1. Y R Yadav, Vijay Parihar, Shailendra Ratre, Yatin Kher
Endoscopic MVD for trigeminal neuralgia and hemifacial spasm: Tips, Tricks and Complication avoidance
Y R Yadav, Vijay Parihar, Shailendra Ratre, Yatin Kher
Department of Neurosurgery
NSCB (Government) Medical College Jabalpur MP India
Recipient of Charak award (IMA MP state 2011)
Chairman fellowship program of one week brain and spine endoscopic training
Executive member of Neurological surgeons society of India
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Web site
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2. Trigeminal neuralgia (TN) is a sudden, severe, brief, stabbing and recurrent pain within one or more branches of the trigeminal nerve.
Type 1 as intermittent
Type 2 as constant pain represent
Type 1 and 2 are considered as distinct clinical, pathological, and prognostic entities.
While other group thinks that type 1 and 2 are same entity

3. Irregular, involuntary muscle contractions on one side of face
Trigeminal Neuralgia
Sudden, severe, brief, stabbing and recurrent pain within one or more branches of the trigeminal nerve.
Hemifacial spasm
Irregular, involuntary muscle contractions on one side of face
Nervus intermedius Neuralgia
Sever, recurrent pain in external ear, nose, mouth and nasopharynx.
Along its cisternal course, the nerve may be difficult to distinguish from the facial nerve. Nerve sectioning or microvascular decompression can relieve pain

4. Disabling positional vertigo
Vertigo recognized by compression of VIII nerve by vessel and clinical and electrophysiological criteria. It is difficult to diagnose. Specific ABR (auditory brainstem response) abnormalities (prolongation of I - III interval). Associated unilateral tinnitus, unilateral hearing loss (pure tone audiometry) and dizziness.. Abnormal electronystagmography.
Glossopharyngeal Neuralgia
Sharp, stabbing recurrent pain in the back of the throat and tongue, the tonsils, and the middle ear.

5. Indications: Spasmodic torticollis
Spasmodic torticollis (ST) is movement disorder, characterized by involuntary tonic or clonic contractions of various neck muscles. Microvascular decompression (MVD) of the spinal accessory nerves, the upper cervical nerve roots and the brainstem.
Severe medically refractory "essential" hypertension.
Indications:
Systolic pressures more than 180 mm Hg refractory to three or more medications,
Severe blood pressure lability, or
Medically resistant HTN at systolic pressures
greater than 160 mm Hg associated with
autonomic dysreflexia
MRI demonstrating left medullary compression.

6. Neurovascular conflict (NCV) is most accepted theory.
Multiple mechanism
Various peripheral pathologies at root
A, vascular
B, others (Compression or traction, fibrosis of root)
Dysfunctions of brain stem, basal ganglion and cortical pain modulatory mechanisms

7. Compression may be
At root entry zone:
More common
Central myelinated part on the root is more prone for demyelination
At distal in nerve:
Less common
Peripheral myelinated portion is more resistant to compression.

8. Selection Criteria disabling tennitus or vertigo
1. Intermittent paroxysmal spells lasting only seconds
(a) Hearing loss at the tinnitus frequency
Associated ipsilateral symptoms from adjacent cranial nerves
(a)  Cryptogenic or overt HFSs
(b)  Bouts of otalgia or feeling pressure in the ear
(c)  Vertiginous spells: short lasting, optokinetically
induced
Positive MRI for vascular compression
Positive brainstem auditory evoked potential

9. Diagnosis is essentially clinically.
MRI is useful
A, To rule out secondary causes,
B, Detect pathological changes in
affected root
C, Detect NVC.

10. Carbamazepine is the drug of choice; Oxcarbazepine, baclofen, lamotrigine, phenytoin and topiramate are also useful. Multidrug regimens and multidisciplinary approaches (antianxiety or anti depression) are useful in selected patients.

11. Microvascular decompression (endoscopic or microscopic):
Treatment of choice in resistant to medical management
Only non destructive procedure.

