Sung Huhn Kim

Gamma Knife radiosurgery for functioning pituitary microadenoma.

Transsphenoidal microsurgery remains the treatment of choice for pituitary microadenomas One hundred and six patients were treated with Gamma Knife radiosurgery (GKRS) for pituitary adenomas, and of these, 23 patients (1 male, 22 female) had microadenomas. Twenty-two of these patients were followed up and endocrinological tests were available for 15 of these 22. Thirteen of these 15 had prolactinomas, while the remaining 2 had acromegaly. The follow-up period was from 3 to 26 months (median 12 months). The mean age was 33.6 years (range 21 to 60 years). The mean maximum tumor dose was 35.7 Gy and the mean margin dose was 22 Gy. Serum prolactin (PRL) was normalized in three patients, decreased in eight and unchanged in two. The growth hormone (GH) secretion in the acromegalic patients has remained unchanged through the follow-up period. Thus, GKRS is a valuable adjuvant to transsphenoidal microsurgery for patients with pituitary microadenomas.

Molecular analysis of the GJB2, GJB6 and SLC26A4 genes in Korean deafness patients

OBJECTIVES Mutations in the GJB2, GJB6 and SLC26A4 genes are a frequent cause of hearing loss in a number of populations. However, little is known about the genetic causes of hearing loss in the Korean population. METHODS We sequenced the GJB2 and GJB6 genes to examine the role of mutations in these genes in 22 hearing loss patients. We also sequenced the SLC26A4 gene in seven patients with inner ear malformations, including enlarged vestibular aqueduct (EVA) revealed by computer tomography. RESULTS Coding sequence mutations in GJB2 were identified in 13.6% of the patients screened. Two different mutations, 235delC and T86R were found in three unrelated patients. The 235delC was the most prevalent mutation with an allele frequency of 6.9% in our patient group. No mutations, including 342-kb deletion, were found in GJB6 gene. Three different variants of SLC26A4 were identified in the EVA patients, including one novel mutation. Four EVA patients carried two mutant alleles of SLC26A4, and at least one allele in all patients was the H723R mutation, which accounted for 75% of all mutant alleles. CONCLUSIONS Our results suggest that GJB2 and SLC26A4 mutations together make up a major cause of congenital hearing loss in the Korean population. Further studies may be able to identify other common variants that account for a significant fraction of hearing loss in the Korean population.

Mastoid and Epitympanic Obliteration in Canal Wall Up Mastoidectomy for Prevention of Retraction Pocket

Objective: To evaluate the surgical outcome in patients who have undergone mastoid and epitympanic obliteration technique. Study Design: Retrospective review. Setting: Tertiary care referral center. Patients: The study group included 151 patients with cholesteatoma who underwent mastoid and epitympanic obliteration technique. This technique was applied to cases who had a strong chance of recurrent retraction pocket and cholesteatoma formation, including those patients with an adhesive drum indicating poor eustachian tube function (n = 52) and patients with a destructive scutum (n = 68). Thirty-one patients had both an adhesive drum and a destructive scutum. Intervention: The connection between the mastoid cavity and the middle ear was blocked by obliterating the epitympanum and antrum with bone pate and the remaining mastoid cavity with abdominal fat. Main Outcome Measures: The postoperative drum state, the incidence of retraction pocket formation and cholesteatoma recurrence, the surgical complications of obliteration, and the hearing outcome. Results: In 114 of 151 patients (75.4%), the middle ear was well healed and well aerated. The retraction pocket formation or cholesteatoma recurrence did not develop in any subject. Postauricular skin depression was the most common complication of this technique (n = 31 [20.5%]). In three patients (2.0%), the bone pate used for obliteration was infected. Of the 56 cases who underwent a staged operation to regain their hearing, 37 resulted in a postoperative air-bone gap less than 20 dB hearing level. Conclusion: Mastoid and epitympanic obliteration is an effective option for preventing a retraction pocket and cholesteatoma recurrence in patients with a poorly functioning eustachian tube or a defective scutum, while preserving the same advantage of the canal wall up technique.

Management of facial nerve schwannoma in patients with favorable facial function

Objective: We report six cases of facial nerve schwannomas in which surgical management allowed the preservation of facial nerve function. Specifically, this paper reports that a stripping surgery may provide favorable functional outcomes.

