Ikuichiro Hiroto

XXX Electromyographic Investigation of Human Vocal Cord Paralysis

Electromyography is one of the most useful techniques in diagnosing pathologies of the lower motor neuron, neuromuscular junction and muscle. It has been utilized extensively with large skeletal muscles, such as those of the extremities, but it has not been a popular clinical test for the intrinsic laryngeal muscles. This lack of popularity may be due chiefly to difficulties met in inserting needle electrodes into the intrinsic laryngeal muscles and difficulties in obtaining the single motor unit potentials so essential to diagnosis. Hiroto, Hirano, Toyozumi and Shin (1962)9 reported transcutaneous methods for approaching the intrinsic laryngeal muscles. These methods make it possible to use electromyography as a routine procedure in diagnosing laryngeal paralysis. METHOD

LXIX Electromyographic Investigation of the Intrinsic Laryngeal Muscles Related to Speech Sounds

Electromyography is one of the most helpful experimental procedures in the field of physiology of the larynx and provides direct information about activity of the laryngeal muscles. Many electromyographic investigations of the intrinsic laryngeal muscles have been made since Weddell et alP first recorded electrical action potentials of these muscles. In almost all of these studies, a needle electrode was inserted into the intrinsic laryngeal muscles through the mouth except in the cricothyroid muscle in which an electrode was always placed through the skin. When the subject has a needle and wire in his mouth and throat, it is extremely difficult or impossible to utter speech sounds normally. In the past, therefore, electromyographic investigations related to phonation, except of the cricothyroid muscle, were limited to only some vowels.

Immunopathological Study of the Larynx: IgA Distribution and Secretory Activity

Using immunofluorescent and histopathological techniques, we studied the distribution and secretory activity of the glands of the larynx from 55 humans. The cavity of the larynx was covered with secretory glandular cells with the exception of the true vocal cords, aryepiglottic folds and upper part of the laryngeal surface of the epiglottis. Immunofluorescent study revealed the presence of IgG and other immunoglobulins throughout the connective tissue ground in each laryngeal mucosa. The most striking was seen in the staining pattern of IgA. Diffuse fluorescence for IgA was observed not only in the submucosal or periglandular connective tissue area but also in the intraepithelial or submucosal glands. Secretory component synthesis was found mainly in each serous-type glandular epithelium or acinus. In the submucosal or periglandular area, IgA producing plasma cells were numerous. Our observations suggest that IgA, produced locally, is secreted via the glandular cells as secretory component — SIgA. Secretory activity of SIgA in these glandular tissues indicates that the larynx is possibly an immunologically active organ in the upper respiratory tract.

Local immune system in the developing fetal larynx

Using histopathological and immunofluorescent techniques, we investigated the development of the glandular system of the larynx from 12 human fetuses. Glandular buds were first observed at the fourth month of gestation and glandular distribution became evident from the fifth month in the larynx. Ciliated or nonciliated epithelium covered the cavity of the larynx, with the exception of the true vocal cord. Immunofluorescent examination revealed the presence of IgG in the fetal larynx, but there was little fluorescence for IgA, IgM and IgE. Secretory component (SC) synthesis, on the other hand, was found in each serous‐type glandular epithelium or acinus from the fourth month on. Our observations suggest that the local immune system by SC, which binds to IgA as SIgA in human laryngeal mucosa, is inherently acquired in the fetal larynx.

Establishment of a New Cell Line from Maxillary Sinus Carcinoma

We succeeded in deriving a long-term tissue culture cell line from human maxillary sinus carcinoma. This cell line, designated as MC, was passaged 100 times in vitro over a period of 18 months. The cells are globular in shape, grow as single cells in the culture medium, and the mean population doubling time is about 12 hours. The plating efficiency rate in soft agar is 78% and chromosomal analysis revealed the modal chromosome number to be between 47 and 51. These MC cells were transplanted into five nude mice, all of which developed a tumor after a latency period of 5 to 8 days and died within 39 days. Complete autopsy of all mice revealed no metastasis. Histopathological findings of the original and the transplanted tumor tissues showed a remarkable similarity.

Muscle Repair for Esophageal Speech

IT IS generally believed that satisfactory esophageal speech is only obtained in 40 to 65% of patients. We concentrated on manipulation ofthe constrictor muscle in laryngectomy as being the key to solving the problem of difficulty in esophageal speech. Thus, we have been devising ways to suture the constrictor muscles. Retrospectively, the patients could be grouped into three categories. In the first group the ends of the thyropharyngeus as well as the cricopharyngeus were sutured tightly together. The patients in the second group had only the thyropharyngeus sutured, while the cricopharyngeus as left as it was. In the third group both muscles remained free after removal of the larynx. Percentages of patients acquiring effective esophageal speech were: 40% (6/15) for Group 1, 80% (33/41) for Group 2 and 88% (15/17) for Group 3.