Transforaminal endoscopic colloid cyst resection [Neurosurgery Wiki]

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====== Transforaminal endoscopic colloid cyst resection ======

Transforaminal endoscopic colloid cyst resection is well described. However, some anatomical colloid cyst variants may warrant a modified approach. Rarely, colloid cysts separate the forniceal columns and grow superiorly within the leaflets of the septum pellucidum. Thus, the authors' goal was to characterize the imaging features, clinical presentation, surgical strategy, and outcomes of patients with this superiorly recessed colloid cyst variant.
Superiorly recessed intraseptal colloid cysts are larger and tend to splay the bodies of the fornix, thus requiring a parasagittal transseptal interforniceal endoscopic approach. This achieves complete removal with comparatively negligible morbidity or rare recurrence (5.9%)
((Tosi U, Uribe-Cardenas R, Lara-Reyna J, Villamater FN, Perera I, Stieg PE, Tsiouris AJ, Souweidane MM. Transseptal interforniceal endoscopic removal of superiorly recessed colloid cysts. J Neurosurg. 2022 Jan 28:1-7. doi: 10.3171/2021.11.JNS211754. Epub ahead of print. PMID: 35090131.)).
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The dual endoscope technique via the bilateral transforaminal approach can achieve better surgical outcome by obtaining direct visualization of the cyst attachment. Although the indication should be limited, this approach can be considered especially for patients with recurrent lesions involving possible adhesion to vital structures
((Nakayashiki A, Kawaguchi T, Niizuma K, Watanabe M, Fujimura M, Tominaga T. Direct Inspection with Dual Endoscope Technique via Bilateral Transforaminal Approach Leading to Complete Resection of Recurrent Colloid Cyst of the Third Ventricle. World Neurosurg. 2020 Sep;141:272-277. doi: 10.1016/j.wneu.2020.06.060. Epub 2020 Jun 15. PMID: 32553604.)).
----



[[Neuroendoscopy]], has been recognised as a viable and safe alternative to microsurgery for the treatment of third ventricle [[colloid cyst]]. 

Controversy remains as to which is superior
((Connolly ID, Johnson E, Lamsam L, Veeravagu A, Ratliff J, Li G. Microsurgical 
vs. Endoscopic Excision of Colloid Cysts: An Analysis of Complications and Costs 
Using a Longitudinal Administrative Database. Front Neurol. 2017 Jun 9;8:259.
doi: 10.3389/fneur.2017.00259. eCollection 2017. PubMed PMID: 28649225; PubMed
Central PMCID: PMC5465269.
)).

Powell et al. are credited with the first successful endoscopic aspiration of the colloid cysts.
((Powell MP, Torrens MJ, Thomson JL, Horgan JG. Isodense colloid cysts of the
third ventricle: a diagnostic and therapeutic problem resolved by
ventriculoscopy. Neurosurgery. 1983 Sep;13(3):234-7. PubMed PMID: 6621836.
))

Less invasive endoscopic techniques have employed rigid endoscopes with single or dual working channels. 

The increased range of viewing angles of the endoscope within the cylinder of access maintained by the tubular retractor facilitates resection of the cyst through a smaller opening 
((Ajlan AM, Kalani MA, Harsh GR. Endoscopic transtubular resection of a colloid 
cyst. Neurosciences (Riyadh). 2014 Jan;19(1):43-6. PubMed PMID: 24419449.)).

====Entry point and trajectory====
An optimal entry point and trajectory for endoscopic colloid cyst (ECC) [[resection]] helps to protect important neurovascular structures. There is a large discrepancy in the entry point and trajectory in the neuroendoscopic literature. 

