Conventional radiotherapy with fractionated external beam radiation has been used as a primary, combined, or salvage treatment in patients with jugular foramen paragangliomas [2]. This modality of treatment is indicated in most cases for malignant tumors, remnants after subtotal resection, unresectable lesions, and in patients in advanced age with comorbidity. In a recent retrospective literature reviewing articles listed in Medline, Suarez C et al. evaluated 20 published series with a total of 461 patients with jugular foramen paragangliomas treated with conventional radiotherapy (total doses ranged from 40 Gy to 65 Gy) [3]. The mean age was 53.2 years and the mean duration of follow-up was 112.6 months. In 411 patients (89.1 %) the control of disease (patient alive with tumor regression or without evidence of progression) was obtained. In 50 patients tumors progressed and 15 patients (3.2 %) died of disease progression. The neurological outcome of 351 patients was reported, on pre-treatment 242 cranial nerves were affected, after radiotherapy 232. Severe complications or irradiation was observed in 57 patients causing nine deaths. The most common complications were hearing loss, osteonecrosis, and brain necrosis.

Radiosurgery (Gamma Knife, LINAC, and CyberKnife) has been reported as a useful, safe treatment option for benign jugular foramen paragangliomas (tumor diameter <3 cm) associated with minimal morbidity (Table 12.1) [5, 7]. Long-term outcome (median follow-up time was 5.3 years) after SRS for temporal bone paragangliomas has been reported. The overall survival rates ranged at 5 years from 100 % to 78 %, at 10 years from 95.2 % to 78 %, and at 20 years 79.4 % [6, 7]. Neurological deficits improved in 42 % of patients and deteriorated in 4 %. Tumor size decreased in 77 % [4]. In conclusion, radiosurgery appears to be both safe and effective in the treatment of jugular foramen paragangliomas (more favorable if tumor diameter <3 cm). Determining whether long-term tumor control and complications will arise will require further investigation.

In the literature the reported number of patients treated with fractionated stereotactic radiotherapy (SRT) is very limited. SRT has been used more frequently to treat patients with vestibular schwannomas with a 5-year tumor control rate of 91.4 % [10].

Described complications of SRT are transient facial nerve palsy (4 %), trigeminal neuropathy (14 %), hydrocephalus (11 %), and balance disturbance (17 %). The risk of a benign or malignant secondary tumor development after SRT may be as high as 2 % [11]. In a study comparing treatment toxicity of SRT with radiosurgery LINAC-based to treat vestibular schwannomas, the authors found no statistically significant difference between the two groups [12].

Radical removal of jugular foramen schwannomas carries the risk of lower cranial neuropathy . Radiosurgery is not curative but is a minimally invasive alternative or adjunct to microsurgery after subtotal resection in some cases. Lower cranial nerve deficits rarely occur as adverse complication of radiosurgery. Long-term follow-up is needed for evaluation of tumor growth control and development of late cranial nerves deficits. Larger tumors require, however, surgical resection. In a series of 34 patients (35 tumors—one patient with bilateral schwannomas) with a mean follow-up of 83 months tumor regression was observed in 17 patients, remained stable in 16, and tumor progression occurred in two. Five- and 10-year control rates were 97 % and 94 %, respectively [13]. A multi-institutional study in Japan evaluated the efficacy and safety of gamma knife radiosurgery in the treatment of 117 patients with jugular foramen schwannomas. Radiosurgery was the primary treatment in 56 cases and 61 patients underwent previous surgical resection. The schwannomas were solid in 73 % of the cases and with cystic components in 27 % of patients. The median tumor volume was 4.9 cm³, the median dose to the tumor margin was 12 Gy, and maximum and marginal doses were 42 and 21 Gy, respectively. With a median follow-up period of 52 months, 62 patients (53 %) showed partial tumor regression, 42 patients (36 %) stable tumors, and 13 (11 %) tumor progression. Pre-radiosurgery brainstem edema and dumbbell-shaped tumors significantly affected progression-free survival that was 91 % and 89 % in 3- and 5-year follow-up, respectively. Twenty patients (17 %) developed symptomatic deterioration (transient in 12 cases and permanent in eight patients). The preexisting hoarseness and swallowing deficits improved in 66 % and 63 % of the patients, respectively [14]. Planned subtotal resection followed by radiosurgery has been proposed as treatment strategy to avoid lower cranial nerves deficits [15].

Delayed development of malignant secondary tumor following radiosurgery is rare. There are many case reports after radiosurgery in the literature, but neither the incidence nor the prevalence of secondary radiation-related tumors is known [16, 17]. In a review of the literature the risk of malignancy in vestibular schwannomas patients was of 1.32–2.08 per 100,000 over 20 years in no irradiated cases. Excluding the neurofibromatoses (NF) cases this risk decreases to 1.09–1.74 per 100,000. In patients after radiation therapy the overall risk over 20 years is 25.1 per 100,000. This risk decreases to 15.6 per 100,000 if cases of NF are excluded. The authors conclude that radiation treatment increases the risk of malignancy by approximately 10 times in non-NF cases [18].

