Change in chorda tympani nerve function after two-stage tympanoplasty for cholesteatoma.

Objectives: Chorda tympani nerve (CTN) function may be damaged more by two-stage than by one-stage surgery for middle ear cholesteatoma. However, few studies have reported the relationship between two-stage cholesteatoma surgery and CTN function. This study aimed to investigate CTN function after two-stage surgery for cholesteatoma. Methods: In this prospective study, 35 patients underwent two-stage canal wall up tympanoplasty (CWUT). Perioperative CTN function was assessed using questionnaires and electrogustometry (EGM). Participants were categorized into minor, major, and section groups, based on the degree of CTN manipulation during surgery. Results: In the first-stage surgery, posterior tympanotomy with an intact canal wall reduced the degree of CTN manipulation. The incidence of taste disorder after the first-stage surgery was 71.4%. Postoperative taste disorder and the EGM threshold improved early in the minor manipulation group. In the second-stage surgery, no new CTN damage occurred, even if this surgery involved removal of residual cholesteatoma. The incidence of taste disorder after second-stage surgery was less than that after first-stage surgery, independent of CTN preservation. However, the recovery rate of the EGM threshold after second-stage surgery was significantly lower in the section group than in those with CTN preservation. Conclusion: CTN function, including symptoms and EGM threshold, can be preserved during two-stage cholesteatoma surgery if care is taken to preserve the CTN in both the first- and second-stage surgeries. A two-stage CWUT, ensuring an intact bony annulus, may be effective to facilitate CTN preservation. Level of Evidence: 2b.

Volume-rendered computed tomography images of the surgical field for endolymphatic sac surgery.

PURPOSE: Identification of the endolymphatic sac has failed occasionally. Postoperative complications have also rarely been reported. Given a safer and more reliable surgery, preoperative anatomical assessments are valuable, however, the vestibular aqueduct has seldom been seen with multi-planar reconstruction (MPR) computed tomography (CT) images yet. Our study aimed to determine the significance and utility of volume-rendered (VR) CT images of the surgical field for identifying the vestibular aqueduct, compared with MPR CT images. SUBJECTS AND METHODS: 14 patients with Meniere's disease who underwent endolymphatic sac surgery between 2008 and 2011. Location and size of the vestibular aqueduct were assessed using VR and MPR CT images, independently. RESULTS: Accuracy of identifying the location differed significantly between VR and MPR CT images (rate of total correct evaluations: 100% by VR CT images vs 75% by MPR CT images, p = 0.02). Size was correctly identified in cases with a small endolymphatic sac using VR CT images (rate of total correct evaluations for size of the vestibular aqueduct: 100% by VR CT vs 57% by MPR CT, p = 0.046). VR CT images also demonstrated clearly the relationship between the endolymphatic sac and high jugular bulb. In two cases, the endolymphatic sac was identified by VR images, not by MPR images. CONCLUSION: Accurate information about the location and size of vestibular aqueduct can allow sac surgeons to identify a tiny endolymphatic sac more easily and certainly, and also aids surgical trainees to learn sac surgery safely.

The gray scale value of ear tissues undergoing volume-rendering high-resolution cone-beam computed tomography.

OBJECTIVE: When the thresholds for VR reconstruction from multi-slice CT images are changed, problems develop when assessing pathologies in the absence of standardized thresholds. The advantages of CBCT include lower radiation exposure compared with other techniques and better visualization of small ear structures. However, a disadvantage is that the scanner provides unstandardized gray scale values, thus not CT numbers (Hounsfield units, HU). METHODS: We analyzed 88 sets of volume data obtained from temporal bones. The gray scale values were measured in aerated areas (two sites), along the ossicular chain (four sites) and in a bone area (one site) in the external and middle ears, and in soft tissue areas (five sites) and bone areas (two sites) in the inner ear. RESULTS: The standard male and female gray scale values were 2448-2970 and 2585-3091 for the aerated areas, 3248-4945 and 3359-5223 for the ossicular chains, 3368-4109 and 3371-4147 for soft tissues, and 4790-5776 and 5044-5959 for bone, respectively. Sex significantly affected the values (p<0.05). Significant differences between aerated areas and ossicular chains, and between soft tissues and bone, were evident (all p<0.0001). CONCLUSION: Volume-rendering (VR) images obtained by cone-beam computed tomography (CBCT) can be standardized simply by using fixed thresholds.

