Facial Nerve Adherence in Vestibular Schwannomas: Classification and Radiological Predictors.

Background Facial nerve palsy is one of the most frequent complications after resection of vestibular schwannomas (VS). Several mechanisms have been implicated in the poor postoperative facial nerve outcome. Adherence between the facial nerve and tumor capsule is one of the most relevant factors. There is no clear preoperative parameter permitting identification of these adhesions. Objective The aim of this study was to identify the correlation between the grade of adherence of the facial nerve to the tumor capsule and its functional outcome after VS resection. Methods A total of 26 patients with sporadic VS (tumor sized T3, T4A, and T4B according to Hannover classification) were evaluated. Grade of adherence of the facial nerve to the tumor capsule was checked during surgery and graduated according to a proposed scale into 1 to 3 different grades. Facial nerve function was assessed postoperatively and after 1-year follow-up. Size of tumor according to Hannover classification, presence of cystic components, "cerebrospinal fluid (CSF) cleft sign," and the contour of tumor capsule were tested as radiological predictors of grade of adherence to the facial nerve. Results and Conclusion Only Grade 2 (11 cases) and 3 (15 cases) of adherence were seen in large VS. Lower grade of adherence was associated with good facial nerve outcome after 1-year follow-up ( p = 0.029). Presence of the "CSF cleft sign" and regular contour of tumor capsule were independent predictors of adherence. When both factors were associated, sensitivity and specificity of this method were 83 and 80%, respectively.

Image Fusion in Neurovascular Compression Syndrome Related to Hemifacial Spasm.

Neurovascular compression syndromes have well characterized clinical symptoms, but precise identification of the pathologic contact between the nerves and vessels can be challenging at neuroimaging. Considering that neurovascular contacts are frequent imaging findings in asymptomatic patients, correct visualization of pathological contact is crucial for the diagnosis and surgical planning. We have used magnetic resonance imaging fusion by overlaying color-coded T1-weighted postcontrast onto high-resolution T2-weighted images to better delineate imaging findings by enhancing vascular structures.

Effect of granulocyte colony-stimulating factor on the cochlear nuclei after creation of a partial nerve lesion: an experimental study in rats.

OBJECTIVE The risk of injury of the cochlear nerve during angle (CPA) surgery is high. Granulocyte colony-stimulating factor (G-CSF) has been found in various experimental models of peripheral and CNS injury to have a neuroprotective effect by inhibiting apoptosis and inflammation. However, to the authors' knowledge, the influence of G-CSF on cochlear nerve regeneration has not been reported. This study investigated the neuroprotective effect of G-CSF after a partial cochlear nerve lesion in rats. METHODS A lesion of the right cochlear nerve in adult male Sprague-Dawley rats was created using a water-jet dissector with a pressure of 8 bar. In the first group (G-CSF-post), G-CSF was administrated on Days 1, 3, and 5 after the surgery. The second group (G-CSF-pre/post) was treated with G-CSF 1 day before and 1, 3, and 5 days after applying the nerve injury. The control group received sodium chloride after nerve injury at the various time points. Brainstem auditory evoked potentials (BAEPs) were measured directly before and after nerve injury and on Days 1 and 7 to evaluate the acoustic function of the cochlear nerve. The animals were sacrificed 1 week after the operation, and their brains were fixed in formalin. Nissl staining of the cochlear nuclei was performed, and histological sections were analyzed with a light microscope and an image-processing program. The numbers of neurons in the cochlear nuclei were assessed. RESULTS The values for Waves 2 and 4 of the BAEPs decreased abruptly in all 3 groups in the direct postoperative measurement. Although the amplitude in the control group did not recover, it increased in both treatment groups. According to 2-way ANOVA, groups treated with G-CSF had a significant increase in BAEP Wave II amplitudes on the right side (p = 0.0401) after the applied cochlear nerve injury. With respect to Wave IV, a trend toward better recovery in the G-CSF groups was found, but this difference did not reach statistical significance. In the histological analysis, higher numbers of neurons were found in the G-CSF groups. In the statistical analysis, the difference in the numbers of neurons between the control and G-CSF-post groups reached significance (p = 0.0086). The difference in the numbers of neurons between the control and G-CSF-pre/post groups and between the G-CSF-post and G-CSF-pre/post groups did not reach statistical significance. CONCLUSIONS The use of G-CSF improved the function of the eighth cranial nerve and protected cochlear nucleus cells from destruction after a controlled partial injury of the nerve. These findings might be relevant for surgery that involves CPA tumors. The use of G-CSF in patients with a lesion in the CPA might improve postoperative outcomes.

