Expert Interview with Prof. Martin Scholz - Brain Tumors and Orbital Tumors Affecting Vision

Prof. Dr. med. Martin Scholz is a leading expert in the field of neurosurgery and has headed the Department of Neurosurgery at Sana Kliniken Duisburg since 2009, one of the largest and most renowned neurosurgical departments in Germany. As a specialist in neurosurgery and specialized neurosurgical intensive care medicine, Prof. Dr. Scholz possesses outstanding expertise in the surgical treatment of diseases of the brain, spine, and spinal cord. With his additional qualifications in oncological, vascular, and spinal neurosurgery, as well as a master’s certificate from the German Spine Society, he offers his patients highly specialized care at the cutting edge of medicine.

Prof. Dr. Scholz places special emphasis on pediatric neurosurgery. This demanding specialty, which he masters with exceptional expertise and empathy, encompasses the treatment of brain tumors, vascular malformations, congenital anomalies, and skull deformities in children. In addition, he is an internationally recognized specialist in the surgical treatment of brain tumors in adults, vascular diseases such as aneurysms and angiomas, and complex skull base tumors. His particular expertise is also evident in his use of modern surgical methods, such as endoscopic surgery, microsurgery, and navigation-guided spinal surgery, which enable precise and minimally invasive procedures.

The Department of Neurosurgery in Duisburg, headed by Prof. Dr. Scholz, is a supraregional center that treats approximately 3,000 inpatients and 7,000 outpatients annually from throughout Germany and abroad. A key focus of the clinic is interdisciplinary collaboration with other specialized departments, such as neurology, neuroradiology, and neuropediatrics, to offer patients the best possible care. Together with his team, Prof. Dr. Scholz consistently pursues the goal of ensuring the highest medical quality and individualized patient care. His outstanding work makes him one of Germany’s leading neurosurgeons, whose expertise and dedication are highly regarded far beyond the region. The editorial team of the Leading Medicine Guide spoke with Prof. Dr. Scholz and learned more about the various types of brain tumors, focusing specifically on those that can impair vision.

Brain tumors and tumors in the eye socket pose a particular challenge in modern medicine, as they not only affect vital structures in the central nervous system but can also disrupt the delicate interaction between the brain and the visual system. One of the consequences of such tumors is the deterioration or loss of vision, which significantly impairs the quality of life for those affected. The causes of these visual impairments are diverse and range from mechanical pressure on the optic nerve to disturbances in blood flow or intracranial pressure. However, thanks to modern diagnostic techniques such as magnetic resonance imaging (MRI) and advanced therapies—including minimally invasive surgeries and innovative radiation therapies—there are now significantly better chances of successful treatment and preservation of vision.

Patients with a tumor in the orbit or adjacent to the visual pathway often seek medical help due to a variety of symptoms caused by the tumor itself or the pressure it exerts on surrounding structures in the brain.

“Patients who come to us with tumors in the orbital region often report visual disturbances, a sensation of pressure in the eye, or swelling of the eyelids. Some patients also describe a foreign body sensation in the eye. These symptoms can vary in severity. In some cases, however, tumors are discovered incidentally—for example, during an MRI scan, when a meningioma or a tumor in the area of the optic chiasm or the optic nerves themselves is suddenly detected. How quickly symptoms become noticeable depends largely on the tumor’s growth rate. If the tumor grows slowly, the optic nerve and the surrounding structures in the eye socket can adapt. In such cases, even larger tumors can grow without causing patients significant discomfort. In contrast, if the tumor grows rapidly, the body has less time to adapt, and symptoms appear more quickly and are often more pronounced,” explains Prof. Dr. Scholz at the beginning of our conversation.

The most common brain tumors can be classified as benign or malignant. A distinction is made between primary brain tumors, which originate directly in the brain, and secondary tumors, which are metastases from cancers in other organs.

“When considering tumors that affect vision, it is important to distinguish between different areas of the eye and the structures of the optic nerve, particularly between the orbit (eye socket) and the optic chiasm. Various tumors can occur in the orbit, or eye socket, that impair vision. Among the most common are metastases—tumor spread from cancers in other parts of the body. These metastases can spread not only to the brain but also to the orbit, which is relatively common. Another common tumor in this area is meningiomas, particularly those originating from the meninges and affecting the optic disc. These tumors are very difficult to remove because they often grow around the optic nerve. In addition, there are cavernomas, which appear as clusters of blood vessels or vascular sponges and can impair vision by exerting pressure on the optic nerve. Although lymphomas that occur in the orbit are less common, they do occur. In the area of the optic chiasm—that is, where the optic nerve enters the intracranial space—tumors at the base of the skull are of particular relevance. These include meningiomas, which can impair vision by exerting pressure on the optic nerve structures, as well as craniopharyngiomas and pituitary adenomas. “These tumors can press on the nerve pathways and also cause visual disturbances,” explains Prof. Dr. Scholz.

