Roman BOSNJAK: Pineal cyst removed by endoscopic supracerebellar-infratentorial approach (eSCIT) in prone Anticoncorde position

This video presents a pure endoscopic approach to the pineal cyst in prone position with head extension ( the so called anticoncorde position) and some head rotation. The head is in gentle extension and rotated 30 degrees to the right shoulder and a surgeon sits at the patient's left shoulder, looking into the patient's occiput.

Pineal cyst are often present on brain MRI imaging, but are rarely symptomatic and rarely there are indications for surgery. Size is important parameter in pineal cysts! Small cysts <10 mm in diameter, surrounded with CSF layer, certainly can not have any compressive effect. There are also cysts larger than 10 mm and asymptomatic.

These are hard neurological signs which represent absolute criteria for surgery: hydrocephalus or asymmetrical ventriculomegaly with signs of compression of lamina tecti and aqueduct stenosis, dorsal midbrain symptoms, diplopia, Parinaud syndrome, positional headache with foggy vision, papilloedema..….Also benign cyst may rarely bleed inside and become compressive (symptoms may resolve with blood absorption).

Some radiological signs may rise suspicion of tumor rather that benign cyst: irregular thick or nodular wall, solid components, irregular enhancement, diffusion restriction, invasion/edema to LQ, progress in size….

Headache alone is not indication, also if accompanied with some soft signs, but not linked to hard signs, such as: intermittent ill defined subjective vision & sleep problems, dizziness, fatigue, cognitive symptoms, attention problems, study problems,.…………………..although symptoms improvement may follow the surgery in more than 90 % of such soft-signs-cases & > 10 mm diameter, but have 23% complication rate.

Selective patients with severe, refractory symptoms and cyst at least > 10 mm, with decrease quality of life may have benefit from surgery (evidence emerging). Young women between 20-30 are mostly affected. Some young patients may be very persistent and insist on surgery, despite the neurosurgeon can't find firm indication; the presence of cyst is considered by some patients as source of their problems, as something is wrong in the head (should not be there) and thus see a pineal cyst removal as a solution of their problems. The trust between patient and neurosurgeon can easily be lost. Very rarely, pineal cysts were reported to contribute to sleep disturbances, which in turn can worsen or trigger psychiatric symptoms.

Asymtomatic cysts are observed, MRI repeated at 12 months, if there is something suspicious, repeat MRI first at 3-6 mo, then at 6 mo and if stable at 12 mo, later stop follow up).

SURGICAL APPROACHES

Microsurgical approaches enable complete or near complete cyst removal, good controlled exposure of pineal veins, qudrigeminal cistern and tectal plate, in some positions (sitting, semisitting) gravitiy effect helps to self-expansion of the corridor– but danger of air pulmonary embolism.

1 paramedian supracerebellar infratentorial corridor (sitting, semissiting, prone concorde)

2 occipital transtentorial (park bench, semiprone)

Endoscopic transventricular approach – ETV (if hydrocephalus or obstruction to CSF flow), sometimes - in larger cyst protruding into 3rd ventricle - enables also biopsy and fenestration of the cyst (flexible endoscope can be used alone or in combination with shaft of the rigid endoscope). This surgery bear risk of fornix injury and are problematic with normal, narrow ventricles (despite navigation device caudate and thalamus can be contuded).

Purely endoscopic supracerebellar- infratentorial approach (eSCIT) enable an access performed through a paramedian suboccipital keyhole (subtorcular) craniotomy, with an assistant holding the endoscope while the surgeon performs bimanual microdissection. Endoscopic surgery can be done in prone, sitting / semisitting / park‑bench /semiprone positions. There are two variants of prone position:

prone – concorde (head in flexion, surgeon sits behind the head and works in reversed anatomy)

prone – anticoncorde (prone with head extension and right-sided rotation; surgeon sits lateral at patient's left shoulder)

Advantages of anticoncorde head position: gravity‑assisted cerebellar relaxation similar to the sitting position, improved venous drainage, reduced risk of venous air embolism compared with sitting/semi‑sitting approaches, panoramic view, safer bimanual dissection through pineal veins, complete microsurgical removal possible.

SUGGESTED READING

Spazzapan P, Velnar T, Bosnjak R. Endoscopic supracerebellar infratentorial approach to pineal and posterior third ventricle lesions in prone position with head extension: a technical note. Neurol Res. 2020 Dec;42(12):1070-1073. doi: 10.1080/01616412.2020.1805926. Epub 2020 Sep 5. PMID: 32892737.

Hua W, Xu H, Zhang X, Yu G, Wang X, Zhang J, Pan Z, Zhu W. Pure endoscopic resection of pineal region tumors through supracerebellar infratentorial approach with 'head-up' park-bench position. Neurol Res. 2023 Apr;45(4):354-362. doi: 10.1080/01616412.2022.2146266. Epub 2022 Dec 12. PMID: 36509700.

Uschold T, Abla AA, Fusco D, Bristol RE, Nakaji P. Supracerebellar infratentorial endoscopically controlled resection of pineal lesions: case series and operative technique. J Neurosurg Pediatr. 2011 Dec;8(6):554-64. doi: 10.3171/2011.8.PEDS1157. PMID: 22132912.