46 Perioperative Management of Hydrocephalus

10.1055/b-0039-169200

46 Perioperative Management of Hydrocephalus

Nickalus Khan, Jon Robertson, and L. Madison Michael III

46.1 Introduction

Hydrocephalus occasionally develops in patients with vestibular schwannomas (VS). Reports of the association between hydrocephalus and VS date back to the early 20th century. A historical piece by the Mayo Clinic in 1956 cited both Cushing’ss. Literatur and Dandy’ss. Literatur experience when treating VS.s. Literatur They described a 44-year-old woman who had a VS resected via an intracapsular approach and underwent a prolonged treatment of over a year for communicating hydrocephalus. Bucy further added one of his cases into this seminal report of a 41 year-old-woman who developed hydrocephalus following a similar procedure.s. Literatur

The incidence of hydrocephalus associated with VS has been reported to be between 3.7 and 13.7%.s. Literatur ^, s. Literatur ^, s. Literatur ^, s. Literatur ^, s. Literatur ^, s. Literatur There is a significant positive correlation of tumor size and hydrocephalus.s. Literatur Some studies show that complete removal of the tumor can resolve hydrocephalus without requiring further modalities of cerebrospinal fluid (CSF) diversion,s. Literatur ^, s. Literatur ^, s. Literatur while other studiess. Literatur ^, s. Literatur show that even with complete resection, hydrocephalus may still persist and warrant treatment.

To better understand this phenomenon, one must classify hydrocephalus in the setting of VS as either communicating or noncommunicating. If noncommunicating hydrocephalus exists—as in the case of large cerebellopontine angle tumors causing mass effect on the fourth ventricle—then complete removal of the tumor should cause resolution of the associated hydrocephalus. However, in the setting of small tumors with associated ventriculomegaly, the theory of mechanical compression of the CSF pathways fails to explain the etiology of the hydrocephalus.s. Literatur There is evidence to suggest that schwannomas with an extracanalicular component may produce protein that is associated with communicating hydrocephalus.s. Literatur ^, s. Literatur ^, s. Literatur This is further supported by documented reports of spinal schwannomas being associated with communicating hydrocephalus.s. Literatur ^, s. Literatur ^, s. Literatur ^, s. Literatur A study in 2003 by Tanaka et al found that the incidence of communicating hydrocephalus was higher in elderly patients.s. Literatur The authors of this study hypothetically attributed the communicating hydrocephalus to slower tumor growth and increased CSF exposure to the tumor.s. Literatur This hypothesis has been recently supported by a study in 2013 by Miyakoshi and colleagues that showed a significant association of elevated CSF protein and extended periods of tumor growth with concomitant hydrocephalus.s. Literatur The focus of this chapter is on the preoperative, intraoperative, and postoperative management of hydrocephalus associated with VS.

46.2 Preoperative Management of Hydrocephalus

There are four possible clinical scenarios for patients with hydrocephalus secondary to VS: (1) asymptomatic communicating hydrocephalus, (2) symptomatic communicating hydrocephalus, (3) asymptomatic noncommunicating hydrocephalus, and (4) symptomatic noncommunicating hydrocephalus. Patients presenting with communicating hydrocephalus are typically older (>60 years old) than those with obstructive hydrocephalus. Symptoms that can occur are those commonly found in normal pressure hydrocephalus, namely, cognitive impairment, urinary incontinence, and gait disturbance.

For patients with symptomatic communicating hydrocephalus, CSF shunting without tumor removal may be the optimal treatment (Fig. 46‑1 ). As these patients are older and often have significant comorbidities, shunting with a low-pressure or programmable valve may result in symptom resolution, obviating the need for tumor resection. Patients with communicating hydrocephalus—whether asymptomatic or symptomatic—who are deemed appropriate for surgery are not treated preoperatively with external CSF drainage. This approach is also taken with patients with asymptomatic noncommunicating hydrocephalus.

**Fig. 46.1** **(a)** CT of the head with contrast reveals a moderate-size vestibular schwannoma without compression of the adjacent cerebrospinal fluid pathways. (b) Overt development of communicating hydrocephalus is demonstrated.

Patients who present with acute noncommunicating hydrocephalus and rapidly developing symptoms of elevated intracranial pressure (ICP) are treated with an external ventricular drain (EVD) or endoscopic third ventriculostomy (ETV) prior to surgery. These patients are taken to surgery after their presenting symptoms resolve, usually within 1 to 2 days. In patients who cannot undergo surgery during the same hospital visit, and who fail an ETV, a permanent ventriculoperitoneal (VP) shunt is placed with plans for future surgical resection.

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