Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Summary

A model protocol to train neurosurgery and otolaryngology resident learners on endoscopic transclival clipping of posterior circulation aneurysms is described. Two endoscopic approaches to access the silicone-injected or perfused posterior circulation of cadaveric heads are established for training. Learners are tasked with clipping of posterior circulation based on clinical scenarios.

Abstract

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed a cadaveric model to train learners on endoscopic clipping of posterior circulation aneurysms. An endoscopic transclival approach (ETA) and a transorbital precaruncular approach (TOPA) to successfully access and clip aneurysms of the posterior circulation are described. The model has flexibility in that a colored silicone compound can be injected into the cadaveric vessels for the purpose of training learners on vascular anatomy. The other option is that the model could be connected to a vascular perfusion pump allowing real-time appreciation of a pulsatile or ruptured aneurysm. This cadaveric model is the first of its kind for training of endoscopic clipping of posterior circulation aneurysms. Learners will develop proficiency in endoscopic skills, appropriate dissection, and appreciation for relative anatomy while developing an algorithm that can be employed in a real operative arena. Going forward, various clinical scenarios can be developed to enhance the realism, allow learners from different specialties to work together, and emphasize the importance of teamwork and effective communication.

Introduction

Treatment of posterior circulation aneurysms presents unique challenges and has higher complication rates compared to other cerebral aneurysms¹. Transcranial clipping of posterior circulation aneurysms is technically challenging, with high complication rates and morbidity². Endovascular coiling and endoscopic endonasal surgery are safe alternatives, as they reduce complication rates and limit traction on the cerebrum³. Endovascular coiling has been shown to have benefits over open skull base approaches, and most centers now use an endovascular approach to treat cerebral aneurysms^....

Protocol

In the development of this model, three cadaveric heads were obtained through the Oregon Health & Science University Body Donation Program and handled per the Code of Ethics approved by the Oregon Health & Science University Institutional Review Board.

1. Head Preparation

1. Obtain fresh cadaveric heads. Secure the head in the sink, resting on a block with the neck facing upwards.
2. Prepare a 5 L 1:100 solution of anticoagulant citrate dextrose and warm water. Use the solution within 72 h.
3. Insert a 5-mm arterial cannula into the right jugular vein (lateral to carotid) and apply an arterial cannula clamp ar....

Results

This model presents learners with multiple clinically-relevant sites for posterior circulation clipping, with either static (silicone compound-injected) or dynamic (perfused) options for training. Once dissection is complete, the investigators may use ETA and TOPA to provide learners with improved visualization of the posterior circulation¹⁴. Overview of ETA and TOPA are illustrated in Figure 1. For success of the model, investigators .......

Discussion

Posterior circulation aneurysms have been historically hard to clip or coil, especially those originating off the SCA and AICA. Several techniques have been tried, such as endovascular pipeline embolization devices, microsurgical skull base approaches, and the supraorbital keyhole approach for clip application^15,16,17. While these techniques are successful in some cases, the widespread applicability is limited due to stark diffe.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Anticoagulant citrate dextrose	Pierce Laboratories	117037
Embalming solution	Chemisphere
10% Formalin fixative	Chemisphere	B2915DR55
Red Microfil solution	Flow Tech	MV-130	Silicone compound
Arterial cannula clamp
5 mm Arterial cannula	Instrument Design & Mfg. Co.	ART187-2-CT	Used for jugular vein and carotid artery cannulation
3 mm Arterial cannula	Instrument Design & Mfg. Co.		Used for vertebral artery cannulation
Curved hemostat	Aesculap	BH139R
Zero-degree endoscope (4 mm diameter, 18 cm length)	Karl Storz	H3-Z TH100
30-degree endoscope (4 mm diameter, 18 cm length)	Karl Storz
Suction - 7 and 10 FR	V. Mueller
11-blade surgical blade	Bard-Parker	371111
Penfield 1	Jarit	285-365
Kerrison rongeur	Aesculap	FM823R, 3mm/180 mm
Pituitary rongeur	Aesculap	FF806R
Transsphenoidal drill	Depuy-Synthes
5 mm coarse diamond burr drill	Depuy-Synthes
Forceps	Jarit	Carb bite I22-500
Iris scissors	Black & Black	B 66110
Perfusion Pump	Belmont Instrument Corporation, Billerica, MA, USA	Belmont Fluid Management System 2000
L-aneurysm clip	Peter Lazic Microsurgical Innovations	45.782
Vessel clip system	Peter Lazic Microsurgical Innovations	45.442
Dural flap clip	Weck	523242