Certain types of tumors impair vision because they are located near structures that are critical for vision, such as the optic nerve (nervus opticus), the optic chiasm (chiasma opticum), or the optic tract.

“Such a condition does not necessarily carry an extreme risk of blindness. The key factor is first and foremost where exactly the pathological process is occurring. If, for example, it is located in the area of the eye socket (orbit) or affects only the optic nerve of one eye, then usually only that one eye is affected. In such cases, unilateral blindness may result. The situation is different if the process is already localized in the area of the optic chiasm—that is, the so-called chiasma opticum. This is where the nerve fibers from both eyes cross, meaning that damage in this area can potentially affect both eyes. In such cases, there is, in principle, a possibility of bilateral visual impairment, up to and including complete blindness. Whether due to tumor growth or another pathological change—as soon as the optic chiasm is affected, the risk of more extensive visual impairment increases significantly. “If, on the other hand, only one optic nerve is affected before the optic chiasm, the visual impairment is usually limited to that eye,” explains Prof. Dr. Scholz.

Vision impairment is usually caused by mechanical pressure from the tumor, which blocks the transmission of signals in the optic nerve, or by an interruption in the blood supply, which leads to damage to nerve tissue. Early diagnosis and treatment can help prevent or limit the progression of these visual disturbances.

If a lesion in the area of the optic nerve is suspected, a structured and thorough diagnostic evaluation is crucial—both for selecting the appropriate treatment approach and for predicting the prognosis of visual function. Modern imaging techniques play just as important a role in this process as current ophthalmological findings and, if necessary, hormonal evaluations. Particular attention must be paid to a differentiated assessment in children, in whom such conditions occur less frequently but are often more difficult to detect, as children are unable to express themselves clearly.

“When a patient presents for a consultation and there is a corresponding indication, a comprehensive and carefully planned diagnostic workup follows. First and foremost, high-resolution cross-sectional imaging is essential—typically, this involves magnetic resonance imaging (MRI). Depending on the clinical presentation, a computed tomography (CT) scan may also be necessary, particularly to visualize bony structures such as the optic canal in detail. At the same time, a thorough ophthalmological examination is conducted. In addition to measuring visual acuity, this examination includes, in particular, perimetry—that is, a visual field test. The latter is especially important because it serves as a baseline for comparison later on—for example, during postoperative follow-up. After all, it would be counterproductive if a surgical procedure were to lead to a deterioration in visual performance. The goal is always to document the condition before and after the procedure in a comparable manner. In certain cases, such as conditions affecting the optic chiasm (chiasma opticum)—for example, suprasellar tumors—an additional endocrinological evaluation is necessary. This means that hormone levels must also be examined to assess any potential effects on pituitary function. “The entire diagnostic process thus combines clinical and imaging methods, on the basis of which an individualized surgical plan is then developed—depending on the location of the lesion and its relationship to the optic chiasm,” says Prof. Dr. Scholz, who also highlights the special considerations involved in treating affected children:

“A particular challenge is managing pediatric patients. Although such findings occur much less frequently in children than in adults, they are often overlooked or misdiagnosed. One real-world example was a teenager with a meningioma near the optic nerve entry point at the base of the skull, who was initially treated under the suspicion of multiple sclerosis. Only a high-resolution MRI made the correct diagnosis possible. In another case this year, we operated on a 15-year-old patient with a vascular malformation in the orbit—a rare diagnosis overall, which, fortunately, occurs only in exceptional cases in children.”

Tumors in the Eye and Skull Base:
Defining Neurosurgical Responsibilities

Retinoblastoma is a tumor that typically occurs in childhood—in fact, it is the most common intraocular cancer in children. However, this tumor affects the eye itself, more specifically the retina, and thus falls within the specialized scope of ophthalmology. Ophthalmologists are responsible for diagnostic evaluation, treatment planning, and—where necessary—surgical procedures. In many cases, the priority is to preserve the eye.

