http://www.medtronic.com/neuro/diathermy_alert/alert_physicians.html

Safety Alert For Physicians

CONTRAINDICATION: Do not use shortwave diathermy, microwave diathermy or
therapeutic ultrasound diathermy (all now referred to as diathermy) on
patients implanted with a neurostimulation system. Energy from diathermy can
be transferred through the implanted system and can cause tissue damage at
the location of the implanted electrodes, resulting in severe injury or
death.

Diathermy is further prohibited because it can also damage the
neurostimulation system components resulting in loss of therapy, requiring
additional surgery for system explantation and replacement. Injury or damage
can occur during diathermy treatment whether the neurostimulation system is
turned “on” or “off.” Advise your patients to inform all their health care
professionals that they should not be exposed to diathermy treatment.

May 16, 2001

Dear Doctor and Medical Staff:

Medtronic Neurological is issuing this Safety Alert to all physicians,
patients and facilities involved with its implanted neurostimulation
systems, which include:

Activa® Systems for deep brain stimulation (DBS)
Spinal Cord and Peripheral Nerve Stimulation Systems
InterStim® Therapy (Sacral Nerve Stimulation)
Enterra® Therapy
Dynamic Graciloplasty

DO NOT use or prescribe shortwave diathermy, microwave diathermy or
therapeutic ultrasound diathermy (all now referred to as diathermy) for
patients implanted with any type of Medtronic neurostimulation system. Use
of diathermy on patients with any implanted neurostimulation device can
cause heating at the tissue/stimulation electrode interface, which under
certain circumstances can result in permanent tissue or nerve damage. Such
tissue damage could lead to permanent injury or even death. The exact nature
of the tissue or nerve damage depends on the location of the stimulation
electrodes implanted in the patient (e.g. brain, spinal cord, sacral nerve,
stomach), and the extent of the exposure to diathermy treatment.

This contraindication applies regardless of where the diathermy treatment is
targeted on the patient’s body in relation to the implanted stimulation
system.
This contraindication applies regardless of whether it is used to deliver
heat or no heat.
This contraindication applies regardless of whether the Medtronic
neurostimulation system is turned “on” or “off”.
This contraindication applies if any individual components of the
neurostimulation system remain implanted in the body.
Medtronic is issuing new labeling for its neurostimulation systems using the
contraindication language printed above. A patient-friendly version of the
above contraindication language will appear in patient manuals and
materials. The FDA has been notified of this issue and of Medtronic’s
notification plans.

What are shortwave diathermy, microwave diathermy and therapeutic ultrasound
diathermy treatments?
Diathermy treatments are used by a variety of health care professionals,
including physical therapists, nurses, chiropractors, dentists, sports
therapists, and others. Health care professionals may refer to diathermy
using the term “deep heat” or similar terms. Diathermy means deep heat, but
these devices may also be used in a way that causes little or no heating.
Diathermy does not include ultrasonic imaging or electrocautery devices.
Diathermy that uses these forms of energy (shortwave, microwave or
ultrasound) can cause permanent nerve or tissue damage in patients with a
neurostimulation system even if the diathermy is set at power levels that do
not cause deep heating.
Diathermy (d_´-a-thur-m_) are treatments that deliver energy to treat
specific areas of the body. These treatments are typically used for the
following purposes:

relieve pain, stiffness and muscle spasms
reduce joint contractures
reduce swelling and pain after surgery
promote wound healing
The contraindication with implantable neurostimulation devices applies to
all forms of diathermy.

Risk to Patients:
Medtronic has received two case reports of patients implanted with deep
brain stimulation systems who received shortwave therapy (diathermy), one
following oral surgery, the other for treatment of chronic scoliosis. In
both cases, the shortwave energy caused severe and permanent brain damage in
the area of the lead electrodes implanted in the brain. Both patients remain
in a comatose condition since receiving shortwave diathermy.

As a result of the above case reports, Medtronic conducted tests on a
neurostimulation system with one type of shortwave diathermy device. The
tests found that the energy generated by the shortwave type of diathermy
will cause heating well above the temperatures required for tissue
destruction.

Due to the widespread use of diathermy for a variety of therapeutic
treatments in the health care community, it is reasonable to assume that all
patients with implanted neurostimulation systems can be at risk of exposure
to diathermy therapy.

Impact on Neurostimulation Systems:
Please note that the permanent nerve or tissue injury is not caused by a
device malfunction. Rather, it is caused by the interaction of two devices
(neurostimulation system and diathermy machine) when they are working
properly. Medtronic has previously cautioned against diathermy, as it poses
a risk of damage to the implanted device. Although the testing subsequent to
the reported events did not show damage to the Medtronic device, Medtronic
continues to believe that diathermy of any type poses a real risk of damage
to implanted neurostimulation devices and should be avoided. Other types of
diathermy equipment have not been tested, and the specific effects of any
individual diathermy system on the neurostimulation systems are unknown.
Routine interrogation of the implanted neurostimulation device can ascertain
its functional integrity.

If you have any questions related to this Safety Alert or any other safety
issues regarding Medtronic’s implantable neurostimulation devices, please
contact Medtronic’s Technical Service line at 1-800-328-0810. Please refer
to the technical manuals provided with your Medtronic products to review the
entire list of other contraindications, precautions, and warnings regarding
the safe use of these devices.

Sincerely,

Cliff Owens
Vice President and General Manager
Medtronic Neurostimulation

Martha Goldberg Aronson
Vice President and General Manager
Medtronic Functional Stimulation

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