Yohei Honkura

NRF2 Is a Key Target for Prevention of Noise-Induced Hearing Loss by Reducing Oxidative Damage of Cochlea

Noise-induced hearing loss (NIHL) is one of the most common sensorineural hearing deficits. Recent studies have demonstrated that the pathogenesis of NIHL is closely related to ischemia-reperfusion injury of cochlea, which is caused by blood flow decrease and free radical production due to excessive noise. This suggests that protecting the cochlea from oxidative stress is an effective therapeutic approach for NIHL. NRF2 is a transcriptional activator playing an essential role in the defense mechanism against oxidative stress. To clarify the contribution of NRF2 to cochlear protection, we examined Nrf2–/– mice for susceptibility to NIHL. Threshold shifts of the auditory brainstem response at 7 days post-exposure were significantly larger in Nrf2–/– mice than wild-type mice. Treatment with CDDO-Im, a potent NRF2-activating drug, before but not after the noise exposure preserved the integrity of hair cells and improved post-exposure hearing levels in wild-type mice, but not in Nrf2–/– mice. Therefore, NRF2 activation is effective for NIHL prevention. Consistently, a human NRF2 SNP was significantly associated with impaired sensorineural hearing levels in a cohort subjected to occupational noise exposure. Thus, high NRF2 activity is advantageous for cochlear protection from noise-induced injury, and NRF2 is a promising target for NIHL prevention.

A case of myoepithelioma of the nasal cavity

Myoepithelioma is a rare tumor, most frequently located in the salivary gland. Case reports of extra-salivary myoepithelioma are sporadic, with only one case in the nasal cavity. A 68-year-old male patient presented with a myoepithelioma of the nasal cavity manifesting as nasal obstruction and epistaxis, which was treated successfully with endoscopic excision. Histological examination revealed myoepithelial cells and myxoid stroma, which confirmed the diagnosis of myoepithelioma. The behavioral pattern is similar to if not identical with that of the mixed tumor, pleomorphic adenoma, which is benign, but the potential for recurrence is always present, especially if complete resection is not achieved.

Pyramidal lobe of the thyroid gland and the thyroglossal duct remnant: A study using human fetal sections

To investigate developmental changes in the thyroglossal duct, we observed serial sagittal sections of eight embryos (crown-rump length (CRL) 6-12 mm; approximately 5-6 weeks of gestation) as well as serial horizontal or cross-sections of 70 embryos and fetuses (CRL 15-110 mm; 6-15 weeks). In the sagittal sections, the thyroglossal duct was identified as a small sheet or mass of relatively large cells with vacuolization anterior, superior or inferior to the fourth pharyngeal arch artery. However, we found no continuous duct-like structure that reached the thyroid gland. Thus, previous classical schemes might have overestimated the continuity of the duct. Among cross-sections of 70 specimens, we found the thyroglossal duct remnant in only two specimens (CRL 15 mm and 100 mm), in contrast to the pyramidal lobe, which was seen in one-third of the specimens. The duct remnant ran downward along the lateral edge of the hyoid body to reach the anterior aspect of the thyroid cartilage. However, the connection between the pyramidal lobe and the duct remnant was interrupted by the anterior cervical muscles. Therefore, it was unlikely that the thyroglossal duct remnant would more frequently be evident in fetuses than in adults. The highly tortuous course of the duct along the lingual aspect of the hyoid body, which has been reported previously, appeared to become established near term. Descent of the thyroid gland was not evident after the CRL 20 mm stage (6 weeks): the gland appeared to retain its position at the level of the third-sixth cervical vertebrae.

