Prof. Dr. med. Martin Scholz is a leading expert in the field of neurosurgery and has been the head of the Department of Neurosurgery at the Sana Clinics Duisburg since 2009, one of the largest and most renowned neurosurgical departments in Germany. As a specialist in neurosurgery and intensive care in neurosurgical medicine, Prof. Dr. Scholz possesses outstanding expertise in the surgical treatment of conditions affecting the brain, spine, and spinal cord. With additional qualifications in oncological, vascular, and spinal neurosurgery, as well as a master certificate from the German Spine Society, he provides his patients with highly specialized care based on the latest medical standards.
Prof. Dr. Scholz places particular emphasis on pediatric neurosurgery. He approaches this demanding subspecialty with exceptional expertise and empathy, treating childhood brain tumors, vascular malformations, congenital anomalies, and cranial deformities. In addition, he is an internationally recognized specialist in the surgical treatment of brain tumors in adults, vascular disorders such as aneurysms and angiomas, and complex skull base tumors. His advanced expertise is also evident in his use of modern surgical techniques, including endoscopic surgery, microsurgery, and navigated spinal surgery, which enable precise and minimally invasive procedures.
The Department of Neurosurgery in Duisburg, led by Prof. Dr. Scholz, is a supra-regional center treating approximately 3,000 inpatients and 7,000 outpatients annually from across Germany and abroad. A key focus of the department is interdisciplinary collaboration with other specialties such as neurology, neuroradiology, and pediatric neurology, to provide patients with the best possible therapeutic outcomes. Together with his team, Prof. Dr. Scholz is committed to delivering the highest medical quality and personalized patient care. His outstanding work has made him one of Germany’s leading neurosurgeons, with expertise and dedication that are highly regarded far beyond the region. The editorial team of the Leading Medicine Guide spoke with Prof. Dr. Scholz to learn more about the various types of brain tumors, with a particular focus on those that can impair vision.
Brain tumors and tumors in the orbital region pose a particular challenge in modern medicine, as they affect not only vital structures of the central nervous system but also the delicate interplay between the brain and the visual system. One potential consequence of such tumors is visual impairment or vision loss, which can significantly reduce a patient’s quality of life. The causes of visual impairment vary and may include mechanical pressure on the optic nerve, as well as disruptions in blood flow or increased intracranial pressure. However, thanks to advanced diagnostic techniques such as magnetic resonance imaging (MRI) and innovative treatment methods—including minimally invasive surgery and cutting-edge radiation therapies—patients today have significantly better chances of successful treatment and vision preservation.
Patients with tumors in the orbit or near the visual pathway often seek medical attention due to a range of symptoms caused by the tumor itself or by 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, tumors are discovered incidentally—for instance, during an MRI scan that unexpectedly reveals a meningioma or a tumor in the area of the optic chiasm or the optic nerves. How quickly symptoms develop largely depends on the tumor’s growth rate. If the tumor grows slowly, the optic nerve and surrounding structures in the orbit may adapt. In such cases, even larger tumors can grow without causing significant discomfort. In contrast, if the tumor grows rapidly, the body has less time to adapt, and symptoms tend to appear more quickly and with greater intensity,” explains Prof. Dr. Scholz at the beginning of our conversation.
The most common brain tumors are classified as either benign (non-cancerous) or malignant (cancerous). A distinction is also made between primary brain tumors, which originate in the brain itself, and secondary tumors, which are metastases from cancers in other parts of the body.
“When examining tumors that affect vision, it is important to differentiate between the various regions of the eye and optic nerve structures—particularly the orbit (eye socket) and the optic chiasm. In the orbit, a number of tumors may impair vision. Among the most common are metastases, meaning cancerous cells that have spread from other areas of the body. These metastases can spread not only to the brain but also to the orbit, which is a relatively frequent occurrence. Another common tumor in this area is the meningioma, especially those originating from the meninges and affecting the optic disc. These tumors are particularly difficult to remove because they often grow around the optic nerve. Additionally, there are cavernomas—vascular tangles or malformations—that can impair vision by exerting pressure on the optic nerve. Lymphomas in the orbit are less common, but they do occur. In the region of the optic chiasm, where the optic nerves enter the brain, skull base tumors are particularly relevant. These include meningiomas, which can impair vision by pressing on the optic nerve structures, as well as craniopharyngiomas and pituitary adenomas. These tumors may compress the nerve pathways and likewise lead to visual disturbances,” explains Prof. Dr. Scholz.
