Toru Minatogawa

Animal model for ischemic facial nerve paralysis with selective vascular embolization.

An experimental model that reliably and easily produces acute ischemic facial nerve paralysis would be useful for the controlled study of treatment and to improve our understanding of the pathophysiology and treatment of facial nerve palsy. Most documented models that simulate clinical facial nerve palsy cause direct damage to the nerve. We describe an experimental model for ischemic facial nerve paralysis in the cat that employs arterial block of the internal and external maxillary and posterior auricular arteries using embolizing material (Avitene). All animals develop stable acute ischemic facial nerve palsy lasting for approximately 2 months. Electromyographic study of this model revealed that the site of the lesion resulting from selective embolization may be within the temporal bone. This model has the advantages of simplicity of technique, cost-effective use of cats, and reproducibility of facial nerve palsy.

Neurophysiology of ischemic facial nerve paralysis in an animal model

The establishment of an animal model for facial nerve paralysis is assuming increasing importance in clinical medicine and also in basic facial nerve research. We previously reported an animal model for ischemic facial nerve paralysis using selective vascular embolization through the internal maxillary and posterior auricular arteries in cats using Avitene which contains bovine microfibril collagen. In this paper, we determined the exact site of the lesion in established facial paralysis. A descending signal produced by direct stimulation to the contralateral motor cortex was able to elicit firing of the motor nucleus of the facial nerve, the extra-temporal portion of the peripheral nerve, and the orbicularis oris muscle. After achieving complete facial nerve paralysis, this descending signal was completely abolished within the temporal bone area, whereas peripheral facial nerve stimulation elicited a normal evoked electromyogram of the orbicularis oris muscle. The present results suggest that the site of the lesion of ischemic facial nerve paralysis produced by embolization in an animal model is within the temporal portion of the seventh nerve, and this animal model may lead to the advancement of future facial nerve research which cannot be conducted in humans.

Results of tympanoplasty for congenital aural atresia and stenosis, with special reference to fascia and homograft as the graft material of the tympanic membrane

The surgical management of congenital aural atresia is a challenging, complex procedure, and the risks are great. The otologic surgeon is responsible for keeping a patent external auditory canal and for achieving satisfactory hearing.

Dermoid cyst in the middle ear

A case of a moderate essentially low tone unilateral conductive hearing loss without a previous history of secretory otitis media in a six-year-old female patient is described. The condition was found to be due to a dermoid cyst in the tympanic cavity, which was confirmed by pathological examination of the surgically removed specimen. This is the sixth documented case of dermoid cyst in the tympanic cavity.

Stellate ganglion block for facial palsy.

Although the cause of Bell’s palsy has still not been clarified, its main pathophysiology is thought to be due to ischemic conditions of the facial nerves in the temporal bone. Since there is an extremely strong relationship between the pathophysiology of Bell’s palsy and circulatory disorders of the nutrient blood vessels in the facial nerves, the main emphasis of the conservative treatment of this disorder by chemotherapy is aimed at circulatory improvement. On the other hand, at the pain clinic, improved blood flow to the facial nerve by stellate ganglion block (SGB) therapy is employed in treating patients with Bell’s palsy. Its efficacy has already been adequately confirmed. The improved blood circulation during treatment of Bell’s palsy by SGB is thought to be brought about by a vasculatory dilatation action due to the blocking effects on the sympathetic nerve. However, the detailed mechanism has not been adequately studied. Therefore, we report the effects of SGB on the common carotid artery blood flow volume and tissue blood flow volume in facial nerve tissue in patients at the acute stage of Bell’s palsy and in experimental animals.

The use of allograft stapes

Since 1981, we have used the stapes allograft, singly or in combination with homograft incus, in 20 cases of tympanoplasty and in 7 cases of fixed stapes. All of the allograft stapes discussed were procured, processed and stored in 1980 by the Hyogo Ear Bank, the first to be established in Japan. The stapes allograft was used in three situations: an intact posterior canal wall, an open mastoidectomy cavity, or a fixed stapes (postinflammatory, congenital or otosclerotic). Two modalities of positioning of the donor stapes were attempted: (1) the allograft stapes was placed in the normal position and a shaped incus or cortical bone or tragal cartilage was placed on the top of the stapedial head and connected and (2) the allograft stapes was placed in the upside-down position and the columella was placed on the stapes footplate. Better results were obtained with the allograft stapes placed in the normal position. A two-stage operation, first to place an allograft stapes in the normal position with myringoplasty and then ossiculoplasty, was preferable to one-stage middle ear surgery.

