The Merritt Center CUMC/Neurology cmpl

FAQ




QUESTIONS



I. General

II. Botulinum toxin (BTx) injections

III. Tests



Tremor analysis

Spiral analysis

Transcranial magnetic stimulation (TMS)

IV. Deep brain stimulation (DBS) surgery




ANSWERS



I. General



How do I know which test or treatment is right for me?

Your referring physician or health care provider should help you determine which of our tests or treatments is appropriate. Generally, a neurologist who can assess your condition will refer you to us for specialized testing, pre-operative evaluation, or for a neurologic consultation. A consultation is needed, for example, if you are considering botulinum toxin injections.

Do I need a doctor's referral to be seen in the Clinical Motor Physiology Laboratory? Can I refer myself?

A referral from a physician is generally needed to make a clinical appointment with us. You cannot refer yourself.

How do I find out about my report?

After your test, a report with your results will be sent to your referring physician. To find out your test results, please speak with your referring physician.


II. Botulinum toxin (BTx) injections



I would like BTx injections for neurologic reasons. How is this arranged?

A limited number of new BTx patients are evaluated on a regular basis. An initial consultation will need to be scheduled so that we can assess the appropriateness of BTx for your condition, explain all the clinical issues, pro’s and con’s of BTx, and the possible side effects. We then decide on a preliminary approach, and the amount of BTx that will need to be pre-authorized by your insurance company. This initial consult is required even if you are being referred by another neurologist.

You will then be scheduled for a separate appointment for the first set of BTx injections. Patients generally do not receive the first injections on the same day as their consult.

What do the actual injections involve?

After determining which muscles need to be injected and the doses to be used, BTx is given through a very small diameter needle that both delivers the medication and measures muscle (EMG) activity. The wire from the needle is attached to an EMG machine that measures muscle activity and, with proper reading of the signals, allows for EMG guidance of BTx into the correct muscle. You will be asked to exert and relax the muscle(s) in question or perform specific tasks while the EMG is recording. Each muscle typically takes several minutes to inject, and patients generally have multiple muscles treated in one visit.



III. Tests



Tremor analysis



What is the purpose of tremor analysis?

Patients are typically referred for tremor analysis to help the referring physician determine the origin and type of tremor or involuntary movement using objective, computerized methods. Different disorders each have characteristic patterns (for example, the nature of the tremor, muscle activity, timing of movements, and relationships from one side to the other). People are often referred to the CMPL to determine if there is evidence consistent with one or more of the following: Parkinson’s disease, dystonia and related disorders, essential tremor, orthostatic tremor, physiologic tremor, or other tremor disorders, myoclonus, or other quick involuntary movements.

What does the tremor analysis testing involve?

The test itself is completely non-invasive and takes anywhere from 45 minutes to two hours depending on the movements and muscles tested. Muscle activation patterns are tested using surface electrodes (stuck on the skin with light adhesive) that passively record muscle activity. No needles or shocks are involved.

Once electrodes are attached, patients are asked to perform a variety of clinically relevant movements. For example, patients are typically asked to hold their arms out in front of their body, touch their finger to their nose, pour water between two cups, and write a simple sentence. Other approaches may be used to bring out whatever involuntary movements exist.

How should I prepare?

Patients are asked to wear loose clothing on the day of testing. If you take medications to suppress your tremors, please discuss with your referring physician and/or our office whether and when you should stop taking them prior to your visit. Tremor analysis is most telling when your movements are not suppressed, and some medications take more than a day to wear off. However, many medications have serious side effects if stopped too quickly, so do not do this without speaking with your doctor and our office first.



Spiral analysis



What is the purpose spiral analysis?

This is a test that records and analyzes hand drawn spirals using a computer graphics tablet. Spiral analysis serves a similar purpose to tremor analysis, that is, to provide information that your referring physician can use to help determine clinical diagnoses. Information about each spiral is run through a program that generates information about pressure, speed, and tremor patterns, among other things. Spiral analysis is often performed in conjunction with tremor analysis, and usually takes 15 to 20 minutes to complete.

What does the testing involve?

Patients are asked to draw twenty spirals, ten with each hand, using a special pen and graphics tablet. There are no wires or other attachments. For a patient with severe tremor, the test can be tiring, but is otherwise easy to take and is painless.



Transcranial magnetic stimulation (TMS)



What is the purpose of TMS?

Transcranial magnetic stimulation (TMS) is used to test how quickly the nerves in the brain and spinal cord react to stimuli. It is a simple, accurate method of detecting upper motor neuron dysfunction.

What does the testing involve?

This test has two parts: First, magnetic stimulation; then, electrical stimulation. Surface electrodes are lightly stuck to the patient’s hands and legs to record response times after the stimuli. The total testing session takes between thirty minutes and one hour.