Central-part laryngectomy is a useful and less invasive surgical procedure for resolution of intractable aspiration

A novel narrow-field laryngectomy procedure known as central-part laryngectomy (CPL) for less invasive laryngeal diversion in patients with intractable aspiration is introduced. We conducted retrospective case reviews of 15 patients who underwent CPL. In this procedure, an area of the glottis including the mid-part of the thyroid cartilage and cricoid cartilage is removed to separate the digestive tract from the air way. The lateral part of the thyroid cartilage, the entire hypopharyngeal mucosa and epiglottis are preserved. The superior laryngeal vessels and nerve are not invaded. All fifteen patients were relieved of aspiration without major complications. In good accordance with cutting of the cricopharyngeal muscles and removal of the cricoid cartilage, postoperative videofluoroscopy demonstrated smooth passages of barium. Ten of 12 patients who had hoped to resume oral food intake became able to do so after CPL and two others also achieved partial oral deglutition. CPL is a useful procedure for treatment of intractable aspiration and offers considerable advantages over other laryngotracheal diversion procedures from the view point of oral food intake.

Cricoarytenoid Articulation in Elderly Japanese With Special Reference to Morphology of the Synovial Tissue

Objective: To clarify composite fibers and cells in the synovial tissues of the cricoarytenoid joint (CA joint). Methods: Routine histology and immunohistrochemistry using sagittal or nearly sagittal sections obtained from 18 elderly cadaveric specimens. Results: The CA joint capsule was thin and contained few elastic fibers. A limited supportive ligament, namely, a thickened fascia of the posterior cricoarytenoid muscles, was sometimes evident on the lateral aspect of the CA joint. However, even in the weaker medial aspect of the joint, no marked destruction of the synovial tissues was found. The CA joint always contained synovial folds—a short medial fold and long lateral folds—but these contained no or few macrophages, lymphocytes, and blood capillaries. In 2 exceptional specimens showing inflammatory cell infiltration in the submucosal tissue of the larynx, the macrophage-rich area extended toward the capsule and medial synovial fold. Conclusions: The lateral aspect of the CA joint was likely to be supported mechanically by the muscle-associated tissues. Strong support of the arytenoid by muscles might reduce the degree of CA joint injury with age. However, some patients with hoarseness due to mucosal inflammation of the larynx might have accompanying synovitis and subsequent cartilage injury in the CA joint.

Surgical treatment for the aberrant internal carotid artery in the middle ear with pulsatile tinnitus

Many previous reports have indicated that pulsatile tinnitus caused by an aberrant internal carotid artery (ICA) should not be treated surgically because of the risk of infection or aneurysm formation. We herein describe a case of aberrant ICA treated by middle ear surgery for which we introduced a novel approach. An 84-year-old man was presented with a one-year history of tinnitus in his right ear. Otoscopic examination demonstrated a whitish mass in the antero-inferior quadrant of the tympanic membrane associated with rhythmic pulsation. Images obtained by CT, MRI and MRA revealed protrusion of the ICA into the tympanic cavity, making contact with the tympanic membrane. Surgery to separate the tympanic membrane from the ICA was performed in order to relieve the pulsatile tinnitus. After the operation, the patients aural activity was preserved and the tinnitus did not recur within a follow-up period of one year. In the present case, delicate middle ear surgery was effective for relief of the tinnitus. When treating patients with aberrant IAC showing features similar to the present case, the surgical approach we have described is worth attempting.

Cricothyroid Articulation in Elderly Japanese With Special Reference to Morphology of the Synovial and Capsular Tissues.

OBJECTIVE The present study aimed to clarify individual variations in the cricothyroid joint (CT joint). METHODS Using 30 specimens of the CT joint obtained from elderly donated cadavers, we examined the composite fibers of the capsular ligament as well as the morphology of the synovial tissue. RESULTS The capsular ligament consistently contained abundant thick elastic fiber bundles on the anterior side of the joint (anterior band) and an elastic fiber-made mesh on the posterior side (posterior mesh). The synovial membrane, lined by synovial macrophages, was usually restricted to the recesses in the medial or inferior end of the joint cavity. Without the synovial lining, elastic fibers of the capsular ligament were subsequently detached, dispersed, and exposed to the joint cavity. We also observed a folded and thickened synovial membrane and a hypertrophic protrusion of the capsular ligament. In six specimens, the joint cavity was obliterated by debris of synovial folds and elastic fiber-rich tissues continuous with the usual capsular ligament. Notably, with the exception of two specimens, we did not find lymphocyte infiltration in the degenerative synovial tissue. DISCUSSION We considered the CT joint degeneration to be a specific, silent form of osteoarthritis from the absence of lymphocyte infiltration. For high-pitched phonation, the elderly CT joint seemed to maintain its anterior gliding and rotation with the aid of elastic fiber-rich tissues compensating for the loss of congruity between the joint cartilage surfaces. Conversely, however, high-pitched phonation may accelerate obliteration of the joint.

