Chronic Epidural Pneumocephalus Due to Hyperpneumatization of the Temporal Bone: Sequelae, Surgical Management, and Long-Term Follow-up

Objective We report the surgical management, long-term follow-up, and unique postoperative sequelae from a rare case of spontaneous epidural pneumocephalus in a patient with congenital tegmen defect and hyperpneumatization of the temporal bone.

Clinical Presentation This patient is a 70-year-old man who presented 21 years earlier with spontaneous epidural pneumocephalus resulting from an unusual tegmen defect and hyperpneumatization of the cranium. This was repaired via a middle cranial fossa approach and obliteration using a temporalis muscle flap and pericranial graft. Several years later, he required tympanoplasty due to outward herniation of the tympanic membrane related to chronic autoinsufflation. Thereafter, he developed a maximal conductive hearing loss and headaches in situations of pressure change, most notably during flights. On clinical exam, he was found to have an obstructing extraluminal pneumatocele of the right external auditory canal, compressible, and based on the posterior canal skin. CT of the temporal bones demonstrated mastoid hyperpneumatization with continuity into the posterior superior bony external auditory canal medial to the bony cartilaginous junction, as well as extradural free air over the tegmen and extending posteriorly over the temporal lobe convexity ([Fig. 1A], coronal CT).

Intervention The patient underwent endaural surgical repair of the bony defect in the right external auditory canal, reconstruction of the ear canal, and reinforcement cartilage tympanoplasty. Intraoperatively, the widely based pneumatocele was identified in continuity with the bony defect in the lateral portion of the bony external auditory canal, extending medially to the tympanic membrane. The margins of the pneumatocele were incised from the healthy native skin that remained adherent to the ear canal and transected medially as a free graft. An 8 × 9 mm bony defect was identified laterally ([Fig. 1B], intraoperative image). Irregularities were smoothed with a diamond drill to better define the extent of the defect. Gelfoam was placed into the largest air cells for support, and OtoMimix calcium phosphate bone void filler was used to reconstruct the defect. Revision tympanoplasty was performed using a composite cartilage-perichondrial graft with concurrent placement of a pressure equalization tube to support satisfactory healing. The free skin graft was used to resurface the bony canal defect.

Conclusion Hyperpneumatization of the temporal bones is rare and can cause spontaneous intracranial pneumocephalus. This case demonstrates an obstructive pneumatocele of the external auditory canal as a rare sequelae related to another bony defect. No recurrence of symptoms, pneumatocele, or pneumocephalus was noted 2 years following this intervention. Based on the literature and the success of this case, the optimal management is surgical obliteration of the involved air cells and repair of communicating defects.

Fig. 1 (A) Coronal CT and (B) intraoperative image.