Because magnetic fields affect some metals, the technician asks patients if they have any metal implanted in their head or chest. Because of the brain stimulation, patients are also asked if they have a history of seizures. If either of these answers is yes, further information will be needed to determine whether TMS can be safely performed.

The magnetic stimulation involves a cap placed over the top of the head, which delivers a magnetic pulse. We start the test at a low intensity; generally, patients feel only slight twitching in the face or arms.

As the intensity is increased, patients feel a brief, totally harmless, jolt. This is not painful, but it may be unpleasant due to a split second of disorientation. This is usually not a problem, but can be unsettling. We do our best to put patients at ease by fully warning before stimuli are given, and answering all questions beforehand.

The laboratory personnel performing TMS have all experienced the procedure, and can give realistic descriptions.

Electrical stimuli, not magnetic pulses, are given to the upper and lower back because the magnetic pulse is not focused enough for these body regions. Electrical stimuli are applied with a different device: a small two-pronged instrument that is placed at the bottom of the neck and the lower back. A very short electrical pulse is given in both these areas that is similar to what are used for a nerve conduction test. Electrical stimulation also causes muscles to contract and the body to move briefly. It can be mildly uncomfortable, although the amount of discomfort varies from patient to patient.

What should I do to prepare?

Wear lose clothing (shorts or sweatpants are good), and try not to wear jewelry because we will ask you to remove it.

Will this test have any short or long term side effects?

TMS is completely safe. There are no serious short term, or long term effects of TMS. It may be briefly unpleasant during the testing itself but will not cause any lingering effects. Rarely, patients briefly feel a mild headache due to contraction of scalp muscles during magnetic stimulation.



IV. Deep brain stimulation (DBS) surgery



I am scheduled for DBS surgery and also for pre-operative testing at your office. How is the Clinical Motor Physiology group involved in my surgery?

Our team has three overall functions for patients undergoing deep brain stimulation (DBS) surgery:

  1. To record your baseline clinical state and measure some of your abnormal movements in an objective and quantitative way using special devices and a computer.
  2. To help ensure optimal and safe DBS placement, in most surgeries, through intra-operative mapping and monitoring.
  3. To measure your changes post-operatively in an objective, quantitative way.

What physiology is done when I am in surgery? What are mapping and monitoring?

In the operating room, we use single cell recording equipment to “listen” to the firing pattern of neurons through a very thin electrode. This is placed painlessly in the brain generally while you are awake or slightly groggy. Initial insertion of this electrode is done by the neurosurgeons on the basis of MRI and other imaging methods, and stereotactic coordinates.

Because each region of the brain, particularly the target we are aiming for, has a distinct firing pattern, we localize and “map” where to place the DBS with great precision based on these recordings.

The mapping electrode is also used to record brain activity when we move your arms or legs or ask you to voluntarily move, or when we shine a light near you. We also “monitor” these actions using physiologic recordings of your movements and vision, in some cases.

Based on the results of these procedures, we isolate the target using coordinates on a map, and then replace the mapping electrode with the actual DBS.

To check accuracy of DBS placement, we generally monitor the same movements of your arms and legs again with the DBS turned on and off. If your symptoms change appropriately, the DBS finally is secured in place.

I am told physiology is noisy in the operating room. Is that true?

Yes, part of physiological mapping and monitoring involves turning some of the measurements into graphic signals and noise that serve as the “signatures” of the deep brain structures and allow optimal placement of the DBS. The noise is never alarming or dangerous, and is a normal part of most DBS surgery.

What does the pre-operative testing involve?

Pre-op patients will have their muscle activation patterns as well as freely drawn spirals assessed using the methods described in Tremor Analysis and Spiral Analysis. Testing takes between 45 and 90 minutes. During this time, your clinical evaluation is reviewed and recorded along with the pre-operative results.

What is the purpose of pre-op testing?

The results of these tests, as well as your clinical exam, help our neurophysiology team assess how you are doing in the operating room, and help us confirm when the DBS is at its optimal placement in the brain.

What should I do to prepare?

If it is clinically warranted and acceptable by your referring physician, do not take medications for Parkinson's disease, essential tremor, or dystonia for at least 12 hours prior to your pre-operative or post-operative appointments with us. If this presents significant difficulty, please call our office for special arrangements. Some medications have serious side effects if you stop them too quickly, so do not do this without speaking with your doctor or our office first.

Please wear loose clothing and minimal jewelry.

Will I be coming back?

Patients are scheduled for a single 6-month follow up appointment to have the same tests repeated. We try to accommodate patients' schedules so that they return on the same day as their implanted pulse generator (IPG) programming, or other testing is being performed.

What is the purpose of post-op testing?

The follow-up testing session provides an objective, quantifiable measure of the efficacy of the DBS procedure.This should occur after your implanted pulse generators (IPG's) have been optimally programmed.

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© 2006 Columbia University Clinical Motor Physiology Laboratory
Updated March 13, 2014
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