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 de scribed. It appeared a few years after the uneventful introduction of a cer ebrospinal fluid shunt and was probably attributable to a defect of the pos terior 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 communica ting hydrocephalus. A computed tomographic scan revealed a posterior fossa pneumatocele without hydrocephalus. INTERVENTION: A simple mastoidectomy was performed. Detection of the area o f the bone defect was followed by mastoid obliteration with abdominal fat. CONCLUSION: Clinicians should be aware that pneumocephalus can occur sponta neously, with or without obvious shunt problems. Treatment should be direct ed toward the area through which air penetrated the posterior fossa.