Certain types of tumors affect vision due to their proximity to critical visual structures such as the optic nerve (nervus opticus), the optic chiasm (chiasma opticum), or the visual pathway.
“Such conditions do not automatically carry the extreme risk of complete blindness. What matters most is the precise location of the pathological process. If it is situated in the orbit or affects only the optic nerve of one eye, usually only that eye is impacted—potentially resulting in unilateral blindness. The situation changes if the process is located at the optic chiasm, where the nerve fibers of both eyes intersect. In this case, damage can potentially affect both eyes, increasing the risk of bilateral visual impairment, possibly even complete blindness. Whether caused by tumor growth or another pathological change—once the optic chiasm is involved, the likelihood of extensive visual impairment rises significantly. In contrast, if only one optic nerve is affected prior to the chiasm, the impairment is typically confined to the corresponding eye,” Prof. Dr. Scholz emphasizes.
Visual impairment is generally caused by the mechanical pressure of a tumor, which blocks signal transmission in the optic nerve, or by disrupted blood flow, which leads to damage of the nerve tissue. Early diagnosis and treatment can help prevent or limit the progression of these visual disturbances.
When a lesion of the optic nerve is suspected, structured and careful diagnostics are essential—both for determining the appropriate therapeutic approach and for assessing the prognosis of visual function. Modern imaging techniques, current ophthalmological findings, and, where necessary, hormonal evaluations all play a role. Special attention must be paid to pediatric cases, where such conditions are rarer but often more difficult to detect, as children may not be able to clearly articulate their symptoms.
“When a patient presents during consultation and there is a corresponding indication, a comprehensive and carefully planned diagnostic process follows. High-resolution cross-sectional imaging is essential—typically magnetic resonance imaging (MRI). Depending on the clinical question, a computed tomography (CT) scan may also be necessary, particularly to provide detailed views of bony structures such as the optic canal. In parallel, a thorough ophthalmologic examination is conducted. This includes visual acuity testing as well as perimetry, or visual field testing. The latter is particularly important, as it serves as a baseline for comparison in postoperative follow-ups. After all, it would be counterproductive if surgery were to worsen visual performance. The goal is always to document the patient’s condition before and after the procedure in a way that allows direct comparison. In specific cases—such as lesions in the region of the optic chiasm, including suprasellar tumors—an endocrinological evaluation is also required. This means hormone levels must be assessed to determine any potential effects on pituitary function. Overall, diagnostics combine clinical and imaging assessments, which then form the basis for individualized surgical planning—depending on the location of the lesion and its relationship to the optic chiasm,” explains Prof. Dr. Scholz, who also highlights the special considerations when treating pediatric patients:
“A particular aspect involves working with pediatric patients. Although such findings are much less common in children than in adults, they are not infrequently overlooked or misdiagnosed. One example from our practice involved an adolescent with a meningioma at the optic nerve entry point at the skull base who was initially treated under the suspicion of multiple sclerosis. Only high-resolution MRI enabled the correct diagnosis. In another case this year, we operated on a 15-year-old patient with a vascular malformation in the orbit—an overall rare diagnosis that, fortunately, occurs only in exceptional cases in children.”
Tumors in the eye and skull base region:
Defining neurosurgical responsibilities
Retinoblastoma is a tumor that typically occurs in childhood and is in fact the most common intraocular cancer in children. However, this tumor affects the eye itself—specifically the retina—and therefore falls under the specialized field of ophthalmology. Ophthalmologists are responsible for diagnosis, treatment planning, and—if necessary—surgical intervention. In many cases, preserving the eye is the primary concern.
