Given the anatomic boundary between the fields of neurosurgery and otolaryngology, skull base surgery is always a challenge for both disciplines. The skull can be described as having two components: the neurocranium (braincase) and splanchnocranium (viscerocranium). The neurocranium in turn has two components, viz. calvarium (skull cap) and basicranium (skull base).

Ossiculoplasty is the surgical restoration/rehabilitation of patients with conductive hearing loss secondary to ossicular dysfunction. This dysfunction manifests as conductive hearing loss and can be the result of congenital causes, or result secondarily as the result of cholesteatoma, tympanosclerosis, or otosclerosis. This module focuses on anatomic and embryologic considerations in ossiculoplasty and ossicular malformations as well as surgical considerations. Otosclerosis and stapedotomy are discussed in detail in another module.

Otosclerosis is a common form of hearing loss diagnosed and treated by the otolaryngologist. This module is designed to describe the embryology and anatomy of the normal middle ear and otic capsule, and then to understand how this differs in otosclerosis. A variety of treatments have been proposed and will be reviewed including amplification, medical therapy, and surgical therapy via stapedectomy or stapedotomy. Common complications from surgery will also be discussed.

CSF leak of the temporal bone may occur spontaneously or result from trauma.  Spontaneous leaks are rising in incidence, and are often associated with obesity, sleep apnea, and benign intracranial hypertension.  The clinical presentation is often a unilateral clear effusion, and profuse otorrhea from a myringotomy tube. Occult leaks may present with meningitis.

The petrous apex is a relatively inaccessible area that can occasionally harbor serious disease. Disease processes that usually cause symptoms are typically inflammatory or neoplastic in nature. Petrous apex lesions typically cause nonspecific symptoms such as headache, but as the lesion becomes more extensive, adjacent structures such as cranial nerves can become involved. A common early and specific sign of a petrous apex process is abducens palsy. Current imaging techniques can usually provide enough supplemental information to allow a focused plan of treatment.

Vestibular schwannoma is a benign tumor found in the internal auditory canal and the cerebellopontine angle.  Symptoms of VS most commonly include ipsilateral hearing loss, tinnitus, and imbalance.   ABR and can be used to screen for VS, but MRI is the definitive diagnostic tool.  About 5% of cases of VS are found in patients with neurofibromatosis type 2 (NF 2).  Patients with NF 2 are prone to develop bilateral VS.  Treatment options for both sporadic, unilateral tumors and bilateral tumors include observation, radiation therapy, and surgical resection with interventions to help maintain

The pathophysiology of facial nerve dysfunction is highly variable. A careful history and physical examination is essential for proper diagnosis. Intervention may be directed toward preservation or improvement of function in acute lesions, while chronic lesions require efforts to minimize deformity and restore movement.   

This module covers central basis of vestibular compensation and multidisciplinary utilization of a vestibular rehabilitative program.

Cochlear implants represent the most successful neural prosthesis to date. Their development is a testament to courageous scientists, surgeons, audiologists, and patients who have pushed the technology forward. The devices work by stimulating spiral ganglion neurons located within the cochlea’s modiolus. A solid understanding of the temporal bone, facial nerve, and cochlea anatomy will optimize surgical placement of the electrode and limit surgical complications.

Hearing amplification devices are powerful tools that can significantly improve quality of life for patients who have mild to moderate hearing loss or bothersome tinnitus. Amplification technology has progressed significantly in recent decades and programming allows for compression and frequency-modulated amplification which can personalize devices. While hearing aids are versatile tools, careful patient selection and device customization are key to success.