Rei Motohashi

Characterization of arytenoid vertical displacement in unilateral vocal fold paralysis by three-dimensional computed tomography

The paralyzed arytenoid is not immobile and is subjected to passive movement during phonation. If anatomical changes during inspiration and phonation are compared by three-dimensional computed tomography (3D CT), it is possible to observe vertical movement of the paralyzed arytenoid. Our aim was to use 3D CT to examine the characteristics of 3D arytenoid movement in unilateral vocal fold paralysis (UVFP). This is a prospective study. A total of 61 patients (18 females and 43 males) with UVFP who had undergone 3D CT imaging between April 2005 and January 2007 were included. Cricoid and arytenoid cartilage was imaged by 3D CT. We detected the movements of the paralyzed side when comparing inspiration and phonation. The degree of cranial displacement of the paralyzed arytenoids was classified into three grades (I for mild to III for severe). The mean flow rate (MFR) was calculated for each grade. By comparing the MFR of each grade with the normal control group, we determined whether cases would worsen according to grade. Passive gliding movement of the paralyzed arytenoids was found in 90.7% of cases. In all cases, the paralyzed arytenoids were displaced cranially compared to the unaffected side. MFR worsened significantly as the grade became more severe. We believe that the passive gliding movements observed when comparing inspiration and phonation are characteristic of paralysis. Even in mild cases, the paralyzed arytenoids are passively displaced cranially during phonation, and the degree of this displacement is one indicator that can be used to evaluate the severity of UVFP.

New approach to diagnose arytenoid dislocation and subluxation using three-dimensional computed tomography

Understanding the complex three-dimensional (3D) arrangement of the arytenoid cartilage is necessary for diagnosing arytenoid dislocation (AD) and arytenoid subluxation (AS). We examined the 3D arrangements of AD and AS (AD/AS) cases by region and considered their new diagnoses. This retrospective study included 2 patients with AD, 10 with AS, and 23 with unilateral vocal fold paralysis (UVFP) for comparison. The etiologies were intubation-induced and idiopathic. We classified the AD/AS position into four joint regions: mediocaudal, laterocaudal, mediocranial, and laterocranial. We generated 3D computed tomography (3DCT) images during rest and phonation to analyze functional movements. We attempted to compare the endoscopic findings and 3DCT images of patients with UVFP and AD/AS. To examine the joint status, we especially focused on the position and movements of the muscular process (MP) on the joint because the arytenoid facet is mainly located on the back of the MP. We were able to obtain endoscopic and 3DCT findings characteristic of each AD/AS region. The dislocated MPs were localized to the mediocaudal, mediocranial, and laterocranial regions. Two AD cases were diagnosed due to complete separation of the joint surfaces during rest and phonation. The finding of MPs displacing partially outside the cricoid facet is common to both severe UVFP and AS. The most important differentiation point was that the MP in UVFP cases was located on both the medial and lateral side regions of the joint, but that of AS was on one side region only. Furthermore, no cases of passive gliding movements characteristic of UVFP that have been described previously by us were observed in AD/AS cases. AD can be diagnosed by findings of complete joint separation. AS can be diagnosed based on positions and movements distinct from those of UVFP.

A new procedure of arytenoid adduction combined with type I thyroplasty under general anesthesia using a laryngeal mask

Laryngeal framework surgery is usually performed under local anesthesia. However, some patients are unable to tolerate extended surgery. A case of an 82-year-old woman who underwent medialization thyroplasty and arytenoid adduction of direct lateral cricoarytenoid (LCA) muscle pulling at the same time under general anesthesia using a laryngeal mask is reported. Endoscopic observation through the laryngeal mask allows direct visual control of the vocal cord. The LCA pulling method does not touch the posterior border of the thyroid cartilage so that the laryngeal mask does not disturb the arytenoid adducts.

Morphological change of the cupula due to an ototoxic agent: A comparison with semicircular canal pathology

Conclusion: The cupula shows various degrees of changes after gentamicin (GM) injection into the inner ear, with or without damage of the sensory cells. This cupula change may be a part of the etiology of peripheral vertigo, and is also potentially one of the mechanisms of reduced caloric response. Objectives: To observe the morphological changes of the cupula after injecting GM in the frog inner ear and to compare the changes of the cupula with those of the ampullary sensory cells. Methods: We injected 300 μg (7.5 μl) of GM into the inner ear of 30 bullfrogs (Rana catesbeiana) using a microsyringe under ether anesthesia. The same amount of saline was injected into the other ear as control. The cupulae were observed at 3, 7, and 14 days after GM injection by stereoscopic microscope. The ampullae were fixed, and the sensory cells were assessed using a scanning electron microscope (SEM). The correlation between the changes in the cupula and sensory cells was evaluated using our own scale. Results: In over half of the cupulae in the 7- and 14-day groups, cupula changes such as shrinkage were observed. In about 50% of the total cases, the degree of cupula and sensory cell change correlated in the two groups. In the 14-day group, these changes were more marked. However, there were cases in which the changes of the cupula and sensory cells did not correlate, indicating that the cupula alone can sustain changes without sensory cell damage.

Direct pull of lateral cricoarytenoid muscle for unilateral vocal cord paralysis

Conclusion. Lateral cricoarytenoid muscle-pull surgery (LCA pull) is a safe and effective method for the treatment of unilateral vocal cord paralysis. Objective. To evaluate the results of an improved method of LCA pull for unilateral vocal cord paralysis. Material and methods. Thirteen patients with unilateral vocal cord paralysis underwent LCA pull between April 2003 and January 2004. A small window was made in the posterior lower part of the thyroid cartilage and 2–3 mm in a cranial direction to the lower edge of the thyroid cartilage. The inner perichondrium was carefully removed to expose the LCA muscle. A 4-0 nylon suture placed through the LCA muscle was pulled to adduct the arytenoid and was tied to the anterior lower part of the thyroid cartilage. All cases were treated by LCA pull alone. In all cases, the maximum phonation time was measured and an auditory evaluation was performed using the grade, roughness, breathiness, asthenia and strain scale. The airflow rate was measured in five cases. Results. Vocal improvement was obtained in 11/13 cases (85%). One of the unimproved cases had cricoarytenoid joint ankylosis. No complications were observed.