Finite element modelling of the surgical procedure for placement of a straight electrode array: Mechanical and clinical consequences

A cochlear implant is an electronic device implanted into the cochlea to directly stimulate the auditory nerve. Such device is used in patients with severe-to-profound hearing loss. The cochlear implant surgery is safe, but involves some risks, such as infections, device malfunction or damage of the facial nerve and it can result on a poor hearing outcome, due to the destruction of any present residual hearing. Future improvements in cochlear implant surgery will necessarily involve the decrease of the intra-cochlear damage. Several implant related variables, such as materials, geometrical design, processor and surgical techniques can be optimized in order for the patients to partially recover their hearing capacities The straight electrode is a type of cochlear implant that many authors indicate as being the less traumatic. From the finite element analysis conducted in this work, the influence of the insertion speed, the friction coefficient between the cochlear wall and the electrode array, and several configurations of the cochlear implant tip were studied. The numerical simulations of the implantation showed the same pattern of the insertion force against insertion depth, thus indicating the different phases of the insertion. Results demonstrated that lower insertion speeds, friction coefficients and tip stiffness, led to a reduction on the contact pressures and insertion force. It is expected that these improved configurations will allow to preserve the residual hearing while reducing surgical complications.info:eu-repo/semantics/publishedVersio

The human otitis media with effusion: a numerical-based study

Otitis media is a group of inflammatory diseases of the middle ear. Acute otitis media and otitis media with effusion (OME) are its two main types of manifestation. Otitis media is common in children and can result in structural alterations in the middle ear which will lead to hearing losses. This work studies the effects of an OME on the sound transmission from the external auditory meatus to the inner ear. The finite element method was applied on the present biomechanical study. The numerical model used in this work was built based on the geometrical information obtained from The visible ear project. The present work explains the mechanisms by which the presence of fluid in the middle ear affects hearing by calculating the magnitude, phase and reduction of the normalized umbo velocity and also the magnitude and phase of the normalized stapes velocity. A sound pressure level of 90 dB SPL was applied at the tympanic membrane. The harmonic analysis was performed with the auditory frequency varying from 100 Hz to 10 kHz. A decrease in the response of the normalized umbo and stapes velocity as the tympanic cavity was filled with fluid was obtained. The decrease was more accentuated at the umbo.info:eu-repo/semantics/publishedVersio

A biomechanical perspective on perineal injuries during childbirth

Background and objective: Childbirth trauma is a major health concern that affects millions of women worldwide. Severe degrees of perineal trauma, designated as obstetric anal sphincter injuries (OASIS), and levator ani muscle (LAM) injuries are associated with long-term morbidity. While significant research has been conducted on LAM avulsions, less attention has been given to perineal trauma and OASIS, which affect up to 90% and 11% of vaginal deliveries, respectively. Despite being widely discussed, childbirth trauma remains unpredictable. This work aims to enhance the modeling of the maternal musculature during childbirth, with a particular focus on understanding the mechanisms underlying the often overlooked perineal injuries. Methods: A geometrical model of the pelvic floor muscles (PFM) and perineum (including the perineal body, ischiocavernosus, bulbospongiosus, superficial and deep transverse perineal muscles) was created. The muscles were characterized by a transversely isotropic visco-hyperelastic constitutive model. Two simulations of vaginal delivery were conducted with the fetus in the vertex presentation and occipito-anterior position, with and without the perineum. Results: The simulation that considered the perineum exhibited higher stresses over an extended area of the PFM, which suggests that including additional structures can impact the obtained results. The maximum stretch of the urogenital hiatus was 2.94 and the maximum stress was 23.86 kPa. The perineal body reached a maximum stretch of 1.95, which was more pronounced near the urogenital hiatus, where perineal tears may occur. The external anal sphincter's transverse diameter decreased by 51% and the maximum principal stresses were observed in the area close to the perineal body, where OASIS can occur. Conclusions: The present study emphasizes the importance of including most structures involved in vaginal delivery in its biomechanical analysis and represents another step further in the understanding of perineal injuries and OASIS. The superior region of the perineal body and its connection to the urogenital hiatus and anal sphincter have been identified as the most critical regions, highly susceptible to injury

Oral platelet gel supernatant plus supportive medical treatment versus supportive medical treatment in the management of radiation-induced oral mucositis: a matched explorative active control trial by propensity analysis

