The aim of this study is to investigate hearing outcomes in patients who have undergone cerebrospinal fluid (CSF) leak repair via a middle cranial fossa (MCF) approach and to identify any variables that influence post-operative hearing outcomes.

This is a multi-centre study. A total of 65 patients who underwent an MCF approach CSF leak repair were included. Retrospective case review was conducted to collect patient demographic and clinical data including pre- and post-operative audiometry.

A total of 65 patients were included: 9 patients (9.2per cent) had an encephalocele confirmed on magnetic resonance (MR) imaging, whilst the remaining patients had biochemically confirmed, beta-trace protein positive CSF leaks. Post-operatively, there was a statistically significant improvement in both bone conduction (Z = -3.71, p < 0.001) and air conduction thresholds (Z = -5.82, p < 0.001). None of the studied variables were found to be associated with the degree of hearing improvement.

The MCF approach for CSF leak repair yields favorable audiological outcomes.

To undertake a systematic review of the role of microsurgery, in relation to observation and stereotactic radiation, in the management of small vestibular schwannomas with serviceable hearing.

The Medline database was searched for publications that included the terms ‘vestibular schwannoma’ and/or ‘acoustic neuroma’, occurring in conjunction with ‘hearing’. Articles were manually screened to identify those concerning vestibular schwannomas under 1.5 cm in greatest dimension. Thereafter, only publications discussing both pre-operative and post-operative hearing were considered.

Twenty-six papers were identified. Observation is an acceptable strategy for small tumours with slow growth where hearing preservation is not a consideration. In contrast, microsurgery, including the middle fossa approach, may provide excellent hearing outcomes, particularly when a small tumour has begun to cause hearing loss. Immediate post-operative hearing usually predicts long-term hearing. Recent data on stereotactic radiation suggest long-term deterioration of hearing following definitive therapy.

In patients under the age of 65 years with small vestibular schwannomas, microsurgery via the middle fossa approach offers durable preservation of hearing.

Endoscopic endonasal techniques have recently become the method of choice in dealing with cerebrospinal fluid leak involving the anterior cranial fossa. However, most surgeons prefer an intracranial approach when leaks involve the middle cranial fossa. This case report illustrates the possibilities of using endoscopic techniques for cerebrospinal fluid leaks involving the middle fossa.

A 37-year-old male patient presented with multiple areas of cranial defect with cerebrospinal fluid leak due to osteoradionecrosis following radiation for nasopharyngeal carcinoma 4 years earlier. Clinical examination showed involvement of all cranial nerves except the IInd and XIth nerves on the left side. A prior attempt to repair the cerebrospinal fluid leak with craniotomy was not successful.

This case demonstrates the successful endoscopic repair of a large cranial defect with cerebrospinal fluid leak.

This study aimed to determine whether or not the middle cranial fossa dural plate is located lower (i.e. more caudally) in patients with chronic otitis media, relative to adjacent structures.

The authors retrospectively investigated computed tomography temporal bone scans of 267 ears of 206 patients who had undergone surgery with a diagnosis of chronic otitis media, together with scans of 222 ears of 111 patients without chronic otitis media. The depth of the middle cranial fossa dural plates was recorded.

The mean depth of the middle cranial fossa dural plate was 4.59 mm in the study group and 2.71 mm in the control group (p < 0.001). The middle cranial fossa dural plate was located lower in the right ear in both the study and control groups.

The middle cranial fossa dural plate was located lower in patients with chronic otitis media, and in the right ears of both patients and controls. Surgeons should take this low location into consideration, and take extra care, during relevant surgery on patients with chronic otitis media.

We report the use of bilateral surgical decompression of the internal auditory canals to treat hyperostosis cranialis interna in an eight-year-old girl presenting with bilateral facial palsy due to hyperostosis cranialis interna.

Using a middle fossa craniotomy approach, both internal auditory canals were unroofed and cranial nerves VII and VIII were decompressed, with a one-year interval between sides. The mimic function recovered. One year post-operatively, the right and left facial sides had been restored to House–Brackmann grades I and II, respectively.

This is the first report of the use of surgical decompression of the internal auditory canal in a case of hyperostosis cranialis interna. Surgical decompression of the internal auditory canal is recommended therapeutically, but may also be performed prophylactically in younger patients with hyperostosis cranialis interna.

To demonstrate that the anatomical structure known as the processus cochleariformis, with its intimate and constant relationships to inner-ear structures, can be used as a reliable landmark during middle cranial fossa surgery, alone or in conjunction with other landmarks.

An anatomical study using cadaveric temporal bones to define six reproducible measurements that relate the processus cochleariformis to inner-ear structures, and to define 14 other measurements that relate inner-ear structures to adjacent structures within the intact bone.

Using 10 cadaver specimens, 20 reproducible measurements were defined. The first six of these defined the relation of the processus cochleariformis to inner-ear structures in the middle cranial fossa approach. The other measurements defined the exact location of the inner-ear structures and adjacent structures within the intact bone.

The vertical crest lies at a 20° angle from the processus cochleariformis to the coronal plane, and at a distance of 5 to 6 mm from the processus cochleariformis. The point at which the medial margin of the basal turn of the cochlea crosses the labyrinthine segment of the facial nerve lies at a 0° angle from the processus cochleariformis to the coronal plane, and at a distance of 6.5 to 7.5 mm from the processus cochleariformis. The superior semicircular canal lies at a 45° angle from the processus cochleariformis to the coronal plane. The other measurements obtained give important clues about the position of the cochlea, vestibulum, greater superficial petrosal nerve and labyrinthine segment of the facial nerve.

If the classical landmarks are indiscernible during middle cranial fossa surgery, then the processus cochleariformis, with its intimate and constant relationships to inner-ear structures, is a safe and constant landmark.