“From a neurosurgical perspective, however, retinoblastoma is not a direct indication for surgery for us, since procedures on the eye itself—particularly within the eye, such as on the retina, lens, or vitreous—do not fall within the scope of neurosurgery. Our work begins where structures surrounding the eye are involved, such as the optic nerve or the skull base. Only in exceptional cases—such as when using specialized access routes like the coronal conjunctival approach—is interdisciplinary collaboration required. The so-called acoustic neuroma—now usually referred to as a vestibular schwannoma—presents a completely different clinical picture. This benign tumor develops in the posterior fossa, more specifically in the internal auditory canal, and primarily affects the auditory nerve as well as neighboring structures such as the vestibular nerve and the facial nerve. Visual disturbances occur only in rare, exceptional cases, such as when the tumor is exceptionally large and compresses neighboring cranial nerves like the trochlear nerve or the abducens nerve. In such cases, eye movement disorders or double vision may occur under certain circumstances. “However, a direct threat to vision is rather the exception and is not the primary symptom for this type of tumor,” explains Prof. Dr. Scholz.

The treatment of brain tumors and eye tumors varies considerably depending on the type of tumor, its location, the patient’s age, and individual circumstances.

Treatment for brain tumors generally involves several options that are combined depending on the type of tumor. One of the most common methods is surgical removal of the tumor if it is located in an accessible part of the brain. When choosing treatment options, surgery is not automatically the first choice for patients. The decisive factor is always an individual assessment of the situation. The primary consideration is whether symptoms are present at all and how they are progressing.

Prof. Dr. Scholz explains this in more detail: “If a patient is experiencing increasing symptoms—such as worsening visual disturbances, increasing pain, or other symptoms that are intensifying—or if imaging tests show that a lesion is growing in size, active intervention becomes necessary. If, on the other hand, the lesion is small, inconspicuous, and asymptomatic—for example, in the orbital region—a watch-and-wait approach with regular follow-up examinations is possible. In such cases, imaging is often performed after three months to assess whether growth is occurring. If the findings remain stable, the follow-up interval can be extended to six months. Surgery becomes unavoidable when serious clinical symptoms appear that indicate significant progression of the disease. These include, for example, a noticeable decline in visual acuity, increasing symptoms, elevated intraocular pressure, or other signs that the disease is taking hold. Although such cases do not represent an immediate life-threatening situation, if left untreated, they can lead to permanent vision loss—a risk that can be prevented through timely intervention. For the treating physicians, these surgeries pose a particular challenge, especially with regard to monitoring and preserving optic nerve function during the procedure. The goal is to remove the lesion as completely as possible—or at least reduce its size—without damaging functional structures such as the optic nerve or the eye muscles. This is because any injury could lead to permanent impairments, such as double vision or a drooping eyelid. The key here is to strike a balance between removing the tumor as completely as possible and preserving function—a balancing act that must also be discussed openly with the patient,” he adds:

“Often, it cannot be guaranteed that the lesion can be completely removed. The primary goal in such cases is to relieve pressure on the optic nerve and prevent further deterioration. To monitor the function of the optic nerve as effectively as possible during surgery, we use what’s known as VEP monitoring—a technique that measures visual evoked potentials. During this procedure, the patient, who is under general anesthesia, receives light stimuli through so-called flash goggles while their eyelids are closed. The transmission of these stimuli is measured via an electrode on the eyelid and a needle at the back of the head—in the area of the visual cortex. Changes in the waveform indicate impaired optic nerve function and require special caution. Such intraoperative monitoring techniques are essential, as the patient cannot provide feedback while under general anesthesia. While it is sometimes possible to work with awake patients during surgeries involving speech or motor function and to test their reactions directly, this is not feasible when dealing with the optic nerves. That is why continuous technical monitoring is of particular importance here.”

These highly specialized procedures require exceptional precision and experience. The psychological strain on patients—who are often confronted with the fear of going blind—is particularly challenging.

