Surgical Method of Lateral Ventriculo-superior Sagittal Sinus Shunt Surgery for Hydrocephalus

Abstract

From August 2016 to June 2018, a total of 7 patients underwent lateral ventriculo-superior sagittal shunt surgeries in our hospital. All cases were followed up for 3 months to 2 years after the surgeries. The results of their head CT scans or MRI scans indicated that the conition of hydrocephalus generally improved, and the symptoms of intracranial hypertension significantly improved or disappeared. The superior sagittal sinus shunt surgery for hydrocephalus is simple to operate and also safe and effective, and it's an important method of treatment for hydrocephalus. This article described the specific surgical procedure for lateral ventriculo-superior sagittal shunt surgery in detail so that this surgical procedure can be better promoted.

From August 2016 to June 2018, a total of 7 patients underwent lateral ventriculo-superior sagittal shunt surgeries in our hospital. All patients had undergone lateral ventriculo-peritoneal fluid shunt surgeries before, which all failed due to the occurrence of various post-surgical symptoms including abdominal infection, intracranial infection, and abdominal absorption disorder. For some patients, the hydrocephalus had not been cured after undergoing multiple shunt adjustment surgeries. Therefore, all the 7 patients underwent lateral ventriculo-superior sagittal shunt surgeries as well as follow-up diagnoses and examinations for the next 3 months to 2 years after the surgeries. The results of their head CT scans or MRI scans indicated that the condition of hydrocephalus generally improved, the symptoms of intracranial hypertension significantly improved or disappeared, and the shunts were unobstructed with no occurrence of serious complications including shunt obstruction, infection of shunt system and cerebral venous sinus thrombosis. The superior sagittal sinus shunt surgery for hydrocephalus is simple to operate and also safe and effective. It is an important method of treatment for hydrocephalus, and especially an effective remedy for the failure of lateral ventriculo-peritoneal fluid shunt surgery [1].

Hydrocephalus is one of the common diseases in the field of neurosurgery, and the most important method of treatment for hydrocephalus is endoscopic third ventriculostomy and fluid shunt surgeries [2], with ventriculo-peritoneal fluid shunt surgery being the most common type of fluid shunt surgery. In 1965, Sharkey first reported his success in performing superior sagittal sinus shunt surbery for the treatment of obstructive hydrocephalus [1]. This surgical procedure is in line with the effort to greatly shorten the drainage pathway, and introduces cerebrospinal fluid directly into the blood circulatory system from the ventricle, which is in line with the reasonable physiological processes [3], and to a large extent, avoids all the common complications caused by several other common fluid shunt surgeries and demonstrates its outstanding advantages. In recent years, there have been an increasing number of reports of lateral ventriculo-superior sagittal shunt surgeries for hydrocephalus, but the specific surgical procedures vary in various reports and are not described in detail. Through the previous surgical experience of our hospital combined with reports from other hospitals, we hope that this article will enable more neurosurgeons to understand more clearly the specific surgical procedure for lateral ventriculo-superior sagittal shunt surgery so that this surgical procedure can be better promoted.

