Introduction: Negative pressure hydrocephalus (NegPH) is a rare entity along the spectrum of hydrocephalic disorders that is very poorly described in the neurosurgery literature and presents a unique challenge in both diagnosis and treatment. A few small case series describe treatment with cerebrospinal fluid (CSF) diversion via ventriculoperitoneal shunting. However, using the negative intrathoracic pressure gradient necessary for inspiration, we describe the first series of NegPH patients successfully treated with a valveless ventriculopleural shunt.
Methods: All patients with NegPH were retrospectively reviewed between 1999-2015 at a large university teaching hospital. NegPH was diagnosed only if 1) signs and symptoms of hydrocephalus were present, 2) there was radiographic confirmation of ventriculomegaly, and 3) patients were proven with ICP recording to have negative ICP. Three patients underwent CSF diversion via ventriculopleural shunt insertion and response to treatment was reviewed.
Results: Three patients were diagnosed with NegPH after previously undergoing intracranial surgery. Each patient underwent initial CSF diversion with an extraventricular drain. Following negative ICP recordings, all three patients responded to CSF diversion with negative pressure drainage to restore adequate CSF flow. The drainage level was set based on patients’ clinical exam. Once stable, a valveless ventriculopleural shunt was inserted in all three patients with good clinical and radiographic response to treatment.
Conclusions: The mechanism of NegPH remains unclear. Every reported case thus far, including those in our series, has previously undergone intracranial surgery, which may mean NegPH is a rare complication associated with hemorrhage into the CSF and development of a negative transmantle gradient with ongoing ventriculomegaly. As a result, the pleural space was chosen as the distal shunt terminus in our series because of its negative pressure gradient created for the driving force of inspiration. We feel ventriculopleural shunting offers the best physiologic solution and provides good long-term outcome in the treatment of NegPH.
Patient Care: Negative Pressure Hydrocephalus (NegPH) is a very rare disorder with only a handful of cases reported in the literature. Because of this, it presents a challenge from both a diagnostic and treatment perspective. With our experience of successful treatment of NegPH, this hydrocephalic disorder can hopefully be considered on their differential by other neurosurgeons and likewise successfully treat NegPH.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of negative pressure hydrocephalus and why it is necessary to treat with negative pressure drainage into the pleural cavity, 2) Discuss, in small groups, the pathophysiology of Negative Pressure Hydrocephalus and possible options for its treatment, and 3) Identify an effective treatment for Negative Pressure Hydrocephalus, which we feel is to harness the negative intrathoracic pressure as a distal terminus for a shunting procedure.