The endoscopic approach to colloid cysts of the third ventricle is usually performed through the [[foramen of Monro]]. However, this route does not provide adequate visualization of the cyst attachment on the tela choroidea. The combined endoscopic transforaminal-transchoroidal approach (ETTA), providing exposure of the entire cyst and a better visualization of the tela choroidea, could increase the chances of achieving a complete cyst resection
((Iacoangeli M, di Somma LG, Di Rienzo A, Alvaro L, Nasi D, Scerrati M. Combined
endoscopic transforaminal-transchoroidal approach for the treatment of third
ventricle colloid cysts. J Neurosurg. 2014 Jun;120(6):1471-6. doi:
10.3171/2014.1.JNS131102. Epub 2014 Mar 7. PubMed PMID: 24605835.)).

Using a more anterior approach, it is easier to reach the roof of the cyst and its possible adherences with the tela choroidea
((Chibbaro S, Champeaux C, Poczos P, Cardarelli M, Di Rocco F, Iaccarino C,
Servadei F, Tigan L, Chaussemy D, George B, Froelich S, Kehrli P, Romano A.
Anterior trans-frontal endoscopic management of colloid cyst: an effective, safe,
and elegant way of treatment. Case series and technical note from a multicenter
prospective study. Neurosurg Rev. 2014 Apr;37(2):235-41; discussion 241. doi:
10.1007/s10143-013-0508-4. Epub 2013 Dec 19. PubMed PMID: 24352893.))
((Nasi D, Iaccarino C, Romano A. Anterior trans-frontal endoscopic resection of 
third-ventricle colloid cyst: how I do it. Acta Neurochir (Wien). 2017
Jun;159(6):1049-1052. doi: 10.1007/s00701-017-3149-5. Epub 2017 Apr 4. PubMed
PMID: 28378097.
)).

Trajectory views from MRI or CT scans used for cranial image guidance in 39 patients who had undergone ECC resection between July 2004 and July 2010 were retrospectively evaluated. A target point of the colloid cyst was extended out to the [[scalp]] through a trajectory carefully observed in a 3D model to ensure that important anatomical structures were not violated. The relation of the entry point to the midline and [[coronal suture]]s was established. Entry point and trajectory were correlated with the ventricular size. Results The optimal entry point was situated 42.3 ± 11.7 mm away from the sagittal suture, ranging from 19.1 to 66.9 mm (median 41.4 mm) and 46.9 ± 5.7 mm anterior to the coronal suture, ranging from 36.4 to 60.5 mm (median 45.9 mm). The distance from the entry point to the target on the colloid cyst varied from 56.5 to 78.0 mm, with a mean value of 67.9 ± 4.8 mm (median 68.5 mm). Approximately 90% of the optimal entry points are located 40-60 mm in front of the coronal suture, whereas their perpendicular distance from the midline ranges from 19.1 to 66.9 mm. The location of the "ideal" entry points changes laterally from the midline as the ventricles change in size. 

The results suggest that the optimal entry for ECC excision be located at 42.3 ± 11.7 mm perpendicular to the midline, and 46.9 ± 5.7 mm anterior to the coronal suture, but also that this point differs with the size of the ventricles. Intraoperative stereotactic navigation should be considered for all ECC procedures whenever it is available. The entry point should be estimated from the patient's own preoperative imaging studies if intraoperative neuronavigation is not available. An estimated entry point of 4 cm perpendicular to the midline and 4.5 cm anterior to the coronal suture is an acceptable alternative that can be used in patients with ventriculomegaly
((Rangel-Castilla L, Chen F, Choi L, Clark JC, Nakaji P. Endoscopic approach to 
colloid cyst: what is the optimal entry point and trajectory? J Neurosurg. 2014
Oct;121(4):790-6. doi: 10.3171/2014.5.JNS132031. Epub 2014 Jun 13. PubMed PMID:
24926648.)).

===== Complications =====

[[Colloid cyst endoscopy complications]].

====Case series====
[[Colloid cyst endoscopy case series]]

===== Transforaminal transchoroidal endoscopic colloid cyst resection =====
[[Transforaminal transchoroidal endoscopic colloid cyst resection]]