E-Book, Englisch, 340 Seiten, ePub
Endoscope-Assisted Techniques - Neuronavigational Techniques - Radiosurgery
E-Book, Englisch, 340 Seiten, ePub
ISBN: 978-3-13-257866-1
Verlag: Thieme
Format: EPUB
Kopierschutz: 6 - ePub Watermark
In Wolfgang Koos' final work, a lifetime of experience in the surgical treatment of the acoustic neurinoma is presented in the style of the brilliantly successful Koos-Spetzler microneurosurgery series.
Diagnosis is a strong point of this atlas, as surgical strategies are planned according to the anatomic location and growth pattern of these tumors.
The preoperative considerations, operating room set-up, patient positioning, and neuronavigational equipment are described for microsurgery in the cerebellopontine angle region.
The operative techniques for removing acoustic neurinomas in correlation with size and extension of the tumor are then provided in step-by-step detail; intraoperative photographs are paired with explanatory colored line drawings of astonishing clarity.
Finally, the tumors of the cerebellopontine angle that may mimic acoustic neurinoma are described.
Zielgruppe
Ärzte
Autoren/Hrsg.
Fachgebiete
- Medizin | Veterinärmedizin Medizin | Public Health | Pharmazie | Zahnmedizin Chirurgie Chirurgische Techniken
- Medizin | Veterinärmedizin Medizin | Public Health | Pharmazie | Zahnmedizin Klinische und Innere Medizin HNO-Heilkunde, Phoniatrie, Audiologie
- Medizin | Veterinärmedizin Medizin | Public Health | Pharmazie | Zahnmedizin Chirurgie Neurochirurgie
Weitere Infos & Material
1 Introduction and History
2 Microanatomy of the Cerebellopontine Angle
3 Diagnosis
4 Microsurgery in the Cerebellopontine Angle
5 Neurinomas of the Vestibular Nerves
6 Other Tumors of the Cerebellopontine Angle
7 Multiple Tumors of the Cerebellopontine Angle
8 Intracranial Reconstruction of the Facial Nerve
9 Endoscopic Methods in Acoustic Neurinomas
10 Radiosurgery in Acoustic Neurinomas
11 Results and Summary
4 Microsurgery in the Cerebellopontine Angle General Concepts Preoperative Considerations (Decision-Making) Neuroanesthesiologic Considerations Operating Room Set-Up Patient Position Approach General Concepts Microsurgical resection, radiosurgery, or a “wait-and-see” policy are the three accepted options that are possible in managing acoustic neurinomas. Deciding which of these is the best choice in the individual case is becoming more difficult, as increasing information becomes available about the natural history of the condition and as long-term follow-up data for radiosurgery accumulate. In addition to classic parameters such as surgical mortality, total tumor removal, and control of tumor size, considerations regarding facial nerve morbidity and preservation of hearing have become increasingly important aspects of the decision-making process. As if this were not enough, other parameters also need to be taken seriously into account in modern neurosurgery. There is the “surgeon factor,” taking the individual surgeon's experience and track record into account; there is also the “patient factor,” involving patient's age, general clinical condition, treatment goals, and expectations of treatment. Underlying all of this, of course, there is the “tumor factor”: the tumor itself has to be taken into account, including the anatomical, morphological, and biological parameters. The aim of this chapter is to present simple algorithms, providing simple management plans for decision-making, in which all of the factors mentioned above are included. Both treatment options—microsurgery and radiosurgery—indisputably provide excellent results. A “wait-and-see” policy is certainly preferable in some cases, however. There are justifications for each of the options, and in most cases these are indicated in the algorithms. Treatment: Yes or No? (Fig. 4.1) Fig. 4.1 The three different groups of factors affecting decision-making. The “surgeon factors” involve three main points. Firstly, there is the operating surgeon's level of experience; secondly, his or her personal preference for one or the other form of treatment; and thirdly, what possibilities the surgeon may already have at his or her disposal. On the other hand, there are the “patient factors.” This group of parameters includes of course the patient's age, general clinical condition, and expectations regarding treatment. A third major group of factors—the “tumor factors,” also have to be taken into account. These include typical morphological parameters, such as tumor size (grades I to IV), recurrent tumor, or special morphological situations such as type 2 neurofibromatosis and hydrocephalus. Microsurgery versus Radiosurgery (Fig. 4.2) Fig. 4.2 In contrast to open surgery, the aim in radiosurgery for acoustic neurinomas is not to remove tumor tissue but to arrest further tumor growth. The effects of radiation take time to develop, and the results of treatment can be difficult to assess on neuroimaging. In general, there are currently no clearly defined rules regarding the choice between microsurgery and radiosurgery in treating these tumors. The decision on which is the best in the individual patient is influenced by the three major factors described in Fig. 4.1. Preoperative Considerations (Decision-Making) Although microsurgical removal was previously regarded as the treatment of choice, particularly in case of small neurinomas, this view has now become controversial. Since the establishment of radiosurgery as a treatment option in