OBJECTIVES:: In this active control trial, the rate of radio-induced WHO grade 3/4 oral mucositis and the change in quality of life, assessed by OMWQ-HN, were measured in subjects with head and neck cancer treated by platelet gel supernatant (PGS) and supportive medical treatment versus subjects treated by supportive medical treatment alone. MATERIALS AND METHODS:: Eighty patients with nonmetastatic head and neck cancer underwent curative or adjuvant radiotherapy. All patients underwent supportive medical treatment and/or PGS at the beginning and during radiotherapy. Sixteen patients received PGS in association with supportive medical treatment. To obtain 2 groups virtually randomized for important clinical characteristics subjects were matched, by propensity analysis, with a group of subjects (64 patients) treated with supportive medical treatment alone. RESULTS:: Subjects treated with standard supportive treatment experienced significant higher WHO grade 3/4 toxicity (55%; 35/64) than subjects treated by PGS (13%; 3/16). The reduced toxicity found in PGS group paralleled with the evidence that they developed later symptoms with respect to controls. The Cox proportional hazard model indicated that patients treated with standard supportive medical treatment experienced 2.7-fold increase (hazard ratio=2.7; 95% confidence interval, 1.3-5.7) in the occurrence of WHO grade 3/4 toxicity. PGS group significantly experienced higher quality of life than control groups as measured by OMWQ-HN. A significant decrease in the opioid analgesics usage was found in the PGS group. CONCLUSIONS:: These preliminary data should be interpreted with caution and could serve as a framework around which to design future trials

A finite element model to predict the consequencesof endolymphatic hydrops in the basilar membrane

Ménière's disease is an inner ear disorder, associated with episodes of vertigo,fluctuant hearing loss, tinnitus, and aural fullness. Ménière's disease is associ-ated with endolymphatic hydrops. Clinical evidences show that this disease isoften incapacitating, negatively affecting the patients' everyday life. The patho-genesis of Ménière's disease is still not fully understood and remains unclear.Previous numerical studies available in the literature related with endolym-phatic hydrops, are very scarce. The present work applies the finite elementmethod to investigate the consequences of endolymphatic hydrops in the nor-mal hearing, associated with the Ménière's disease. The obtained results forthe steady state dynamics analysis are in accordance with clinical evidences.The results show that the basilar membrane is not affected in the same inten-sity along its length and that the lower frequencies are more affected by theendolymphatic hydrops. From a clinical point of view, this work shows therelationship between the increasing of the endolymphatic pressure andthe development of hearing loss.info:eu-repo/semantics/publishedVersio

Neuroendocrine neoplasms of the esophagus and stomach.

Esophageal neuroendocrine neoplasms (E-NENs) are much rarer than other gastro-entero-pancreatic neuroendocrine neoplasms, the majority showing aggressive behavior with early dissemination and poor prognosis. Among E-NENs, exceptionally rare well differentiated neuroendocrine tumors (E-NET) and more frequent esophageal poorly differentiated neuroendocrine carcinomas (E-NEC) and mixed neuroendocrine-non neuroendocrine neoplasms (MiNEN) can be recognized. E-NECs usually exhibit a small cell morphology or mixed small and large cells. Esophageal MiNEN are composed of NEC component admixed with adenocarcinoma or squamous cell carcinoma. Gastric (G) NENs encompass a wide spectrum of entities ranging from indolent G-NETs to highly aggressive G-NECs and MiNENs. Among G-NETs, ECL-cell NETs are the most common and, although composed of histamine-producing cells, are a heterogeneous group of neoplastic proliferations showing different clinical and prognostic features depending on the patient's clinico-pathological background including the morphology of the peri-tumoral mucosa, gastrin serum levels, presence or absence of antral G-cell hyperplasia, and presence or absence of MEN1 syndrome. In general, NET associated with hypergastrinemia show a better outcome than NET not associated with hypergastrinemia. G-NECs and MiNENs are aggressive neoplasms more frequently observed in males and associated with a dismal prognosis

Induction of annexin-1 at transcriptional and post-transcriptional level in rat brain by methylprednisolone and the 21-aminosteroid U74389F

Brain tissue of rats pretreated with methylprednisolone or with the 21-aminosteroid U74389F, and that of untreated control rats, was assessed for the expression of annexin-1 (Anx-1) and the transcription of its mRNA. For this purpose Anx-1 cDNA was amplified and simultaneously a T7-RNA-polymerase promoter was incorporated into the cDNA using a polymerase chain reaction (PCR). Then digoxigenin-11-UTP was incorporated into the transcribed cRNA with T7-RNA-polymerase. With this probe in situ hybridization was carried out on sections of the brain. The probe was visualized by an immunoassay using an antidigoxigenin antibody conjugate. Anx-1 protein was assessed by means of immunohistochemistry using a polyclonal antibody. The various brain areas of the control animals showed an appreciable amount of Anx-1 at mRNA or protein level; on the other hand, the animals which had been pretreated with either steroid, showed a more intense Anx-1 mRNA signal than the controls in many areas. In the pretreated animals Anx-1 immunostaining was unchanged in cortex, basal ganglia, amygdala and septum, but more intense in hippocampus, hypothalamus and thalamus. In ependyma, choroid plexus, meninges, and vascular walls there was no Anx-1 mRNA transcription detectable. An opposite profile was shown by the Anx-1 immunoreactivity, the protein was present in control animals as well as the steroid-pretreated animals, suggesting that here the protein was either from systemic origin, or has diffused from adjacent structures. The results indicated that Anx-1 mRNA transcription is upregulated by either steroid, and that in the untreated animals there is a resting level of Anx-1 mRNA transcription, presumably reflecting physiological influences on Anx-1 expression