Comparison of microscopic and endoscopic view of the internal acoustic meatus: A cadaveric study.

The endoscope is thought to provide an improved exposure of the internal acoustic meatus after retrosigmoid craniotomy for microsurgical resection of intrameatal tumors. The aim of this study is to quantify the differences in internal acoustic meatus (IAM) exposure comparing microscopic and endoscopic visualization. A retrosigmoid approach was performed on 5 cadaver heads. A millimeter gauge was introduced into the internal acoustic meatus, and examinations with a surgical microscope and 0°, 30° and 70° rigid endoscopes were performed. The extent of IAM depth visualized with the microscope and the different angled endoscopes were analyzed. The microscopic view allowed an average IAM depth visualization of 2.8 mm. The endoscope allowed an improved exposure of IAM in all cases. The 0°, 30° and 70° endoscopes permitted an exposure that was respectively 96% (5.5 mm), 139% (6.7 mm) and 200% (8.4 mm) more lateral than the microscopic view. Angled optics, however, provided an image distortion, specifically the 70° endoscope. The endoscope provides a superior visualization of the IAM compared to the microscope when using a retrosigmoid approach. The 30° endoscope represented an ideal compromise of superior visualization with marginal image distortion. Additional implementation of the endoscope into microsurgery of intrameatal tumors likely facilitates complete tumor removal and might spare facial and vestibulocochlear function. Clin. Anat. 31:398-403, 2018. © 2017 Wiley Periodicals, Inc.

Calcifying pseudoneoplasm of the inferior colliculus: an unusual location for a rare tumor: case report.

OBJECTIVE: Quadrigeminal plate lesions are rare and usually present with a silent clinical course. Tumors, vascular lesions, inflammatory and infectious processes have been described in this region. Calcifying pseudoneoplasms, also reported as fibro-osseous lesions, cerebral calculi, and brain stones, are unusual lesions in the central nervous system. They can be revealed by cranial radiography, computed tomography, and magnetic resonance imaging as calcified masses and should be differentiated from neoplastic, inflammatory, and vascular lesions. To the best of our knowledge, the occurrence of a calcifying pseudoneoplasm located at the quadrigeminal plate has not yet been reported. CLINICAL PRESENTATION: A 67-year-old woman with a 6-month history of several daily attacks of dizziness presented to our service. Magnetic resonance imaging studies revealed a tumor in the right inferior colliculus. This lesion was isointense on T1-weighted imaging, hypointense on T2-weighted imaging, and homogeneously enhanced with contrast. INTERVENTION: The lesion at the quadrigeminal plate was completely removed, and the patient was successfully treated without any new neurological deficit. At the time of follow-up, all preoperative symptoms had resolved. CONCLUSION: We report the first case of a calcifying pseudoneoplasm of the inferior colliculus. Complete surgical removal of this type of tumor is feasible. We propose surgical treatment in this location when this tumor becomes symptomatic.

The influence of hypothyroidism on liver regeneration: an experimental study in rats.

