Newton J. Coker

Histopathology of Cochlear Implants in Humans

The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users.

Intracranial and intratemporal facial neuroma.

Primary tumors of the facial nerve are relatively rare and have a variety of presenting symptoms. This article reviews 248 cases of facial neuroma in the worlds literature and adds seven cases that were managed at the Baylor College of Medicine. Facial weakness was most common symptom, with facial spasm or tics, hearing loss, and masses in the external auditory canal also being frequently seen. At surgery, the tympanic, vertical, and labyrinthine segments were the most commonly involved areas. On the basis of this review, general principles have been drawn up to help the clinician in diagnosis and management of this (at times) difficult problem.

Coronal Computed Tomography Prevalence of Superior Semicircular Canal Dehiscence

OBJECTIVES The relatively new clinical entity superior canal dehiscence syndrome (SCDS) is diagnosed by clinical symptoms and signs. Coronal computed tomography (CT) has been used to confirm the diagnosis. A consecutive series of temporal bone CT scans was reviewed to define the prevalence of a dehiscent-appearing superior semicircular canal. STUDY DESIGN AND SETTING Temporal bone CT scans performed over a 2-year period at a university-based tertiary referral center were reviewed independently by 3 individuals. Scans were excluded if coronal images were not obtained or reconstructed from axial images. Prevalence figures for dehiscent-appearing superior semicircular canal were determined by consensus. Medical records of selected individuals with a dehiscent-appearing canal were reviewed for study indications and otologic symptoms. RESULTS A dehiscent-appearing superior semicircular canal was seen in 9% of studies. Correlation among examiners was greater than 94%. Medical records indicated symptoms suggestive of or compatible with the diagnosis of SCDS in rare cases. CONCLUSION The prevalence of a dehiscent-appearing superior semicircular canal on coronal CT of the temporal bones performed with 1.0-mm collimation is substantially greater than that predicted by temporal bone histologic study. Clinical symptoms compatible with the diagnosis were seldom recorded, suggesting low specificity. The high sensitivity and low specificity of CT scan create a risk for overdiagnosis of SCDS if the coronal CT scans are not correlated with clinical symptoms.

Otomycosis: Clinical features and treatment implications

OBJECTIVES: To determine the clinical presentation, predisposing factors, complications, and treatment outcomes of otomycosis. STUDY DESIGN AND SETTING: Retrospective review of 132 patients with a clinical diagnosis of otomycosis treated from 1998 to 2004 in an academic otology practice. RESULTS: Otalgia and otorrhea were the most common presenting complaints (48%). Prior otologic procedures increase the risk of developing otomycosis. Residual disease was observed in 13% and recurrence in 15% of the subjects. The presence of a mastoid cavity was associated with higher recurrent and residual disease rates. Topical ketoconazole, cresylate otic drops, and aluminum acetate otic drops were all relatively effective with >80% resolution rate on initial application, although topical ketoconazole had a higher resolution rate and lower rate of disease recurrence. CONCLUSIONS AND SIGNIFICANCE: Otomycosis can usually be diagnosed by clinical examination and often occurs in the setting of persistent otorrhea. Complications are not uncommon but usually resolve with application of appropriate topical antifungal agents. Eradication of disease is more difficult in the presence of a mastoid cavity.

Facial nerve regeneration in the silicone chamber: The influence of nerve growth factor

The role of nerve growth factor (NGF) was examined in the neural repair of adult rabbit facial nerves using an in vivo preparation. A 35-microliters nerve growth chamber was created by suturing the proximal and distal ends of a transected facial nerve (superior buccal branch) into a silicone tube. A gap of 8 mm in the chamber remained after removal of a 5-mm piece of nerve and insertion of the proximal and distal stumps into the tube. Animals were operated bilaterally; one side of the chamber was filled with NGF and the contralateral side was filled with Ringers solution. Regeneration of the nerves was examined 1 to 5 weeks following the surgery. The caliber of the nerve bundle, the distribution pattern of regenerating motoneurons, axon number per fascicle, size distribution, and the total number of cells were compared to the preoperative morphology pattern found for that animal. Each buccal branch served as its own control. The NGF-filled chambers demonstrated an overall larger caliber of nerve regeneration at 5 weeks and a higher density distribution of axon growth at 3 and 5 weeks. In the early regeneration case (3 weeks), the axon growth profile exhibited more fascicles and less axons than the preoperative controls. In the more advanced state (5 weeks), the fascicle number was reduced and the axon number was increased. After 5 weeks of regeneration the number of fascicles was still more than that found in the preoperative state. Axon size at 5 weeks was 80% that of the preoperative controls and the thickness of the myelin sheath was less than the preoperative level. The histogram of the size distribution revealed the same distribution as in the preoperative control section.

