11.1 Introduction

Multiloculated, or multicompartmental hydrocephalus is a challenging conglomeration of diseases, mostly attributable to intrauterine meningitis and intraventricular hemorrhage in neonates. Although the incidence of the disease is not well established, with a decrease in infant mortality, many children with a history of intrauterine infection or hemorrhage are candidates for the development of multi-compartmental hydrocephalus. In one series looking at the long-term follow-up of infants affected by posthemorrhagic hydrocephalus, compartmentalization was noted in 7% of cases.1 Historically, many different treatment strategies including shunting and open surgical fenestration have been attempted for the treatment of multiloculated hydrocephalus. With advances in endoscopy, it is possible to simplify shunting procedures and even render the patient shunt independent.

11.2 Pathophysiology

As noted above, the majority of cases of multiloculated hydrocephalus are attributed to intrauterine infections or intraventricular hemorrhage.2,3,4 Other less common causes include shunt-related infection,5 direct ependymal trauma during intracranial surgery or shunt insertion,6 and iatrogenic overdrainage.7

11.3 Clinical Features

Patients with multiloculated hydrocephalus may present with a host of symptoms including those attributable to increased intracranial pressure (ICP), growing head circumference, and neurocognitive decline or failure to advance and meet developmental milestones.2,8

11.4 Diagnosis and Imaging

The diagnosis of multiloculated hydrocephalus is usually made during work-up for increased ICP or for an enlarged or enlarging head circumference. Frequently patients with hydrocephalus are children with a history of intrauterine infection or intraventricular hemorrhage. These children are frequently followed with sequential ultrasonography. When appropriate, fine cut computed tomography or magnetic resonance imaging (MRI) could aid in the visualization of intraventricular membranes or cysts.9 A cerebrospinal fluid (CSF) dye study can aid in planning of the operation by demonstrating isolation or communication of cysts. Some groups have utilized intraoperative MRI10 to aid with the intraoperative management of multiloculated hydrocephalus, but in our experience this has not been necessary (Fig. 11.1).

11.5 Treatment

The indications for surgery include multiloculated hydrocephalus of any etiology that is untreated or at the time of operation treated using complex shunting strategies.

The goals and rationale for endoscopic surgical treatment of multiloculated hydrocephalus are to allow for communication between isolated cerebrospinal fluid (CSF) compartments, to allow for restoration of native CSF pathways, and to decrease or eliminate shunt dependency. This is in comparison to standard shunting techniques, which simply attempt to bypass points of obstruction and allow a path of least resistance for CSF into the peritoneum, pleura, or atrium. Complex shunting techniques are associated with risks of shunt failure, catheter mal-positioning, and infection. The goal of treatment of multiloculated hydrocephalus should be to decrease the need for insertion of multiple shunt catheters or ultimately to render the patient shunt independent.

Several techniques including endoscopic third ventriculostomy, septum pellucidotomy, endoscopic cyst fenestration, aqueductoplasty, and fenestration of multiple disconnected compartments can be used to treat multiloculated hydrocephalus.

• 
  

  Endoscopic third ventriculostomy (ETV): The technique for performing an ETV has been previously reported.11,12 We prefer to place the entry bur hole on the nondominant side, just anterior to the coronal suture and 3 cm from the midline. Image guidance may be used to optimize the location of this bur hole.13 Upon entry and verification of anatomical features of the third ventricle, the endoscope is used to create a 4 to 5 mm stoma between the mammillary bodies and the infundibular recess. See Chapter 21 for more detail.

  
  
• 
  

  Septum pellucidotomy (septum pellucidum fenestration): When using a rigid endoscope, we preferentially place the bur hole for septum pellucidotomy just anterior to the coronal suture and 5 cm from the midline on the side of the larger of the lateral ventricles. This more lateral approach minimizes the likelihood of injury to the floor of the contralateral ventricle. Alternatively, the septum pellucidum can be approached via a posterior parietal bur hole. Again image guidance can assist in the optimal placement of the bur hole. In our experience, the optimal site of fenestration of the septum is 1 cm anterior and above the foramen of Monro. When using a flexible endoscope, the same entrance for the ETV is used. See Chapter 23 for more detail.

  
  
• 
  

  Simplifying multicompartmental hydrocephalus using a rigid endoscope: The optimal position for an entry bur hole for multicompartmental hydrocephalus is dependent on anatomical considerations, the number and location of ventricular catheters, and the number and type of membranes separating CSF compartments. In general, care should be taken to place the bur hole in a position that minimizes passage through eloquent cortex and gains entry to the largest CSF space. The trajectory chosen should allow for fenestration of the compartment into an adjacent CSF pathway or subarachnoid space. If multiple loculations are present, the trajectory should fenestrate a majority of the loculations. Ideally, one should attempt to fenestrate as many membranes and loculations prior to committing the patient to a shunt. The membranes should be opened to a diameter of 4 to 5 mm using sharp technique. The more fenestrations that are made into membranes separating compartments, the higher the likelihood of obtaining a durable communication.

  
  
• 
  

  Simplifying multicompartmental hydrocephalus using a flexible endoscope: In general, when using the flexible endoscope the entry bur hole remains the same as for ETV and other procedures, 2 to 3 cm off the midline and at the coronal suture or slightly anterior. One of the great advantages that the flexible endoscope offers is its maneuverability, allowing navigation in any direction within the ventricles and loculations with minimal brain manipulation. Image-guided neuronavigation does not apply to flexible endoscopes yet. One of the difficulties when using the flexible endoscope is intraoperative orientation. The neurosurgeon should be able to orient him- or herself using anatomical landmarks such as the foramen of Monro, choroid plexus, veins, etc. This is particularly difficult in patients with multiloculated hydrocephalus because is not uncommon to be associated with distorted anatomy. Detailed analysis of the preoperative MRI is necessary for the surgeon to be familiar with the anatomy of the ventricules and loculations.

  
  
• 
  

  Cyst fenestration: Arachnoid cysts should be fenestrated into the basal cisterns when possible. Suprasellar cysts can be difficult to fenestrate into the subarachnoid space due to the usually thick membranes of these cysts. If a suprasellar cyst is deemed dangerous for fenestration, ventriculocystostomy is an acceptable option. See Chapter 17 for more detail.

  
  
• 
  

  Aqueductoplasty: The technique for aqueductoplasty has been previously published.14 In cases of collapsed lateral ventricles, the fourth ventricle can be approached via a midline suboccipital approach. In cases of ventriculomegaly, the fourth ventricle can be approached via a bur hole 8 cm behind the nasion and 3 cm from the midline. The aqueduct is dilated using hydrodissection and a balloon catheter. See Chapter 22 for more detail.