Usefulness of the Saccharin Test for Assessment of Eustachian Tube Function in Patients With Chronic Otitis Media With Perforation.

OBJECTIVE: The eustachian tube (ET) has two important functions, ventilation and clearance of the middle ear. We evaluated the ET ventilator function by the sonotubometry and the inflation-deflation test that are widely used today, and the ET clearance function by the saccharin test. Results of both tests were compared with surgical outcomes, and assessed which test was more closely related to the surgical outcomes. STUDY DESIGN: Prospective case series. SETTING: A single university hospital. PATIENTS AND INTERVENTION: One hundred four ears of 95 patients with chronic otitis media with perforation underwent type I tympanoplasty. MAIN OUTCOMES AND MEASURES: Based on sonotubometry and the inflation-deflation test, the patients were divided into normal, stenosis, and patulous types. Based on the saccharin test, they were divided into a normal function group and a partial/gross dysfunction group. Surgical outcomes about the hearing results and the condition of the eardrum were assessed 1 year postoperatively. Preoperative evaluation of ET function was compared with the surgical outcome. RESULTS: Sonotubometry and inflation-deflation tests showed there was no significant difference among the groups about the hearing improvement and the surgical success rate. The saccharin test showed that the rate of the hearing improvement was significantly lower in the gross dysfunction group and that the success rate of Type I tympanoplasty was significantly higher in the normal group than in the dysfunction group. CONCLUSION: There is a relationship between the saccharin test results and surgical outcomes.

A case of pneumolabyrinth induced by Eustachian tube air inflation.

OBJECTIVES: Here, we report a case of pneumolabyrinth induced by Eustachian tube air inflation (ETAI) with a catheter and present evidence that multiple air bubbles entered the perilymphatic space through a preexisting oval window fistula. SETTING: Tertiary referral center. PATIENT: Sixty-six-year-old woman. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Air bubbles in the perilymphatic space revealed by cone beam computed tomography (CT) volume rendering imaging. RESULTS: The patient was referred to us because of vertigo, unsteadiness, and right hearing loss after ETAI using a Eustachian tube catheter. On Day 2, an audiogram showed right total deafness, and the perilymphatic space could not be identified on T2-weighted magnetic resonance imaging. A high-resolution cone beam CT scan obtained on Day 3 showed multiple air bubbles in the labyrinth. The volume rendering images clearly revealed a larger air bubble in the vestibule inside the footplate of the stapes and small air bubbles in the horizontal semicircular canal, superior semicircular canal, and basal and second turns of the cochlea. This finding indicates that the air bubbles entered the perilymphatic space through an oval widow fistula caused by a sudden elevation in intratympanic air pressure. Two months later, the air bubbles had disappeared, and the patient's high tone hearing had improved slightly. CONCLUSION: ETAI can cause a pneumolabyrinth if the intratympanic pressure rises beyond a certain critical level. In this situation, volume rendering imaging of high-resolution cone beam CT can be used to quantify and identify the air bubbles present. The images taken in this study suggest that air bubbles entered the perilymphatic space through a perilymphatic fistula.

Position of TORP on the stapes footplate assessed with cone beam computed tomography.

