Trigeminal neuralgia (TN or TGN) is a long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face, and motor functions such as biting and chewing. It is a form of neuropathic pain. There are two main types: typical and atypical trigeminal neuralgia. The typical form results in episodes of severe, sudden, shock-like pain in one side of the face that lasts for seconds to a few minutes. Groups of these episodes can occur over a few hours. The atypical form results in a constant burning pain that is less severe. Episodes may be triggered by any touch to the face. Both forms may occur in the same person. It is regarded to be one of the most painful disorders known to medicine and often results in depression.

1. THE RADIATION THERAPISTS PERSPECTIVE
SUBRATA ROY
SR. RADIATION THERAPIST
HCG CANCER CENTRE MUMBAI
SUBRATA ROY
SR. RADIATION THERAPIST
TREATMENT OF TGN WITH CYBERKNIFE FRAMELESS RADIOSURGERY SYSTEM

2. Table of Presentation
 What is TGN
 History Behind Trigeminal Neuralgia
 Classifications of TGN
 Types of TGN
 General Characteristics of TGN
 Treatment strategies for Trigeminal Neuralgia
 Cyberknife Treatment Preparation for TGN
 Treatment Delivery (Therapists Role & Observations)
 Efficiency Of Cyberknife System In View of Treating Small Field Target
 Results and outcome Analysis.
 Conclusions

3. What Is TGN
Trigeminal neuralgia or tic douloureux is a neuropathic
disorder of trigeminal nerve that causes episodes of
intense pain in eyes, lips, scalp, forehead and jaws.
It has been labeled as Suicide disease due to insignificant
number of people taking their own life because they are
unable to have their pain controlled by medication or
surgery.
Synonyms:
Tic Doulourex Trifacial Neuralgia Fothergills
disease

4.  TGN is 5th Cranial Nerve (CN V)
 It is largest of the cranial nerves
 Trigeminal (tri- three , geminus-twinned)
 Responsible for sensation in the face and motor functions
 The patients typically presents with severe episodic
lancinating, shock like pain sensation in face
 TGN is most chronic pain condition of the trigeminal
nerve
 Incidence - 4-5/1 lac population

5. History of Trigeminal Neuralgia
 Aretaeus of Cappadocia –At the end of first century -1st clinical description of TN
 1677 John Locke, gave the first full description with its treatment.
 1756 Nicolaus Andre - tic douloureux
 1773 John Fothergill in published detailed description of TN

6. Classifications of Trigeminal Neuralgia
TGN
TYPICAL TGN
ATYPICAL TGN
PRIMARY
/IDIOPATHIC
SECONDARY
 Typical idiopathic TN due to vascular
compression with morphologic changes of
the trigeminal nerve root
 Diagnosis of secondary TN relies on the
demonstration of a major neurologic disease
that causes the neuralgia. A tumor at the
cerebellopontine angle or MS causes TN in
15% of patients
 TN with continuous pain TN type 2 or
atypical, idiopathic TN. (Danger!!!)

7. • V1- Supraorbital ridge affected
side
• V2 –Skin of upper
Lip,Ala,Cheeks & Upper gums.
• V3-Lower lip, teeth or gums of
lower jaw
Trigger Zones & Trigger Points

8. Washing the FACE
Brushing Teeth
Shaving
Vibrations from Walking
Going Out In Cold Wind
Trigger Factors
Eating ,drinking water

9. Types Of TGN
 Typical Trigeminal Neuralgia
 Atypical Trigeminal Neuralgia
 Pre- Trigeminal Neuralgia
 Multiple Sclerosis Related Trigeminal Neuralgia
 Secondary Or Tumour Related Trigeminal Neuralgia
 Trigeminal Neuropathy Or Post- Traumatic Trigeminal Neuralgia
 Failed Trigeminal Neuralgia

10. General Characteristics Of TGN
Incidence: 8 : 1,00,000
Age: 5th – 6th decade of life
Sex: Female > male ; 1.6 > 1.0
Affliction for side: Right > left
Division of trigeminal nerve involvement: V3>V2>V1

11. Treatment strategies for Trigeminal Neuralgia
First line treatment option: Medical management
(Pharmacotherapy)
Treatment options for medically refractory TGN:
• Surgical: microsurgical vascular decompression (MVD) or ablative
procedures like rhizotomy
• Minimal-invasive percutaneous retro gasserian rhizotomies (PRR)
• Nerve block
• Gycerol injection
• Stereotactic Radiosurgery

12. Stereotactic Radiosurgery Options
Cyberknife Gamma Knife X-Knife (LINAC BASED)

13. There is a Treatment Option that can be done without going under the
knife that called as Cyberknife
Thanks to modern technology,
Now Patients can have some
surgeries without being cut open!

