there is a small risk of infection where the needle electrodes are inserted.

CT SCANS - used to view soft tissue or bony abnormalities

Computed Tomography (CT) imaging is also known as CAT scanning (Computed Axial Tomography). The machine resembles a large square with a ring in the middle. CT has the unique ability to image soft tissues (e.g. blood vessels) and renders more detail of bony structures than MRI (Magnetic Resonance Imaging). CT images reveal the relationships between soft tissue and bone. Some CT examinations require a contrast agent to be injected (or intravenously) into the patient's bloodstream. A contrast agent serves to enhance a particular body part (e.g. intervertebral discs).

During the test, the patient must lie still and may be asked to hold their breath for a several seconds from time to time. The patient may hear the scanner rotating during the study - this noise may be soft or more audible. Depending on the type of study, the CT scanner or table will move slightly as low intensity x-ray beams are rotated at many angles around the patient. A computer collects the data from the scanner, calculates the density of a given cross-sectional slice, and produces the image onto film for study by a radiologist.

*Discomfort and Risks

Without contrast: None

With contrast: There may be some minor bleeding and there is a small risk of infection where the IV is started. There is also a risk of an allergic reaction to the contrast dye.

MRI's - used to detect soft tissue or bony abnormalities

Magnetic Resonance Imaging (MRI) is a radiation-free, computer-assisted technique used to produce high quality sectional images of the inside of the body. MRI is performed in a hospital, medical center, or an MRI facility. Many facilities utilize 'open-air' MRI scanners, beneficial to patients who are claustrophobic. When an open-air scanner is unavailable, patients who feel anxious are given a mild sedative. During the scan, the patient lies comfortably on a motorized table inside the scanner surrounded by huge powerful magnets. The technician observes the patient throughout the exam through large windows in the adjacent control room. The technician converses with the patient by means of an intercom. Typically, the test takes up to an hour to complete.

Unlike MRI, some imaging studies require the patient to change position during the examination. Conversely, an MRI is able to generate images in the sagittal (left/right), coronal (front/back), axial (head/toe), and oblique (slanted) planes without moving the patient. Certain MRI studies utilize a contrast medium to enhance particular body structures.

MRI is able to produce vivid complex images in 256 levels of gray characterizing relationships between vertebrae, intervertebral discs, the spinal cord, and nerve roots. It is a valuable diagnostic and pre-surgical planning tool, and replaces some invasive diagnostic procedures.

*Discomfort and Risks

There may be discomfort if you are claustrophobic. Please tell your doctor if you have trouble in small spaces. Open-sided MRI's are available in certain areas or sedatives can be prescribed. Patients also need to tell their physician if their body contains any ferromagnetic objects such as shrapnel, a pacemaker, or aneurysm clips. These patients cannot undergo MRI study. Ferromagnetic objects are attracted by the MRI's magnet.

Testing for Vascular TOS

Adson's Maneuver

To perform Adson's maneuver, the practitioner finds the client's radial pulse at the wrist, then brings the client's arm back into extension and lateral rotation. The client is instructed to look over his/her shoulder toward the affected side and take in a deep breath. If the intensity of the pulse diminishes, the client is suggested to have entrapment of the brachial plexus and subclavian artery by the anterior and middle scalene muscles -- or thoracic outlet syndrome. The problem with this procedure is that a large number of people who do not have any symptoms test positive (diminishing radial pulse) when this test is performed. Thus, this test does not have a high degree of specificity.

*Discomfort and Risks

Weakness and/or tingling in the arm may occur during this test.

Doppler Study

A Doppler Study is simply an ultra-sound image of the veins and arteries. It is a non-invasive and completely pain free procedure used to detect vascular TOS. A liquid jelly is applied to the skin to make close contact between the skin and transducer, eliminating air pockets. This will ensure that the sound waves are freely conducted into and out of the body. The radiologist or technologist presses the transducer firmly to the skin and moves it back and forth to obtain complete images of areas of interest. The entire area of interest will be scanned, obtaining images from different perspectives. The examiner may want to obtain images while you are standing upright or laying down. The radiologist also may ask you health-related questions during the exam and may repeat some images to clarify the findings. When the transducer is over a vein or artery, it will become visible on the ultra-sound screen, showing up in different colors. The entire procedure usually takes about 30 minutes. The images will be evaluated by a radiologist and given to your doctor. A Doppler Study is not always accurate in diagnosing TOS.

*Discomfort and Risks

None

MRA

Magnetic Resonance Angiography (MRA) is an MRI study of the blood vessels. MRA provides detailed images of blood vessels without using any contrast material, although a special form of contrast is sometimes given to make the MR images more clear. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind. The patient is placed on a special table and positioned inside the opening of the MRI unit. A typical exam consists of two to six imaging sequences, each taking from 2 to 15 minutes. Depending on the type of exam being done, the total time needed can range from 10 to 60 minutes, not counting the time needed to change clothing and have an IV put in (if contrast is needed). When contrast material is needed, a substance called gadolinium is given by IV injection during one of the imaging sequences. It highlights blood vessels, making them stand out from surrounding tissues.

*Discomfort and Risks

There may be discomfort if you are claustrophobic. Please tell your doctor if you have trouble in small spaces. Open-sided MRI's are available in certain areas or sedatives can be prescribed. Patients also need to tell their physician if their body contains any ferromagnetic objects such as shrapnel, a pacemaker, or aneurysm clips. These patients cannot undergo MRI study. Ferromagnetic objects are attracted by the MRI's magnet

With contrast: There may be some minor bleeding and there is a small risk of infection where the IV is started. There is also a risk of an allergic reaction to the contrast dye.

Venogram

A venogram is a procedure that looks at your blood vessels (veins) by simultaneously injecting x-ray dye and taking x-rays. It is used to determine if/where there is restricted bloodflow in the veins. A venogram is the most accurate way to diagnose vascular TOS.

First, an IV (intravenous catheter) will be started in the limb you are experiencing symptoms in (ex. for TOS, it is usually somewhere between the wrist and elbow). Ultra-sound may be used to help the radiologist locate a vein. Once the IV is started, a small tube is inserted into the vein that needs to be viewed. The tube is then secured and the test will begin.

The radiologist will have you stand/lay in the symptomatic position. X-ray dye will then be injected into the IV tube. You may feel a warm sensation from the dye. X-rays will be taken throughout the procedure. These pictures will be displayed on a TV monitor so the radiologist can clearly see problem areas during the test. You may be asked to change positions several times throughout the test.

After the procedure, saline is usually flushed through the IV to make sure the veins are clear of any x-ray dye. The IV is then removed and if you are free to go home. The radiologist will review the films and contact your doctor with the results.

* Be sure to tell the radiologist of any pain during this procedure. Once the IV is in, there should be a minimal amount of pain during the actual test. Also, if there is a certain position that brings on the vascular symptoms, be sure to tell the radiologist before the test begins. Testing should be done in the symptomatic position!

*Discomfort and Risks

There may be some minor bleeding and there is a small risk of infection where the IV is started. There is also a risk of an allergic reaction to the contrast dye.