12. Indications for Partial sensory root sectioning, or combing:
Negative vessel explorations during surgery
Large intraneural vein (which can not be mobilized).

13. Patients with significant medical comorbidities, without NVC and multiple sclerosis are generally recommended to undergo Gamma knife radiosurgery, Percutaneous balloon compression, Glycerol rhizotomy and Radiofrequency thermocoagulation procedures.

14. RFTC=Radiofrequency thermocoagulation
GKRS=Gamma knife radiosurgery
GR=Glycerol rhizotomy
PBC=Percutaneous balloon compression

15. Limitations of microvascular decompression:
Multiple compression
Anteriorly located compression
More brain retraction
Difficult to visualize whole root from pons to ganglion

16. Advantages of endoscopic technique:
Endoscopic technique can be used alone for vascular decompression or as an adjuvant to microscope.
Better visualization structures and improved localization of neurovascular conflicts within the cerebello-pontine angle .
Without any brain retraction.

17. Advantages of endoscopic technique: Better for ventral aspect compression. For completeness of decompression. New vascular conflicts can be identified.

18. Endoscopic Vascular Decompression of the Trigeminal Nerve
Indications:
Unresponsive to medical treatment.
Preferably presence of vascular conflict.
Typical neuralgia.

19. Endoscopic Vascular Decompression of the Trigeminal Nerve
Postoperative pain relief was graded as described by Barker et al.
“complete” when 98 % pain relief without need for medication,
“satisfactory” when more than 75 % relief with only intermittent use of pain medicine,
“none” when less then 75 % pain relief or required continuous pain medication.

20. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
Supine position with the head turned to the opposite side.
A 4–5 cm retroauricular (1.5 cm behind ear) skin incision
About 3 cm craniectomy.

21. Mark land marks (Zygomatic arch, Inion, mastoid tip and mastoid process

22. Meatus to Inion line Digastric groove line Intersection of these lines or mastoid emissary vein or The asterion (although variable) is junction of transverse and sigmoid junction

23. Incision 1-2 cm behind ear cm in length starting 1-2 cm above line extending from Zygomatic arch to Inion Extending towards about 1cm behind tip of mastoid process.

24. Incision along the hairline starting at intersection of the two lines

26. Identify suture (asterion) between mastoid, occipital and parietal bone

27. Expose junction of transverse and sigmoid sinus

28. Open dura in C shape manner few mm away from sinus to allow suturing.

29. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
The telescope (4 mm 0 ° 30 cm long Karl Storz, Germany) supported by the holder.
Cerebrospinal fluid was drained from cisterna magnum to make the brain relax (most important)
Lumbar drain

30. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
No brain retractor.
Microinstruments, routinely used for microsurgery, are passed by the sides of the telescope.
The arachnoid membrane near the trigeminal nerve is cut with arachnoid knife.
Arrachnoid over 7 and 8 cranial nerve is left intact
Offending vessels identified and separated from the nerve

31. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
The 0 ° scope is used during most of the procedure
30 ° telescope is helpful to see and dissect the conflict anterior to the nerve.
The 30 ° telescope is also useful for the visualization of the trigeminal nerve from the pons to the Meckel’s cave.

32. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
The 0 ° telescope is positioned in the centre of the operative field and the instruments are passed by sides of the telescope.
The 30 ° scope is positioned at the corner of the operative field.

33. Arrangement of division at root
Conflict for second branch is mostly distributed in the cranial and medial area, and for third branch in the lateral and caudal area.
Arrangement of division at root
Motor division

34. Endoscopic Vascular Decompression of the Trigeminal Nerve
Procedure:
Small pieces of dura patch (G patch marketed by Surgiwear made up of polypropylene) interposed between the nerve and the vessel.
Tissue glue is used to prevent migration of the dura patch.
Fold to make it round

35. All vessels, including the veins from REZ to meckel’s cave should be decompressed.
There may be multiple vessels related to the root.

36. Small intraneural vein: can be sacrificed
Large vein: PSRS or combing is preferred over extensive mobilization of large vein.
Intraneural artery: Wrapping techniques can better decompress.