14. Introducing Cyberknife Frameless Radiosurgery System

15. Functional Neurosurgery requires the less possible invasive treatment
Frameless radiosurgery reduces as much as possible the invasively of a
surgical approach to trigeminal neuralgia
The non-isocentric approach introduces a series of new and unexplored
issues for treatment with a non-isocentric technique, the dose is not
the only parameter to consider actually,
Volume of the treated nerve and the dose received by the surrounding
structures must be taken into consideration
What Makes It Distinct Cyberknife
In order to better understand about Cyberknife, lets take a look at
the following Highlights about this…

17. Cyberknife Treatment:-
Cyberknife Frameless Radio surgical System Offering highly Precise ,Non-Surgical Treatment for TGN.

18. Cyberknife Treatment Preparation for TGN
 The Cyberknife is made up of a radiation delivery device (Linac) attached to a robotic arm.
 Cyberknife is capable to treat tumors anywhere in the body.
 There is no need for a patient to be still or head frames to hold them in place because the Cyberknife
automatically adjusts to the movement of the patient or tumor.
 The Cyberknife is Pain-free, no anesthesia is required
Treatment Preparation in Cyberknife Usually Completed in Following Steps :-
 U frame Thermoplastic Mould Preparation
 Acquiring CT Scan with Predefined Standard Cyberknife 6D Skull TGN Protocol
 Obtaining MRI Series
 Treatment Planning Using Cyberknife Treatment Planning System

19. Radiation Therapists Played an Immense Role In the Treatment Preparation &
Treatment delivery Of Trigeminal Neuralgia, While they are involving in Following
Steps to made this Delivery Successfully:-
 U Frame Thermoplastic Mould Preparation (Immobilization Part)
 Acquiring CT Scan with Predefined Standard Cyberknife 6D Skull TGN Protocol.
U Frame Thermoplastic Mould Preparation (Immobilization Part)
U Frame Thermoplastic Mask is Having a thickness of 1.25 mm & giving high
quality rigidness which is very essential while we are delivering high dose of
radiation to the pinpoint Target 0.01 c.c
While making the U frame Mask Needs to be very confirmative on the selection of
proper Head Rest Which will directly reflating on the Patient Comfort and as well as
the reproducibility and minimizing the setup error in Sub mm range.

20. • All TGN Patients Head Mask, Proper Nasal Impression Should be given by
therapist which will create impact on the Setup accuracy as per the Standard.
• In Case Of Female Patients Long Hair will always gives a bigger challenge to
the therapists to reproduce the setup on daily basis .
• Immobilization with Hair Out Or Hair In Should be mentioned on the Patient
Setup Information page and same protocol needs to be fixed on institutional
basis to improve the Bench mark of Good Patient setup

21. Acquiring CT Scan with Predefined Standard Cyberknife 6d Skull TGN Protocol
 All patient immobilization devices that will be used during patient
treatment must be used during CT scanning. Include the CT table top, U
Frame Base Plate, Head Rest, index bar, and any pads used.
 Field of View (FOV): Include the entire circumference of the skull.
 Use the smallest FOV that encompasses the anatomy for the best pixel
resolution.
 Include part of the headrest and extend 1 cm anterior past the tip of the
nose & as much anatomy as possible.
 The CT scan is used to create Digitally Reconstructed Radiographs (DRR)
images. DRR images must have a 0 – 1 cm gap anterior and superior to
the patient skull.
 AP and lateral scout images help ensure there are approximately 0 – 1 cm
gaps anterior and superior to the skull.

22. Things to Keep in Mind by Therapists While Performing CT Simulation
Guidelines For Patient Orientation as Per Cyberknife Protocol
Patient Simulation Orientation Must
be Checked Before Performing

23. Treatment Planning Using Cyberknife Treatment Planning System
• RT planning CT and MRI (T1 ,T2) images fused with deformable
image registration software
• Trigeminal nerve is delineated till it enters in meckel’s cave
• Choice of target – Anterior (Cisternal) OR Posterior (Dosral root
entry zone - REZ) decided depending neurovascular conflict
location
• OARs Contouring - Brainstem, Temporal Lobe, Blood vessel,
Cochlea, VII-VIII nerve complex
Target Delineation Fusion & Contouring

24. Treatment Plan Preparation Dose Volume Histogram

25. TGN Dose Prescription & Treatment Planning :-
Sharp fall off of Dose around the small Field Target
Plan Approval Criteria's:
• Target Coverage
• Sharp Dose Fall Off
• 95%, 50%,30% Dose
• Dose Heterogeneity
• Brain Stem and Other OAR Dose Limits
A dose of 80-85Gy max dose prescribed to the Dorsal
root entry zone and 20% IDL touching the brainstem.

