Supratentorial cerebrospinal fluid diversion using image-guided trigonal ventriculostomy during retrosigmoid craniotomy for cerebellopontine angle tumors

Abstract

Background: Cerebellar contusion, swelling and herniation is frequently encoutered upon durotomy in patients undergoing retrosigmoid craniotomy for cerebellopontine angle (CPA) tumors, despite using standard methods to obtain adequate cerebellar relaxation.

Objective: The aim of this study is to report an alternative cerebrospinal fluid (CSF)-diversion method using image-guided ipsilateral trigonal ventriculostomy.

Methods: Single-center retro- and prospective cohort study of n = 62 patients undergoing above-mentioned technique. Prior durotomy, CSF-diversion was performed to the point where the posterior fossa dura was visibly pulsatile. Outcome assessment consisted of the surgeon's intra- and postoperative clinical observations, and postoperative radiological imaging.

Results: Fifty-two out of n = 62 (84%) cases were eligible for analysis. The surgeons consistently reported successful ventricular puncture and a pulsatile dura prior durotomy without cerebellar contusion, swelling or herniation through the dural incision in n = 51/52 (98%) cases. Forty-nine out of n = 52 (94%) catheters were placed correctly within the first attempt, with the majority of catheter tips (n = 50, 96%) located intraventricularly (grade 1 or 2). In n = 4/52 (8%) patients, postoperative imaging revealed evidence of a ventriculostomy-related hemorrhage (VRH) associated with an intracerebral hemorrhage [n = 2/52 (4%)] or an isolated intraventricular hemorrhage [n = 2/52 (4%)]. However, these hemorrhagic complications were not associated with neurological symptoms, surgical interventions or postoperative hydrocephalus. None of the evaluated patients demonstrated radiological signs of upward transtentorial herniation.

Conclusion: The method described above efficiently allows CSF-diversion prior durotomy to reduce cerebellar pressure during retrosigmoid approach for CPA tumors. However, there is an inherent risk of subclinical supratentorial hemorrhagic complications.

Keywords: cerebellopontine angle; cerebrospinal fluid diversion; hemorrhage; image guided surgery; retrosigmoid craniotomy; trigonal; upward transtentorial herniation; ventriculostomy.

Figure 1

Patient inclusion profile: Patients, where standard methods of CSF-release without a ventriculostomy (n = 23) or a ventriculostomy via a right frontal trajectory (n = 3) was used were excluded from the study, resulting in n = 62 eligible patients. Additionally, patients with a pre-existing permanent CSF-diversion (n = 11), and patients with missing information on pre- (n = 8) or postoperative imaging (n = 3), were excluded. Certain patients met more than one exclusion criteria. Eventually, n = 52 patients were included into the final analysis.

Figure 2

Patient positioning and general concept: Artistic rendition of the supratentorial cerebrospinal fluid diversion method using image-guided trigonal (T) ventriculostomy via the Keen’s point (Ks’P) to achieve cerebellar relaxation during retrosigmoid craniotomy for cerebellopontine angle tumors. The patient is in a supine position and the head fixated in rotation and slightly latero-flexed to the contralateral side using a standard Mayfield clamp. Transverse sinus (TS); sigmoid sinus (SS).

Figure 3

Supratentorial image-guided trigonal ventriculostomy: After myocutaneous skin incision, the course (blue lines) of the transverse (TS) and sigmoid sinus (SS) and the transverso-sigmoid junction (TSJ) are defined superficially along the bony surface. A burr hole is placed with the trajectory aimed towards ipsilateral occipital horns of the lateral ventricle, the dura is opened and a small corticotomy is performed. A sterile image-guidance probe (StP) replacing the supply trocar of the external ventricular drain (EVD) is inserted into the ipsilateral occipital horn of the lateral ventricle (usually with a loss of resistance after 4–5 cm), aimed in a slight cephalic direction, and under constant image-guidance (IGS). The ventricular catheter is further advanced in soft pass technique after positive CSF-outflow out of the catheter (usually up to 6–7 cm).

Figure 4

Retrosigmoid craniotomy: The transverse (TS) and the sigmoid (SS) sinus as well as the transverso-sigmoid junction (TSJ) are dlineated and skeletonized. The bone flap is then raised using a craniotome and the posterior fossa dura (PFD) is visualized. The external ventricular drain (EVD) is then tunneled from the Keen's point (Ks'P) out about 5 cm away from the surgical field.

Figure 5

Ventriculostomy-related supratentorial complications: ventriculostomy-related intracerebral hemorrhage in the left parieto-occipital parenchyma within the area of the trigonal ventriculostomy [upper]; ventriculostomy-related hemorrhage along the catheter track; grade 3 malposition (catheter through parenchyma and tip position in the basal ganglia) [lower].