Tetsuro Hayashida

Distribution of gentamicin by immunofluorescence in the guinea pig inner ear

SummaryWe studied the distribution of gentamicin in the inner ear, brain and kidney of the guinea pig following intraperitoneal administration or perfusion of gentamicin through the perilymphatic space. The resulting histopathologcial changes were examined by immunofluorescence using antigentamicin antiserum. After perfusion of gentamicin through the perilymphatic space, specific fluorescence was found in the cochlea, and was especially prominent in the outer hair cells, basilar membrane and basilar crest. Although no fluorescence was observed in the cochlea following intraperitoneal administration of high doses of gentamicin, type I hair cells in the vestibule were seen to be selectively stained with the antibody. Furthermore, some of the vestibular ganglion cells, Purkinje cells and unidentified nuclei in the brain stem were also stained. In particular, fine granules showing relatively intense fluorescence were recognized in the cytoplasm of the stained cells. In the cortex of kidney, only proximal tubular cells were stained with intense fluorescence. Our results suggest that the aminoglycoside antibiotics have two sites of action: one is the cell membrane of the sensory hair cells and the other is the cytoplasm.

Neuro-otological and Neuropathological Findings in two Cases with Machado-Joseph Disease

We report chronological changes of neuro-otological findings and associated neuropathological findings in 2 patients. Concerning gaze limitation, upward gaze was primarily disturbed, followed by downward gaze and abduction. Adduction tended to be preserved although convergence was disturbed at the early stage. And, upward gaze limitation was followed by loss of oculocephalic responses (OCRs). Bells phenomenon was preserved until the late stage of the disease. Caloric nystagmus was absent at the early stage. One patient showed dissociation between nystagmus and vestibulo-collic reflex in the caloric test at the early stage of the disease. Neuropathological examination revealed gliosis in the interstitial nucleus of Cajal and the MLF as well as neuronal loss and gliosis in the oculomotor nuclei. The vestibular nuclei also showed gliosis and atrophy of nerve cells.

Olfactory Dysfunction in Parkinson’s Disease

An olfactory function test in 18 patients with Parkinsons disease (PD) and 10 age-matched control subjects was performed. Both detection and recognition thresholds were measured with five kinds of synthesized odorants (T & T olfactometry). Before each test, rhinoscopic inspections were performed to exclude subjects who could have respiratory hyposmia. Both detection and recognition thresholds in patients with PD were significantly elevated in comparison with those of control subjects. Auditory acuity of PD patients, however, was well preserved and there was no significant correlation between auditory and olfactory threshold. On the basis of the present study, the authors conclude that olfactory dysfunction is one of the characteristic symptoms of PD and it may be attributed to lesions in the olfactory neural pathway including olfactory neuroepithelium.

An immunohistochemical method for the study of aminoglycoside ototoxicity in the guinea pig cochlea using decalcified frozen sections

SummaryAn immunohistochemical technique with decalcified frozen sections was used to study aminoglycoside ototoxicity. Decalcified guinea pig cochleas were cut with a fine blade parallel to the plane of the modiolus to facilitate the penetration of inclusion material and the manipulation of frozen sections. Light microscopy was carried out and additional frozen sections were employed for an immuno-electron microscopic study. Twenty-four hours after a single transtympanic injection of 10 mg gentamicin, there was a definite distribution of the drug in only type I hair cells of the ampullae as well as in both inner and outer hair cells along the length of the cochlea. In those animals treated intraperitoneally with 200 mg/ kg amikacin for 8 days, the drug was located in the outer hair cells of the cochlea, with a tendency to decrease from base to apex and in the inner hair cells towards the apex.

Laryngeal dystonia in a case of severe motor and intellectual disabilities due to Japanese encephalitis sequelae

Laryngeal dystonia is characterized by stridor due to vocal cord dystonia and is observed in extrapyramidal disorders. Recently, botulinum toxin injection has been used as a primary therapy. Generally, severe motor and intellectual disabilities (SMID) are frequently complicated by various types of respiratory disorders. We report a SMID case with Japanese encephalitis sequelae showing repeated vocal cord abductor disturbance due to laryngeal dystonia, in addition to generalized dystonia, in whom MRI revealed basal ganglia lesions. Tracheostomy was effective for the case, and we believe that botulinum toxin injection may be inappropriate in SMID, both ethically and technically. Also, laryngeal dystonia should be considered as a cause of respiratory disorders in SMID.

Biochemical Study of Cholesteatoma and Cholesterol Granuloma – Occurrence of Δ7-Cholestenol in the Tissues of Cholesteatoma

Qualitative and quantitative analyses of sterol derivatives in the tissue of cholesteatoma and cholesterol granuloma were performed by gas-liquid chromatography, mass spectrometry and mass fragmentography after the extraction of total lipids with organic solvents. Cholesterol was the major component in both tissues. The molar ratios of cholesterol to lipid-bound phosphorus in cholesterol granulomas were higher than those in cholesteatomas. In addition, delta 7-cholestenol (lathosterol) was contained in all tissues of cholesteatoma examined. However, cholesterol granuloma tested did not contain delta 7-cholestenol, indicating that the metabolism of cholesterol differed from that in cholesterol granuloma.

Postcaloric Nystagmus by Positional Change and Other Neurootological Findings

The postcaloric nystagmus (PCN) by positional change from the supine position to the upright position and other neurootological findings were studied. Twenety-one patients with a clinical diagnosis of spinocerebellar degeneration or Arnold-Chiari malformation were studied. There was a significant negative correlation between maximum slow phase eye velocity in postcaloric nystagmus by positional change (V2) and maximum slow phase eye velocity in optokinetic nystagmus pattern test (r = -0.47; n = 21). Moreover, patients with vertical gaze nystagmus (VN) had significantly larger V2 than patients without VN. However, there was no significant difference for V2 between patients with and without rebound nystagmus. Through these studies, the authors discussed probable mechanisms and responsible lesions for the exaggerated PCN by positional change.

Auditory Brainstem Response and Neuropathology in a Case of Systemic T-Cell Lymphoma with Intracranial Metastasis

A 58-year-old male with systemic T-cell lymphoma involving the brainstem eccentrically, showed varying abnormal auditory brainstem responses (ABRs). The initial ABR demonstrated a prolonged V wave peak latency and an I-V IPL on admission. Four months later, all waves were absent bilaterally. Neuropathological examination at autopsy revealed that most of the nuclei and tracts associated with the auditory system were destroyed by lymphoid cell infiltration. It suggested that in the early stages of this disease, lymphoid cells could have involved the lower brainstem and, subsequently, in the advanced stages invaded the inferior colliculus.