RHIZOTOMY PROCEDURES FOR TN

Overview of Treatments

Medications
Microvascular
Decompression
Surgery

Rhizotomies
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†††††When medications have failed to control TN, not all sufferers are good candidates or wish to undergo microvascular decompression surgery.† An alternative category of treatment are the destructive procedures (rhizotomies) that injure some portion of the trigeminal nerve. Rhizotomies are less likely to "cure" TN compared to MVD, as the neurovascular compression is not alleviated. However, these procedures are technically simpler and may be repeated if pain recurs.

††††There are several techniques to achieve trigeminal injury or rhizotomy, as outlined below. These aim to alter trigeminal nerve function, resulting in partial or complete alleviation of TN pain. An expected side effect is some loss of feeling (numbness) in the trigeminal distribution. In rare cases, the numbness is bothersome or even associated with a new form of pain (ie. post-traumatic neuralgia/trigeminal neuropathy).


In percutaneous needle procedures, a needle is passed through the cheek up to the gasserion ganglion.
Percutaneous Rhizotomy Techniques

     These procedures involve inserting a needle through the cheek and into an opening at the skull base (foramen ovale). There, a controlled injury to the trigeminal nerve and Gasserion ganglion may be produced in one of three ways:

 

A glycerol rhizotomy.     1) Percutaneous glycerol rhizotomy:
The chemical glycerol is delivered to the space surrounding the Gasserion ganglion and trigeminal nerve root. The glycerol produces a relatively mild injury to the nerve, with minimal risk of permanent facial numbness.†

    While the majority of patients achieve early relief of TN, pain recurs in approximately half of sufferers within a couple of years.†The procedure is performed under local anesthesia, usually on an out-patient basis, and may be repeated when necessary.


An inflated balloon in Balloon Compression Rhizotomy.     2) Balloon compression rhizotomy:
A catheter is advanced to the needle tip and a balloon is inflated to compress the Gasserion ganglion and trigeminal nerve root. The injury from this compression maybe particularly effective for pain involving the upper face (V1), as sensation of the cornea is usually preserved. However, many patients develop at least temporary weakness of the chewing muscles following this balloon compression procedure, and the degree of facial numbness is often more severe than with glycerol rhizotomy.†The procedure is performed under general anesthesia, followed by overnight hospital admission.

Radiofrequency rhizotomy
     3) Radiofrequency rhizotomy:†A small electrode is advanced through the needle. Its correct position within the Gasserion ganglion is tested with gentle electrical stimulation that causes tingling in parts of the face. The electrode is then heated to produce a thermal injury of the nerve. Effective treatment usually necessitates at least partial facial numbness in the affected trigeminal area. The procedure is performed under local anesthesia with intravenous sedation added during electrode heating.


Stereotactic Radiosurgery (Gamma Knife)

     
This new technique allows for focused radiation to be delivered to the trigeminal nerve root, causing injury similar to the percutaneous rhizotomy procedures.†The procedure involves the attachment of a frame to the patientís head, followed by a Magnetic Resonance Imaging (MRI) to localize the trigeminal nerve root target. The patient is then positioned in a Gamma Knife where beams of cobalt radiation are precisely focused. The resulting trigeminal nerve root injury usually reduces TN pain within a few weeks. The higher the dose of radiation used, the longer the pain control may last, but this also increases the risk of developing facial numbness and/or new pain.



Peripheral Rhizotomies

     TN pain may be treated by injuring the peripheral branches of the trigeminal nerve, which are found just beneath the skin or mouth lining. Injury may be produced by the injection of alcohol, cutting (sectioning), or removing (avulsion) of the nerve fibers exiting the skull. While these techniques are usually effective immediately, they also cause severe or complete numbness of the affected area, at least temporarily. TN pain often recurs, and therefore other surgical interventions are usually chosen for long-term pain management.



Microsurgical Rhizotomy
     Partially cutting the trigeminal nerve root near the brain stem is one of the most effective and oldest treatments for TN. However, this technique has been largely replaced by microvascular decompression (MVD) which uses the same surgical approach, or the simpler percutaneous rhizotomy techniques.

 

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Prepared by A. M. Kaufmann & M. Patel
© 2001 Centre for Cranial Nerve Disorders, Winnipeg, University of Manitoba, Health Sciences Centre. The information provided on this web-site is intended for educational purposes only, and should not be used to diagnose or treat a disease or disorder. This information is not intended to substitute, supplement, or in any way qualify the services or advice provided by a qualified health care professional. Please consult with a certified health care professional before pursuing any form of medical action. Duplication in any part or form of this document is strictly prohibited. All rights reserved. For further information please read our disclaimer. Web-Site related inquiries can be directed to the Information Provider.