“Overall, we perform about 400 surgeries on neurotumors each year. However, by no means do all of these procedures directly involve the optic nerve. Of these 400 cases, only a fraction are located in the immediate vicinity of the optic nerve or along the visual pathway—that is, in areas such as the optic chiasm, the visual cortex, or the orbit. True optic nerve-sparing procedures are significantly less common, ranging from about 30 to a maximum of 50 cases per year. These are highly specialized, extremely complex surgeries that are not performed on a daily basis. Precisely because this is such a specialized field, we receive many referrals from colleagues in other specialties—such as neurologists, ophthalmologists, ENT specialists, or endocrinologists. Each clinic has its own network of referring physicians. In addition, international patients regularly turn to us, often seeking a second opinion. In many cases, there is a great deal of uncertainty—especially when it comes to the optic nerve, which is crucial for vision. Many of these people are understandably very anxious. Some already have impaired vision in one eye, perhaps due to a childhood accident that resulted in vision loss. When it comes to their remaining functioning eye, the fear of potential blindness is immense. Even minor findings—such as those involving the retina—can trigger intense anxiety in those affected. After all, this concerns vision, something so fundamental that it cannot be restored once lost. This psychological strain must not be underestimated. It accompanies patients from the time of diagnosis through the decision for or against surgery—and often beyond. This makes it all the more important to support them along this journey with professional competence and compassion,” explains Prof. Dr. Scholz.

The Future of Neurosurgery:
Innovations Through AI and Individualized Treatment Approaches

“At our clinic, we offer comprehensive neurosurgical care covering all subspecialties of neurosurgery. We would particularly like to highlight our extensive experience in the field of optic nerves, where we place special emphasis on monitoring procedures. Our patients can come to us at any time, even for a second or third course of treatment. We offer personalized treatment plans tailored to each patient’s specific needs. In some cases, we also work closely with radiation oncologists, as certain treatment plans require follow-up therapy—whether through stereotactic follow-up treatment or chemotherapy. “The decision always depends on the tissue findings and is made on a case-by-case basis,” emphasizes Prof. Dr. Scholz, who also addresses the increasingly important role of AI (artificial intelligence):

“AI has the potential to significantly transform medical practice. It can be of great benefit, particularly in the rapid retrieval of information and the analysis of scientific questions. In the past, one had to search for specific information in extensive literature databases—today, AI can provide this information almost instantly. Another area where AI plays an important role is visualization. AI programs can be used to create images and illustrations that used to be produced by a medical illustrator. Today, AI can take on these tasks, which is extremely valuable not only for scientific publications but also for teaching students. With AI, sketches and illustrations can be quickly and easily adapted and refined. When it comes to surgical planning, AI also offers many advantages. It can analyze imaging data and, for example, identify tumors and their location relative to surrounding blood vessels. This type of analysis significantly facilitates preoperative planning. AI also greatly simplifies the search for current studies and research findings. However, there are still certain limitations to the use of robots in surgery. While AI is already highly advanced in information processing and visualization, the use of robots in surgery remains rather limited. During complex procedures, surgeons must make many decisions in real time—up to 120 to 130 during a single operation. In such cases, a robot would have to constantly seek clarification, which raises liability issues and leaves the surgeon’s role as the responsible decision-maker unclear. It will still be several years before robots play a major role in surgery and are eventually able to make autonomous decisions. Similar to autonomous driving—where, so far, only a few buses have been operating autonomously on private property—it will also take several more years in surgery before we see truly autonomous operations. However, developments in AI and robotics are promising, and it will be exciting to see how these technologies evolve in the coming years.”

There are various causes for the development of tumors, and genetic changes play a role in this. In fact, genetic changes or mutations are often detected in tumors that have contributed to their development.

“However, there are also tumors that originate as primary tumors in specific regions of the body and then spread. These tumors metastasize—they spread or establish themselves elsewhere—and this is primarily a biological process. In such cases, the origin of the disease cannot be attributed exclusively to genetic factors—statistical probabilities and biological processes also play an important role here. Therefore, the question of a tumor’s cause cannot always be answered unequivocally. As far as neurosurgery is concerned, this field is particularly interesting because it operates on an interdisciplinary basis and works closely with various other specialties. Of particular note is the close collaboration with neuroradiologists and interventional radiologists. These specialists can embolize tumors—that is, use a catheter to cut off their blood supply—which makes our work as surgeons significantly easier. Preparation through such embolization makes it possible to operate on the tumor under significantly reduced blood flow and with greater control. This is particularly advantageous when the surgery takes place in complex areas such as the skull base, where anatomical conditions are confined and the risk of injury is high. In some cases where tumors were previously considered inoperable, this method makes successful surgery possible for the first time. So it’s fair to say that this technique represents a significant improvement in surgical options,” states Prof. Dr. Scholz, and with that, we conclude our conversation.

Thank you very much, Professor Dr. Scholz, for this fascinating information!