Spontaneous pneumocephalus in the posterior fossa in a patient with a ventriculoperitoneal shunt: Case report

OBJECTIVE AND IMPORTANCE: A unique case of spontaneous pneumocephalus is described. It appeared a few years after the uneventful introduction of a cerebrospinal fluid shunt and was probably attributable to a defect of the posterior mastoid plate. CLINICAL PRESENTATION: A 65-year-old man presented with a subacute onset of vertigo, vomiting, and atactic gait instability. The patient had undergone a ventriculoperitoneal shunt implantation 2 years previously for communicating hydrocephalus. A computed tomographic scan revealed a posterior fossa pneumatocele without hydrocephalus. INTERVENTION: A simple mastoidectomy was performed. Detection of the area of the bone defect was followed by mastoid obliteration with abdominal fat. CONCLUSION: Clinicians should be aware that pneumocephalus can occur spontaneously, with or without obvious shunt problems. Treatment should be directed toward the area through which air penetrated the posterior fossa.