“From a neurosurgical perspective, however, retinoblastoma is not a direct indication for surgery, since procedures involving the interior of the eye—particularly the retina, lens, or vitreous body—do not fall within the scope of neurosurgery. Our work begins when the structures surrounding the eye are involved, such as the optic nerve or the skull base. Only in exceptional cases, such as those requiring specialized access routes like transconjunctival approaches, is interdisciplinary collaboration necessary. A very different condition is what’s known as an acoustic neuroma—more commonly referred to today as a vestibular schwannoma. This benign tumor arises in the posterior cranial fossa, specifically in the internal auditory canal, and primarily affects the auditory nerve along with adjacent structures such as the vestibular (balance) nerve and the facial nerve (nervus facialis). Visual disturbances occur in rare exceptional cases—usually only if the tumor grows unusually large and compresses nearby cranial nerves such as the trochlear nerve or the abducens nerve. In such cases, patients may experience eye movement disorders or double vision. However, a direct threat to vision is uncommon and is not a leading symptom of this tumor type,” Prof. Dr. Scholz explains.
The treatment of brain and eye tumors varies significantly depending on tumor type, location, patient age, and individual circumstances.
The treatment of brain tumors generally involves multiple options that may be combined depending on the type of tumor. One of the most common approaches is surgical removal of the tumor—provided it is located in an accessible area of the brain. However, surgery is not automatically the default treatment. What matters most is the individual evaluation of each case. A key question is whether symptoms are present at all, and how they are progressing.
Prof. Dr. Scholz explains more precisely: “If a patient presents with worsening symptoms—such as deteriorating vision, increasing pain, or other intensifying complaints—or if imaging shows that a lesion is growing, active intervention becomes necessary. On the other hand, if a small, asymptomatic lesion is detected, for example in the orbit, a watch-and-wait approach with regular follow-up examinations may be appropriate. In such cases, imaging is often performed after three months to assess potential growth. If the findings remain stable, the follow-up interval can be extended to six months. Surgery becomes unavoidable when serious clinical symptoms appear that clearly indicate disease progression. These include noticeable declines in visual acuity, increasing discomfort, elevated intraocular pressure, or other signs suggesting the disease is advancing. Although these situations are not immediately life-threatening, if left untreated, they may lead to permanent vision loss—a risk that timely intervention can prevent. These types of surgeries are especially challenging for the treating physicians, particularly with regard to monitoring and preserving optic nerve function during the procedure. The goal is to remove or at least reduce the lesion as completely as possible, without damaging functional structures such as the optic nerve or eye muscles. Injury in these areas could result in permanent impairments such as double vision or drooping eyelids. Striking a balance between aggressive tumor removal and function preservation is key—and this balance must be discussed openly with the patient,” he adds:
“It is often not possible to guarantee complete removal of the lesion. In such cases, the primary goal is to relieve pressure on the optic nerve and prevent further deterioration. To monitor optic nerve function during surgery as precisely as possible, we use what is called VEP monitoring—a technique that measures visually evoked potentials. Under general anesthesia, the patient receives light stimuli through a flash goggle with closed eyelids. An electrode on the eyelid and a needle on the back of the head—near the visual cortex—record the signal transmission. Changes in the waveform indicate a possible impairment of optic nerve function and require extra caution. These intraoperative monitoring techniques are essential, as the patient under general anesthesia cannot provide feedback. In contrast to surgeries involving speech or motor function—where awake surgery with direct patient interaction is sometimes feasible—this is not practical for the optic nerve. Therefore, continuous technical monitoring is particularly important in this area.”
These highly specialized procedures require exceptional precision and experience. A particularly challenging aspect is the psychological burden patients face, often accompanied by the fear of blindness.
