Prof. Andreas Gruber, M.D., is a highly specialized neurosurgeon with an outstanding reputation in the treatment of brain and spinal disorders. As Director of the University Clinic for Neurosurgery at Kepler University Hospital and Chair of Neurosurgery at the School of Medicine, he brings extensive experience and expertise to both clinical practice and academic teaching.
Prof. Dr. Gruber possesses comprehensive knowledge and skills in a wide range of specialized neurosurgical disciplines, including spinal surgery, tumor surgery, vascular surgery, epilepsy surgery, pediatric neurosurgery, radiosurgery, and functional neurosurgery. His scientific and clinical focus lies particularly in cerebrovascular and endovascular neurosurgery, as well as in neurosurgical intensive care medicine.
Following various fellowship programs at renowned university hospitals in England and the United States and his tenure as a senior physician at MedUni Vienna, Prof. Dr. Gruber now leads the neurosurgical team in Linz, which performs approximately 2,600 surgeries annually in five operating rooms. These procedures are highly complex and require not only state-of-the-art technical equipment but also the expertise of specialists with extensive experience.
The neurosurgery department at the hospital in Linz surgically treats a wide range of diseases and disorders of the central nervous system and peripheral nerves, including spinal stabilization procedures, disc surgery, and reconstructive skull surgery. Among the most commonly treated conditions are epilepsy, tumors, and vascular diseases, with pediatric neurosurgery being a particular focus. Here, the specialists are dedicated specifically to the diagnosis and treatment of neurological disorders in children.
In addition to his clinical work, Prof. Dr. Gruber is also active in research. Under his leadership, the team is working on the development of innovative technologies, such as a three-dimensional training simulation for the surgical treatment of cerebral aneurysms. This simulation enables surgeons to practice difficult procedures on a computer using real surgical instruments and to receive haptic feedback, thereby significantly improving their preparation for actual surgeries.
Prof. Dr. Andreas Gruber combines excellent surgical skills with a deep commitment to medical education and innovative research, making him a leading figure in neurosurgery.
The editorial team of the Leading Medicine Guide spoke with Prof. Dr. Gruber, focusing on the treatment of aneurysms.
The treatment of aneurysms is a highly complex and vital medical specialty that is constantly advancing through innovative techniques and state-of-the-art equipment. Aneurysms—dangerous bulges in the walls of blood vessels—require precise diagnosis and tailored therapeutic approaches to prevent serious complications such as ruptures. Thanks to advanced surgical and endovascular procedures, patients today have better chances of recovery and an improved quality of life. Close collaboration among specialists and the use of the latest technologies play a crucial role in this.
A brain aneurysm—a sac-like bulge in the walls of blood vessels—usually develops due to a weakening of the vessel wall.
This weakening can be triggered by various factors, including long-term high blood pressure, atherosclerosis (hardening of the arteries), genetic predisposition, traumatic injuries, infections, or inflammatory diseases. Congenital abnormalities of the vessel wall can also lead to the formation of an aneurysm. Prof. Dr. Gruber explains this at the beginning of our conversation: “An aneurysm is not a congenital condition, but rather a weakness in a brain artery that develops over the course of a person’s life and typically occurs in very specific locations. The weak spot of a cerebral aneurysm looks different from an aortic aneurysm, which has a tubular structure, whereas a saccular aneurysm in the brain is identified as a sac-like dilation of the blood vessel wall.” The symptoms of an aneurysm can vary and often depend on its location and size. “Most patients are unaware of an aneurysm, as many aneurysms initially cause no obvious signs or symptoms and are often discovered by chance during imaging tests for other conditions. 3–4% of people have an aneurysm and may die of a heart attack at age 95 without ever knowing they had one. In many cases, treatment would actually do more harm than good. Nevertheless, certain types of aneurysms, especially if they grow larger or rupture, can lead to serious symptoms,” explains Prof. Dr. Gruber.
A ruptured cerebral aneurysm can cause a sudden, extremely severe headache, often described as “the worst headache of my life.” Other possible symptoms include nausea, vomiting, neck stiffness, sensitivity to light, visual disturbances, speech difficulties, and even loss of consciousness. Aortic aneurysms, which occur in the aorta, can also remain asymptomatic for a long time. An abdominal aortic aneurysm may cause abdominal or back pain, sometimes accompanied by a pulsating sensation in the abdomen. A ruptured aortic aneurysm leads to sudden, severe pain in the abdomen or back, a drop in blood pressure, and possibly loss of consciousness. Peripheral aneurysms, which occur in other blood vessels such as the leg arteries, may present with pain, swelling, or circulatory problems in the affected extremities. They can also form blood clots that obstruct blood flow in the affected vessels and may lead to further complications.