Surgical method and procedure: We choose the Medtronic adjustable pressure shunt whose proximal end towards the sagittal sinus features an anti-reflux fissure umbrella, and this design can prevent the blood from flowing back into the shunt lumen, which is the main reason we choose the Medtronic shunt for our surgery. The shunt pump should be adjusted to the appropriate pressure based on the patient's preoperative intracranial pressure, and the intrinsic internal venous pressure of the superior sagittal sinus ranging from 5–10 cm H₂O should also be taken into consideration when setting the pressure. The patients undergo general anesthesia and lie in the supine position, and two roughly 3 cm-long scalp incisions are made (see Fig. 1 ). One incision serves as a conventional puncture point for accessing the frontal horn of the lateral ventricle, and is located 2 cm anterior to the coronal suture as an oblique incision with its center being 2.5 cm from the mid-line. This incision is perpendicular to the longitudinal direction of the fluid shunt and shunt pump, and efforts are made to prevent too much part of the shunt from remaining under the incision. The actual incision can also be fine-tuned based on the position of previous surgical scars and bone windows. The other incision is the sagittal sinus incision which is located 5 to 7 cm posterior to the coronal suture to ensure sufficient space for placing the shunt pump, with the direction of incision being parallel to the first incision. All layers of the scalp tissues should be cut open to expose the outer surface of the skull roof, and a hole should be drill at the midpoint of each incision. A cross-shaped 2 cm-long incision is made along with the electrofulguration on the frontal dura, and the ventricular end of the shunt is inserted into the frontal horn of the lateral ventricle, with the direction of puncture aiming towards the midpoint of the bilateral external auditory canal. After ensuring that the cerebrospinal fluid outflow is unobstructed, efforts are made to prevent too much part of the ventricular end of the shunt from remaining inside the ventricle as well as being too close to and obstructed by the choroid plexus. The shunt pump and the proximal end of the shunt towards the sagittal sinus are connected sequentially and tightly ligated to prevent the shunt from coming off, and the reservoir of the fluid shunt is pressed several times to enable the cerebrospinal fluid to fill the shunt lumen and also prevent the influx of blood flow from the sagittal sinus chamber. The subcutaneous tissues (preferably the subperiosteal tissues) should be expanded with a vascular clamp, and the fluid shunt system should be introduced subcutaneously from the frontal incision into the scalp incision on the sagittal sinus for use. A rongeur can be used to slightly enlarge the hole in the bone to determine the position of the sagittal sinus. A longitudinal incision on the superior wall of the sagittal sinus is made, and an aspirator is used to aspirate all the blood from hemorrhaging. Then the proximal end of the shunt towards the sagittal sinus is inserted into the sagittal sinus with the length of the inserted part being roughly 5–6 cm. The above process should be performed gently and quickly to avoid the opening of the anti-reflux fissure umbrella of the shunt after being stressed. After the shunt is placed inside, the incision on the sagittal sinusis generally no longer bleeds. If a small amount of bleeding still occurs, the gelatin sponge and cotton sheets should be used and pressed against the incision for a few minutes to stop the bleeding without suturing or other special hemostatic treatments. A smooth bone groove is gouged out using the rongeur along pathway of the fluid shunt inserted through the hole in the bone to prevent the obstruction of the fluid shunt caused by pressure applied upon the fluid shunt. The gelatin sponge is then used to fill the hole in the bone, and finally the periosteum, epicranial aponeurosis, subcutaneous tissues and scalp near the two incisions should all be sutured by layers (see Fig. 2 ). The patient should undergo a head CT scan 4–6 hours after the surgery. If the result of scan indicates that the fluid shunt has not been properly placed inside the sagittal sinus or that the fluid shunt has proceeded into the central sulcal vein, the patient should undergo another surgery immediately to ensure the fluid shunt be properly re-inserted into the sagittal sinus.

Figure 1

Design of surgical incisions.

Figure 2

Image of post-surgical CT scan and 3D reconstruction of the sagittal sinus shunt (the arrow shows the proximal end of the fluid shunt towards the sagittal sinus).

Although the ventriculo-sagittal sinus shunt surgery has its outstanding advantages, it also has some disadvantages, especially the likelihood of occurrence of insufficient fluid shunting to patients with normal pressure cranial hydrocephalus and low pressure hydrocephalus after the intracranial pressure surgeries [4].

In recent years, there have been an gradually increasing number of reports of the ventriculosagittal sinus shunt surgeries, while the choice of the types of shunt pumps, as well as the position, direction and length of the placement of the proximal end of the fluid shunt towards the sagittal sinus all vary in different hospitals and demonstrate their own advantages and disadvantages [5,6]. This article only describes the detailed procedure and basic principles of the surgery in our hospital, and it still takes a longer time for the further follow-up observations to determine which method is better.