acoustic neurinomas. The decision has become much more complicated and uncertain both for the surgeon and the patient, despite the large numbers of publications that have appeared in recent years on the topic. The focus in contemporary publications is largely on the outcomes of radiosurgical options, which are increasingly being used as an alternative to open surgery. Figures 4.3 and 4.4 provide a simple algorithm for decision-making. It is reasonable, given certain assumptions, to create a simple management plan that offers clinically proven support in the choice between microsurgery, radiosurgery, or waiting and rescanning. We prefer to provide patients with full information about their situation and the nature of the pathology, as well as all the treatment options, and to discuss this with them in detail. To give patients added confidence in their decisions, we encourage them to obtain a second opinion from another well-experienced surgeon. Fig. 4.3 Small acoustic neurinomas are defined as grade I and grade II. Nowadays, particularly as a result of earlier detection with improved magnetic resonance imaging (three-dimensional spin echo sequences), this group of tumors is increasing in number. As we know that the signs and symptoms of the tumor correlate directly with the size of the tumor, these patients generally have good hearing and no neurological symptoms. When one is dealing with small acoustic tumors, the importance of the growth rate should be borne in mind. The growth rate has been shown to be highly unpredictable. Some tumors will show no change over many years; 6 % actually decrease in size without any treatment, while some can increase in diameter by up to 20 mm per year. The range usually reported is 1–10 mm per year. Fig. 4.4 Large acoustic neurinomas are defined as grades III and IV. Because of the size of the tumor, more signs and symptoms may occur, and these have to be taken into account when creating a treatment algorithm. The management plan in such cases is therefore more complex, but can be followed in the same way as in Fig. 4.3. Acoustic Neurinomas in the Only Hearing Ear In general, if the clinical situation remains stable (i.e., there is no significant change in hearing or other symptoms), we try to wait as long as possible. We prefer to wait and rescan. The follow-up is organized at short intervals, with frequent neuro-otological examinations (every 3 months) and magnetic resonance examinations (every 6 months). These patients are also encouraged to enter special programs to learn other means of communication, such as lip-reading. If hearing starts to deteriorate, or the tumor size increases in younger patients, we prefer to operate. Our approach of choice is a retromastoid one with careful tumor debulking, with an attempt being made to preserve hearing. If the patient's motivation to have open surgery is low, radiosurgery is an option, depending on the size of the tumor (less than 2.5 cm). However, it should be remembered in these cases that radiosurgery is not without complications—complete hearing loss is also possible, as well as cranial nerve deficits or associated hydrocephalus. In patients with type 2 neurofibromatosis who are treated with radiosurgery, the failure rate appears to be higher, with early reports describing growth in about 15–20% of cases after radiosurgery. However, this difficult decision has to be discussed with the patient in detail, and the final decision has to take into account both the surgeon's judgment and the patient's choice. Acoustic Neurinomas in Patients in Poor Clinical Condition (Fig. 4.5) If there is a reason for the patient's poor clinical condition (e.g., internal medical problems) we manage that first and try to bring the patient into as good a condition as possible, so that all treatment options can be considered. The same approach is used in cases of concomitant hydrocephalus. In these cases, we prefer to carry out an endoscopic third ventriculostomy first, and if this is not possible, a shunting procedure is performed. If the patient's condition remains stable but does not improve, we prefer to proceed with radiosurgery as the only treatment option. In the case of elderly patients with small tumors (grade I or II), the wait-and-see option is preferred, on the basis of the known natural history of these tumors. Fig. 4.5 Most importantly, the question that has to be answered is: should the individual patient be treated or not? A no-treatment policy, i.e. a “wait-and-rescan” approach, is preferable in older patients (over 70) who are asymptomatic and have small lesions, if the lesion is in the only hearing ear, or when the patient is in poor clinical condition. We follow these patients with MRI scans every 6 months for the first year. If the lesion remains stable, scans are performed annually. If neurological complications or rapid tumor growth occur, we follow the algorithms shown in the figure. Selection of the Patient's Position on the Operating Table In our department, the retromastoid (transmeatal) approach, with the patient in the sitting (or semisitting) position, is preferred. In our opinion, the advantage of the sitting position is that blood and cerebrospinal fluid drain away from the operative site, providing clear exposure. In most cases, the surgeon's position is much more comfortable. open foramen ovale, our decision is to operate However, this is a controversial point in neurosurgery. Many surgeons feel more...