“Aneurysms that have bled must be treated because the rate of rebleeding is high and life-threatening. Asymptomatic aneurysms are also treated if they are 7 mm or larger. However, if additional risk factors are present—such as in smokers or patients with high blood pressure—treatment is also warranted even for smaller aneurysms. Aneurysms that cause symptoms due to compression of the cranial nerves must also be treated, as the cranial nerves can suffer permanent damage. Unlike abdominal aortic aneurysms, cerebral aneurysms have the advantage, due to their structure, that the sac-like formation can be closed off while the underlying vessels—the arteries—remain intact. “If one were to attempt to close an aortic aneurysm, one would simultaneously close off the aorta,” explains Prof. Dr. Gruber, highlighting the danger posed by aneurysms: “It’s fair to say that one-third of patients die before the doctor arrives; two-thirds are admitted to the hospital, of whom one-third survive. Of these survivors, some are left with a permanent disability, while others make a full recovery. Unfortunately, those affected have nonspecific symptoms such as headaches or mild dizziness, which is why aneurysms are usually discovered incidentally. A bleeding aneurysm is actually relatively rare. We don’t yet know much about the growth rate of an aneurysm—not even whether they grow continuously or erupively. Some grow quickly, some grow slowly, and some remain unchanged for a lifetime. However, we can definitely assume that they grow, since this is not a congenital but an acquired weakness. Those affected are usually over 40 years old, and women are more commonly affected due to the increased vulnerability of their blood vessel walls caused by hormonal changes. Children can also develop aneurysms, but these are usually very unstable, bleed, and are more likely to experience recurrent bleeding, which makes the overall prognosis poor.”
The latest treatment methods for aneurysms include a range of innovative technologies and procedures aimed at improving treatment outcomes and minimizing risks for patients.
“If an aneurysm is detected, a neurosurgeon should be consulted as soon as possible. After diagnosis, the neurosurgeon can then assess whether it is dangerous and requires treatment or whether a ‘watch and wait’ approach is appropriate. I have been practicing neurosurgery since 1992 and have also been trained in neurointervention since 1993. It is therefore a core competency I have acquired to assess which cases are better suited for surgery and which can be treated with embolization. “The decision on which treatment technique to use in a specific case is usually made during an interdisciplinary neurovascular conference, in which neurosurgeons, neuroradiologists, and neurologists contribute their expertise,” said Prof. Dr. Gruber.
Embolization is a minimally invasive method for treating aneurysms, in which one or more materials are precisely introduced into the aneurysm to stop blood flow in that area. The goal is to isolate the aneurysm from the blood circulation to minimize the risk of rupture and prevent blood flow through the aneurysm. In the field of embolization techniques, coiling has become the standard procedure, in which platinum coils are inserted into the aneurysm to interrupt blood flow and seal off the aneurysm. Modern coils are often coated or feature additional mechanisms to promote clot formation.
A significant advancement is endovascular therapy, which uses stent grafts to seal the aneurysm from the inside and divert blood flow. These minimally invasive surgical procedures have established themselves as effective alternatives to open surgery. Particularly noteworthy are branched and fenestrated stent grafts, which were developed for the treatment of aneurysms in complex anatomical areas. They allow for more precise coverage of the aneurysm and the preservation of blood flow to critical organs. Another innovative method is the use of flow-diverting stents, which are primarily used to treat intracranial aneurysms. These stents divert blood flow away from the aneurysm sac and promote clot formation within the aneurysm, leading to its shrinkage and stabilization.
“In principle, one must distinguish here between reconstructive and deconstructive techniques. With the former, the aneurysm can be occluded while the vessel containing the aneurysm remains open (clip, coil, stent), whereas in a deconstructive procedure, the aneurysm and the vessel containing it are closed off—which can also be done under bypass protection to prevent potential strokes. This requires genuine expertise with bypasses! As for the decision between these two approaches, I have published a highly detailed decision matrix that lists all possible parameters. These include details on the patient’s age, the structure, shape, and location of the aneurysm, information on its growth, the catheter’s access route, whether the patient has a narrow or wide neck, the presence of bleeding, etc.,” explains Prof. Dr. Gruber.
