Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature

Abstract Introduction Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR. Objective The present study was undertaken to assess the various parameters of FR and round window visibility, which may be of relevance for cochlear implant surgery. Methods Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of FR and posterior tympanum. Photographs were taken with an 18megapixels digital camera, which were then imported to a computer to determine various parameters. Results The mean distance from the take-off point/crotch of the chorda tympani nerve (CTN) to the stylomastoid foramen was 4.08 ± 0.8 mm(range of 2.06 - 5.5mm). The variations in the course of the CTN included origin at the level of the lateral semicircular canal. Themean chorda-facial angle in our study was 26.91° ± 1.19°, with a range of 25° to 28.69°. The mean FR length ranged between 9.4 mm and 18.56 mm (mean of 12.41 ± 2.91mm) and varied with the origin of the CTN and pneumatization of temporal bone. The average maximum width of the FR was 2.93 ± 0.4 mm (range 2.24-3.45 mm) and the mean width of the FR at the level of the round window was 2.65 ± 0.41 mm. Conclusion The FR approach provides good access to the round windowmembrane in all cases. In some cases, table adjustment is required.

Tone-deaf ears in moths may limit the acoustic detection of two-tone bats.

Frequency alternation in the echolocation of insectivorous bats has been interpreted in relation to ranging and duty cycle, i.e. advantages for echolocation. The shifts in frequency of the calls of these so-called two-tone bats, however, may also play its role in the success of their hunting behavior for a preferred prey, the tympanate moth. How the auditory receptors (e.g. the A1 and A2 cells) in the moth's ear detect such frequency shifts is currently unknown. Here, we measured the auditory responses of the A1 cell in the noctuid Spodoptera frugiperda to the echolocation hunting sequence of Molossus molossus, a two-tone bat. We also manipulated the bat calls to control for the frequency shifts by lowering the frequency band of the search and approach calls. The firing response of the A1 receptor cell significantly decreases with the shift to higher frequencies during the search and approach phases of the hunting sequence of M. molossus; this could be explained by the receptor's threshold curve. The frequency dependence of the decrease in the receptor's response is supported by the results attained with the manipulated sequence: search and approach calls with the same minimum frequency are detected by the moth at the same threshold intensity. The two-tone bat M. molossus shows a call frequency alternation behavior that may enable it to overcome moth audition even in the mid-frequency range (i.e. 20-50 kHz) where moths hear best.

Ossification of the petrotympanic fissure: morphological analysis and clinical implications.

The petrotympanic fissure, a narrow slit in the temporal bone, allows the temporomandibular joint (TMJ) and the middle ear to communicate. Both the chorda tympani and the ligament cross the fissure between the posterior region of the joint disk and the malleolar ossicle. The parasympathetic fibers of the chorda tympani spread into the major salivary glands and are responsible for the taste sensibility on the anterior two-thirds of the tongue. After chronological identification of 30 human skulls, petrotympanic fissures were macroscopically and stereomicroscopically analyzed for the presence and disposition of ossification areas. Digitalized images were analyzed using computer program UTHSCSA ImageTool 3.0 (developed by the Department of Dental Diagnostic Science at The University of Texas Health Science Center, San Antonio, Texas). The total extension of the fissures and ossification areas was measured. The macroscopic analysis did not constitute an appropriated method for this evaluation and the ossification of the fissures increased with aging, suggesting its influence on the causes of otalgia in cases of TMJ dysfunction.

Anatomical variations of the mandibular nerve and its branches correlated to clinical situations.

AIM: The mandibular division of the trigeminal nerve is the largest of the three major divisions of the trigeminal nerve (fifth cranial nerve). In this way, many health professionals belonged to different fields are commonly evaluating patients suffering with orofacial pain and stomatognatic dysfunction associated to this structure. But, in the most cases, it is difficult to establish a correct diagnosis due to the anatomical complexity of the head and neck surfaces, especially when the focus is the trigeminal nerve. Thus, the objective of this research was to present the anatomical variations of the mandibular nerve and its branches correlated to more common clinical situations. METHODS: For this purpose, 20 human heads were anatomically dissected, so to study their structures, an external, medial and endocranial view. RESULTS: No significant variations related to ophthalmic and maxillary nerves were observed. Anatomical variations were observed in 20% of the total human heads dissected, all related to mandibular nerve and its branches: masseter, temporal, auriculotemporal and lingual. Variations in three to seven, on the number of the following nerves ramus, masseter and temporal were described. CONCLUSIONS: According to the present data using the described methodology, it was possible to conclude that anatomical variations are present in many subjects and they can explain many clinical situations that involve the stomatognathic structures.