OBJECTIVE: To improve hearing outcomes of ossiculoplasty with a total ossicular replacement prosthesis (TORP) in ears lacking a footplate superstructure, 3-dimensional computed tomography (3D CT) images were reconstructed to verify the position of the TORP on the footplate and contact between the TORP and the stapes footplate. STUDY DESIGN: Retrospective study. SETTING: University-affiliated tertiary referral center. PATIENTS: Six ears of 6 patients who underwent ossiculoplasty with TORP and were followed for greater than 3 years postoperatively. INTERVENTION: Cone beam CT (CBCT) images. MAIN OUTCOME MEASURES: An en face view of the stapes footplate and a volume-rendered 3D image were reconstructed. RESULTS: The en face view of the stapes footplate showed whether the TORP was centered on the stapes footplate. Volume-rendered 3D CBCT images revealed TORP malpositioning or migration, which were not detected on 2-dimensional CBCT images. In such cases, the TORP shaft was in contact with the wall of the oval window niche or the TORP had moved from the stapes footplate. CONCLUSION: Accurate visualization of TORP location on the footplate is important. Images that accurately show the position of the TORP on the stapes footplate will help improve hearing outcomes.

Taste disturbance after stapes surgery--clinical and experimental study.

CONCLUSION: Most of the clinical cases experienced taste disturbance after stapes surgery, and in a few cases this disturbance persisted for a long time. The animal experiment suggested the role of geniculate ganglion (GG) cells in nerve generation. OBJECTIVES: To clinically examine taste disorder and its recovery after stapes surgery and experimentally demonstrate a role of GG. PATIENTS AND METHODS: Taste function after preservation of chorda tympani nerve (CTN) in stapes surgery was prospectively investigated with a questionnaire and electrogustometry (EGM). Further, expression of neurotrophic factors in GG after injury of CTN was examined by in situ hybridization histochemistry (ISSH) and RT-PCR. RESULTS: Among the cases, 15/18 (83.3%) were associated with taste disturbance and 6/18 (33.3%) were associated with tongue numbness 2 weeks after surgery; however, the symptoms ceased in 14/18 cases (77.8%). Two weeks after surgery, the EGM threshold was found to be elevated in 15/18 cases (83.3%), while in 10/18 cases (55.6%), it did not decrease until 1 year after surgery. Expression of ISSH and amplified bands of BDNF and GFR increased at 7 and 14 days after nerve injury in ipsilateral GGs and also increased at 7 days on the contralateral side.

[Treatment outcome in patients with taste disturbance].

The importance of taste has been recently evaluated from the standpoint of quality of life, but few reports exist on the clinical status of taste disturbance. We classified taste disturbance by cause and studied the effect of treatment and recovery duration. Subjects were 321 patients with taste disturbance, i.e., 131 men and 190 women (mean age: 59.9 years). Electrogustometry (EGM) and filter paper disks (FPD) were used to assess taste function in all subjects. We also asked them all about the degree of symptoms using visual analog scale (VAS). Statistical analysis was done using the unpaired t-test, with p<0.05 considered significant. Patients were treated with zinc sulfate, ferrotherapy, herbal medicine, and minor tranquilizers. Causes of taste disturbance were classified into idiopathic, post-common-cold, drug-induced, psychogenic, constitutional, and iron deficiency. Idiopathic taste disturbance was the commonest cause (125 cases, 38.9%), followed by drug-induced (62 cases, 19.3%), and post common cold (38 cases, 11.8%). Drug induced and psychogenic taste disturbance have increased. Recovery from symptoms was 79/103 (76.7%) in idiopathic taste disturbance, 24/33 (72.7%) in post-common-cold, and 14/17 (82.4%) in iron deficiency. Recovery took 22.2 weeks. Recovery was 32/50 cases (62.4%) in drug induced, taking 48 weeks. For all causes, EGM and FPD results were not associated with the degree of symptoms. Both tests tended to show delayed improvement compared to symptoms. Cases taking more than 6 months from symptom onset to medical examination showed significantly lower improvement and longer recovery time than those taking 6 months on less (p = 0.04).