Introduction

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.

Rationale

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.