Spontaneous otogenic posterior fossa pneumocephalus.

A 74-year-old female presented to an outside medical facility with gradual decline in neurological status over a period of 6 to 8 weeks. The patient’s symptoms began with headache and progressed to confusion, altered sensorium, escalating ataxia, and expressive aphasia. The patient was transferred to our medical center. Review of the patient’s past medical history was negative for head trauma, prior neurosurgical or otologic procedures, neoplasms of the skull base, or chronic infections of the middle ear or mastoid. Secondary to the presence of a pacemaker, magnetic resonance imaging (MRI) was contraindicated; therefore, CT of the head was obtained and revealed a 5 by 3 cm pneumatocele in the area of the posterior fossa. Imaging showed evidence of compression of the right middle cerebellar peduncle and posterior right upper pons with associated hydrocephalus. (Fig. 1) The mastoid appeared to be hyperpneumatized and a small bony dehiscence was identified in the right posterior mastoid air cells just superior to the vestibular aqueduct. (Figs. 2A and 2B) The intracranial compartment and temporal bones were otherwise unremarkable. Medical workup revealed no other etiology for the patient’s neurological decline. The patient was initially observed as an inpatient, but showed no improvement in her neurological status.