Keiji Fukuoka

The Mechanism of Irritative Nystagmus and Paralytic Nystagmus: A Histochemical Study of the Guinea Pig's Vestibular Organ and an Autoradiographic Study of the Vestibular Nuclei

To establish the difference of mechanism between irritative and paralytic nystagmus, alterations of Na-K-ATPase and succinic dehydrogenase activity in the vestibular sensorineural elements were investigated for 20 guinea pigs, and glucose uptake of the vestibular nuclei for 13 guinea pigs were measured by the [14C]-2-deoxy-D-glucose method. Irritative and paralytic nystagmus were experimentally provoked by introducing K+ into the perilymphatic space. From the results it was concluded that irritative nystagmus is provoked by increased excitability of vestibular sensory cells, while paralytic nystagmus is provoked by decreased excitability. However, the direction of nystagmus was eventually decided by the tonus imbalance between the bilateral vestibular nuclei. The ipsilateral vestibular nucleus was predominant during irritative nystagmus, while the contralateral vestibular nucleus was predominant during paralytic nystagmus.

Experimental studies on mechanism of the Menière's attack: investigation into vestibulo-cochlear response of the guinea pig induced by potassium ion.

After introducing potassium ion through the round window into the perilymphatic space of 40 guinea pigs by means of iontophoresis, physiological and histochemical investigations were performed to determine the role of the high perilymphatic potassium concentration in the vertiginous attack of Ménières disease. About 15 min after the iontophoretic procedure, electronystagmography revealed irritative nystagmus for the first 5 min and then paralytic nystagmus for the following 6 to 24 hr. Histochemical analysis of the vestibular sensory epithelia revealed the increased activity of succinic dehydrogenase and Na-K-ATPase during irritative nystagmus and the decreased activity during paralytic nystagmus. The Na-K-ATPase activity was dominant in the synaptic area between the hair cells and the nerve-endings of the vestibular sensory epithelia. There was some delay between the reversal of nystagmus-direction and the change of enzyme activity. This delay was thought to be produced by the central regulatory mechanism for the disturbed tonus-balance in the vestibular nucleus. On the other hand, electrocochleography revealed the decrease of the action potential without any initial irritative cochlear sign, and the enzyme activity of the cochlear sensory cells was decreased from the beginning.

An Experimental Study on the Mechanism of the Ménière’s Attack: The Influence of High Perilymphatic Potassium Concentration on the Vestibular System

Clinical characteristics of Meniere’s disease are episodic vertigo and fluctuating hearing loss, the origin of which is still obscure. It is well known that nystagmus is always present during the attack, as described by Aschan and Stahle [1], but whose character is not always the same. According to a previous study [2], irritative, paralytic, and reversal nystagmus were observed during the Meniere’s attack in 25%, 36%, and 39% of patients, respectively. To explain such complicated clinical manifestations, Schuknecht’s membrane rupture theory [3] would be most acceptable. He ascribed the episodic vertigo and fluctuating hearing loss to the rupture and repairing process in the endolymphatic system. His findings were supported by Silverstein [4], who provoked nystagmus by perfusing the perilymphatic space with artificial endolymph. Silverstein thought that sensorineural excitability might be altered by high perilymphatic potassium concentration. Dohlman [5] theorized that, on the basis of the membrane rupture theory, an initial ipsilateral nystagmus could occur due to partial depolarization of the vestibular nerve by the leaking endolymph, and then as the depolarization became more complete, the direction of nystagmus would turn to the contralateral side. Molinari [6] considered that the irritative nystagmus was due to the excitation of the vestibular receptor cells, and that the paralytic nystagmus was due to the inhibitory rebound in the central nervous system. Meissner [7] speculated that the potassium concentration in perilymph determined the extent of depolarization of the sensorineural synpase and brought about the tonus imbalance of the vestibular nuclei followed by ipsior contralateral nystagmus.

Sulpiride (Dogmatyl) treatment of pharyngo-laryngeal abnormal sensation.

The effect of the anti-depressant: Sulpiride on pharyngolaryngeal abnormal sensation was evaluated in 50 patients treated for 4 weeks. The depressive state of the patients was evaluated by the Self-Rating Questionnaire for Depression (SRQ D). 1) Depression was noted in 12 of the patients (24%). 2) Sulpiride improved the SRQ D scores of 70% of the depressed patients and of 36.8% of the non-depressed patients. 3) However, subjective symptoms were reduced in 84.2 % of the non-depressed patients and in 60% of the depressed patients. 4) Mild side-effects were noted in 4 patients (8%) during administration of this drug.

Effect of plasmapheresis on advanced malignant tumor of the head and neck.

The effect of the plasmapheresis using an IBM blood cell separator was evaluated in 5 patients. Three patients with malignant tumor of head and neck were histologically diagnosed as having squamous cell carcinoma, adenoid cystic carcinoma and malignant melanoma, the remaining 2 patients had Wegeners granulomatosis.After plasmapheresis, the improvement of performance status was observed in 4 patients, and all patients showed a remarkable reduction of serous immunosuppressive factors. However, these effects were transient and diminished soon after the treatment.To maintain the condition improved by the plasmapheresis, other immunochemotherapies should also be given.

Evaluation of laryngeal function after reconstruction following laryngeal injury.

Laryngeal function was evaluated in six patients after treatment of laryngeal trauma. The patients were all male, aged 18 to 61 years (average age 41.0 years). The injury in three patients was caused by automobile accidents, in two patients by industrial accidents, and in one patient by contusion due to being kicked in the neck. Treatment included tracheostomy, repositioning of fragments, grafting, arytenoidectomy, trough method, cricopharyngeal myotomy, upward fixation of the hyoid bone and thyroid cartilage, and introduction of silicon rubber T-tubes.The six patients answered questionnaires concerning their laryngeal symptoms: hoarseness, dyspnea, and dysphagia. Five patients were examined by phonation analyzer (PS-77, Nagashima Co.) and automatic analyzable system for pulmonary function (autospiror HI-498, Chest Co.)Two patients still complained of severe hoarseness, and four of moderate or slight hoarseness. Two patients still complained of slight dyspnea and four of slight dysphagia.The curve of the phonation analyzer in all patients demonstrated by fundamental frequency and intensity a disappearance of normal vocal cord vibration.The flow-volume curve of the autospiror showed decreased peak expiratory flow plateau formation in three patients.All patients except one with a gait disturbance, returned to work with only slight laryngeal symptoms.In the follow-up of laryngeal function in patients with laryngeal injury and in advising them about rehabilitation, the newly developed phonation analyzer and respirometer are very useful.