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Biomedical subjects

R F Bento

Publications and source records attributed to R F Bento.

18 recordsLinked to original sources

Anaglyphic three-dimensional stereoscopic printing: revival of an old method for anatomical and surgical teaching and reporting.

The authors describe how to use the three-dimensional (3D) anaglyphic method to produce stereoscopic prints for anatomical and surgical teaching and reports preparation by using currently available nonprofessional photographic and computer methods. As with any other method of producing stereoscopic images, the anaglyphic procedure is based on the superimposition of two slightly different images of the object to be reproduced, one seen more from a left-sided point of view and the other seen more from a right-sided point of view. The pictures are obtained using a single camera, which following the first shot can be slid along a special bar for the second shot, or by using two cameras affixed to a surgical microscope. After the images have been distinguished from each other by applying different complementary color dyes, the images are scanned and superimposed on each other with the aid of nonprofessional imaging-manipulation software used on a standard personal computer (PC), and are printed using a standard printer. To be seen stereoscopically, glasses with colored lenses, normally one red and one blue, have to be used. Stereoscopic 3D anaglyphic prints can be produced using standard photographic and PC equipment; after some training, the prints can be easily reproduced without significant cost and are particularly helpful to disclose the 3D character of anatomical structures.

Anatomy↗

Magnetic resonance imaging of the temporal bone in patients with Ménière's disease.

Ménière's disease (MD) is still controversial in several aspects. The vestibular aqueduct, the osseous channel that carries the endolymphatic duct and sac, has previously been studied by tomography and computed tomography, with shortening and narrowing of this structure observed. These findings are apparently correlated to the development of the endolymphatic hydrops present in MD and related to its episodic symptoms. In studying the endolymphatic duct, the key structure in the pathology of this disease, magnetic resonance imaging (MRI) studies of the temporal bone were performed in 12 patients with unilateral MD and in 9 bilateral cases; the results were compared with images obtained from 30 normal ears. The endolymphatic duct appeared to be statistically less visible in MD patients, with no difference between symptomatic and asymptomatic ears in the presence of unilateral disease. No relationship was found between visualization of the endolymphatic duct and time of evolution or response to clinical treatment in these cases. The distance from the posterior semicircular canal to the posterior temporal border was found to be bilaterally reduced in MD. The authors conclude that although the demonstration of endolymphatic hydrops "in vivo" is not yet possible by MRI, some features can be observed that can support a clinical hypothesis of MD.

Adult↗

Lidocaine test in patients with tinnitus: rationale of accomplishment and relation to the treatment with carbamazepine.

OBJECTIVES: There is strong evidence in the literature about the effect of local anesthetics such as lidocaine in controlling tinnitus; these agents act by stabilizing hair cell membrane and cochlear nerve fibers. However, the effect of intravenous lidocaine is transient, and its oral analog (tocainide) does not have the same efficacy for long-term treatment in patients with tinnitus. Some oral anti-epileptic drugs (carbamazepine, for instance) have been used alternatively in several studies. The aim of this work is to evaluate the response to intravenous lidocaine in patients with intractable tinnitus and the effect of oral carbamazepine in long-term maintenance of tinnitus relief. PATIENTS AND METHODS: We studied prospectively 50 patients (28 females and 22 males; mean age 50.9 years) who underwent the lidocaine test, performed by a 3-min intravenous infusion of 2% lidocaine chloridrate. The patients who experienced any relief after the test started treatment with oral carbamazepine in ascending dosages (50-600 mg/day). RESULTS: The results were classified as tinnitus abolition (18%), marked relief (32%), partial relief (26%), unchanged (22%), or worsening (2%). The lidocaine test showed favorable results in 76% of patients, especially those with bilateral tinnitus (P < 0.001). Afterwards, 50% of patients treated with carbamazepine maintained the improvement of tinnitus (P = 0.0034). CONCLUSION: The authors conclude that intravenous lidocaine is effective in reducing intractable tinnitus and that there is a close association between lidocaine and oral carbamazepine effects. Therefore, carbamazepine can be used for the treatment of tinnitus when the patient achieves improvement of symptom after the lidocaine test.