Unexpected reading dissociation in a Brazilian Nisei with crossed aphasia

There is an increased interest in reading impairments in the Japanese language, due to its particular writing system which includes two different scripts, Kanji (logograms) and Kana (phonograms). Reading dissociations between Kanji and Kana have been described, showing that each system is processed differently by the cerebral hemispheres. We describe the case of a 68 year old Brazilian "nisei" (i.e. born from Japanese parents) who had knowledge of both Japanese and Portuguese. He presented an ischemic stroke affecting the right hemisphere and subsequently developed a Broca's aphasia and an unexpected reading dissociation, with an impairment in Kana reading comprehension and a good performance in Kanji and in Portuguese. These findings suggest that the patient's right and left hemispheres have assumed opposite roles not only for oral but also for written language decodification. Keywords: Brazil-Broca's aphasia -Cerebral dominance -Cerebral infarction -Japan -Reading disability INTRODUCTION Japanese is a unique language since it includes two different writing systems, Kana (phonograms) and Kanji (logograms). Reading impairments in Japanese have been increasingly investigated in the last two decades and several studies have described reading dissociations between Kana and Kanji in aphasic and alexic patients Much debate still exists about the anatomical basis of the Japanese reading process. Recent data suggest that the left hemisphere participates in both Kana and Kanji reading, but that different structures are involved in the process of each writing system In the present study, we addressed this question describing a particular reading dissociation found in a bilingual patient presenting an aphasia of the Broca's type, following a right hemispheric stroke. The patient spoke both Japanese and Portuguese. We discuss our findings and suggest some possible factors that could have determined the striking cerebral organization for language observed in this patient. Moreover, the articulation of a functional model for reading allows an interpretation of the clinical picture of an unexpected reading dissociation between three writing systems. CASE REPORT The patient was a 68 year old right-handed man born in Brazil, called a "nisei" since his parents were Japanese, and who had no family history of left handedness. He studied both Portuguese and Japanese at school (2 years of schooling in Portuguese and 3 years in Japanese). Despite his low educational level, he was a skilled reader, was able to speak both languages at home and at work, and to write fluently in both. His writing skills in Japanese were so good that he became a scribe for his friends and relatives who wanted to send letters to Japan. In December 1989, he developed left hemiparesis and an aphasia of sudden onset. This clinical picture remained stable until he was first seen in January 1990 in the Hospital das Clinicas of the University of Sao Paulo School of Medicine, Brazil. At the time of neurological examination, the patient was alert, oriented, and aphasic. His left hemiparesis included the face and was more pronounced in the left upper limb. There were also marked oral and constructional apraxias. There were no signs of anosognosia, prosopagnosia or hemineglect; no visual field deficits were observed on confrontation. A campimetric evaluation was not available. The computed tomography (CT) scan showed a large low-density area in the distribution of the right 166 Behavioural Neurology. Vol 7 . 1994 P. CARAMELLI ET AI.. middle cerebral artery. Magnetic resonance imaging (MRI) revealed that this ischemic lesion involved the cortical and subcortical aspects of the medial, superior and transversal temporal gyri and of the inferior frontal gyrus, the lateral parts of the precentral and post-central gyri, the inferior parietal lobule and the insula. An older and smaller lesion, located posteriorly to the left lateral ventricle and subcortically distributed, was also identified in the left hemisphere Language evaluation Five months later, in May 1990, the patient was submitted to a formal language evaluation using the Portuguese version of the Montreal-Toulouse (MT-86 If) Aphasia Battery The spontaneous speech was mainly characterized by unintelligible segments. The patient was unable to produce correct responses in naming tasks. In repetition of Portuguese words and non-words, he presented phonemic paraphasias in 40.4% of the stimuli and a 44.2% rate of absence of response. Among the 15.4% of words correctly produced, there were 10 open-class words, one closed-class, and five neologisms, with an evident word length effect. In repetition tasks of Japanese words and non-words, the patient correctly repeated only 27.9% of the stimuli (15 open-, two closed-class words and 10 neologisms), also presenting a length effect. Phonemic paraphasias accounted for 51 .9% of the responses and there was a 20.2% rate of no response. The patient's performance in reading aloud in Portuguese was extremely poor (81.3% of no response). In 14.9% of the stimuli, the patient produced phonemic paralexias or he produced the word only after phonemic/ semantic facilitators given by the examiner. Only four words (3.7%) were correctly read, all of them being open-class and