Multisensory neurons in the dorsal cochlear nucleus (DCN) achieve their bimodal response properties [Shore (2005) Res., 78,[901][902][903][904][905][906][907]. A unique feature of multisensory neurons is their propensity for receiving cross-modal compensation following sensory deprivation. Thus, we investigated the possibility that reduction of VIIIth nerve input to the cochlear nucleus results in trigeminal system compensation for the loss of auditory inputs. Responses of DCN neurons to trigeminal and bimodal (trigeminal plus acoustic) stimulation were compared in normal and noise-damaged guinea pigs. The guinea pigs with noise-induced hearing loss had significantly lower thresholds, shorter latencies and durations, and increased amplitudes of response to trigeminal stimulation than normal animals. Noise-damaged animals also showed a greater proportion of inhibitory and a smaller proportion of excitatory responses compared with normal. The number of cells exhibiting bimodal integration, as well as the degree of integration, was enhanced after noise damage. In accordance with the greater proportion of inhibitory responses, bimodal integration was entirely suppressive in the noise-damaged animals with no indication of the bimodal enhancement observed in a sub-set of normal DCN neurons. These results suggest that projections from the trigeminal system to the cochlear nucleus are increased and/or redistributed after hearing loss. Furthermore, the finding that only neurons activated by trigeminal stimulation showed increased spontaneous rates after cochlear damage suggests that somatosensory neurons may play a role in the pathogenesis of tinnitus.
The UK’s Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method (“rinse-wipe-rinse”) for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants.
Subgingival marginal discrepancies of the magnitude measured in this study have been shown to cause periodontal problems. It is probable that the marginal discrepancy of CeraOne restorations, as tested, can be improved. Efforts should be made to enhance the marginal accuracy of these restorations.
Introduction. Esotropia is a form of strabismus that can give the affected individual a “cross-eyed” appearance. Acute onset of esotropia is an uncommon form; in the vast majority of cases, no underlying neurological etiology is found. Case Presentation. A 22-year-old female with a long history of opiate abuse presented with acute onset of diplopia. She noted her eyes were crossing and started seeing double. She stopped using heroin 11 days prior to presentation. There was large inward deviation of her left eye. Convergence was difficult and accompanied by horizontal nystagmus. Diplopia resolved by covering each eye. Further investigations including imaging studies were normal. Discussion. Acute onset esotropia is rare and must be investigated right away to exclude central nervous system pathologies, where no opiates use is reported. Diplopia in the form of acute esotropia may manifest in up to 30% of individuals undergoing heroin withdrawal. Evaluating acute esotropia requires detailed information of medical history with an emphasis on drug use. Conclusion. Acute onset esotropia with double vision can be caused by abrupt withdrawal of opiates. This case should serve to raise awareness among health care professionals, to avoid costly and unnecessary diagnostic evaluations and interventions.
Purpose: Neurotrophic keratitis (NK) is a rare condition which may result in visual loss. This case review investigates if there may be an association between NK and the blink reflex in the absence of facial nerve palsy and lagophthalmos. Methods: This is a retrospective case review of 5 patients with trigeminal nerve damage referred to the oculoplastic department with suspected anesthetic corneae. Information on etiology, symptoms, duration, associated medical conditions, medications, examination findings including Mackie stage of keratopathy, management of keratopathy, and blink electrophysiology results was obtained. Results: All 5 patients demonstrated absence of corneal sensation. All patients had preserved facial nerve function with no evidence of lagophthalmos. Keratopathy ranged from Mackie stage 0–2. Management ranged from ocular lubricants to Botulinum-toxin-induced ptosis. Blink studies demonstrated reduction in amplitude as well as increased latency in 2 patients, conferring reduced blink strength. Two patients demonstrated an absent blink reflex on the affected side. One patient had blink latency within the normative range; this patient recovered corneal sensation and was discharged. Conclusions: Our finding of reduced amplitude in blink studies offers both a factor in pathogenesis of NK and a potential therapeutic target. Additionally, blink studies may provide prognostic information for recovery and therefore guide management. We suggest performing blink electrophysiology in patients with trigeminal nerve damage to assess nerve function.
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