Page 31 - Delaware Medical Journal - January/February 2020
P. 31
REVIEW ARTICLE
Figure 4. The Accuray CyberKnife device
one month of CyberKnife SRS treatment, with a mean recurrence time of 19 months. At their last follow-up
Seventy-two percent of patients did
not have any post-treatment facial numbness; in addition, at a median facial numbness improvement.
A fourth study, conducted in Milan, Italy by Romanelli et al,14 patients with medically intractable TN between November 2010 and March 2014. They prescribed an average dose of 60 Gy in a single fraction. Using the BNI scale, and calling a score of IIIa or below controlled, 76% of patients had controlled pain at 36 months follow-up. disturbances. They also predicted that shorter nerve length (<6 mm vs. 6 mm), smaller nerve volume (<30 mm vs.
>30 mm), and lower prescription dose
treatment failure.
LOCAL RESULTS OF TREATMENT WITH CYBERKNIFE SRS
At the Helen F. Graham Cancer Center at ChristianaCare, we have treated more than 1,500 patients
with the CyberKnife device since for TN. We utilized a mean dose of following the Stanford technique described by Adler et al.12 In the first seven years, we had a high success rate, but had a significant rate of
late complete facial numbness. It is a well-established principle of radiation oncology that increasing the number of fractions of radiation therapy can maintain acute treatment effects while decreasing the risk of late normal- tissue complications. Over the past three years, we initiated a program of
treating TN using three consecutive daily fractions with a total of 99 Gy of radiation. This dose fractionation scheme was chosen to approximate the acute effects of the single-fraction Stanford technique. We chose this method of three fractions because it would allow us to treat the trigeminal nerve with a higher dosage — ~90 Gy — while the multiple fractions would allow the trigeminal nerve to recover between treatments. To the best of our knowledge, we are the first center in the United States to report on this technique.
Over the past three years, 25
patients have been treated with
the three-fraction regimen, and we have minimum one-year follow-up information available for 15 of those patients using the BNI scale. Patients were excluded if they were treated with salvage CyberKnife treatment after previous radiosurgery failure or had secondary trigeminal neuralgia. We irradiated a length of trigeminal nerves ranging from 7-12 mm, with a maximum brainstem dose of 65.5 Gy on average.
For our Christiana Hospital Institutional Review Board-approved retrospective study, all of the patients had medication refractory TN with
an initial BNI score of V. After a median follow-up of 17 months (range 12-29), 93% of the patients with TN achieved a BNI pain score I-III with a median response time of one month. Of the 14 responding patients, 21% relapsed at a mean of eight months. Seventy-three percent of the patients had controlled pain at the time of last follow-up. Female gender and MRI vascular conflict were associated with a pain treatment response (p< 0.05). Forty percent of the patients developed bothersome facial numbness at a mean time of 22 months. Facial numbness
Del Med J | January/February 2020 | Vol. 92 | No. 1
31