Trastornos del gusto posestapedostomías / Post stapedectomy taste disorders

Introducción: En su trayecto por el oído medio el nervio cuerda del tímpano (CT), se ve expuesto a lesiones quirúrgicas. Los trastornos del gusto se presentan como posibles secuelas del daño sobre la CT, lo cual puede afectar la calidad de vida de los pacientes. En las estapedostomías, la CT debe ser movilizada frecuentemente, y a veces seccionada para accederá la platina del estribo. Objetivo: Evaluar la evolución temporal de los trastornos del gusto posestapedostomías y su correlación con la preservación de la CT. Material y método: Estudio retrospectivo entre los años 2002 y 2007. Se analizaron las fichas clínicas y protocolos operatorios en busca de preservación o sección de la CT durante la cirugía. Se aplicó un mini cuestionario para evaluar la función gustativa y su evolución en el tiempo. Resultados: La CT fue preservada en 131 pacientes (93 por ciento) y seccionada en 10 pacientes (7 por ciento). La incidencia de alteraciones del gusto fue 7,6 por ciento> (10 pacientes) en el grupo con preservación de la CT y 20 por ciento> (2 pacientes) en el grupo que se seccionó (p >0,05). Todos los pacientes tuvieron una recuperación completa en su función gustativa antes de 12 meses luego de la cirugía, siendo más rápida en el grupo con preservación que en el que se seccionó la CT(5 meses versus 11 meses respectivamente). Conclusiones: Las alteraciones del gusto están presentes en pacientes sometidos a estapedostomías incluso cuando la CT es preservada. Cuando es seccionada no siempre se presentan trastornos del gusto, pero cuando están son más severos y duraderos.

Introduction: In its course through middle ear, the chorda tympani nerve (CTN) is potentially exposed to surgical injury. Possible sequels of CTN injury are taste disorders, which can affect the life quality of patients. During stepedectomies, the CTN often must be displaced or even severed in order to gain access to the stapes footplate. Aim: To assess the temporal evolution of post stepedectomy taste disorders and their correlation with CTN preservation. Material and Method: A retrospective study was conducted between 2002 and 2007. Medical records of 141 patients subjected to stapedectomy were analyzed in search for CTN preservation or section during surgery. A questionnaire was applied to evaluate postoperative taste function and its evolution over time. Results: CTN was preserved in 131 patients (93 percent) and sectioned in 10 patients (7 percent). The incidence of taste disorders was 7.6 percent (10 patients) in the CTN preserved group and 20 percent> (2 patients) in the CTN severed group (p>0.05). All patients had fully recovered taste function by 12 months after surgery, recovery being faster in the CTN preserved group than in the CTN severed group (5 months vs. 11 months respectively). Conclusions: Taste disorders may be present in patients subjected to stapedectomy even when CTN is preserved; taste disorders are more severe and long lasting in cases where the CTN is sectioned.

Olfactory threshold increase in trigeminal neuralgia after balloon compression.

Idiopathic trigeminal neuralgia (ITN) is a well-known disease often treated with neurosurgical procedures, which may produce sensorial abnormalities, such as numbness, dysesthesia and taste complaints. We studied 12 patients that underwent this technique, in order to verify pain, gustative and olfactory thresholds abnormalities, with a follow-up of 120 days. We compared the patients with a matched control group of 12 patients. Our results found a significant difference in the olfactory threshold at the immediate post-operative period (p=0.048). We concluded that injured trigeminal fibers are probably associated with the increase in the olfactory threshold after the surgery, supporting the sensorial interaction theory.

Miringoesclerose em pacientes renais crônicos: estudo em 116 pacientes / Miringoesclerosis in pacients with chronic renal faillure: study of 116 patients

A timpanoesclerose é uma alteração da lâmina própria da orelha média, resultante de processo inflamatório, que envolve a deposição de cálcio neste tecido. Com o objetivo de avaliar a influência de distúrbios do metabolismo do cálcio neste processo, os autores estudaram a freqüência de miringoesclerose em 116 pacientes portadores de insuficiência renal crônica, encontrando uma prevalência de índice de 9,5 por cento, o que reflete a possibilidade da influência desta doença na gênese da timpanosclerose

Sympathetic mediation of salivation induced by intracerebroventricular pilocarpine in rats.

Central cholinergic activation by pilocarpine induces salivation dependent on the integrity of forebrain areas. The present work investigates the autonomic mediation of this salivation. Pilocarpine (500 nmol/rat) was injected into the lateral ventricle (LV) of tribromoethanol-anesthetized adult male rats. Preweighed cotton balls were inserted into the oral cavity and weighed again 7 min later. Alpha-adrenoceptor antagonists (3-50 micromol/kg) prazosin (alpha1), yohimbine (alpha2) or propranolol (beta) injected intraperitoneally (i.p.) produced, 80%, 20% and 0% inhibition respectively of the LV pilocarpine-induced salivation. Intracerebroventricular injections (160 nmol) of the antagonists did not alter the effects of pilocarpine injected into the LV. Bilateral section of chorda tympani nerve or bilateral sympathetic cervical ganglionectomy produced 0% and 40% inhibition of pilocarpine-induced salivation, respectively. Ganglionectomy did not alter salivation induced by i.p. injection of pilocarpine (4 micromol/kg). The results indicate that there is a large sympathetic contribution to the salivation induced by central cholinergic activation.

