Trochlear nerve: Celebrating 500 years of description

The history of the description and classification of the cranial nerves has paralleled the development of anatomy and its role in providing rationality to medicine. About five hundred years ago, the “Anatomical Notes by the Great Alexander Achillinus of Bologna” (1520) provided the first description of the trochlear nerve. In this article, we review the most important macroscopic achievements through different epochs and pioneers such as Herophilus of Chalcedon, Galen of Pergamon, Andreas Vesalius, Bartolomeo Eustachi, Realdo Colombo, Gabriele Falloppio, Antonio Molinetti, Caspar Bartholin, Thomas Willis and Samuel Thomas von Soemmerring. Each of them contributed to a better understanding of the cranial nerves as we know today. Galen's classification was enduring through his seven pairs of cranial nerves. Realdo Colombo coined the name pathetic nerve or nervus oculorum pateticos to the trochlear nerve in 1559, and Molinetti, nervus trochlearis, in 1669. The term trochlear nerve is derived from the Latin word pulley, trochlea, as it innervates the superior oblique muscle that ends in a tendon that bends through a pulley of connective tissue. Besides description and naming, the inclusion into current cranial nerve classification system and how such knowledge applies to current microsurgical understanding is also discussed

Zur Elektrophysiologischen Ableitung der Funktion des Nervus fazialis bei Operationen am Kleinhirnbrückenwinkeln mittels transkranieller Elektrostimulation

Objective: This study was conducted to investigate the success rate of the orbicularis oculi and oris muscles motor evoked potentials (FMEP) for facial nerve function monitoring by using a stepwise protocol and to evaluate its usefulness in predicting facial nerve outcome during cerebellopontine angle (CPA) surgeries. Methods: FMEPs were recorded intraoperatively from 60 patients undergoing CPA surgery. Transcranial electrocortical stimulation (TES) was performed using corkscrew electrodes positioned at a hemispheric montage (C3/C4 and CZ). The contralateral abductor pollicis brevis muscle was used as the control response. Stimulation was always applied contralaterally to the affected side using 1, 3 or 5 rectangular pulses ranging from 200 to 600V with 50 microseconds of pulse duration and an interstimulus interval (ISI) of 2 miliseconds (ms). Facial potentials were recorded from needles placed in the orbicularis oculi and oris muscles. Results: FMEP from the orbicularis oris and oculi muscles could be reliably monitored in 86.7% and 85% of the patients, respectively. The immediate postoperative facial function correlated significantly with the FMEP ratio in the orbicularis oculi muscle at 80% amplitude ratio (p = 0.037) and orbicularis oris muscle at 35% ratio (p = 0.000). FMEP loss was always related to postoperative facial paresis, although in different degrees. Conclusions: FMEPs can be obtained reliably using TES with 3 to 5 train pulses. Stable intraoperative FMEPs can predict a good postoperative outcome of facial function. However, further refinements of this technique are still necessary in order to minimize artifacts and to make this method even more reliableZiel: Diese Studie untersucht bei chirurgischen Eingriffen am Kleinhirnbrückenwinkel, bei denen der Nervus facialis anatomisch und funktionell gefährdet ist, die Durchführbarkeit des Facialis-Monitoring und dessen prognostischen Wert für das postoperative Ergebnis mittels elektrophysiologischer Ableitung motorisch evozierter Potenziale (MEP) des Musculus orbicularis oculi und Musculus orbicularis oris (FMEP). Methoden: Bei 60 mikrochirurgischen Eingriffen am Kleinhirnbrückenwinkel wurden intraoperative FMEPs abgeleitet. Eine transkranielle Elektrostimulation (TES) wurde mit Corkscrew-Elektroden an den Positionen C3, C4 und CZ nach gängiger hemisphärischer Montage durchgeführt. Der kontralaterale Musculus abductor pollicis brevis wurde als Kontrollantwort verwendet. Die Stimulation erfolgte immer kontralateral der betroffenen Seite. FMEPs wurden von Nadeln registriert, die in den M. orbicularis oculi und den M. orbicularis oris gelegt waren. Dazu wurden 1, 3 oder 5 Rechteckimpulse im Intervall von 200 V bis 600 V mit einer Impulsdauer von 50 Mikrosekunden und eines Zwischenstimulus-Intervalls von 2 Millisekunden verwendet. Ergebnisse: In 86.7% der Fälle konnte ein FMEP des M. orbicularis oris und in 85 % der Fälle ein FMEP des M. orbicularis oculi zuverlässig abgeleitet werden. Die unmittelbare postoperative Funktion des Nervus facialis korrelierte signifikant mit den Werten der FMEPs: 80% der Amplitudenrate bei dem M. orbicularis oculi (p = 0.037) 35% der Amplitudenrate bei dem M. orbicularis oris (p = 0.000). Ein FMEP-Verlust war immer mit postoperativen Fazialisparesen in verschiedenen Schweregraden verbunden. Schlussfolgerungen: FMEPs können zuverlässig abgeleitet werden, indem TES mit 3 bis 5 Train-Pulsen verwendet werden. Stabile intraoperative FMEPs haben eine Voraussagekraft für ein gutes postoperatives Ergebnis des N. facialis. Eine weitere Verfeinerung der Technik wird jedoch in Zukunft noch notwendig sein, um Artefakte zu minimieren und diese Methode als zuverlässiges intraoperatives Monitoring sich etablieren zu lassen.