BACKGROUND: The influence of hypothyroidism in liver regeneration has been a controversial opinions. PURPOSE: The aim of this study is to identify the relationship between hypothyroidism and liver regeneration in rats. METHODS: Forty male Wistar rats divided into two groups of 20 specimens each. One group (C) consisted of euthyroid rats, and the other (H) of hypothyroid rats. All the animals were anesthetized with xylazine and ketamine and subjected to a longitudinal incision in the anterior cervical region. The thyroid was completely resected in group H and left intact in group C. Ten days after the first surgery, both groups of rats were weighed and submitted to partial hepatectomy, in which the left lateral and median lobes were resected and weighed. Examinations were carried out after 24 hours and, on day 7, using 3 methods: KWON et al.'s formula to identify increase in volume; mitotic figure count in five fields; and the percentage of PCNA-positive nuclei in five fields. RESULTS: Using KWON's formula, the regeneration rate for Group C after 24 hours was 58.49% whereas that for Group H was 50.42% (p=0.0165). After 7 days, the regeneration rate for Group C was 93.04% and Group H 93.74% (p=0.2165). The average number of mitotic figures after 24 hours was 14 +/- 1.5 for Group C and 9.8 +/- 2.2 for Group H (p=0,00016). After 7 days the corresponding figures were 5.4 +/-1.1 and 5.1+/- 1.2 (p=0,6343). The average number of PCNA-positive nuclei after 24 hours was 13.55+/- 3.84 in Group C and 7.7 +/- 2.11 in Group H (p =0,0006)). The corresponding figures after 7 days were 3.5 +/- 2.39 for Group C and 4.11 +/-1.90 for Group H (p>0.05). CONCLUSION: We conclude that hypothyroidism in rats causes a delay in hepatic regeneration in the first 24 hours, but that after seven days the rate of regeneration is equal to that in euthyroid rats.

The influence of hypothyroidism on liver regeneration: an experimental study in rats

BACKGROUND: The influence of hypothyroidism in liver regeneration has been a controversial opinions. PURPOSE: The aim of this study is to identify the relationship between hypothyroidism and liver regeneration in rats. METHODS: Forty male Wistar rats divided into two groups of 20 specimens each. One group (C) consisted of euthyroid rats, and the other (H) of hypothyroid rats. All the animals were anesthetized with xylazine and ketamine and subjected to a longitudinal incision in the anterior cervical region. The thyroid was completely resected in group H and left intact in group C. Ten days after the first surgery, both groups of rats were weighed and submitted to partial hepatectomy, in which the left lateral and median lobes were resected and weighed. Examinations were carried out after 24 hours and, on day 7, using 3 methods: KWON et al.'s formula to identify increase in volume; mitotic figure count in five fields; and the percentage of PCNA-positive nuclei in five fields. RESULTS: Using KWON's formula, the regeneration rate for Group C after 24 hours was 58.49 percent whereas that for Group H was 50.42 percent (p=0.0165). After 7 days, the regeneration rate for Group C was 93.04 percent and Group H 93.74 percent (p=0.2165). The average number of mitotic figures after 24 hours was 14 ± 1.5 for Group C and 9.8 ± 2.2 for Group H (p=0,00016). After 7 days the corresponding figures were 5.4 ± 1.1 and 5.1 ± 1.2 (p=0,6343). The average number of PCNA-positive nuclei after 24 hours was 13.55 ± 3.84 in Group C and 7.7 ± 2.11 in Group H (p =0,0006)). The corresponding figures after 7 days were 3.5 ± 2.39 for Group C and 4.11 ± 1.90 for Group H (p>0.05). CONCLUSION: We conclude that hypothyroidism in rats causes a delay in hepatic regeneration in the first 24 hours, but that after seven days the rate of regeneration is equal to that in euthyroid rats.

BACKGROUND: A influência do hipotireoidismo na regeneração hepatica tem opiniões controvérsas. OBJETIVO: Identificar a relação entre o hipotireoidismo e a regeneração hepatica, em ratos. MÉTODOS: Quarenta ratos Wistar, machos, divididos em dois grupos de 20 animais. Um grupo (C) constituído de ratos eutireoideanos e outro (H) de ratos hipotireoideanos. Todos os animais foram anestesiados com xilasina e quetamina e submetidos a uma incisão cervical longitudinal. A tireóide foi completamente ressecada no animais do grupo H e deixada intacta no grupo C. Dez dias após a primeira intervenção ambos os grupos de ratos foram pesados e submetidos à hepatectomia parcial, retirando-se os lobos lateral esquerdo e mediano, que foram pesados. Foram examinados com 24 horas e com 7 dias usando-se 3 métodos: formula de KWON et al. que identifica o aumento de volume; contagem de figures de mitose em cinco campos e de núcleos PCNA positivos em cinco campos. RESULTOS: Usando a formula de KWON et al. a taxa de regeneração do grupo C, após 24 horas, foi de 58.49 por cento enquanto que a do grupo H foi de 50.42 por cento (p=0.0165). Após 7 dias, a taxa de regeneração no grupo C foi de 93.04 por cento e do grupo H 93.74 por cento (p=0.2165). A média de figures de mitose após 24 horas foi de 14 ± 1.5 no grupo C e de 9.8 ± 2.2 no groupo H (p=0,00016). Após 7 dias foi de 5.4 ± 1.1 e 5.1 ± 1.2 (p=0,6343). A média de núcleos PCA positivos, após 24 horas, foi de 13.55 ± 3.84 no grupo C e 7.7 ± 2.11 no grupo H (p =0,0006)). Com 7 dias foi de 3.5 ± 2.39 no groupo C e de 4.11 ± 1.90 for Group H (p>0.05). CONCLUSÃO: Concluiu-se que o hipotireoidismo, em ratos, causa atraso da regeneração hepatica nas primeiras 24 horas, mas após 7 dias a regeneração se equivale à dos ratos eutireoideanos.

