The Endoscope-Assisted Minimally Invasive Retro-Sigmoid Approach (EAMIRSA): A Combination of Techniques for Improving Middle Skull Base Surgery

Summary

The endoscope-assisted minimally invasive retro-sigmoid approach (EAMIRSA) is a surgical technique that can be used for the treatment of the cerebellopontine angle (CPA) and internal auditory canal (IAC) disease. Here, we describe the material necessary to perform EAMIRSA and illustrate the technique using a step-by-step cadaver dissection.

Abstract

EAMIRSA is a surgical technique that can be used for the treatment of the cerebellopontine angle (CPA) and internal auditory canal (IAC) diseases, as well as for treating schwannoma, for decompression surgeries (e.g., loops of the anterior inferior cerebellar artery (AICA)), and for the vestibular neurectomy in patients with invalidating vertigo. This technique combines the use of an endoscope and a microscope; the former allows a perfect view of the surgical area (CPA, IAC, and brain structures) and the latter ensures safety of the surgery maneuvers. The use of a minimally invasive approach reduces post-surgery headaches and the risk of a Cerebrospinal Fluid (CSF) leak. Our group successfully used EAMIRSA during decompression procedures for treating a hemi-facial spasm and tinnitus. Results were satisfactory in terms of function recovery. Sequelae and surgical complications were observed in less than 1% of patients. In acoustic schwannoma surgery, facial nerve damage was observed in less than 1% of cases and the recurrence rate was 0.3%. This article describes the material necessary for performing EAMIRSA and illustrates the technique using a step-by-step cadaver dissection.

Introduction

Surgical approaches to the cerebellopontine angle (CPA) and internal auditory canal (IAC) are associated with high risks due to a limited view of the target areas. Techniques that totally rely on endoscopy have been proposed^1,2, but the high risk of facial nerve sequelae¹, significant learning curves, and the need for a third hand for maintaining the endoscope in position² have limited their applicability.

The endoscope-assisted minimally invasive retro-sigmoid approach (EAMIRSA), originally proposed in 1976³, w....

Protocol

This study was approved by the Human Ethic Committee of University Hospital of Perugia and was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki.

The sample was represented from subject over 18 years, with equal sex distribution.

1. Preparation of the Patient

1. Set up the operating room as shown in Figure 1. Place the patient on the surgical table and connect the anesthesia monitoring .......

Discussion

Loops in the CPA and IAC ultimately manifest with a number of symptoms/signs, including HFS and tinnitus. In our previous studies^6,7, we quantified the correlation between the loop presence and the occurrence of HFS (or tinnitus) on the ipsilateral side. We also found that in cases where tinnitus was due to a loop impingement involving the cochlear nerve, the minimum caliber of the impinging vessel was 0.8 mm⁶.

.......

Materials

Name	Company	Catalog Number	Comments
No Consumable
Facial nerve monitoring system	NIM (Medtronic Jacksonville (FL), USA)	8253002
Video Column	AIDA, Storz	S-1263
Video Camera	STORTZ	S-1263
Focal Operatory microscope	ZEISS OPMI SENSERA	S-0607
Rigid Endoscope 0°	STORZ	7229 AA
Rigid Endoscope 45°	STORZ	7229 FA
Drill Stilus Legend	MEDTRONIC	1898001
Electric Scalpel DIATERMO MB 380	GIMA	30692
Aspiration system: 1 continuous and 1 with finger-control	TOBI	28234
Instruments for the otoneurology approach:
- Stainless cups.
- Large cup warms serum.
Lempert elevator	MILTEX	19-1340
- Scalpel Handle No. 3, 4, and 7.
- Needle holder: 1 strong, 1 less strong.	MAYO HEGART	26531
- Two pairs of scissors Allaine: 1courbe, 1 right.	EMEA	Curved : PO144123 ; Straight: PO143282
-Dissection griffes, foam, De Bakey	SURGIWAY	14.1012T
- Aspirations:
o Three Fraziers No. 10.12.15.	INTEGRA
o Otoneurology suction set: 1 * 2.0, 1 * 1.8; 2 * 1.5; 3 * 1.2 (long); 2 * 1.0.	INTEGRA	3724218; 3724172; 3724210
- Retractors:
o Faraboeuf: 1pair thin, 1 thick pair 12-14 cm	INTEGRA
o Auto-static of Wulstein or Beckmann	INTEGRA	o-28-8
DRILL BURRS	MEDTRONIC
	Cutting	See on productor catalogue
	Diamonds	See on productor catalogue
Micro-instruments of otoneurology:
Fine bipolar forceps Magnan	INTEGRA	CP392BI and CP392BS
A pair of scissor Sterkers.	NOT AVAILABLE
Two pairs of scissors Yasargil (1 right, 1 curve).	SKLAR	98-2114
Two-surgical forceps (one right, one curve upward).	INTEGRA Metzbound	Curved: CP351-3; Straight: CP351-2
A dura scalpel	STORTZ	28164 EL
A dura elevator	STORTZ	663535
In case of IAC first: surgical scissors straight strong
Straight instruments:
A hook	INTEGRA	MCO31
A blunt hook.	INTEGRA	MCO813
Two Marquet periostal elevator (1 left, 1 right).	INTEGRA	MCO950
Bayonet instruments
House Hartman	INTEGRA	3721036
One pointed and sharp hook	INTEGRA Causse	MCO657
Four small periostal elevator (facing up, down, left, right)	STORTZ	223982
Four large periostal elevator (facing up, down, left, right)	INTEGRA	MCO224A-2-0
Four hooks (facing up, down, left, right)	STORTZ	223942; 223943
MORTINI Set	STORTZ	28164 MDA
Instruments for otoneurosurgery approach :
Scalpel n°23
Dissection griffes	INTEGRA MAC INDOE	CP 400 ; CP 407 ;CP 415
Wulstein auto-static	INTEGRA	o-28-8
Elevator Lampert	MILTEX	19-1340
Bipolair forceps	INTEGRA	CP392-2R
Scalpel for dura	STORTZ	28164 EL
Scalpel n°11
Dissection griff DeBakey	SURGIWAY	14.1012T
Scissor Allaine	EMEA	Curved : PO144123 ; Straight: PO143282
Needle holder	MAYO HEGART	26531
Consumable Material
Two suction tubes, with suction cannulas of different sizes.
Operating light handpiece.
Microscope case, camera cover, instrument pocket.
Xomed / Medtronic 2-channel electrode set for monitoring the facial nerve.
Scalpel blades: 22, 11.	Medtronic
Glass scalpel blades.
Surgical gloves and caps
Adhesive surgical (craniotomy pack).
Sterile woven and nonwoven compresses.
Syringe and needle infiltration.
Drugs: 0.5% adrenaline xylocaine, saline, sterile water
Neuropatch	B/Braun-Aesculap, Tuttlingen, Germany
Fibrillar Surgicel	Braun
Biological glue 2ml	TIssucol
Horsley Wax
Cottons of neurosurgery cut into various sizes that will be carefully counted (opposite)
Teflon cut into various sizes then crushed to be thinned	Codman
Lyophilized hardstock or Durapatch Ethisorb Polyglactin 910 / Polydioxanon	Bard PTFE
Re-absorbable suture	Ethicon
Not-resorbable suture	Vicryl
Urethane sponge	Novafil 2.0