Bilateral endoscopic endonasal marsupialization of nasopalatine duct cyst

Nasopalatine duct cysts are the most common non-odontogenic cysts in the maxilla, and are conventionally treated through a sublabial or palatine approach. Recently, the endoscopic approach has been used, but experience is extremely limited. We treated a 29-year-old male with nasopalatine duct cyst by endoscopic marsupialization, but paresthesia of the incisor region occurred after surgery. This paresthesia gradually remitted within 6 months. The nasopalatine nerve, which innervates the upper incisor region, enters two lateral canals separately at the nasal floor and exits the central main canal at the palate. Damage to the bilateral nasopalatine nerves might lead to paresthesia, so we recommend careful examination for nerve fibers during endoscopic surgery, especially if fenestration is performed on both sides.

Enteric neurons of the esophagus: an immunohistochemical study using donated elderly cadavers.

PurposeTo describe and discuss the normal anatomy and function of enteric neurons in the esophagus of aged individuals.MethodWe examined ganglion cells in esophagus specimens obtained from 15 elderly cadavers without any macroscopic pathology in the mediastinum and abdomen. Neuronal nitric oxide synthase and vasoactive intestinal polypeptide were used as parasympathetic nerve markers, and tyrosine hydroxylase as a sympathetic nerve marker.ResultsThe thoracic and abdominal esophagus contained a well-developed myenteric nerve plexus (S100 protein-positive area) in the intermuscular layer: 0.02–0.03 mm2 per 1-mm length of the circular esophageal wall. The cervical esophagus usually contained no ganglion cells. The number of parasympathetic ganglion cells was maximal in the upper or middle thoracic esophagus (mean 18–23 cells per section), whereas sympathetic cells were considerably less numerous at any sites (mean 1–3 cells).ConclusionIn comparison with previous data from elderly cadavers, the esophagus carried much fewer ganglion cells than the intestine and colon; sympathetic cells were particular less numerous. Esophageal smooth muscle exhibits a unique mode of peristalsis characterized by a rebound contraction with a long latency after stimulation. This type of peristalsis appears to be regulated by inhibitory, nNOS-positive nerves with a sparse distribution, which seems to account for the long-span peristalsis unique to the esophagus. The extreme sparsity of ganglion cells in the cervical esophagus suggests that enteric neuron-integrated peristalsis, like that in the intestine and colon, is unlikely. Surgical treatment of the esophagus is likely to change or impair these unique features.

Osseous hamartoma arising from the Eustachian tube

A fairly quite rare case of osseous tumor arising from the Eustachian tube (ET) is described. A 56-year-old man presented with a smooth bulky mass in the nasopharynx and secretory otitis media in the right ear. Computed tomography and magnetic resonance imaging indicated a solid tumor-like region occupying the nasopharynx with apparent extension to the right ET. Transnasal endoscopic surgery demonstrated that the tumor had originated from the ET, and the tumor was partially removed in the area where it had expanded into the nasopharynx. The pathological diagnosis was an osseous hamartoma consisting of bony tissue, fat cells and fibroblasts. To our knowledge, this is the first reported case of osseous hamartoma arising from the ET in the world literature. The patient presented symptoms of nasal obstruction and unilateral aural fullness. Reduction surgery and tympanostomy tube insertion were useful for accurate diagnosis and resolution of the symptoms.