Rupture of Internal carotid artery pseudoaneurysm in the sphenoid sinus as a complication of deep neck space infection

Background : Pseudoaneurysm of the internal carotid artery (ICA) is a very rare but potentially fatal complication of deep neck space infection. Methods : This paper describes a very rare case of an ICA pseudoaneurysm rupture in the sphenoid sinus caused by a deep neck abscess. Results : A 62-year-old male with a deep neck space infection underwent surgical drainage. On the postoperative 21st day, however, he suddenly had massive epistaxis. A transnasal endoscopic examination found massive bleeding out of the sphenoid sinus. Immediate intra-arterial angiography revealed two pseudoaneurysms of the left ICA at the cavernous segment (C4) and the clinoid segment (C5), which were embolized with coils. The patient made an uneventful recovery after the embolization. Conclusion : We found no reports in the literature that pseudoaneurysms associated with a deep neck infection rupture in the sphenoid sinus. Prompt treatment along with accurate diagnosis is essential for successful management of such cases

Neural mechanisms of motion sickness

Three kinds of neurotransmitters : histamine, acetylcholine and noradrenaline, play important roles in the neural processes of motion sickness, because antihistamines, scopolamine and amphetamine are effective in preventing motion sickness. Histamine H1-receptors are involved in the development of the symptoms and signs of motion sickness, including emesis. On provocative motion stimuli, a neural mismatch signal activates the histaminergic neuron system in the hypothalamus, and the histaminergic descending impulse stimulates H1-receptors in the emetic center of the brainstem. The histaminergic input to the emetic center through H1-receptors is independent of dopamine D2-receptors in the chemoreceptor trigger zone in the area postrema and serotonin 5HT3-receptors in the visceral afferent, which are also involved in the emetic reflex. Antihistamines block emetic H1-receptors to prevent motion sickness. Scopolamine prevents motion sickness by modifying the neural store to reduce the neural mismatch signal and by facilitating the adaptation/habituation processes. The noradrenergic neuron system in the locus coeruleus is suppressed by the neural mismatch signal. Amphetamine antagonizes mismatch-induced suppression of noradrenergic neural transmission, resulting in preventing motion sickness

The effect of visual-vestibulosomatosensory conflict induced by virtual reality on postural stability in humans

In this study, we examined the effects of sensory inputs of visual-vestibulosomatosensory conflict induced by virtual reality (VR) on subjective dizziness, posture stability and visual dependency on postural control in humans. Eleven healthy young volunteers were immersed in two different VR conditions. In the control condition, subjects walked voluntarily with the background images of interactive computer graphics proportionally synchronized to their walking pace. In the visual-vestibulosomatosensory conflict condition, subjects kept still, but the background images that subjects experienced in the control condition were presented. The scores of both Graybiel’s and Hamilton’s criteria, postural instability and Romberg ratio were measured before and after the two conditions. After immersion in the conflict condition, both subjective dizziness and objective postural instability were significantly increased, and Romberg ratio, an index of the visual dependency on postural control, was slightly decreased. These findings suggest that sensory inputs of visual-vestibulosomatosensory conflict induced by VR induced motion sickness, resulting in subjective dizziness and postural instability. They also suggest that adaptation to the conflict condition decreases the contribution of visual inputs to postural control with re-weighing of vestibulosomatosensory inputs. VR may be used as a rehabilitation tool for dizzy patients by its ability to induce sensory re-weighing of postural control

Comparison of the efficacy of the Epley maneuver and repeated Dix–Hallpike tests for eliminating positional nystagmus: A multicenter randomized study

Background and objectivesPatients with benign paroxysmal positional vertigo of the posterior canal (pc-BPPV) exhibit BPPV fatigue, where the positional nystagmus diminishes with the repeated performance of the Dix–Hallpike test (DHt). BPPV fatigue is thought to be caused by the disintegration of lumps of otoconial debris into smaller parts and can eliminate positional nystagmus within a few minutes [similar to the immediate effect of the Epley maneuver (EM)]. In this study, we aimed to show the non-inferiority of the repeated DHt to the EM for eliminating positional nystagmus after 1 week.MethodsThis multicenter, randomized controlled clinical trial was designed based on the CONSORT 2010 guidelines. Patients who had pc-BPPV were recruited and randomly allocated to Group A or Group B. Patients in Group A were treated using the EM, and patients in Group B were treated using repeated DHt. For both groups, head movements were repeated until the positional nystagmus had been eliminated (a maximum of three repetitions). After 1 week, the patients were examined to determine whether the positional nystagmus was still present. The groups were compared in terms of the percentage of patients whose positional nystagmus had been eliminated, with the non-inferiority margin set at 15%.ResultsData for a total of 180 patients were analyzed (90 patients per group). Positional nystagmus had been eliminated in 50.0% of the patients in Group A compared with 47.8% in Group B. The upper limit of the 95% confidence interval for the difference was 14.5%, which was lower than the non-inferiority margin.DiscussionThis study showed the non-inferiority of repeated DHt to the EM for eliminating positional nystagmus after 1 week in patients with pc-BPPV and that even the disintegration of otoconial debris alone has a therapeutic effect for pc-BPPV. Disintegrated otoconial debris disappears from the posterior canal because it can be dissolved in the endolymph or returned to the vestibule via activities of daily living.Classification of evidenceThis study provides Class II evidence of the non-inferiority of repeated DHt to the EM for eliminating positional nystagmus after 1 week.Registration numberUMIN000016421