26. • Prescription dose 80 Gy to 85 Gy at Isocenter (Maximum Point Dose)
• More than 50Gy (58% ISDL) to encompass TGN
• Maximum Brainstem Point dose 25Gy (30% ISDL) or 0.03cc 18Gy
• Vestibular cochlea nerve max dose < 6Gy
• Temporal Lobe Max Dose 30 Gy
Institutional Plan Evaluation Criteria

27. Dose Distribution & Target Coverage ( CT Plane )

28. Dose Distribution & Target Coverage on 3D FIESTA seq MRI

29. Dose Distribution & Target Coverage

30. Treatment Delivery (Therapists Role & Observations)
Treatment Delivery Console
The treatment delivery computer is the main computer used for delivering and monitoring patient
treatment. It includes a flat panel monitor. The monitor, keyboard, and mouse are located in the Control
Room. The treatment delivery computer is usually located in the Equipment Room.
6D Skull Tracking System
The 6D Skull Tracking system enables tracking of intracranial targets without the need for stereotactic
frames. 6D Skull Tracking mode works by computing the offset between Live X-ray images and
reference DRR images by identifying and matching skeletal features of the skull. Tracking the target
relies on the fixed relationship between the target volume and these skeletal features.

31. Left and Right Screens of the Delivery Phase The Delivery phase for 6D Skull Tracking mode

32. Non-Isocentric Beam Delivery
 Highly collimated beams
 Non-convergent beams
 Superior conformality while
 Maximizing homogeneity
Non-Coplanar Beam Delivery
 Automatically minimizes entrance/exit beam
interactions.
 No patient or Linac re-positioning required.

33.  6D Skull tracking system used for intra-cranial lesions up to C2,Bony anatomy of the skull is
used as reference for tracking
 This tracking feature allows direct and non-invasive tracking of Intracranial lesions
 Target tracking and motion compensation are accomplished by identifying and tracking rigid
Skull anatomy image intensity and brightness gradients between the DRR and LIVE images
 The naming of this method as 6D because the corrections are made for the 3 translational motions
and 3 rotational motions

34. All the Offset Correction values should be
Constantly below 0.3mm during the entire course
of Treatment in all direction including the
rotational Correction ,if the Planning done on
Normal Skull Path
Image Interval Should be kept as low as Possible (Usually
30/min) ( To Observe and made corrections for intrafraction
Movement)
LONGITUDINAL
LATERAL
VERTICAL
ROLL
PITCH
YAW

35. Efficiency of CK in view of Treating Small Field Target
Among the advanced Technologies available, Cyberknife Radiosurgery
System is a more recent image-guided frameless robotic system, which is
designed for SRS and stereotactic radiation therapy (SRT)
The associated 6D skull tracking system enables highly conformal
intracranial high-dose tumour targeting, with sub-mili-meter precision in
beam delivery allowing for steep dose gradients achievable around the
contoured tumour. An additional benefit is the frameless nature of the
system which makes it easy to opt for hypofractionation regimens to
minimize toxicity
Single fraction SRS can be used to treat small to moderate sized OGMs
(< 10 cm3) that are not spatially associated with the optic apparatus while
larger OGMs (> 10 cm3) can be treated using fractionated planning to
achieve normal tissue sparing and preserve cranial nerve function.

36. Cyberknife is a safe, effective, minimally invasive and potentially cost-effective treatment modality for
patients with medically intractable TN or those who are ineligible or refuse open surgery.
Our results demonstrate that a CKRS treatment is associated with good outcomes in the majority of patients
with sustained relief of TN pain in most responding to therapy
AS THIS STUDY SHOWS

37. Results & Outcome Analysis
Pain relief after Cyberknife Radiosurgery
A large proportion of patients (42.9%) reported pain relief within 1 month following CKRS treatment.
19 % of patients reported relief within 6 months of treatment and another 19% reported relief no relief of
symptoms.
In 14.3% relief was experienced within 3 months from treatment. The median time to recurrence of severe pain
was 19 months (mean 27.8 months; range 1–129 months).
Treatment related complications
The majority of the patients (18 or 72%) did not experience any new bothersome post-treatment facial numbness
2 patients developed new somewhat bothersome facial numbness
No patients developed any new very bothersome facial numbness
Indeed 2 patients reported improvement in her facial pain from very bothersome facial numbness to no facial
numbness.

38.  Sex (M vs. F)
 Age (<60 vs. >60 years)
 Side (Right vs. Left)
 Pain type (TN1 vs. TN2)
 Target length (<5 vs. 5 to 6 mm)
 Target volume (<30 mm3 vs. >30 mm3)
 Target dose (<58 versus >58 Gy)
Factors affecting outcome:-

39. Conclusions
Safe handling and Operation of the Cyberknife System requires careful attention
familiarity with emergency procedures & constant Close View on CCTV while Robot
moves around the patient
Careless operation of the Cyberknife System can damage the system, its components
or other property; cause poor performance; or lead to serious bodily injury and
possibly death. Therapists who operates the Cyberknife System must read,
understand, and be thoroughly familiar with the information in the manual.
Trigeminal Neuralgia has been an enigma to physicians for a long course of time.
There have been various advances in the understanding of the pathogenesis of the
disease per se and the treatment modalities.

40. THANK YOU FOR KIND ATTENTION