37. Prominent suprameatal tubercle can be drilled out for better exposure of entire trigeminal nerve and vascular conflicts in microscopic technique,
Usually not required in endoscopic approach.
Laterally placed craniotomy better

38. Supracerebellar route permit identification and dissection of the offending supracerebellar artery.
Preservation of the vestibular nerve arachnoid minimizes complications and optimizes surgical outcome.

39. Transposing vessel from nerve
Autologous muscle graft,
oxidized regenerated cellulose,
Fibrin glue alone
Teflon wool
Slings. (Aneurysm clip, unabsorbable sling)
Arachnoid membrane of CPA can be used as a sling to transpose the superior cerebellar artery.

40. Adhesion between the trigeminal root and surrounding structures, secondary to fibrin glue or prosthesis, can stretch nerve, which can cause recurrence.
Prosthesis if used should be lying in subarachnoid space or cistern avoiding contact to root, dura matter or tentorium.

41. Combing or PSRS can be combined with MVD when no vascular conflict is detected.
Re surgery is an effective and safe after failed MVD.
The preservation of the petrosal vein and its tributaries is important.

42. Prevention of CSF leak
Muscle pieces interposition between the duramatter,
Use of artificial dura mater,
Cranioplasty,
Sealing of mastoid sinus by bone wax and muscle

43. a Endoscopic image showing cranial nerve 7 th and 8 th (left arrow) and trigeminal nerve (right arrow). b Branch of superior cerebellar artery (arrow)
seen on the right side of trigeminal nerve, ( c, d, e, f ) compressing vessel being dissected away from the trigeminal nerve, ( g, h, i ) dura patch is being
interposed between the nerve and the vessel.

44. Tortuous basilar artery as conflict

45. Endovascular decompression procedure and per operative findings:
Offending vessel
Single vessel majority
2 vessels around 10%
Superior cerebellar artery more common
Anterior inferior cerebellar artery next common

46. Endovascular decompression procedure and per operative findings:
Offending vessel
Touching nerve
Grooving of nerve
Displacement of nerve

47. Endovascular decompression procedure and per operative findings:
Vascular contact at root entry zone in majority.
Away from root entry zone
All conflicts (artery, vein or fibrosis)
Anterior conflict was seen in 8 cases (17 %) which could have been difficult to see by microscope

49. Important tips
Correct site of incision: Junction of transverse and sigmoid sinus
Drain CSF from cisterna magna or lumbar drain
Do not dissect or suck on 7,8 cranial nerve.
Part of telescope holder should not obstruct

50. Important tips All vessels at REZ or distally transposed
Could be multiple vessels
Could be vessels, fibrosis, kinking
Bimanual technique preferred over single hand dissection

51. Prevent bleeding Bleeding from superior petrosal vein could be brisk, simply putting Surgicel and gentle pressure stops hemorrhage.

52. Control of bleeding

53. For trigeminal nerve
For facial nerve

54. For thin and long neck patient incision about 0
For thin and long neck patient incision about 0.5 cm behind hair line one third above and two third below transverse and sigmoid junction and for thick and short neck incision is curved medially.

55. Conclusion:
Endoscopic vascular decompression is an effective and safe alternative to endoscopic assisted microvascular decompression in trigeminal neuralgia and hemifacial spasm.

56. References:
Yadav YR, Parihar V, Agarwal M, Sherekar S , Bhatele PR. Endoscopic vascular decompression of trigeminal nerve. Minim Invasive Neurosurg Jun;54(3):110-4.
Yadav YR, Parihar V, Ratre S, Khare Y (2014) Vascular Decompression in Trigeminal Neuralgia. JSM Neurosurg Spine 2(5): 1042.
Yadav YR, Parihar V, Kher Y. Complication  avoidance and its management in endoscopic neurosurgery. Neurol India 2013;61:
Yadav YR, Parihar V, Ratre S, Iqbal M. Microneurosurgical skills training. J Neurol Surg A Cent Eur Neurosurg in press.