Quantitative Sudomotor Autonomic Reflex Testing (QSART)

Cardiovascular Autonomic Testing

Quantitative Sensory Testing (QST)

Muscle Biopsy

Quantitative Sudomotor Autonomic Reflex Testing (QSART)

QSART is used to diagnose:

• Painful small fiber neuropathy when nerve conduction test results are normal
• Disturbances of the autonomic nervous system, which controls the sweat glands, heart, gastrointestinal tract, other organs, and blood pressure
• Complex regional pain syndrome or reflex sympathetic dystrophy.

The focus of QSART is the small nerve fibers which go to the sweat glands. The test site is usually on the patient’s foot, leg, or forearm. A capsule is placed over the skin on the test site. The technologist stimulates a nearby sweat gland by delivering a chemical through the skin, electrically. The patient feels warmth, but no electric shock. The effect of the chemical lasts for approximately five minutes. During the test, the amount of sweat under the capsule is measured at various times. A computer analyzes the results, determining how well the sweat gland functions and how well the nerves functioned to help the gland release sweat at a “normal” time.

Quantitative Sudomotor Autonomic Reflex Testing

Patients should not take medications that interfere with sweating before this test.

Tricyclic antidepressant medications (and the brand names) that should be discontinued 5 days prior to the test are:

• Amitriptyline (Elavil)
• Nortriptyline (Pamelor)
• Protriptyline (Triptil, Vivactil)
• Doxepin (Sinequan)
• Trazodone (Desyrel, Desyrel Dividose)
• Desipramine (Norpramin)
• Imipramine (Tofranil)

SSRI antidepressant medications (and the brand names) that should be discontinued 48 hours prior to the test are:

• Sertraline (Zoloft)
• Fluoxetine (Prozac)
• Citalopram (Celexa)
• Venlafaxine (Effexor)
• Paraxeline (Paxil)
• Fluvoxamine (Luvox)
• Bupropion (Wellbutrin)
• Maprotiline (Ludiomil)
• Duloxetine hydrochloride (Cymbalta)
• Escitalopram (Lexapro)

Antihistamines that should be discontinued 48 hours prior to the test are: Diphenhydramine hydrochloride (Allerdryl, Banophen, Belix, Ben-Allergin, Bena-d, Benadryl, Benahis, Benoject, Benylin, Compoz, Diahist, Dihydrex, Sominex 2, Tussatat, Twilite, Valdrene, Wehdryl, and Hydroxyzine hydrochloride (Atarax).

Newer antihistamines, such as Allegra and Claritin, can be used.

Unless you are being tested for complex regional pain syndrome/ RSD, you should ask your prescribing physician/doctors if the following “classes” of heart or blood pressure medications might be held on the day of testing as they may interfere with the tilt test (see Cardiovascular Autonomic Testing below):

• Nitro patches
• Beta blockers
• Calcium channel blockers
• Water pills
• ACE inhibitors

For more information, please call (412) 647-5424

Cardiovascular Autonomic Testing

The autonomic nervous system also controls heart rate and blood pressure. Using breathing techniques and a tilt-table, a technician can assess autonomic function via non-invasive monitoring of blood pressure and heart rate. This test is useful in assessing patients with light-headedness, other neurologic symptoms that occur with shifting to the standing position, possible small-fiber neuropathy, and a number of other disorders that affect the autonomic nervous system.

Patients should be well hydrated and avoid caffeine or alcohol before the test. Ideally, patients should not take blood pressure medications on the day of testing, but they should get approval from their primary care physicians before making any change in the way that they take the prescribed medications.

If you are having this test, you should ask your prescribing physician/doctors if the following “classes” of heart or blood pressure medications might be held on the day of testing as they may interfere with the tilt test:

• Nitro patches
• Beta blockers
• Calcium channel blockers
• Water pills
• ACE inhibitors

To Schedule QSART and Autonomics Testing, call 412-647-5424.

Quantitative Sensory Testing (QST)

QST assesses the small nerve endings that detect changes in temperature, and the large nerve endings that detect vibration. The testing involves a computer system that delivers mild stimulation, such as coolness or vibration, of known and reproducible quantities and duration.

In a quiet room, the patient is asked if he or she can detect the changes in temperature or vibration which are transmitted to a finger or toe. The computer compares the patient’s results to “normal” results, and a physician studies the analysis to diagnose or assess the patient’s condition.

QST testing

QST is useful in diagnosing neuropathies, especially those involving small nerve fibers, and it may be used to detect whether a neuropathy is getting better or worse.

To Schedule QST, call 412-647-5424

Muscle Biopsy

Sometimes a small piece of muscle must be removed (biopsied) and analyzed. The physician who orders a muscle biopsy will specify a needle biopsy or an “open” biopsy.

In a needle biopsy of muscle, a neurologist uses a needle to remove a small amount of tissue. A needle biopsy is a quick outpatient procedure, usually performed after an EMG. The EMG is used to guide the selection for the muscle to be biopsied. The biopsy requires no incision and causes minimal trauma to the biopsied area. The resulting scar is almost invisible.

An open biopsy of muscle is used to get a relatively large piece of tissue. Like a needle biopsy, and open biopsy is a minor outpatient procedure. Unlike a needle biopsy, a surgeon performs an open biopsy and the procedure requires an incision. The specimens are then evaluated by a neuromuscular pathologist, David Lacomis, MD.