Important safety information

Activa® Parkinson's Control Therapy and Tremor Control Therapy Indications, Contraindications, Warnings, Precautions, and Adverse Events

Activa® Parkinson's Control Therapy and Tremor Control Therapy: Product technical manual must be reviewed prior to use for detailed disclosure

Indications:
The system is indicated as a therapy for patients with disabling tremor or symptoms of Parkinson's disease. Recent studies have shown that deep brain stimulation is effective in controlling Essential Tremor and the symptoms of Parkinson's disease which are not adequately controlled with medications. Additionally, deep brain stimulation is effective in controlling dyskinesias and fluctuations associated with medical therapy for Parkinson's disease.

Contraindications: Contraindications include patients who will be exposed to MRI using a full body radio-frequency (RF) coil or a head transmit coil that extends over the chest area, patients for whom test stimulation is unsuccessful, or patients who are unable to properly operate the neurostimulator. Also, diathermy (e.g., shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy) is contraindicated because diathermy's energy can be transferred through the implanted system (or any of the separate implanted components), which can cause tissue damage and can result in severe injury or death. Diathermy can damage parts of the neurostimulation system.

Warnings/ Precautions/Adverse Events: There is a potential risk of tissue damage using stimulation parameter settings of high amplitudes and wide pulse widths. Extreme care should be used with lead implantation in patients with a heightened risk of intracranial hemorrhage. Physicians should consider underlying factors, such as previous neurological injury or prescribed medications (anticoagulants), that may predispose a patient to the risk of bleeding. Theft detectors and security screening devices may cause stimulation to switch ON or OFF, and may cause some patients to experience a momentary increase in perceived stimulation. Although some MRI procedures can be performed safely with an implanted System, clinicians should carefully weigh the decision to use MRI in patients with an implanted System. MRI can cause induced voltages in the neurostimulator and/or lead possibly causing uncomfortable, jolting, or shocking levels of stimulation. MRI image quality may be reduced for patients who require the neurostimulator to control tremor, because the tremor may return when the neurostimulator is turned off.

Important Diathermy Safety Information
Once a patient is implanted with an Activa® System, it is important to remind the patient about the dangers of diathermy. They receive information about diathermy in their patient handbook, but it is helpful to print out this information and discuss diathermy with them as well.

Medtronic Neurological issued the following Safety Alert on May 18, 2001, 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

Safety Alert:
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 interclass, 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.

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 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.