This document discusses the application of Perfexion Gamma Knife radiosurgery for infra-skull base lesions. It presents 14 cases where Perfexion Gamma Knife was used to treat lesions located in challenging areas such as the foramen magnum, neck region, and extracranial spaces. The results showed tumor shrinkage, stabilization or improvement in symptoms for all cases. Precise immobilization was important to minimize motion error, especially for extracranial lesions. In conclusion, Perfexion Gamma Knife can effectively treat infra-skull base lesions while overcoming previous technical limitations of location.

1. Neurosurgery Department
Shuang Ho Hospital
New Taipei City, Taiwan
Wei-Lun Lo, M.D.
THE APPLICATION OF
PERFEXION GAMMA KNIFE
RADIOSURGERY
FOR INFRA-SKULL BASE LESIONS

2. TECHNICAL LIMIT OF GKS
Traditional lower limit of treatment related to lesion
locations: Foramen mangnum
Kondziolka et al: Radiosurgery of meningiomas. Neurosurg Clin N Am 3:219–230,
1992
 However, the data from new Perfexion version was not
included.
J Craniovertebr Junction Spine. 2010 Jan-Jun; 1(1): 23-28

3. • Primary lesion at
neck
• Extracranial
↑↓
Intracranial
POSTING DIFFICULTY FOR GKS

4. COMPARISON OF GK SYSTEMS

5. CASE DISTRIBUTION (N = 14)
Meningioma
Paraganglioma
Low brain stem
cavernoma
Trigeminal
neuroma
Low cranial
nerve
neuroma
Skull base
metastasis
Dural
arteriovenous
fistula
3
4
1
3

6. Paraganglioma
39 y/o female
horseness and
dysphonia;
paraganglioma from
posterior fossa with
extension to neck
region s/p partial
resection by ENT doctor
2013/10/15
TV: 18.3
2014/4/22
TV: 7
Volume: 18.3c.c.
RV: 23.5c.c.
PD: 12.5 Gy
MD: 22.3 Gy
ID: 56%
Mean dose: 16.7 Gy

7. Foramen Mangnum
Meningioma
37 year-old female
Meningiomatosis in
petroclival, foramen
magnum , and ventral C5
regions
s/p surgical excision of C5
meningioma
2013/8/23
TV: 1.2
2014/2/24
TV: 1.2
Volume: 1.2 c.c.
RV: 3.3 c.c.
PD: 12 Gy
MD: 21.8 Gy
ID: 55%
Mean dose: 16.6 Gy

8. Skull Base
Metastasis
74 year-old female
Hx of breast cancer
s/p operation; facial
numbness, difficult
swallowing, tongue
atrophy
2013/7/11
TV: 27.2
2014/7/24
TV: 3.5
Marked regression
Improvement of tongue atrophy
& swallowing function
Volume: 27.2 c.c.
RV: 35.2 c.c.
PD: 12.8 Gy
MD: 24.6 Gy
ID: 52%
Mean dose: 17.5 Gy

9. PRELIMINARY RESULT
Tumor
• Tumor shrinkage, stationary, or loss of central
enhancement in all cases
Vascular lesion
• No interval hemorrhage in follow up period

10. MOTION ERROR
J Neurosurg (Suppl) 117: 211-216, 2012
Cervical
Immobilization !!

11. GKS FOR EXTRACRANIAL LESION:
CAROTID BODY TUMOR
C2
C3

12. PRE-TREATMENT MANAGEMENT
Cervical immobilizationFeasibility evaluation

13. TV: 3.2 c.c.
Radiation volume: 4.8 c.c.
Peripheral dose: 15.5 Gy
Maximum dose: 28.2 Gy
Isodose level at periphery: 55%
Mean dose: 22.4 Gy

14. THANKS FOR ATTENTION