Electrophysiological parameters of facial motor evoked potential predict postoperative facial function during vestibular schwannoma resection

O potencial evocado motor facial (PEMF) tem-se mostrado um excelente método de monitorização do nervo facial, gerando resultados bastante confiáveis e reprodutíveis no que tange à predição da função facial pós-operatória. O critério eletrofisiológico mais utilizado até então para tanto tem sido a relação de amplitude do PEMF final-valor de base. Os objetivos deste trabalho foram avaliar as alterações intraoperatórias da amplitude e da complexidade do PEMF, correlacioná-las com o prognóstico facial no pós-operatório imediato e tardio e verificar se amplitude e complexidade constituem variáveis independentes de predição funcional. Os registros dos potenciais intraoperatórios dos músculos orbiculares do olho e da boca de 35 pacientes portadores de schwannoma vestibular (SV) foram coletados e analisados retrospectivamente de acordo com tempos cirúrgicos preestabelecidos: inicial, abertura da dura-máter, dissecação do tumor (TuDis), ressecção do tumor (TuRes) e final. No pós-operatório imediato, a função facial apresentou uma significativa correlação negativa com as relações de amplitude do PEMF durante a TuDis, a TuRes e ao final do procedimento nos músculos orbiculares do olho (p =0,003, 0,055 e 0,028, respectivamente) e da boca (p=0,002, 0,104 e 0,014, respectivamente). No último seguimento, entretanto, a correlação foi significativa apenas para o músculo orbicular da boca, durante a TuDis (p=0,005) e ao final do procedimento (p=0,102). As variações da complexidade dos potenciais alcançaram resultados mais significativos tanto no pós-operatório imediato, quanto no tardio, de forma que houve uma correlação negativa no músculo orbicular do olho apenas nas medidas finais (imediato, p=0;023; seguimento, p=0,116) e no músculo orbicular da boca durante a TuDis, a TuRes e a medida final (imediato, p=0,071, 0,000 e 0,001, respectivamente; seguimento, p=0,015, 0,001 e 0,01, respectivamente). As alterações intraoperatórias das relações de amplitude e de complexidade dos PEMFs parecem representar variáveis independentes, podendo ser utilizadas na predição da função facial pós-operatória durante cirurgias de ressecção de SV. Baseados nos resultados deste trabalho, a monitorização evento-valor de base é bastante útil, justificando mudanças imediatas da estratégia cirúrgica, com o intuito de reduzir as chances de uma lesão definitiva do nervo facial.Facial motor evoked potential (FMEP) amplitude ratio reduction at the end of the surgery has been identified as a good predictor for postoperative facial nerve outcome. We sought to investigate variations in FMEP amplitude and waveform morphology during vestibular schwannoma (VS) resection and to correlate these measures with postoperative facial function immediately after surgery and at the last follow-up. Besides we analyzed the relationship between quantitative parameters. Intraoperative orbicularis oculi and oris muscles FMEP data from 35 patients undergoing surgery for VS resection were collected, then analyzed by surgical stage: initial, dural opening, tumor dissection (TuDis), tumor resection (TuRes) and final. Immediately after surgery, postoperative facial function correlated significantly with the FMEP amplitude ratio during TuDis, TuRes and final in both the orbicularis oculi (p´s=0.003, 0.055 and 0.028, respectively) and oris muscles (p´s=0.002, 0.104 and 0.014, respectively). At the last follow-up, however, facial function correlated significantly with the FMEP amplitude ratio only during TuDis (p=0.005) and final (p=0.102) for the orbicularis oris muscle. At both time points, postoperative facial paresis correlated significantly with FMEP waveform deterioration in orbicularis oculi during final (immediate, p=0.023; follow-up, p=0.116) and in orbicularis oris during TuDis, TuRes and final (immediate, p´s=0.071, 0.000 and 0.001, respectively; follow-up, p´s=0.015, 0.001 and 0.01, respectively). FMEP amplitude ratio and waveform morphology during VS resection seem to represent independent quantitative parameters that can be used to predict postoperative facial function. Event-to-baseline FMEP monitoring is quite useful to dictate when intraoperative changes in surgical strategy are warranted to reduce chances of facial nerve injury

The principle of autonomy in Brazil: one needs to discuss it ...

The principle of patient autonomy is a cornerstone of bioethics. According to this concept, patients should be given the power to make decisions related to their treatment. It is an important component of modern medical ethics, which has received much interest in current literature. However, the rate of participation of patients and their willingness to participate are variable according to the cultural, social and family environments in which they are inserted. The aim of this paper is to promote a brief descriptive review on autonomy, the preferences of patients and the use of informed consent as an instrument for the exercise of autonomy in literature, and to stress the lack of debate, as well as the pressing need for discussion of these current issues nationwide

Malignant peripheral nerve sheath tumor with and without neurofibromatosis type 1

ABSTRACT Objective In this study, we review the institution’s experience in treating malignant peripheral nerve sheath tumors (MPNSTs). A secondary aim was to compare outcomes between MPNSTs with and without neurofibromatosis type 1 (NF1). Methods Ninety-two patients with MPNSTs, over a period of 20 years, were reviewed. A retrospective chart review was performed. The median age was 43.5 years (range, 3–84 years) and 55.4% were female; 41 patients (44.6%) had NF1-associated tumors. Results Mean tumor sizes were 15.8 ± 8.2 cm and 10.8 ± 6.3 cm for patients with and without NF1, respectively. Combined two- and five-year overall survival was 48.5% and 29%. Multivariate analysis confirmed the association of tumor size greater than 10 cm (hazard ratio (HR) 2.99; 95% confidence interval (CI) 1.14–7.85; p = 0.0258) and presence of NF1 (HR 3.41; 95%CI 1.88–6.19; p < 0.001) with a decreased overall survival. Conclusion Tumor size and NF1 status were the most important predictors of overall survival in our population