A mitochondrial DNA mutation at nucleotide 1555 in the ribosomal RNA gene was recently reported as a cause of maternally inherited non-syndromic sensorineural deafness. We assumed that the 1555 mutation is also associated with sporadic non-syndromic deafness and screened for the mutation in seven randomly selected sporadic cases with bilateral sensorineural hearing loss of unknown etiology. The mutation was found in one patient, who first noticed hearing loss when she was in her early teens with subsequent gradual progression. The results suggest that the 1555 mutation may contribute to the etiology of idiopathic bilateral sensorineural hearing loss in some cases.
A mitochondrial tRNA Leu(UUR) mutation at nucleotide 3,243 is known to be found in most patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) and has also been identified in several families with maternally inherited diabetes mellitus and hearing loss. We report here audiologic features in patients with hearing loss associated with the mutation. Four patients without and five with MELAS were studied. Most of the patients had bilateral progressive sensorineural hearing loss. The most common shape of the audiogram was sloping, while cases in the advanced stages had flat audiograms. Speech discrimination scores were generally poor and did not parallel the degree of hearing loss. The present study suggests that the lesion for hearing loss could include both cochlear and retrocochlear involvement, but does not demonstrate a significant difference in the audiologic findings between patients with and without MELAS.
Recent developments have extended the indications for endovascular intervention to include endovascular lesions, such as aneurysms and sclerotic arterioocclusive disease. Although conventional treatment of pseudoaneurysms is mainly surgical intervention, the development of stent grafts has made this treatment less invasive than previously. We placed a stent graft in a pseudoaneurysm of the iliac artery with good results, as described in this report. Treatment of a pseudoaneurysm with a stent graft avoids the risk associated with general anesthesia and reduces surgical invasiveness, similar to laparotomy. We expect that this therapeutic mode will be developed further in the future.
A series of highly organic-soluble [bis(trialkylsiloxy)]silicon tetrakis(alkylthio)-2,3-naphthalocyanines [(R13SiO)2SiNc(SR2)4] have been synthesized, and their 1H NMR, electronic absorption and fluorescence spectra measured. These spectra indicate that (R13SiO)2SiNc(SR2)4 are monomeric in solution (10–2–10–7 mol dm–3). In their solid films, all Q-band absorption maxima of (R13SiO)2SiNc(SR2)4 are red-shifted from their monomeric Q-band maximum. The extent of shift significantly increases with decreasing R1 length of the axial substituents, but the effect is far less with ring substituents, R2. These observations are clearly explained using the exiton model. Our results indicated that novel naphthalocyanine (R13SiO)2SiNc(SR2)4 molecules have a J-type molecular arrangement in thin solid films.
Large vestibular aqueduct (VA) syndrome is a distinct congenital inner ear anomaly characterized by a large aperture in the vestibular aqueduct. Among our outpatients with sensorineural hearing loss (SNHL) of unknown etiology evaluated between 1995 and 1997, the nine patients (17 ears) with large VA are presented.Their history, in addition to results of physical examination, computed tomography, serial audiograms and vestibular function, were reviewed. The average hearing level of the 17 ears was 70.7dB. Eight ears had severe hearing loss, four ears demonstrated more hearing loss in the highfrequency range than in the low-frequency range, and two ears had normal hearing. Positional nystagmus and positioning nystagmus were found in seven cases. Caloric test findings were as follows; four ears had canal paresis, six ears had vestibular dysfunction and three were normal. CT showed three cases with inner ear anomalies other than large VA syndrome.Fluctuating, or progressive SNHL was present in four of five patients who were followed over a period of three years. Stable SNHL was present in the one-year-follow-up cases. These observations indicate that the functionality of the inner ear in patients with a large VA varies over the longer term. In three of the cases with fluctuating or progressive SNHL, conservative therapy was performed including intravenous steroid therapy, stellate ganglion block, and Co2 inhalation, which seemed to be of a little benefit. In one patient who became deaf 14 years after the initial examination, cochlear implant surgery was performed. Effective therapy to prevent fluctuating or progressive SNHL remain unknown.
Otitis media, especially chronic otitis media with cholesteatoma continues to be a frequent cause of intracranial complications despite the benefits of antibiotics and computed tomographic examinations. In the present study, we report two cases of intracranial complications caused by the uncommon infectious extension of cholesteatoma and granulations from the membranous labyrinth to the internal auditory meatus. The first case was a 44-year-old man with meningitis who was treated by intraveous antibiotics. Cholesteatoma and granulations were found to erode the surgical dome and extend to the fundus of the internal auditory meatus at surgery. The second case was a 40-year-old man who complained of right facial nerve palsy, fever and otalgia. A CT scan and MRI showed meningitis and cerebellar abscess secondary to labyrinthitis and cholesteatoma. In this case, cholesteatoma and granulations also extended to the fundus of the internal auditory meatus via the cochlea. Cholesteatoma has been infrequently reported to invade the fundus of the internal auditory meatus through the labyrinth. However, we should consider possible otogenic intracranial complications caused by labyrinthine extension of the cholesteatoma when we conservatively treat patients with cholesteatoma.
An A to G transition at nucleotide 3, 243 in the tRNALeu (UUR) gene of mitochondrial DNA has recently been identified as a pathogenic point mutation which is associated with diabetes mellitus and sensorineural deafness in several pedigrees. We have also reported a family showing the association of deafness and diabetes mellitus as the predominant clinical features with this mutation. Audiologic data from two patients in this family are presented. Both had a bilaterally symmetrical sensorineural hearing loss at all frequencies. As is often the case with deafness associated with a mitochondrial disorder, the pure-tone threshold values were maximal at high frequencies in both patients. The audiologic work-up presented not only cochlear characteristics but also signs suggestive of retrocochlear disturbance with poor speech discrimination scores as compared to pure-tone thresholds, although auditory brain-stem responses showed neither wave delay nor prolonged interpeak latencies. Caloric excitability was not impaired.
