stereotactic gamma knife raiodusrgery for vestibular schwannoma ming-hsi sun hung-chuan...
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Stereotactic Gamma Knife Raiodusrgery For
Vestibular Schwannoma
Ming-Hsi Sun Hung-Chuan Pan Chiung-Chyi Shen
NeurosurgeryTaichung Veterans General Hospital
Neuroscience combined conference
1968 - The first prototype of Leksell Gamma Knife® was installed in Stockholm, Sweden.
The delivery of a single, high dose of irradiation to a small and critically located intracranial volume through the intact skull
Protective shielding
Spherical collimator helmet
Leksell Stereotactic System®
Isocenter/Target in the brain
Automatic Positioning System™
201 sources of radiation
Bony wall of
Internal acoustic canal
Superior vestibular nerve Facial nerve
Cochlear nerve
Vestibular tumor arising from Inferior vestibular nerve
50% isodose line
Depiction of the internal auditory canal and its content in the sagittal plane
Inferior vestibular nerve
Selectivity in radiosurgery
Selectivity - describes how well a desired biological effect is achieved in a target volume without complications.
target biological effect
=
Conformity of dose to target
The two pictures show the necessity for multiple isocenters in order to minimize dose delivered to normal tissue.
target target
Selectivity & ConformityConformity describes only how well the prescription dose is fitted to the target volume, whereas selectivity also takes irradiation to normal tissue into account.
Conformal
Conformal and selective
Gamma Knife® surgery
95-3
92-9
93-3
Indications for Gamma Knife® surgery
Vascular disorders (15%)
Benign tumors (35%)
Malignant tumors (42%)
Functional disorders (7%)
Ocular disorders (1%)
Vascular DisordersAVMAneurysmCavernous AngiomasOther Vascular
Benign TumorsVestibular SchwannomaTrigeminal SchwannomaOther SchwannomaBenign Glial Tumors (Grade I+II)MeningiomaPituitary Adenoma (Secreting)Pituitary Adenoma (Non-secreting)Pineal Region TumorHemangioblastomaHemangiopericytomaCraniopharyngiomaChordomaGlomus TumorOther Benign Tumors
Malignant TumorsMalignant Glial Tumor (Grade III+IV)Metastatic TumorChondrosarcomaNPH CarcinomaOther Malignant Tumors
Functional DisordersTrigeminal NeuralgiaParkinson's DiseaseIntractable PainEpilepsyOCDOther Functional
Ocular DisordersUveal MelanomaGlaucomaOther Ocular Disorder
Source: Leksell Gamma Knife Society, June 2004
Neurilemmomas
Vestibular n. 12*Trigeminal n. 3Faical n. 1Hypoglossal n. 2
Total 18
July 2003 --- April 2006 follow up > 12 months in VGHTC
* Two cases of Neurofibromatosis type II
Treatment Plan : Dose –volume
Mean Margin
Dose Gy
Mean Max.
Dose GyIsodose %
at margin
Ave. Tx volume
CC
Neurilemmoma
12 24.9 50% 5.35
(11-13) (22-30) (40-50%) (0.17-20.00)
2004-02-24
2004-08-10
2005-02-03
58 y/o MGamma knife on 2004-2-2412 Gy at 50% /4.4 CC
Radiographic follow-up
Tumor volume decrease Stable Enlarge Failure
Control rate
Acoustic
Neurilemmoma
(12)
4 6 1 1* 91.6%
5 cases in hearing function (audiometry : 1 improvement, 1 worsening , 3 stable )Facial nerve function preservation :all
*One large acoustic neuroma underwent surgical resection 6 months after GKS due to persistent dizziness and imbalance
2004-8-12 2005-2-242004-3-8
62 y/o F 11 Gy at 40% /19.7CC
62 y/o F
2004-10-20 2005-04-04
Surgical resection 2005-04-30
12 Gy , 40% isodose ; 20 CC
Microsurgery
•Retrosigmoid ( Suboccipital ) Approach •Transslabyrinthine Approach
•Middle Cranial Fossa Approach
Functional Outcome of Microsurgery
Facial function Overall 80% H-B grade I-II
Size < 1.5 cm >90% ; >4 cm 40-50%
Hearing impairment Overall 30-80% preservation
8-57% retrosigmoid approach
32-68% middle fossa approach
Tinnitus Post-op immediate new symptom 30-50%
Worse 6-20%; No change: most cases; improve 25-60%
Complications CSF leakage : 2-20% ; 2.9-18% retrosigmoid approach
Death 0.5%
ICH: 1-2%
Subcutaneous hematoma 3%
Cerebellar , brainstem edema 1.2%
Hemiparesis 1.2%
Meningitis 1.2%
Cranialnerve paresis 1-2%
Recurrent rate 5-10%
Study No. Patients % of local control Facial nerve morbidity Loss of hearing
Lunsford LD,2005 829 97% 1% 21%
Regis J,2004 1000 97% 1.3% 2.2%
Landy HJ,2004 34 97% 0% 0%
Rowe JG,2003 234 92% 1% 25%
Iwai Y,2003 51 96% 0% 41%
Unger F,2002 100 96% 2% 45%
Litvack ZN,2003 134 97% 0% 38%
Petit JH,2001 45 96% 0% 12%
Bertallanfy A,2001 32 91% 12.5% 21%
Prasad D,2000 153 92% 2% 35%
Liscak R,1998 122 96% 1.9% 17%
Kwon Y,1998 63 95% 5% 35%
Noren G, 1998 669 95% 2% 30%
Radiosurgery
Treatment of choice
Source: Neurosurgery 1998; 43/3 (475-481). Pollock B.E., Lunsford L.D., Norén G.
“Vestibular Schwannoma Management in the Next Century: A Radiosurgical Perspective”
Num
ber
of
Case
s
Gamma Knife® Surgery
Microsurgery
Tumor diameter > 3 cmSymptomatic brainstem compression
Management Algorithm for Acoustic Tumors
Tumor Size,Brainstem Compression
Intracanalicular tumor Tumor diameter < 3 cmNo or mild brainstem compression
Age,Health Review of Treatments, GoalsPatient’s choice
> 75 yr < 75 yr
Observation
Tumor growth Tumor growth
Radiosurgery
Residual or Recurrent tumor
Observation
MicrosurgeryMicrosurgery
Microsurgery
Microsurgery
Residual tumor Complete resection
Radiosurgery
Radiosurgery Radiosurgery
Tumor growth
Radiosurgery Practice Guideline By L. Dade Lunsford; Ajay Niranjan
IRSAIRSA
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