Successful Posterior Canal Wall Reconstruction with Tissue-Engineered Cartilage.

Difficulties are associated with reconstruction of middle ear bony structures in surgery for destructive lesions, including cholesteatoma. Although autologous cartilage appears to be the optimal choice because of its resistance to infection, the harvesting of sufficient volumes may be challenging. Therefore, regenerative medicine techniques to obtain sufficient material for reconstruction are awaited. We herein present a case of middle ear surgery for cholesteatoma with a sufficient volume of stick-shaped tissue-engineered cartilage produced from a piece of autologous auricular cartilage and autologous serum, with sufficient firmness to reconstruct bony structures. During surgery, sections of tissue-engineered cartilage were placed side by side to reconstruct the posterior canal wall. The postoperative course was uneventful. This is the first-in-human report of reconstructing middle ear bony structures with tissue-engineered cartilage. The results suggest a promising future for the satisfactory reconstruction of middle ear structures with minimal morbidity at the donor site.

Epidural abscess caused by Schizophyllum commune: A rare case of rhinogenic cranial complication by a filamentous basidiomycete.

Central nervous system (CNS) infections due to filamentous basidiomycetes are extremely rare. We encountered a case of epidural abscess due to Schizophyllum commune that extended from sinusitis. A 53-year-old Japanese man presented at our hospital with a headache. Computed tomography (CT) of the cranium and sinuses showed ethmoid and sphenoid sinusitis with no intracranial abnormalities. The patient was diagnosed with acute sinusitis and underwent antibiotic treatment. However, the symptoms deteriorated, and the patient came to our hospital again with consciousness disturbance. CT scan of the cranium and sinuses showed no improvement of sinusitis after antibiotic therapy and an epidural abscess emerged in the middle cranial fossa. Therefore, emergency craniotomy and endoscopic sinus fenestration were performed. Filamentous fungal elements were observed in both rhinorrhoea and epidural abscess. The symptoms improved after the operation and administration of liposomal amphotericin B. The clinical isolate was identified as S. commune by a molecular-based method. To our knowledge, this is the first report of epidural abscess due to this fungus. Although rare, clinicians should be aware that S. commune could be a causative agent of CNS infections.

Admittance tympanometry with 2-kHz probe tones in patients with low-frequency hearing loss.

OBJECTIVES/HYPOTHESIS: To assess the reliability of admittance tympanometry with 2-kHz probe tones in diagnosing ears with endolymphatic hydrops in patients with low-frequency hearing loss. STUDY DESIGN: Case-control study. METHODS: Thirty-six Japanese patients with low-frequency hearing loss (including 21 with Mènière disease, three with delayed endolymphatic hydrops, and 12 with acute or repetitious low-frequency sensorineural hearing loss), 18 patients with other types of hearing loss, and 16 subjects with normal hearing were enrolled at University of Tokyo Hospital. We measured the width of the splitting peaks in the admittance tymapnometry with 2-kHz probe tones. RESULTS: Widths of the probe pressure corresponding to splitting peaks of admittance (Y) tympanometry were significantly greater in the ears with endolymphatic hydrops than in the ears without endolymphatic hydrops in patients with low-frequency hearing loss. Furthermore, the widths in the ears with endolymphatic hydrops were greater than those in ears with other types of hearing loss. Widths of >255 daPa were observed in 38% of ears with endolymphatic hydrops and low-frequency hearing loss and in 21% of ears with other types of hearing loss. CONCLUSIONS: The current study demonstrated that wide splitting peaks of Y tympanometry are more frequently observed in ears showing low-frequency hearing loss than in those with other types of hearing loss, indicating that Y tympanometry can be used to diagnose endolymphatic hydrops in daily practice.

Carhart notch 2-kHz bone conduction threshold dip: a nondefinitive predictor of stapes fixation in conductive hearing loss with normal tympanic membrane.

