Facial pain: Treating trigeminal neuralgia with stereotactic radiosurgery
Some individuals live with intermittent intense episodes of facial pain, which can significantly affect their quality of life.
Often, they initially seek medical attention with their dentist believing that the pain is likely secondary to a toothache. However, the source of their pain actually might be from abnormal firing of signals from a large cranial nerve. This nerve’s usual function is to transmit sensations from the face to the brain and control facial muscles used for chewing.
It is not unusual to experience pain for months or years before these individuals are diagnosed with trigeminal neuralgia. Fortunately, one option for pain relief can be found in the form of a very precise radiation treatment: a procedure typically used to eradicate cancer.
Trigeminal neuralgia is a chronic pain condition that affects the fifth cranial nerve, also known as the trigeminal nerve. This condition causes extreme, sporadic, shock-like or sudden burning facial pain. The trigeminal nerve is one of 12 pairs of cranial nerves. The nerve has three branches that conduct sensations from the upper, middle and lower portions of the face as well as the oral cavity.
Blood vessels pressing on the root of the trigeminal nerve are thought to be one possible cause of the condition. The pain can present as sudden, severe and stabbing or a more constant aching, burning sensation. Attacks may increase over time, and medication to control the pain may become less effective.
Once the diagnosis is confirmed, initial management often consists of oral medications to control and lessen the pain. However, medical management is not always effective long term, and individuals often are then evaluated for surgical options by neurosurgeons.
One form of treatment available at McLeod Regional Medical Center to treat trigeminal neuralgia is stereotactic radiosurgery (SRS), using the TrueBeam STx linear accelerator. This treatment requires extreme precision and accuracy, because the nerve that is targeted is located only three to four millimeters from the brain stem.
The SRS team includes a radiation oncologist, a neurosurgeon, a medical physicist and the neuro-oncology navigator.
Key components of preparing for stereotactic radiosurgery are patient immobilization with a very tight-fitting mask, and obtaining high resolution CT and MRI images. The medical team takes a multidisciplinary approach to create an SRS treatment plan to precisely target a portion of the nerve while minimizing dose delivery to normal brain tissue around the nerve. Treatment is scheduled once the radiation oncologist and neurosurgeon approve the plan and ensure that everything is set to match up perfectly when the patient is on the treatment table.
The TrueBeam STx linear accelerator rotates in a 360-degree arc around the patient, delivering the radiation beam to any part of the body from virtually any angle. In addition, the treatment table is designed to move in six different directions, and the machine is equipped for image-based adjustments during treatment.
When treating trigeminal neuralgia, radiation is focused into a circular beam approximately the diameter of a pencil. These pencil beams move in an arc around the patient’s head and converge at the same point in space, creating a high dose area about the size of a pea. The radiation dose targets the site where the trigeminal nerve exits the brain stem. The targeted radiation dose disrupts the transmission of sensory signals to the brain. The dose used to perform this procedure is approximately 40 times larger than the daily dose a typical cancer patient receives.
McLeod offers one of the only active linear accelerator (LINAC) based stereotactic radiosurgery programs from the midlands to the coast. Since installation in October 2014, a total of 152 patients have received intracranial stereotactic radiosurgery. Of that total, 13 patients have undergone treatment for trigeminal neuralgia.
For more information on the treatment of trigeminal neuralgia, contact McLeod Neuro-Oncology Navigator Leslie Herndon at 843-777-5779.
Dr. Virginia Clyburn-Ipock is a board certified radiation oncologist with the McLeod Center for Cancer Treatment and Research. She received her medical degree from the Medical University of South Carolina in Charleston. She completed a residency in Radiation Oncology at the University of Texas Health Science Center at San Antonio, where she served as chief resident. Clyburn-Ipock also has special training in stereotactic body radiation therapy and IMRT.