Elsevier

World Neurosurgery

Volume 103, July 2017, Pages 702-712
World Neurosurgery

Original Article
Frameless Stereotactic Radiosurgery for Treatment of Multiple Sclerosis–Related Trigeminal Neuralgia

https://doi.org/10.1016/j.wneu.2017.04.102Get rights and content

Background

Trigeminal neuralgia (TN) affects 7% of patients with multiple sclerosis (MS). In such patients, TN is difficult to manage either pharmacologically and surgically. Radiosurgical rhizotomy is an effective treatment option. The nonisocentric geometry of radiation beams of CyberKnife introduces new concepts in the treatment of TN. Its efficacy for MS-related TN has not yet been demonstrated.

Methods

Twenty-seven patients with refractory TN and MS were treated. A nonisocentric beams distribution was chosen; the maximal target dose was 72.5 Gy. The maximal dose to the brainstem was <12 Gy. Effects on pain, medications, sensory disturbance, rate, and time of pain recurrence were analyzed.

Results

Median follow-up was 37 (18–72) months. Barrow Neurological Institute pain scale score I–III was achieved in 23/27 patients (85%) within 45 days. Prescription isodose line (80%) accounting for a dose of 58 Gy incorporated an average of 4.85 mm (4–6 mm) of the nerve and mean nerve volume of 26.4 mm3 (range 20–38 mm3). Seven out of 27 patients (26%) had mild, not bothersome, facial numbness (Barrow Neurological Institute numbness score II). The rate of pain control decreased progressively after the first year, and only 44% of patients retained pain control 4 years later.

Conclusions

Frameless radiosurgery can be effectively used to perform retrogasserian rhizotomy. Pain relief was satisfactory and, with our dose/volume constraints, no sensory complications were recorded. Nonetheless, long-term pain control was possible in less than half of the patients. This is a limitation that CyberKnife radiosurgery shares with other techniques in MS patients.

Introduction

Trigeminal neuralgia (TN) is the most common craniofacial pain syndrome, with an incidence of up to 5 in 100,000. It is a severe condition requiring long-term medical treatment. Nonetheless, up to 10% of patients suffer major adverse drug-related events and require some type of surgical treatment.1, 2 About 1%–2% of TN cases are caused by demyelinating plaques of multiple sclerosis (MS) along the trigeminal pathway, nerve, and brainstem. Trigeminal pain affects up to 7% of patients with MS, and symptoms are often atypical or bilateral.3 In such patients, TN is often difficult to manage either pharmacologically or surgically, with lower response rates than idiopathic TN.4, 5, 6

Pioneered by Lars Leksell in 1951,7 stereotactic radiosurgery is a proven and valuable method to treat TN. A remarkable body of experience is available in the use of Gamma Knife single isocenter treatments of TN.8, 9, 10, 11, 12, 13, 14, 15, 16 On the other hand, only a handful of dedicated studies about the treatment of MS-related TN are available to date.17, 18, 19, 20, 21, 22, 23 Whether the radiosurgical rhizotomy for TN can be performed using a frameless technique is often questioned. The CyberKnife (Accuray Inc., Sunnyvale, California, USA), a frameless robotic system,24, 25, 26 has been proposed for the treatment of functional disorders. The nonisocentric geometry of radiation beam delivery provides the possibility of homogeneous irradiation of an extended segment of the trigeminal nerve, thus introducing new concepts for the radiosurgical treatment of TN. Despite the limited number of series reported to date, clinical results of CyberKnife radiosurgery seem to be satisfactory. Whether frameless radiosurgery can be successfully applied to patients with TN secondary to MS has yet to be demonstrated. We report our results on this issue.

Section snippets

Patients' Selection

Between September 2009 and November 2015, we treated and followed up 27 patients presenting with medically intractable TN and MS at the CyberKnife Center, University of Messina, Italy. Patients fulfilling the criteria of the International Headache Society (2003)27 were included. Evaluation of the type of trigeminal pain was made according to the classification proposed by Eller et al28 into idiopathic TN1 and TN2. Patients were categorized as having TN1 (typical) if pain was described as

Target and Treatment Data

All treatments were performed in a single session. Median prescription isodose line (80%) accounting for a dose of 58 Gy incorporated an average of 4.85 mm (4 to 6 mm) segment of the trigeminal nerve, with a mean nerve volume of 26.4 mm3 (range 20–38 mm3) (Figure 2). The median maximal dose was 72.5 Gy (range, 71.8–Gy74.4). Median number of beams was 105 (range 90–110); median number of nodes was 87 (range 85–90). Treatment time ranged 45–55 minutes with beam-on time ranging 15–21 minutes. The

Discussion

In our series, the first on the use of frameless, nonisocentric radiosurgery technique to treat MS-related TN, we observed initial pain relief in 85% of the patients. This result is consistent with the data of Gamma Knife radiosurgery for idiopathic TN, in which initial pain relief has been reported in 50%–96%.8, 9, 10, 12, 16, 30 Overall, the studies specifically addressing the use of radiosurgery for TN cases associated with MS report clinically relevant benefits in 57%–100% of the patients17

References (47)

  • L. Bennetto et al.

    Trigeminal neuralgia and its management

    BMJ

    (2007)
  • M. Obermann

    Treatment options in trigeminal neuralgia

    Ther Adv Neurol Disord

    (2010)
  • K.J. Burchiel et al.

    On the natural history of trigeminal neuralgia

    Neurosurgery

    (2000)
  • G. Broggi et al.

    Operative findings and outcomes of microvascular decompression for trigeminal neuralgia in 35 patients affected by multiple sclerosis

    Neurosurgery

    (2004)
  • Y. Kanpolat et al.

    Percutaneous controlled radiofrequency rhizotomy in the management of patients with trigeminal neuralgia due to multiple sclerosis

    Acta Neurochir (Wien)

    (2000)
  • D. Kondziolka et al.

    Long-term results after glycerol rhizotomy for multiple sclerosis-related trigeminal neuralgia

    Can J Neurol Sci

    (1994)
  • L. Leksell

    Sterotaxic radiosurgery in trigeminal neuralgia

    Acta Chir Scand

    (1971)
  • D. Kondziolka et al.

    Gamma Knife stereotactic radiosurgery for idiopathic trigeminal neuralgia

    J Neurosurg

    (2010)
  • K. Marshall et al.

    Predictive variables for the successful treatment of trigeminal neuralgia with Gamma Knife radiosurgery

    Neurosurgery

    (2012)
  • N. Massager et al.

    Gamma Knife surgery for idiopathic trigeminal neuralgia performed using a far-anterior cisternal target and a high dose of radiation

    J Neurosurg

    (2004)
  • J. Regis et al.

    Prospective controlled trial of Gamma Knife surgery for essential trigeminal neuralgia

    J Neurosurg

    (2006)
  • R.I. Riesenburger et al.

    Outcomes following single-treatment Gamma Knife surgery for trigeminal neuralgia with a minimum 3-year follow-up

    J Neurosurg

    (2010)
  • J. Sheehan et al.

    Gamma Knife surgery for trigeminal neuralgia: outcomes and prognostic factors

    J Neurosurg

    (2005)
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    Conflict of interest statement: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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