3D conformal external beam radiation therapy can offer local tumor control in 90–95 % of cases [23]. It is usually indicated for larger tumor (>3.5 cm in diameter) and for lesion close to structures, such as the optic chiasm and brainstem. Excellent results of meningiomas treated primarily with external beam radiotherapy and fractionated stereotactic radiotherapy have been reported [24–26]. With image-based techniques the recommended doses range from 50 to 55 Gy in fractions of 1.8 to 2.0 Gy [24, 27]. Side effects of external beam radiotherapy have been described. In a series of 189 patients treated with a highly conformal stereotactic approach (median daily fractions of 1.8 Gy to a mean dose of 56.8 Gy) four patients (2.2 %) presented reduced vision, a new visual-field deficit, and trigeminal neuropathy , with a median follow-up of 3 years [28]. Brainstem necrosis has been uncommonly observed [29].

SRS is generally indicated for small meningiomas (less than 3–4 cm in diameter) with a margin doses ranging from 12 to 16 GY [30–32]. In approximately 8 % of patients new or worsened cranial nerves deficits were observed with higher margin doses (14–16 Gy). The optic, cochlear, and trigeminal nerves were more commonly affected [33–35].

Jugular foramen meningiomas are very rare and no series reporting primarily radiosurgical treatment of these tumors has been reported in the literature. In a series of 62 posterior fossa meningiomas treated with gamma knife surgery included 26 cases of jugular foramen/petrous bone meningiomas. In a relatively short follow-up (median 28.7 months) the authors observed reduction or disappearance of the lesion in 55 % (34/62) cases of the all series, stable radiological imaging in 40 % (25/62), and progression in 5 % (3/62) [36]. Long-term results are needed to know the efficacy of radiosurgery to control tumor growth in benign skull base meningiomas. In a recent report, Chohen-Inbar O et al. evaluated long-term results in a series of 135 patients with WHO-grade I skull base meningiomas treated with a single-session gamma knife radiosurgery [37]. Median follow-up was 102.5 months, median tumor volume 4.7 cm, and median margin dose 15Gy. Tumor volume control was achieved in 88.1 %. The 5-, 10-, and 15-year actuarial progression-free survival were 100 %, 95.4 %, and 68.8 %, respectively. In a report of the North American Gamma Knife Consortium , 675 patients with posterior fossa meningiomas treated with gamma knife radiosurgery were evaluated. There was a female preponderance at a ratio of 3.8 to 1. The median patient age was 57.6 years (range 12–89 years) and 43.3 % underwent previous resection. The mean tumor volume was 6.5 cm³ and the median margin dose was 13.6 Gy (range 8–40 Gy). At a mean follow-up of 60.1 months the control of tumor growth was achieved in 91.2 % of cases. Actuarial tumor control was 95 %, 92 %, and 81 % at 3, 5, and 10 years after gamma knife. Clival, petrous, or cerebellopontine angle location when compared with petroclival, tentorial, and foramen magnum location was predictive factor of neurological decline after radiosurgery [38]. Improvement of signs and symptoms after gamma knife radiosurgery was observed in 30 % of cases of skull bases meningiomas [39].

The role of adjuvant radiation and the type of radiation used remain a subject of discussion. Proton beam radiation is considered to offer the best long-term follow-up and efficacy [41]. In 1989, Austin-Seymour M et al. first reported the efficacy of proton beam radiation for chordomas [42]. Sixty-eight patients with chordoma or low-grade chondrosarcoma at the base of the skull received fractionated high-dose postoperative radiation delivered with a 160-MeV proton beam. With a minimum follow-up period of 17 months (median of 34 months) the 5-year actuarial local control rate was 82 % and disease-free survival rate was 76 %. In a series of 40 patients with chordomas of the skull base and cervical spine proton beam radiotherapy was performed in 75 % of the cases with a mean dose of 68.9 cobalt gray equivalents. With a median follow-up of 56.5 months, the 5-year PFS and OS rates were 70 % and 83.4 %, respectively. The authors concluded that multimodal surgery and proton therapy improved the results [43].

The emerging technology committee of the American Society of Radiation Oncology (ASTRO) found evidence for a benefit of proton beam radiation therapy over photon therapy in large chordomas [44]. Other authors, however, observed similar results with proton- and photon-based radiotherapy [45, 46]. Complications of proton beam radiotherapy for clival chordomas such as delayed optic nerve neuropathy and blindness have been described [47].

Adjuvant proton-beam, carbon ion, and modern fractionated photon radiation therapy techniques offered a similar rate of PFS and OS at 5 years [45]. Table 12.2 summarizes the relative pros and cons of each modality presented at a panel discussion on Carbon vs proton for innovative applications of particle beam therapy [48].