Allograft stapes surgery for conductive hearing loss in patients with ossicular chain anomalies

An allograft stapes was used during surgical intervention for conductive hearing loss due to ossicular malformations in 11 ears of seven patients. The external auditory canal and tympanic membrane were normal in all ears. The surgical findings for the ossicles were stapes fixation (7 ears), stapes fixation with discontinuity of the incudostapedial joint (in both ears of one patient), a deformed incus and stapes crura compressed by the facial nerve (one ear in which the stapes was not fixed) and an anomaly of the incus and stapes combined with a dermoid cyst (in one ear in which the stapes was also not fixed). In all ears, the following procedures were performed: stapedectomy followed by sealing the oval window with a vein graft and placing an allograft stapes between the oval window and the lenticular process of the incus or the handle of the malleus. The allograft stapes was placed with its capitulum on the oval window in all cases, and fibrin glue was used for stabilizing the seal and the allograft stapes. The indications for stapedectomy for conductive hearing loss due to ossicular chain anomalies and the utility of allograft stapes are discussed.

Effect of Oral Moisture on Taste Sensation

Taste disorders can be caused by various factors, including zinc deficiency, adverse drug reactions, cold and xerostomia, and the number of patients seeking medical assistance for such disorders is increasing. However, because taste disorders are often difficult to treat, some medical institutions will not treat these complaints.In the Department of Otolaryngology at Osaka Dental University Hospital, a clinic was opened on September 1, 2004, to treat patients with taste disorders.We treated 1 outpatient who lost one side of parotid gland due to malignancy, then lost the function of the remaining salivary gland due to Sjogrens syndrome.Subjects comprised 17 patients complaining of taste disorders with xerostomia without subjective symptoms of other otolaryngological diseases.In the present study, 4 patients were prescribed zinc by another physician, but only 2 patients actually displayed zinc deficiency. Zinc administration did not improve symptoms in any of the patients.According to the diagnostic criteria for xerostomia in our department, 17 patients had xerostomia, and 4 of these 17 patients were diagnosed with Sjogrens syndrome. These patients were instructed to gargle with cevimeline hydrochloride, and taste sensation improved in 12 patients.We have examined 17 patients to data and consider this number insufficient to draw definitive conclusions but the data we have currently suggests to the following conclusions:1. Latent Sjogrens syndrome should be suspected in patients presenting with taste disorder with xerostomia.2. In taste disorder patients with xerostomia, gargling with cevimeline hydrochloride appears very useful.3. One patient had lost a side of salivary gland, and Sjogrens syndrome caused loss of function of the remaining salivary gland. In this patient, favorable results were also obtained by gargling with cevimeline hydrochloride.

A Case of Tullio's Phenomenon after Stapedotomy.

A 29-year-old male had complained of bilateral hearing loss and bilateral tinnitus since five years ago. He was diagnosed with otosclerosis, and a stapedotomy was performed in the right ear two years ago at another hospital. Following surgery, he complained of oscillopsia during loud sounds. His eye movements were subsequently recorded, during loud sound stimulation. With left ear stimulus nystagmus was not detected, but with right ear stimulus, pendular nystagmus in the vertical plane was seen with sounds of 500Hz 100dBHL. An exploratory tympanotomy was subsequently performed. Except for findings associated with poststapedotomy, there was no evidence of abnormalities, including leakage of perilymph. We thought that the piston wire might be stimulating the labyrinth membrane, so the wire was removed, together with the footplate. The oval window was closed with a vein graft and allograft stapes were inserted in the inverted position. Tullios phenomenon with downbeat and torsional nystagmus was seen during one month after surgery.Although the origin of vertical eye movement is unclear, observations suggest that Tullios phenomenon in this case was caused by hyperexcitability of the otolith organs.

Developmental anomaly of the process of Folius.

We present four cases of an ossicular anomaly considered to consist of an abnormality of the anterior process and manubrium mallei (malleus handle). In one case, a thick bony bar was found extending from the neck of the malleus which fused with the posterior bony wall or the tympanic bone. No trace of the short process and umbo of the malleus was recognized. In two other cases, a similar bony bar was seen as well as a cartilaginous malleus handle that apparently was attached to the anterior part of the bony bar. On the basis of these findings, the bony bar was assumed to represent abnormally developed mesenchyme bone (os goniale), which later develops into the anterior process of the malleus. In the last case, no bony bar was seen, but a V -shaped ossicle was recognized, one end of which was connected to the malleus head by fibrous tissue. Since this abnormally shaped ossicle was bony and hard and no trace of the short process and umbo characteristic of the handle of the malleus was found, it was thought to be an abnormally developed os goniale.