Neuroma of the chorda tympani nerve.

The authors present a case of Neuroma of the Chorda Tympani Nerve, which is extremely rare. Apparently, only two (2) cases have been reported to date. The initial manifestation was a hard tumor that occupied the posterior wall of the external auditory canal. There were no other symptoms.

Facial nerve near the external auditory meatus in man: computer reconstruction study--preliminary report.

The anatomy of the facial nerve relative to its intratemporal and extratemporal courses varies over time with developmental changes. Otologic and parotid surgery in infants and children demands detailed knowledge of the precise anatomy of the facial nerve with respect to the tympanic ring and external auditory canal. The authors analyzed this area using our three-dimensional (3-D) computer-aided reconstruction and measurement method studying the spatial relations of the facial nerve to the tympanic ring and stylomastoid foramen. Temporal bones from five normal individuals aged 36 gestational weeks, 3 months, 8 months, 4 years, and 17 years were retrieved from the temporal bone collection stored at the Elizabeth McCullough Knowles Otopathology Laboratory in Pittsburgh. Three-dimensional reconstruction of the facial nerve comparing the developmental anatomy across the various age groups provides the surgeon with the technical information necessary to address problems in this area.

Variaçöes anatômicas do nervo corda do tímpano / Anatomic variations of chorda tympani nerve

Os autores apresentam um estudo das variaçöes anatômicas do nervo corda do tímpano encontradas em 30 ossos temporais humanos que foram dissecados. A seguir fazem uma revisäo bibliográfica e discutem o assunto, enfocando a correlaçäo anatômica entre o nervo facial e o nervo corda do tímpano

O seio sigmóide no acesso mastóide ao nervo facial e conduto-auditivo interno / Sigmoid sinus in mastoid access to facial nerve and internal auditory pathway

Os autores estudam as medidas anatômicas do seio sigmóide em relaçäo ao nervo facial, no seu segundo joelho e na emergência do nervo-corda do tímpano, com o intuito de prevenir-se para abordagem cirúrgica de mastóide, especialmente para ouvido interno. Foi elaborada uma relaçäo anatômica/radiográfica a partir de medidas de 52 ossos temporais humanos dissecados. A partir dessa previsäo pode o cirurgiäo prevenir-se quanto à possibilidade de ter que afastar o seio sigmóide para estes procedimentos

Autonomic nervous system regulation of murine immune responses as assessed by local surgical sympathetic and parasympathetic denervation.

The effect of local sympathetic denervation on immune responses of submaxillary lymph nodes (SmLN) of mice was examined in animals subjected to unilateral superior cervical ganglionectomy (SCGx). Norepinephrine (NE) content in ipsilateral SmLN decreased by 90% 7-20 days after SCGx, while bilateral SCGx resulted in a 91% decrease of SmLN NE content. SmLN of mice subjected to unilateral SCGx exhibited greater plaque-forming cell (PFC) response than the innervated contralateral SmLN, when challenged i.d. or i.p. with sheep red blood cells (SRBC) 10-20 days after surgery. In mice challenged with SRBC at an early phase of sympathetic nerve paralysis (i.e., 2 h after SCGx), PFC response was already increased in the ipsilateral SmLN whereas during the anterograde degeneration of nerve endings (6-24 h after SCGx) an impending depression of PFC number was observed. Contact hypersensitivity and allogeneic delayed-type reactions were also enhanced in the ear ipsilateral to SCGx. Primed SmLN cells of nodes located ipsilaterally to SCGx, when injected to (BALB/c x C57BL/6) F1, resulted in significantly higher spleen index than similarly treated, contralateral SmLN. In contrast, mitogenic stimulation under various experimental protocols failed to reveal significant differences between proliferation of cell populations obtained from ipsilateral and contralateral SmLN of unilaterally SCGx mice. SmLN of mice parasympathetically decentralized by unilateral sections of the chorda tympani-lingual nerve trunk showed lower PFC response than the innervated contralateral SmLN, when challenged with SRBC 8-28 days after surgery. These results suggest a regulatory function of the autonomic nervous system in immune reaction.