highly frequent words. He READING DISSOCIATION IN A BRAZILIAN "NISEI" was unable to read any non-word. In Kanji reading, only four words were correctly produced. In 52.7% of the stimuli there was an absence of response and in the remaining 32.6% of the words either phonemic paralexias occurred or the words were produced following the presentation of phonemic facilitators. In reading aloud Kana stimuli, the patient did not read any of the 72 words and 72 non-words presented to him. These overall results indicate that the patient showed deficits of the Broca's aphasia type. Finally, a severe constructional apraxia allowed him to draw only simple geometric forms and drastically affected his written output. Additional matching tasks were devised to further assess his auditory comprehension of both Portuguese and Japanese words. He was also submitted to written language comprehension tests, in Portuguese and Japanese, including Kana and Kanji stimuli. In each test, the patient was requested to point to the correct response. Patient's performance was compared with that of two normal controls, matched for age, languages and education. The first subject (Controll) was a 58 year old Brazilian "nisei" woman, with 4 years of schooling in Japanese and 12 in Portuguese, who was also a skilled reader and writer in Japanese. The second control was a 63 year old female "nisei", who learned Japanese and Portuguese essentially at home, and was thus able to read and write in both languages, especially in Japanese (she writes letters and reads newspapers regularly). The patient and the controls gave informed consent for all tests. The patient's and controls' results were as follows. Auditory word and picture-matching task. This task included 50 different line drawings of common objects. The subjects were requested to match an utterance of the examiner with one of four line drawings presented to them on a single display. The patient's score was perfect (100%) in Portuguese. He made few errors in Japanese, obtaining a score of 88.0%. Control subjects obtained perfect scores (100%) in both languages. Written word and picture-matching task. This task comprised 50 written words and the same 50 line drawings used previously. The subjects were requested to match a written word with one of four line drawings presented on a single display. In Portuguese, the patient obtained a score of 80.0010 whereas in Japanese, his score was better in Kanji (86.0%), than in Kana (20.0%). Control 1 achieved 100% in Portuguese and in Kanji, and 98% correct responses in Kana. The second control made no errors in this task (100% of correct responses in the three writing systems). Auditory and written word-matching task. In this task, a card with four written words was presented to the subjects. The examiner read one of the words aloud and the subjects had to select the appropriate word. They were submitted to a total of 80 trials in Kanji and in Portuguese. Targets included an equal number of frequent and non-frequent words, and also an equal number of imageable and nonimageable words, that is, 20 for each type. Kanji frequent words were coded between levels 1 and 4, and non-frequent Kanjis between levels 6 and 8, according to the classification of The patient was correct on 56.2% of the items in Kanji and on 76.2% of the items in Portuguese. As for the frequent and imageable words, he recognized 80.0010 of them when they were written in Kanji and 95.0% when written in Portuguese. On the other hand, the patient could identify neither Katakana writing nor Hiragana writing. His performance attained 12.5% of correct responses and was totally at random. Both controls performed flawlessly in this task (100%). Auditory and written non-word matching task. Non-words were presented to the subjects, once in Portuguese and once in Hiragana. For each language, there was a total of 45 trials. It is impossible to create non-words in Kanji because Kanji characters do not have separable phonemic components. The subjects were asked to select among four written non-words the one spoken by the examiner. The patient was able to correctly select only 28.9% in Portuguese and 11.1% of the non-words in Hiragana. Control 1 obtained a perfect score (100%) in Portuguese and in Kana, while Control 2 achieved 95.5% correct responses in Portuguese and a perfect score (100%) in Kana

Neutrino Detection with Inclined Air Showers

The possibilities of detecting high energy neutrinos through inclined showers produced in the atmosphere are addressed with an emphasis on the detection of air showers by arrays of particle detectors. Rates of inclined showers produced by both down-going neutrino interactions and by up-coming $\tau$ decays from earth-skimming neutrinos as a function of shower energy are calculated with analytical methods using two sample neutrino fluxes with different spectral indices. The relative contributions from different flavors and charged, neutral current and resonant interactions are compared for down-going neutrinos interacting in the atmosphere. No detailed description of detectors is attempted but rough energy thresholds are implemented to establish the ranges of energies which are more suitable for neutrino detection through inclined showers. Down-going and up-coming rates are compared.Comment: Submitted to New Journal of Physic