Meningoencephalocele of the temporal bone: Pictorial essay on transmastoid extradural-intracranial repair

Purpose: A spontaneous meningoencephalocele of the temporal bone may present with effusion in the middle ear, a cerebrospinal fluid leak, hearing loss, or rarely otitic meningitis. Repair of spontaneous encephaloceles in the temporal bone has been performed using transmastoid and transcranial middle fossa approaches or a combination of the two with varied results. The authors present a technical paper on the transmastoid extradural intracranial approach for the management of temporal lobe encephaloceles. Materials/Methods: Case reports and cadaver dissections are used to provide a pictorial essay on the technique. Advantages and disadvantages compared with alternative surgical approaches are discussed. Results: Traditional transmastoid approaches are less morbid compared with a transcranial repair as they avoid brain retraction. However, in the past, there has been a higher risk of graft failure and hearing loss due to downward graft migration and a potential need for ossicular disarticulation. For the appropriate lesion, the transmastoid extradural intracranial approach lesion offers a stable meningoencephalocele repair without the comorbidity of brain retraction. Conclusion: The authors describe a transmastoid extradural intracranial technique via case reports and cadaver dissections for the repair of spontaneous meningoencephalocele defects larger than 2 cm. This approach provides more support to the graft compared to the conventional transmastoid repair.