Administration, Oral↗

Continuous, high-frequency objective tinnitus caused by middle ear myoclonus.

Myoclonus of the middle ear is a rare condition characterized by abnormal repetitive muscle contractions of the tympanic cavity. In this paper we describe what we believe is the first reported case of continuous high-frequency objective tinnitus caused by middle ear myoclonus. During exploratory tympanomastoidectomy it was hypothesized that a small dural arteriovenous malformation not identified on previous tests was the cause of the tinnitus. However, complete disappearance of the tinnitus during administration of curare for anesthesia led us to believe that the tinnitus might have been caused by myoclonus of the middle ear. Sectioning of the stapedius and tensor tympani tendons rendered the patient asymptomatic and confirmed the diagnosis of middle ear myoclonus. At follow-up of one year, the patient's quality of life had improved substantially; the tinnitus did not recur and she no longer had vertigo.

Adult↗

Otological lesions in pachyonychia congenita syndrome.

The authors report a case of a patient with pachyonychia congenita syndrome, a rare genodermatosis inherited as an autosomal dominant trait, who also had otological lesions beyond the other classic signs and symptoms of the syndrome. Many kinds of treatment have already been proposed, but all failed to show satisfactory results. A new, cheap and easy-to-use treatment was developed in this study, using keratoplastics interpolated with humectant lotion for 90 days. The results after three years of follow-up are still thoroughly satisfactory.

Adult↗

A pathway for information transmission to the ear.

The use of implantable hearing aids and cochlear implants as an aid to neurosensory deafness is becoming an established procedure. The transmission of a processed speech signal is accomplished either transcutaneously via radiofrequency or percutaneously by connector coupling. Whereas the former is sensitive to electromagnetic interference, the latter increases the risk of infection. To overcome these disadvantages, an infrared (IR) system for transmission through the tympanic membrane was devised and tested. The transmitter/receiver consisted of an IR light emitting diode (LED; 920nm) and a photovoltaic cell. The LED was placed inside the auditory canal of four dogs and the photovoltaic cell in the tympanic cavity over the cochlear promontory. A sinusoidal signal modulation was applied to the LED. The emitted signal was detected undistorted after crossing the tympanic membrane, with an average absorbance of 20%. High-frequency cut-off was adequate for cochlear implant purposes and audio prosthetic devices in general. The authors conclude that the tympanic membrane may be used as a translucent sealed interface to transmit data in the audio range to the middle and inner ears, with small power loss, good frequency response, and immunity to interface.

Animals↗

Anastomosis of the intratemporal facial nerve using fibrin tissue adhesive.

This work aimed at studying the results obtained by the repair of complete lesions of the facial nerve in its intratemporal portions. Clinical, electrophysiological and surgical techniques were studied. Twenty-three patients with traumatic facial nerve lesions were operated. Nerve grafts were made in 10, and end-to-end anastomosis in thirteen. The surgical technique performed was the coaptation of the stumps and stabilization with fibrin tissue adhesive. Sixteen months after surgery, a clinical and electrophysiological evaluation was made. The use of fibrin tissue adhesive to stabilize intratemporal anastomosis of facial nerve showed clinical and electrophysiological evidence of axonal growth and reinnervation of mimical muscles of the face. These results were similar to that obtained by other authors that used other methods of microanastomosis. The use of fibrin tissue adhesive is an effective technique to utilize in intratemporal anastomosis of the facial nerve.

Adult↗

["Osteogenesis imperfecta": some differential particularities with otospongiosis].