OBJECTIVE: To evaluate the significance of the Carhart notch (a 2-kHz bone conduction threshold dip [2KBD]) in the diagnosis of stapes fixation by comparing its incidence among ears with various ossicular chain abnormalities. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: A total of 153 ears among 127 consecutive patients with a congenital ossicular anomaly or otosclerosis. MAIN OUTCOME MEASURES: The 2KBD depth was defined as the threshold at 2 kHz minus the mean of thresholds at 1 and 4 kHz. The presence of 2KBD (depth, ≥10 dB), 2KBD depth, relationship between 2KBD depth and air-bone gap, and 2-kHz bone conduction recovery after operation were evaluated in a stapes fixation group (which included cases of otosclerosis and congenital stapes fixation), an incudostapedial joint detachment group, and a malleus or incus fixation group. RESULTS: A 2KBD was present in 32 of 102 stapes fixation ears (31.4%), 5 of 19 incudostapedial joint detachment ears (26.3%), and 6 of 20 malleus or incus fixation ears (30.0%) (12 ears had other diagnoses). The mean (SD) 2KBD depths were 17.3 (5.2) dB in the stapes fixation group, 18.5 (2.2) dB in the incudostapedial joint detachment group, and 16.3 (2.1) dB in the malleus or incus fixation group. No statistically significant differences were noted among these 3 groups. No correlation was noted between 2KBD depth and air-bone gap extent. Recovery of 2-kHz bone conduction threshold in the stapes fixation group was less than that in the other 2 groups. CONCLUSION: Incidence of 2KBD was similar among the stapes fixation, incudostapedial joint detachment, and malleus or incus fixation groups, implying that 2KBD is not a useful predictor of stapes fixation.

Preservation of vestibular function after scala vestibuli cochlear implantation.

A 58-year-old man, in whom the cochlear implant (CI) had been inserted into the left ear, had right middle-ear cancer. The CI was removed immediately before receiving subtotal removal of right temporal bone. Four months later, the CI was again inserted in his left cochlea. Because of obliterated scala tympani, the 22 active electrodes of the CI were placed into the scala vestibuli. After the surgery, the patient complained that he experienced rotary vertigo and "jumbling of vertical direction" of objects on walking. Using rotation test, we evaluated vestibular function of remaining left ear. Numerous horizontal nystagmus beats were induced during earth-vertical axis rotation, whereas vertical downbeat nystagmus was scarcely induced during off-vertical axis rotation. The horizontal vestibulo-ocular reflex (VOR) was almost normally induced by sinusoidal stimulation at 0.8Hz. These data suggest that the scala vestibuli insertion of CI would be not so invasive against the lateral semicircular canal.

Language and music: differential hemispheric dominance in detecting unexpected errors in the lyrics and melody of memorized songs.

Using magnetoencephalography (MEG), we report here the hemispheric dominance of the auditory cortex that is selectively modulated by unexpected errors in the lyrics and melody of songs (lyrics and melody deviants), thereby elucidating under which conditions the lateralization of auditory processing changes. In experiment 1 using familiar songs, we found that the dipole strength of responses to the lyrics deviants was left-dominant at 140 ms (M140), whereas that of responses to the melody deviants was right-dominant at 130 ms (M130). In experiment 2 using familiar songs with a constant syllable or pitch, the dipole strength of frequency mismatch negativity elicited by oddballs was left-dominant. There were significant main effects of experiment (1 and 2) for the peak latencies and for the coordinates of the dipoles, indicating that the M140 and M130 were not the frequency mismatch negativity. In experiment 3 using newly memorized songs, the right-dominant M130 was observed only when the presented note was unexpected one, independent of perceiving unnatural pitch transitions (i.e., perceptual saliency) and of selective attention to the melody of songs. The consistent right-dominance of the M130 between experiments 1 and 3 suggests that the M130 in experiment 1 is due to unexpected notes deviating from well-memorized songs. On the other hand, the left-dominant M140 was elicited by lyrics deviants, suggesting the influence of top-down linguistic information and the memory of the familiar songs. We thus conclude that the left- lateralized M140 and right-lateralized M130 reflect the expectation based on top-down information of language and music, respectively.

Acute sensorineural hearing loss associated with aortitis syndrome.

CONCLUSIONS: Steroid treatment was effective in improving hearing in most episodes in our and previously reported patients with acute hearing loss associated with aortitis syndrome. This suggests that inflammatory changes due to autoimmune responses may play an important role in the manifestation of hearing loss in aortitis syndrome. OBJECTIVES: To clarify clinical features in patients with aortitis syndrome who exhibited hearing loss. CASE REPORTS: We describe two patients, 39-year-old and 53-year old women, who developed several episodes of acute sensorineural hearing loss associated with aortitis syndrome. RESULTS: In both patients, hearing loss involved the cochlea and hearing recovered following corticosteroid treatment. A literature review revealed that hearing loss was commonly manifested in middle-aged females and involved bilateral ears. Corticosteroid treatment was effective in improving hearing in most episodes in the previously reported cases as in our patients.

Dynamic synapses as archives of synaptic history: state-dependent redistribution of synaptic efficacy in the rat hippocampal CA1.

