Lateral Ventricular Fenestration

Lateral Ventricular Fenestration

Andy Shores

Mississippi State University, Mississippi State, MS, USA


Endoscopic third ventriculostomy (ETV) is a well‐established surgical procedure for hydrocephalus treatment [1] in infants [2] and adults [3]. And while the size of our veterinary patients essentially prevents the performance of this endoscopic technique, the same principle is possible with fenestration or marsupialization of the lateral ventricle. This technique was reported in a presentation in 2015 and included five patients [4]. Fairly recent research on canine hydrocephalus suggests we have a lot to learn about the pressure changes in patients with non‐obstructive hydrocephalus and that normotensive communicating hydrocephalus does exist [5]. We also have learned from some recent papers that a reduction in volume of the cerebral ventricles does correlate with improvement in at least come clinical signs [6]. When considering these facts and the complications that can be associated with ventriculoperitoneal (VP) shunting in veterinary patients, this technique should be considered as an alternative to VP shunts in specific circumstances, especially when size/age related factors and client economic restraints are a consideration. This chapter will describe the technique and give the author’s recommendation for indications. In addition, potential complications will be discussed.


Shunting of CSF into another cavity is used to treat hydrocephalus and other disorders that cause secondary obstructive hydrocephalus and increased intracranial CSF accumulation [7]. Conventional valve shunting for treatment of hydrocephalus has been associated with complications, as high as 22% in one study [8] and over 30% in a more recent publication [9]. Reported complications include dislodgement, occlusion, infections, ventricle collapse, and subdural hematoma. The necessity for shunt revision surgery is reported [9]. In humans, complication frequency is related to young age and was 32% in a study of 14 000 patients and 23.8% in a study of over 1700 cases [10].

Because of the level of complications associated with ventriculoperitoneal shunts and possibly a higher rate of complications in very young dogs and cats, the author sought a different method of treating hydrocephalus in small animals. Human infants may be preferentially treated with endoscopic assisted third ventricle fenestration into the subarachnoid space through the basilar cistern. The size of the young canine or feline ventricular system, however, is prohibitively small for this procedure and often for any type of VP shunt system. An alternative procedure (lateral ventricle fenestration) was initially designed with these factors in mind. The procedure initially had successful short‐term outcomes in five patients, but three were lost to long‐term follow‐up. In a domestic short‐haired kitten (10 weeks old) and a Labrador puppy (14 weeks old), following an obstructive hydrocephalus diagnosis using advanced imaging, clinical signs resolved or improved over a period of six months. Follow‐up imaging demonstrated patency of the fenestrations and reduced ventricle sizes [4]. Follow‐up conversations with these owners at six years post fenestration revealed that both these patients were alive, had no perceived neurologic deficits, and were seizure free. The same technique has continued to be performed by the author without adverse events and by many others in the United States, Europe, and South America. The technique is quick, not complicated, and has had a high level of success (improvement) in most patients.

Photos depict a graphic representation of the lateral ventricular fenestration technique.

Figure 23.1 A graphic representation of the lateral ventricular fenestration technique. 1. The dotted line shows the shape of the initial dural incision. 2. The dural flap has been created and secured with a stay suture. The fenestration is made into the ventricle through a gyrus. 3. The SIS patch has been fashioned to suture to the dura. The goal is to create a dome‐like structure over the fenestration. 4. The completed duroplasty.


A graphic overview of the technique is illustrated in Figure 23.1. The objective of this procedure is the creation of a conduit of communication between the lateral ventricle and the subarachnoid space proximal and rostral to the lateral apertures. Patients are placed in sternal recumbency with the head and neck slightly extended and with no pressure on the area of the jugular veins. The cranium is sterilely prepped and draped (Figure 23.2). A curved (approximately 4 cm) skin incision is made to the right or left of midline (or bilaterally if both ventricles are to be fenestrated), extending from above the zygomatic process, dorsally toward midline, and caudally toward occipital protuberance, using a #10 scalpel blade or electroscalpel. Monopolar and bipolar electrocautery are used for hemostasis. The subcutaneous tissues and temporalis muscle are bluntly dissected to expose the external calvarium. A small rostrotentorial craniectomy is performed. Often the opening only needs to be a 3–4 × 3–4 cm square or rectangle using a nitrogen‐powered or electric drill (Figure 23.3). The placement of the craniectomy should be 50–60° off the dorsal midline of the skull (Figure 23.4). The exposed dura is carefully incised in a specified manner (Figure 23.5) using a #12 scalpel and reflected using 5‐0 stay sutures (Figure 23.6).

The most common site for the ventriculostomy (fenestration) is at the ectosylvian gyrus as this should correlate with the 50–60° point off the dorsal midline. Next, the gyrus is incised longitudinally using a #11 scalpel blade to enter the lateral ventricle. An uninflated, 4 Fr. anal sac catheter1

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Jun 21, 2023 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Lateral Ventricular Fenestration

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