Autonomic nervous system regulation of murine immune responses as assessed by local surgical sympathetic and parasympathetic denervation

En ratones sometidos a gangliectomia simpática cervical superior (SCGx) unilateral se estudió el efecto de la desnervación local sobre la respuesta imune de ganglios linfáticos submaxilares (SmLN). El contenido de norepinefrina (NE) de SmLN disminuyó en un 90% a los 7-20 dias luego de la SCGx uni o bilateral. Los SmLN ipsilaterales de ratones SCGx unilateralmente 10-20 días antes e inyectados i.d. o i.p. con eritrocitos de carnero mostraron una respuesta de células formadoras de placa (PFC) significantivamente mayor que el control invervado contralateral. En ratones inyectados con eritrocitos de carnero en al fase temprana de parálisis neural simpática (2 h luego de la SCGx), se detectó una respuesta PFC aumentada mientras que durante la fase de degeneración anterógrada de los terminales (6-24 h luego de SCGx), se observó una disminucióm crecimente de PFC. En ratones crónicamente SCGx se detectó también un aumento significativo en la hipersensibilidad por contacto y reacción alogeneica retardada en al oreja ipsilateral a la operación. Al inyectar células de SmLN desnervados a F1 de (BALB/c x C57Bl/6) o de (BALB/c x AKR) se obtuvbieron índices esplénicos significativamente mayores que los observados luego de inyectar células controles. La estimulación mitogénica en diferentes protocolos experimentales no resultó en diferencias significativas entre SmLN desnervados e inervados. Luego de la descentralización local por sección unilateral del tronco lingual-cuerda del tímpano, los SmLN ipsilaterales exhibieron menor respuesta PFC 8-28 días luego de la cirugía. Estos resultados indican función modulatoria del sistema nervioso autónomo en la respuesta inmune (AU)

Autonomic nervous system regulation of murine immune responses as assessed by local surgical sympathetic and parasympathetic denervation

En ratones sometidos a gangliectomia simpática cervical superior (SCGx) unilateral se estudió el efecto de la desnervación local sobre la respuesta imune de ganglios linfáticos submaxilares (SmLN). El contenido de norepinefrina (NE) de SmLN disminuyó en un 90% a los 7-20 dias luego de la SCGx uni o bilateral. Los SmLN ipsilaterales de ratones SCGx unilateralmente 10-20 días antes e inyectados i.d. o i.p. con eritrocitos de carnero mostraron una respuesta de células formadoras de placa (PFC) significantivamente mayor que el control invervado contralateral. En ratones inyectados con eritrocitos de carnero en al fase temprana de parálisis neural simpática (2 h luego de la SCGx), se detectó una respuesta PFC aumentada mientras que durante la fase de degeneración anterógrada de los terminales (6-24 h luego de SCGx), se observó una disminucióm crecimente de PFC. En ratones crónicamente SCGx se detectó también un aumento significativo en la hipersensibilidad por contacto y reacción alogeneica retardada en al oreja ipsilateral a la operación. Al inyectar células de SmLN desnervados a F1 de (BALB/c x C57Bl/6) o de (BALB/c x AKR) se obtuvbieron índices esplénicos significativamente mayores que los observados luego de inyectar células controles. La estimulación mitogénica en diferentes protocolos experimentales no resultó en diferencias significativas entre SmLN desnervados e inervados. Luego de la descentralización local por sección unilateral del tronco lingual-cuerda del tímpano, los SmLN ipsilaterales exhibieron menor respuesta PFC 8-28 días luego de la cirugía. Estos resultados indican función modulatoria del sistema nervioso autónomo en la respuesta inmune

Alteraçöes morfológicas da glândula submandibular do rato, após secçäo do nervo corda do tímpano: observaçäo após um ano / Morphological alterations in rat submandibular glands after cutting the chorda tympani nerve

No presente trabalho foram estudadas as alteraçöes morfológicas das glândulas submandibulares de rato, após secçäo do nervo corda do tímpano. Com base nos resultados foi possível concluir: o peso médio das glândulas experimentais foi maior nos grupos de 1 e 2 dias para as que tiveram o corda do tímpano seccionado. Para todas as outras glândulas desnervadas, o peso da glândula experimental foi menor do que a controle. O aumento de peso inicial foi atribuído à uma retençäo ou acúmulo de secreçäo no interior das células acinares. A partir de 3 dias foram observadas regiöes de atrofia mais acentuada na regiäo acinar do que nas outras estruturas, as glândulas ficaram menores, fibrosadas, com reduçäo da parte glandular acinosa e com grande invasäo de polimorfonucleares. Nas glândulas com secçäo do nervo corda do tímpano foram observadas fibras nervosas e neurônios com características normais. A partir de 60 dias de observaçäo após secçäo do nervo, a glândula parece caminhar para uma regeneraçäo do parênquima