The authors present 3 cases of osteogenesis imperfecta, with auditory repercussions similar to otospongiosis. A review of the literature of the pathology highlights its relationship with the temporal bone. The findings and treatment of 3 cases are discussed. The author conclude that this pathology may suggest otospongiosis with a progressive neuro-sensorial loss of hearing. The treatment of choice is the use of a hearing aid, rather than surgery.

Adult↗

Comparison between fibrin tissue adhesive, epineural suture and natural union in intratemporal facial nerve of cats.

Our objective was to study intratemporal anastomosis of the facial nerve in cats. Clinical, electrophysiological and histological results of the use of fibrin tissue adhesive, epineural suture and natural adhesion were compared. The 30 adult cats studied had undergone mastoidectomy exposure, and section of the facial nerve 1 cm before its exit from the stylomastoid foramen. Anastomosis was then undertaken, using epineural suture combined with stabilization through fibrinic tissue adhesive, and union of the stumps without stabilizing them. Each type of anastomosis was carried out in 10 animals. Clinical, electrophysiological and histological assessments of both the site of anastomosis and the ventral branch of the facial nerve followed the aforementioned procedures. By means of statistical analysis, the authors reached the following conclusions: 1) Considering the clinical assessment per se, both groups with fibrinic tissue adhesive and suture showed similar features and results, which in both cases were better than those following natural union. 2) Considering the electrophysiological results per se, the use of fibrin tissue adhesive was superior to any other method used. 3) Considering the histological examination per se, both groups with fibrin tissue adhesive and suture revealed similar features which were more favourable than those shown by natural union. 4) In the overall comparison of the various parameters in the three groups, the use of fibrin tissue adhesive achieved better results than any other method. Based on the results of this study, the authors conclude that the use of fibrin tissue adhesive has technical advantages, and that the results of this use outweigh those achieved with both epineural suture and natural union. The authors recommend this technique as the most beneficial to be resorted to, for intrapetrous anastomosis of the facial nerve.

Anastomosis, Surgical↗

X-linked mixed hearing loss: four case studies.

To present four cases of an X-linked inner ear malformation, the authors studied inner ear malformations and present here all the radiological, genetic, and audiological tests of these patients. The importance of this paper is to reinforce the differential diagnosis between this pathology and otosclerosis in order to avoid surgical procedures.

Acoustic Impedance Tests↗

A pathway for information transmission to the inner ear. Application to cochlear implants.

The use of cochlear implants as an aid to neurosensory deafness is becoming an established procedure. The transmission of a processed speech signal is accomplished either transcutaneously via radiofrequency or percutaneously by connector coupling. Whereas the former is sensitive to electromagnetic interference, the latter increases the risk of infection. To overcome these disadvantages, an infrared (IR) system for transmission through the tympanic membrane was devised and tested. The transmitter/receiver consisted of an IR light emitting diode (LED; 920 nm) and a photovoltaic cell. The LED was placed inside the auditory canal of four dogs and the photovoltaic cell in the tympanic cavity over the cochlear promontory. A sinusoidal signal modulation was applied to the LED. The emitted signal was detected undistorted after crossing the tympanic membrane, with an average absorbance of 20%. High frequency cut-off was adequate for cochlear implant purposes and audio prosthetic devices in general. The authors conclude that the tympanic membrane may be used as a translucent sealed interface to transmit data in the audio range to the middle and inner ears, with small power loss, good frequency response, and immunity to interference.

Acoustic Stimulation↗

Human lagochilascariasis treated successfully with ivermectin: a case report.

A 15 year old male patient was diagnosed as being infected with the nematode Lagochilascaris minor, presenting as abscesses over the left mastoid region, and invading the temporal bone, mastoid sinuses and possibly the CNS. Surgical drainage and administration of cambendazole and levamisole led to improvement, followed by an early relapse and poor tolerance to the antihelminthic drugs. Repeated doses of ivermectin (an animal preparation) were used for the first time to treat this condition and resulted in complete remission of signs of infection, maintained for 15 months after the end of drug therapy, indicating cure of the disease.

Adolescent↗