Effect of aging on liver regeneration in rats

OBJETIVO: Acredita-se que idosos tenham maior dificuldade de regenerar e/ou cicatrizar tecidos. O fígado é um dos mais complexos órgãos do corpo humano, e está envolvido em diversas funções. A regeneração hepática representa um mecanismo de proteção orgânica contra a perda de tecido hepático funcionante. O objetivo do presente estudo é reconhecer a capacidade regenerativa do fígado de animais velhos e compará-la com a de animais adultos jovens.MÉTODOS: Foram utilizados 34 ratos Wistar, 17 com 90 dias (jovens) e 17 com 460 dias (velhos). Aproximadamente 70% do fígado foi cirurgicamente removido. As aferições foram feitas com 24 horas e com 7 dias, com 3 métodos: Fórmula de KWON et al para reconhecer ganho de volume, contagem das figuras de mitose existentes em 5 campos e percentual dos núcleos PCNA positivos em 5 campos. RESULTADOS: O remanescente hepático ganhou maior volume nos animais jovens tanto com 24 horas (p=0,0006) quanto com 7 dias (p=0,0000). Os cortes histológicos revelaram maior número de figuras de mitose nos fígados dos jovens avaliados com 24 horas (p=0,0000). Na avaliação com 7 dias houve recuperação nos velhos, que se aproximaram dos jovens (p=0,2851). A contagem dos núcleos PCNA positivos foi maior nos cortes dos fígados dos jovens, com 24 horas (p=0,0310) e enquanto diminuiu nos jovens com 7 dias, nos velhos houve recuperação (p=0,0298). CONCLUSÃO: Os dados confirmam que a idade está relacionada com o atraso da regeneração hepática, em ratos.

Effect of aging on liver regeneration in rats.

PURPOSE: Regeneration and/or healing of tissues is believed to be more difficult in elderly people. The liver is one of the most complex organs in the human body, and is involved in a variety of functions. Liver regeneration is the body's protection mechanism against loss of functional liver tissue. The aim of this study is to identify the regenerative capacity of the liver in older animals and to compare it with that of young adult animals. METHODS: Thirty-four Wistar rats were used, of which 17 were 90 days old (young animals) and 17 were 460 days old (old animals). Approximately 70% of the liver was surgically removed. Examinations were carried out after 24 hours and on day 7, using 3 methods: KWON et al.'s formula to identify increase in volume; mitotic figure count in 5 fields; and the percentage of PCNA-positive nuclei in 5 fields. RESULTS: The increase in volume of the remaining liver was greater in the young animals after both 24 hours (p=0.0006) and on day 7 (p=0.0000). Histological cuts showed a greater mitotic figure count in young animals evaluated after 24 hours (p=0.0000). Upon evaluation on day 7, recovery was observed in the old animals. This recovery was similar to that of the young ones (p=0.2851). The PCNA-positive nucleus count was greater in the young animals' liver cuts after 24 hours (p=0.0310), and, while it had decreased in young animals by day 7, recovery was observed in the older animals (p=0.0298). CONCLUSION: The data confirm that age is related to delay in liver regeneration in rats.