Adverse Events and Discomfort During Magnetic Resonance Imaging in Cochlear Implant Recipients

IMPORTANCE Patients with cochlear implants (CIs) should be fully informed before undergoing magnetic resonance imaging (MRI) about the possibility of discomfort or pain. Prior to an MRI scan, patients need to fully understand not only the potential complications but also the potential discomfort that they may experience during the scan. OBJECTIVE To assess the adverse events during MRI in patients with CIs and to investigate the safety and diagnostic efficiency of MRI in patients with CIs with internal magnets. DESIGN, SETTING, AND PARTICIPANTS Retrospective review of the medical records of 18 patients with CIs undergoing MRI between September 2003 and February 2014 at a single tertiary referral center. INTERVENTIONS Sixteen patients underwent MRI in a 1.5-T scanner, and 2 patients underwent MRI in a 3.0-T scanner. Twelve brain MRI scans were performed, and 18 MRI scans were performed in areas outside the brain. MAIN OUTCOMES AND MEASURES Discomfort or pain, adverse events, and auditory performance after MRI were evaluated using medical records or interviews. RESULTS Thirteen of 18 patients completed their MRI scans (25 of 30 scans). Five patients with head bandages were unable to complete their MRI scans owing to pain; one of these patients experienced magnet displacement, and another underwent surgery for magnet removal and reinsertion. Finally, 1 patient experienced polarity reversal of the magnet. Artifacts induced by the CI internal magnet compromised the diagnosis of ipsilateral brain lesions under 1.5-T MRI. Auditory performance in the CI recipients who had major events was unaffected. CONCLUSIONS AND RELEVANCE Even with protective head bandages, 1.5-T MRI in patients with CIs led to a variety of adverse events, including discomfort or pain and displacement of the internal magnet. Therefore, sedation and careful head positioning may be appropriate for some patients with CIs who undergo MRI, and these patients should be carefully monitored to decrease the likelihood of such adverse effects.

Autoimmunity as a Candidate for the Etiopathogenesis of Meniere's Disease: Detection of Autoimmune Reactions and Diagnostic Biomarker Candidate

Menieres disease is an inner ear disorder that can manifest as fluctuating vertigo, sensorineural hearing loss, tinnitus, and aural fullness. However, the pathologic mechanism of Menieres disease is still unclear. In this study, we evaluated autoimmunity as a potential cause of Menieres disease. In addition we tried to find useful biomarker candidates for diagnosis. We investigated the protein composition of human inner ear fluid using liquid column mass spectrometry, the autoimmune reaction between circulating autoantibodies in patient serum and multiple antigens using the Protoarray system, the immune reaction between patient serum and mouse inner ear tissues using western blot analysis. Nine proteins, including immunoglobulin and its variants and interferon regulatory factor 7, were found only in the inner ear fluid of patients with Menieres disease. Enhanced immune reactions with 18 candidate antigens were detected in patients with Menieres disease in Protoarray analysis; levels of 8 of these antigens were more than 10-fold higher in patients than in controls. Antigen-antibody reactions between mouse inner ear proteins with molecular weights of 23–48 kDa and 63–75 kDa and patient sera were detected in 8 patients. These findings suggest that autoimmunity could be one of the pathologic mechanisms behind Menieres disease. Multiple autoantibodies and antigens may be involved in the autoimmune reaction. Specific antigens that caused immune reactions with patients serum in Protoarray analysis can be candidates for the diagnostic biomarkers of Menieres disease.

A cupulolith repositioning maneuver in the treatment of horizontal canal cupulolithiasis

OBJECTIVE We evaluated outcomes and their significance of a new treatment method for horizontal canal cupulolithiasis that could be applied regardless of the side of the cupula where otoliths are attached. METHODS Consecutive 78 patients who showed persistent apogeotropic horizontal canal positional vertigo (horizontal canal cupulolithiasis) were enrolled, and they were treated with the new cupulolith repositioning maneuver. RESULTS Horizontal semicircular canal cupulolithiasis was alleviated in 97.4% of patients, after an average of 2.1 repetitions of the maneuver. Otoliths were suspected to be attached to the canal side of the cupula in 30 cases and the utricular side in 44 cases. CONCLUSION The cupulolith repositioning maneuver is an effective method for treating horizontal canal cupulolithiasis. It may also provide an insight into the side of the cupula where otoliths are attached.