Clipping is a surgical procedure for treating intracranial aneurysms in which a special device called a “clip” is used to isolate the aneurysm from normal blood flow. This procedure is typically performed via open surgery and aims to minimize the risk of aneurysm rupture and thus prevent potentially life-threatening bleeding in the brain.
Coiling (also known as endovascular coil embolization) is a minimally invasive procedure for treating intracranial aneurysms. In this procedure, a thin, flexible wire—called a “coil”—is inserted into the aneurysm to seal it off and thus minimize the risk of rupture. This technique is often used as an alternative to surgical clipping, particularly for aneurysms that are difficult to access or for patients who prefer a less invasive method.
A stent graft is a medical device used in the minimally invasive treatment of aneurysms, particularly aortic aneurysms. It is a combination of a stent and a graft. The stent is a tubular metal mesh that keeps the artery open, while the graft is a synthetic sleeve that channels blood flow and reinforces the weakened segment of the vessel. Together, they form an internal support that is inserted into the affected artery to seal the aneurysm from the inside, thereby minimizing the risk of rupture.
Bleeding aneurysms must be treated immediately.
“Bleeding aneurysms must always be treated immediately. They can be embolized, or they can be surgically repaired. There is a study indicating that aneurysms that are amenable to embolization should indeed be embolized, which requires neurointerventional capabilities. If there is uncertainty in the decision, it is certainly always better to perform embolization. There are no guidelines for non-bleeding aneurysms. The only thing to note here is that the clip is more stable than the coil—the coil is far less invasive,” states Prof. Dr. Gruber, citing an example: “For example, we have a medidefucation aneurysm (a specific type of aneurysm that occurs at the point where the middle cerebral artery (MCA) branches. The mid-division is the point where a larger artery branches into smaller branches), with a recent hemorrhage and a large space-occupying cerebral hemorrhage—in this case, there would be a clear indication for surgery. A narrow-necked, bleeding cerebral aneurysm, on the other hand, would be a good indication for embolization.”
Aneurysms can be located in various parts of the body, and their location influences both the risk of rupture and the technical feasibility and risks of treatment. “The location of the aneurysm plays only a limited role. Size, too, plays only a limited role. It’s fair to say that the larger the aneurysm, the more difficult the surgery. However, a large aneurysm does make endovascular therapy more challenging. Aneurysms located near the base of the skull can be treated very effectively with modern flow diversion (Flow diversion is an advanced method for treating intracranial aneurysms that helps reduce the risk of an aneurysm by redirecting blood flow within the vessel),” explains Prof. Dr. Gruber.
Another factor that is taken into account is the aneurysm’s proximity to critical anatomical structures. Aneurysms near major arterial branches, such as the renal arteries or the arteries supplying the brain, often require more complex planning and execution of the surgery to ensure that blood flow to these vital organs is maintained.
Rapid Mobilization and a Message to Patients
“Immediately after surgery, which lasts between 3 and 5 hours, the patient spends one night in the intensive care unit and remains in the hospital for a total of about ten days because they need to be closely monitored. On the day of the surgery, however, the patient is already back on their feet—in other words, mobilization occurs very quickly. Planning the surgery is crucial for the surgical team, following the motto ‘Well planned is well done!’ If everything goes well, the patient’s stitches are removed after eight days, and they are discharged after ten days. Typically, the patient returns for a follow-up visit after 4–6 weeks and again after six months. “Postoperatively, the patient may initially experience some physical fatigue and be less resistant to stress. After all, the brain was exposed to air, which causes these symptoms—but they eventually disappear,” explains Prof. Dr. Gruber.
“I am currently president of the Austrian Society for Neurosurgery and a member of the executive board of the Vascular Section of the European Society for Neurosurgery. As a hybrid neurosurgeon with dual training, I was fortunate to study under Prof. Dr. Riechling in Vienna in 1992 and under Prof. Dr. Bernstein in New York, and can therefore say that I truly know what I’m doing. For this reason, my personal wish is that brain conditions prone to hemorrhage should generally be treated only by physicians who are truly capable of doing so. This is where it makes sense to establish specialized centers equipped with all the technology that might be required in case of an emergency. We must not forget that with some bleeding aneurysms, we have to act very quickly!” urges Prof. Dr. Gruber, and with that, we conclude our conversation.
Thank you very much, Professor Dr. Gruber, for the insight into the challenging treatment of aneurysms!
