MRI & Other Questions

Warnings and Precautions

Discuss these warnings and precautions with your physician before undergoing any major medical procedure.

Medical Treatments Generating Induced Currents

Some medical treatments generate induced currents that may cause tissue damage or permanent damage to the cochlear implant. Warnings for specific treatments are given below.

• Electrosurgery: Electrosurgical instruments are capable of inducing radio frequency currents that could flow through the electrode array. Monopolar electrosurgical instruments must not be used on the head or neck of a cochlear implant patient as induced currents could cause damage to cochlear tissues or permanent damage to the implant. Bipolar electrosurgical instruments may be used on the head and neck of patients. However, the cautery electrodes must not contact the implant and should be kept more than ~ 1/2 in. (1 cm) from the extracochlear electrodes.
• Diathermy: Do not use therapeutic or medical diathermy (thermopenetration) using electromagnetic radiation (magnetic induction coils or microwave). High currents induced into the electrode lead can cause tissue damage to the cochlea or permanent damage to the implant. Medical diathermy using ultrasound may be used below the head and neck.
• Neurostimulation: Do not use neurostimulation directly over the cochlear implant. High currents induced into the electrode lead can cause tissue damage to the cochlea or permanent damage to the implant.
• Electroconvulsive Therapy: Do not use electroconvulsive therapy on a cochlear implant patient under any circumstances. Electroconvulsive therapy may cause tissue damage to the cochlea or damage to the cochlear implant.
• Ionizing Radiation Therapy: Do not use this therapy directly over the cochlear implant because it may cause damage to the implant.

Magnetic Resonance Imaging (MRI):

Magnetic Resonance Imaging (MRI) is contraindicated except under the circumstances described below. Do not allow patients with a cochlear implant to be in the room where an MRI scanner is located except under the following special circumstances.

The Cochlear Nucleus Freedom cochlear implant, Nucleus 24 cochlear implant and some Nucleus 22 cochlear implants have a removable magnet and specific design characteristics to enable it to withstand MRI up to 1.5 tesla, but not higher. Those with a magnet in place must not enter a room with an MRI operating.

If the cochlear implant’s magnet is in place, it must be removed surgically before the patient undergoes an MRI procedure. The patient must take off the speech processor and headset before entering a room where an MRI scanner is located.

If the implant’s magnet is still in place, tissue damage may occur if the recipient is exposed to MRI. Once the magnet is surgically removed, the quality of the MRI will be affected by the metal in the cochlear implant. Image shadowing may extend as far as ~2.5 in. (6 cm) from the implant, thereby, resulting in loss of diagnostic information in the vicinity of the implant.

If the physician is unsure that the patient has a cochlear implant with a removable magnet, the physician should use an X-ray to check the radiopaque lettering on the implant. There are three platinum letters printed on each implant. If the middle letter is a ‘C’, ‘H’, ‘J’, ‘L’ or ‘T’, the implant has a removable magnet. Once the magnet has been removed, MRI can be performed. If you require additional information about removal of the magnet, please contact Cochlear.

Meningitis

Prior to implantation, candidates should consult their primary care physician and implanting surgeon regarding vaccination status against organisms that cause meningitis. Meningitis is a known risk of inner ear surgery and candidates should be appropriately counselled of this risk. In addition, certain preoperative conditions may increase the risk of meningitis with or without a cochlear implant. These conditions include:

• Mondini’s syndrome and other congenital cochlear malformations
• Concurrent Cerebrospinal Fluid (CSF) shunts or drains
• Recurrent episodes of bacterial meningitis prior to implantation
• Perilymph fistulas and skull fracture/defect with CSF communication.

Loss of residual hearing

Insertion of the electrode into the cochlea will result in complete loss of residual hearing in the implanted ear.

Long-term effects of electrical stimulation by the cochlear implant

Most patients can benefit from electrical stimulation levels that are considered safe, based on animal experimental data. For some patients, the levels needed to produce the loudest sounds exceed these levels. The long-term effects of such stimulation in humans are unknown.

Small parts hazard

Parents and caregivers should be counselled that the external implant system contains small parts that may be hazardous if swallowed or may cause choking if inhaled.

Battery ingestion

Batteries can be harmful if swallowed. Ensure that batteries are kept out of reach of young children. If swallowed, seek prompt medical attention at the nearest emergency facility.

Head trauma

A blow to the head in the area of the cochlear implant may damage the implant and result in its failure. Young children who are developing their motor skills are at greater risk to receive an impact to the head from a hard object (e.g. a table or chair).

Overheating

Remove your processor immediately if it becomes unusually warm or hot, and seek advice from your clinician. Parents and caregivers should touch their child’s or recipient’s processor to check for heat if the child or recipient is showing signs of discomfort.

Scuba diving

Nucleus Freedom is safe at depths less than 40 m. (131 ft.), and Nucleus 22 and 24 Series are safe to 25 m. (81 ft.). Recipients should seek medical advice before participating in a dive for conditions that might make diving contraindicated, e.g. middle ear infection, etc. When wearing a mask, avoid pressure over the implant site.

Sleeping

Do not wear your processor while sleeping, as you may not become aware of your processor becoming unusually warm or hot. Do not allow children or recipients with disabilities to wear their processor while sleeping.

Retention aids

When using retention aids such as the Snugfit™ or LiteWear, be aware that it may take longer to remove the processor if the processor becomes unusually warm or hot. Do not attach the LiteWear beneath layers of clothing.