“Each year, we perform around 400 neurosurgical tumor operations. However, not all of these involve the optic nerve directly. Of those 400 cases, only a portion are located near the optic nerve or along the visual pathway—such as in the optic chiasm, visual cortex, or orbit. Truly optic nerve-preserving surgeries are much rarer, accounting for approximately 30 to a maximum of 50 cases per year. These are extremely specific, highly complex procedures that are not routine. Because this field is so specialized, we receive many referrals from other medical disciplines—such as neurologists, ophthalmologists, ENT specialists, or endocrinologists. Each clinic has its own network of referring physicians. Additionally, international patients often contact us, frequently seeking a second opinion. The uncertainty is often very high—especially when it involves the optic nerve, which is essential for vision. Many of these individuals are understandably anxious. Some have already lost vision in one eye—perhaps due to a childhood injury—so when their only remaining functional eye is at risk, the fear of going blind is enormous. Even minor findings, such as those affecting the retina, can trigger strong anxiety. After all, we're talking about eyesight—something so central and irreversible if lost. This psychological burden should not be underestimated. It accompanies patients from diagnosis to the decision for or against surgery—and often beyond. That’s why it’s so important to support them with both professional expertise and genuine compassion,” says Prof. Dr. Scholz.
The future of neurosurgery:
Innovations through AI and individualized treatment concepts
“At our clinic, we offer comprehensive neurosurgical care covering all subspecialties of neurosurgery. We place special emphasis on our extensive experience with the optic nerve, where we focus particularly on monitoring techniques. Our patients are welcome at any time, including for second or even third opinions. We offer individualized treatment concepts tailored to each patient's needs. In some cases, we also work closely with radiation oncologists, as certain treatment plans may require follow-up therapy—be it stereotactic radiation or chemotherapy. Treatment decisions always depend on the histological findings and are made on an individual basis,” emphasizes Prof. Dr. Scholz, who also addresses the growing role of artificial intelligence (AI):
“AI has the potential to significantly transform medical practice. It is particularly useful for quickly gathering information and addressing scientific questions. In the past, one had to search extensively through large databases—now AI can provide relevant information almost instantly. Another area where AI plays an important role is visualization. AI programs can now create images and illustrations that were previously the job of a medical illustrator. This is valuable not only for scientific publications but also for teaching students. AI makes it easy to create, adapt, and refine medical sketches and illustrations. AI also offers advantages for surgical planning. It can analyze imaging data and identify tumors and their relationship to surrounding blood vessels. This type of analysis greatly simplifies preoperative planning. Furthermore, searching for recent studies and research findings has become much easier with AI. However, there are still limitations in the use of robotics in surgery. While AI is already highly advanced in information processing and visualization, the use of robots in surgery remains somewhat limited. In complex procedures, surgeons must make many real-time decisions—sometimes as many as 120 to 130 during a single operation. A robot would need to constantly query these decisions, raising unresolved questions around liability and the surgeon’s role as the responsible decision-maker. It will likely take several more years before robots play a larger role in surgery and perhaps make autonomous decisions. Similar to autonomous driving—where fully autonomous vehicles are currently limited to private grounds—it will still be some time before we see fully autonomous surgeries. Nevertheless, developments in AI and robotics are promising, and it’s exciting to see how these technologies will continue to evolve in the years ahead.”
There are various causes for the development of tumors, and genetic mutations play a role. In fact, genetic alterations or mutations are often detected in tumors and contribute to their formation.
“However, some tumors arise as primary tumors in specific regions of the body and then spread. These tumors metastasize or seed elsewhere, and this is primarily a biological process. In such cases, the origin of the disease cannot be attributed solely to genetic factors—statistical probability and biological mechanisms also play a significant role. Therefore, the question of what causes a tumor cannot always be answered definitively. Neurosurgery is a particularly fascinating field because of its interdisciplinary nature and its close collaboration with various specialties. Especially important is our cooperation with neuroradiologists and interventional radiologists. These specialists can embolize tumors—reducing their blood supply with a catheter—which greatly facilitates surgical removal. This preoperative embolization allows tumors to be operated on with significantly less bleeding and more control. This is particularly valuable for surgeries in complex areas such as the skull base, where anatomical conditions are tight and the risk of injury is high. In some cases, where tumors were previously considered inoperable, this technique makes successful surgery possible for the first time. It can be said that this approach significantly enhances the surgical possibilities available to us,” concludes Prof. Dr. Scholz, and with that, we end our conversation.
Thank you, Professor Dr. Scholz, for these fascinating insights!