Intracanalicular facial nerve schwannoma.

Objective: To investigate the capability of preoperative evaluations in predicting the precise anatomic origin of intracanalicular tumors. Study Design: We conducted a retrospective case review. Setting: Tertiary referral center. Patients: A total of 11 patients (8 men and 3 women, 26-70 years old) with intracanalicular tumors who were treated surgically were included. Interventions: Pure-tone average, auditory brainstem response, caloric test, and temporal magnetic resonance imaging were done in all 11 patients. Electroneuronography has only been performed since 2003, and only 3 patients were evaluated. Main Outcome Measure: Preoperative symptoms, pure-tone average, auditory brainstem response, caloric test, electroneuronography, and magnetic resonance imaging were compared between patients with facial nerve schwannomas and patients with vestibular schwannomas. Results: Postoperatively, facial nerve schwannomas were diagnosed pathologically in 2 (18%) of 11 patients. There were not any clues suggesting facial nerve schwannoma in preoperative evaluations. Conclusion: A facial nerve schwannoma may be misdiagnosed as a vestibular schwannoma, especially when the tumor is confined to the internal auditory canal. There are no useful preoperative evaluation tools in predicting the precise nerve origin of intracanalicular tumors. These emphasize the need to fully inform the patient preoperatively.

Functional and molecular expression of epithelial sodium channels in cultured human endolymphatic sac epithelial cells.

Hypothesis: Epithelial sodium channels are expressed in cultured human endolymphatic sac (ES) epithelial (HESE) cells and epithelial sodium channel (ENaC) expression is suppressed by interleukin 1&bgr;. Background: The ES is part of the membranous labyrinth in the inner ear that plays an important role in maintaining homeostasis of the endolymphatic fluid system. However, the exact mechanism of fluid volume regulation is not yet known. Methods: The ES specimens were harvested during acoustic neuroma surgery (n = 13) using the translabyrinthine approach and were subcultured with high-epidermal growth factor (25 ng/mL) media. Results: The serially passaged HESE cells differentiated into a monolayer of confluent cells and some of the cultured cells had features of mitochondria-rich cells. Reverse transcription-polymerase chain reaction revealed that ENaC subunits are expressed in the cultured HESE cells. We also confirmed the presence of an ENaC-dependent short-circuit current in the cultured HESE cells. Interestingly, ENaC mRNA expression and ENaC-dependent current decreased after treatment with interleukin 1&bgr; (10 nmol/L for 24 h). Conclusion: These findings suggest that ENaC plays an important role in fluid absorption in the human ES and that its function may be altered during inflammatory conditions.

Interferon‐γ suppresses Na+–H+ exchanger in cultured human endolymphatic sac epithelial cells

Adequate regulation of endolymphatic pH is essential for maintaining inner ear function. The Na+–H+ exchanger (NHE) is a major determinant of intracellular pH (pHi), and facilitates Na+ and fluid absorption in various epithelia. We determined the functional and molecular expression of NHEs in cultured human endolymphatic sac (ES) epithelial cells and examined the effect of IFN‐γ on NHE function. Serial cultures of human ES epithelial cells were generated from tissue samples. The molecular expression of NHE1, ‐2, and ‐3 isoforms was determined by real‐time RT‐PCR. The functional activity of NHE isoforms was measured microfluorometrically using a pH‐sensitive fluorescent dye, 2′,7′‐bis(carbonylethyl)‐5(6)‐carboxyfluorescein (BCECF), and a NHE‐inhibitor, 3‐methylsulfonyl‐4‐piperidinobenzoyl guanidine methanesulfonate (HOE694). NHE1, ‐2, and ‐3 mRNAs were expressed in human ES epithelial cells. Functional activity of NHE1 and ‐2 was confirmed in the luminal membrane of ES epithelial cells by sequentially suppressing Na+‐dependent pHi recovery from intracellular acidification using different concentrations of HOE694. Treatment with IFN‐γ (50 nM for 24 h) suppressed mRNA expression of NHE1 and ‐2. IFN‐γ also suppressed functional activity of both NHE1 and ‐2 in the luminal membrane of ES epithelial cells. This study shows that NHEs are expressed in cultured human ES epithelial cells and that treatment with IFN‐γ suppresses the expression and functional activity of NHE1 and ‐2. J. Cell. Biochem. 107: 965–972, 2009.