Plastic modifications of synaptic strength are putative mechanisms underlying information processing in the brain, including memory storage, signal integration and filtering. Here we describe a dynamic interplay between short-term and long-term synaptic plasticity. At rat hippocampal CA1 synapses, induction of both long-term potentiation (LTP) and depression (LTD) was accompanied by changes in the profile of short-term plasticity, termed redistribution of synaptic efficacy (RSE). RSE was presynaptically expressed and associated in part with a persistent alteration in hyperpolarization-activated I(h) channel activity. Already potentiated synapses were still capable of showing RSE in response to additional LTP-triggering stimulation. Strikingly, RSE took place even after reversal of LTP or LTD, that is, the same synapse can display different levels of short-term plasticity without changing synaptic efficacy for the initial spike in burst presynaptic firing, thereby modulating spike transmission in a firing rate-dependent manner. Thus, the history of long-term synaptic plasticity is registered in the form of short-term plasticity, and RSE extends the information storage capacity of a synapse and adds another dimension of functional complexity to neuronal operations.

Activity-evoked capacitative Ca2+ entry: implications in synaptic plasticity.

The Ca2+ influx controlled by intracellular Ca2+ stores, called store-operated Ca2+ entry (SOC), occurs in various eukaryotic cells, but whether CNS neurons are endowed with SOC capability and how they may operate have been contentious issues. Using Ca2+ imaging, we present evidence for the presence of SOC in cultured hippocampal pyramidal neurons. Depletion of internal Ca2+ stores by thapsigargin caused intracellular Ca2+ elevation, which was prevented by SOC channel inhibitors 2-aminoethoxydiphenyl borate (2-APB), SKF96365, and La3+. Interestingly, these inhibitors also accelerated the decay of NMDA-induced Ca2+ transients without affecting their peak amplitude. In addition, SOC channel inhibitors attenuated tetanus-induced dendritic Ca2+ accumulation and long-term potentiation at Schaffer collateral-CA1 synapses in hippocampal slice preparations. These data suggest a novel link between ionotropic receptor-activated SOC and neuroplasticity.

Mossy fibre synaptic NMDA receptors trigger non-Hebbian long-term potentiation at entorhino-CA3 synapses in the rat.

Hippocampal CA3 pyramidal cells receive two independent afferents from the enthorinal cortex, i.e. a direct input via the temporoammonic pathway (TA, perforant path) and an indirect input via the mossy fibres (MF) of dentate granule cells. In spite of past suggestions that the TA is assigned an important role in exciting the pyramidal cells, little is known about their physiological properties. By surgically making an incision through the sulcus hippocampi and a small part of the dentate molecular layer, we succeeded in isolating TA-mediated monosynaptic responses in CA3 stratum lacunosum-moleculare. The TA-CA3 synaptic transmission was completely blocked by a combination of D,L-2-amino-5-phosphonopentanoic acid (AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), NMDA and non-NMDA receptor antagonists, respectively, and displayed paired-pulse facilitation and NMDA receptor-dependent long-term potentiation, which are all typical of glutamatergic synapses. We next addressed the heterosynaptic interaction between TA-CA3 and MF-CA3 synapses. The TA-CA3 transmission was partially attenuated by single-pulse MF pre-stimulation at inter-pulse intervals of up to 70 ms. However, surprisingly, burst stimulation of the MF alone induced long-lasting facilitation of TA-CA3 synaptic efficacy. This non-Hebbian form of synaptic plasticity was efficiently prevented by local application of AP5 into the MF synapse-rich area. Therefore, MF-activated NMDA receptors are responsible for the heterosynaptic modification of TA-CA3 transmission, and thereby, the history of MF activity may be etched into TA-CA3 synaptic strength. Our findings predict a novel form of spatiotemporal information processing in the hippocampus, i.e. a use-dependent intersynaptic memory transfer.

Stereocontrolled addition of enolates to chiral 2-acyl-1,3-oxathiane derivatives.

Both enantiomers of 3-hydroxyalkanoates and -alkanones were prepared by the diastereocontrolled addition of enolates to ketones containing (R)-6-methyl-1,3-oxathiane moiety as a chiral auxiliary; a formation of enolate from samarium(II) iodide and alpha-bromoamide is also discussed.

Auditory behaviors and auditory brainstem responses of infants with hypogenesis of cerebral hemispheres.

Three infants with an almost complete absence of the cerebral hemispheres as a result of brain anomalies were studied both audiologically and neurologically. The brain anomalies were diagnosed by means of MRI and CT scans. Behavioral audiometry revealed reactions only to loud sound stimulations but auditory brainstem responses showed wave configurations and thresholds compatible with the ages of the infants. There were significant differences in the thresholds obtained by behavioral audiometry and auditory brainstem responses. It can be considered that these auditorily stimulated behavioral responses are evoked by auditory motor reflexes originating in the brainstem, but not by auditory perception.