Traumatic Infratemporal Facial Nerve Injury: Management Rationale for Preservation of Function

A retrospective review of 29 cases of infratemporal facial nerve injuries included 18 temporal bone fractures, 7 gunshot wounds, and 4 iatrogenic complications. Surgical exploration confirmed involvement of the fallopian canal in the perigeniculate region in 14 longitudinal and 3 transverse or mixed fractures of the petrous pyramid. Gunshot and iatrogenic injuries usually occurred within the tympanic and vertical segments of the facial canal and at the stylomastoid foramen. When hearing is salvageable, the middle fossa approach provides the best access to the perigeniculate region of the facial nerve. In the presence of severe sensorineural hearing loss, the transmastold-translabyrinthine approach is the most appropriate for total facial nerve exploration. Grade I to III results can be anticipated in timely decompression of lesions caused by edema or intraneural hemorrhage. Undetectable at the time of surgery, stretch and compression injuries with disruption of the endoneural tubules often lead to suboptimal results. Moderate-to-severe dysfunction (Grade IV), with slight weakness and synkinesis, is the outcome to be expected from the use of interpositional grafts.

Adult Spontaneous CSF Otorrhea: Correlation with Radiographic Empty Sella:

OBJECTIVE: To determine the prevalence of radiographic empty sella in patients with spontaneous cerebrospinal fluid (CSF) otorrhea. STUDY DESIGN AND SETTING: Retrospective case series of adult patients with CSF otorhinorrhea at an academic tertiary medical center. Patients with history of skull base surgery, trauma, tumor, or chronic ear disease were excluded. Available imaging studies were reviewed with attention to the sella turcica. RESULTS: Eight patients were diagnosed with spontaneous CSF otorrhea. Five of seven patients with adequate imaging studies (71%) had a radiographic empty sella. Seven of eight patients were clinically obese, with a body mass index BMI >30 kg/m 2 . CONCLUSIONS: Empty sella is a common radiologic finding in patients with spontaneous CSF otorrhea. This supports the theory that increased intracranial pressure contributes to development of spontaneous CSF otorrhea. SIGNIFICANCE: Radiographic empty sella predicts elevated intracranial pressure, which may require further evaluation and treatment in patients with spontaneous CSF otorrhea. EBM rating: C-4

Obliteration of the Middle Ear and Mastoid Cleft in Subtotal Petrosectomy: Indications, Technique, and Results

Lateral surgical approaches to the base of the skull through the temporal bone often result in a large cavity with exposed dura and vascular structures and no possibility of reconstruction of the middle ear conductive hearing mechanism. Subtotal petrosectomy with tympanomastoid obliteration provides a relatively safe and secure closure of the surgical defect in the temporal bone and eliminates the problems associated with an open mastoid cavity. Eradication of all accessible air cell tracts and mucosa in the petrous pyramid, obliteration of the eustachian tubal orifice, closure of the external auditory canal, and fat obliteration of the middle ear and mastoid clefts are essential in the procedure. Over the last 10 years this technique has been utilized in 372 base of skull procedures with a complication rate of less than 5%. Infection occurred only in those cases with draining cavities or contaminated wounds.

Inflammatory pseudotumor of the temporal bone.

Objective To characterize the clinical presentation, imaging characteristics, intraoperative findings, and key histopathologic features of inflammatory pseudotumors of the temporal bone. Findings from an index case are presented, and the literature is reviewed for comparison. Study Design Retrospective case review. Setting University tertiary referral center. Patients Cases were identified by review of surgical specimens from the temporal bone and lateral skull base with histopathologic confirmation. A single case was identified at our institution. Nine additional cases were identified in the literature; clinical features were reviewed. Intervention Of reported cases, treatment consisted of complete surgical excision in eight cases and subtotal excision in one. The index patient underwent surgical excision with postoperative corticosteroid therapy for adjacent meningeal involvement, after histopathologic interpretation. Corticosteroids were administered to one patient with residual microscopic tumor, and external beam radiotherapy was used for residual/recurrent disease in one case. Results The lesions were typically locally aggressive with extensive bony erosion. Three cases (33%) demonstrated labyrinthine and otic capsule involvement. Four cases (44%) involved the facial nerve. Characteristic histopathologic features included fibroblastic proliferation and a mixed inflammatory cell infiltrate in all cases. Mitotic figures, nuclear pleomorphism, and necrosis were rare or nonexistent. Conclusions Inflammatory pseudotumors of the temporal bone are rare but aggressive lesions. Therapy should consist of surgical excision with steroids reserved for residual or intracranial disease or in patients in whom surgery is not an option. These lesions must be differentiated from other infectious, granulomatous, and neoplastic lesions on the basis of histopathologic and immunohistochemical findings.

Cost-effectiveness of the diagnostic evaluation of vertigo

Objective: To evaluate the cost‐effectiveness of several diagnostic tests used in the evaluation of vertigo.