Extracranial arteriovenous malformations (AVMs) are regarded as rare diseases and are prone to complications such as pain, bleeding, relentless growth, and high volume of shunted blood. Due to the high vascular pressure endothelial cells of AVMs are exposed to mechanical stress. To control symptoms and lesion growth pharmacological treatment strategies are urgently needed in addition to surgery and interventional radiology. AVM cells were isolated from three patients and exposed to cyclic mechanical stretching for 24 h. Thalidomide and bevacizumab, both VEGF inhibitors, were tested for their ability to prevent the formation of circular networks and proliferation of CD31⁺ endothelial AVM cells. Furthermore, the effect of thalidomide and bevacizumab on stretched endothelial AVM cells was evaluated. In response to mechanical stress, VEGF gene and protein expression increased in patient AVM endothelial cells. Thalidomide and bevacizumab reduced endothelial AVM cell proliferation. Bevacizumab inhibited circular network formation of endothelial AVM cells and lowered VEGF gene and protein expression, even though the cells were exposed to mechanical stress. With promising in vitro results, bevacizumab was used to treat three patients with unresectable AVMs or to prevent regrowth after incomplete resection. Bevacizumab controlled bleeding, pulsation, and pain over the follow up of eight months with no patient-reported side effects. Overall, mechanical stress increases VEGF expression in the microenvironment of AVM cells. The monoclonal VEGF antibody bevacizumab alleviates this effect, prevents circular network formation and proliferation of AVM endothelial cells in vitro. The clinical application of bevacizumab in AVM treatment demonstrates effective symptom control with no side effects. Graphical abstract Mechanical stress increases VEGF expression in endothelial AVM cells, possibly causing the VEGF upregulation in the microenvironment of AVM cells. The resulting RAS/RAF/MEK/ERK signaling in leads to progression of fast-flow malformations. The monoclonal VEGF-A antibody bevacizumab alleviates this effect, prevents circular network formation and proliferation of AVM endothelial cells in vitro. Sporadically occurring slow-flow malformations (LMs, VMs) have mutations in TEK or PIK3CA. TEK encodes the endothelial receptor tyrosine kinase TIE2. Sporadic extracranial fast-flow malformations (AVMs) show mutations in KRAS, BRAF and MAP2K1, which encodes the dual specificity mitogen-activated protein kinase MEK1. Combined targeting of the molecular causes of the disease could be key to achieve symptom control and reduce lesion growth. Orange: gain-of-function; Blue, circled with orange: enhanced signaling.

Background: The use of endoscopes in neurosurgery is well established, but the integration of a full high definition signaling, 45° angled endoscopic tool into a digital surgical microscope, is new. We report our first experiences in a cadaveric study and a clinical case series using the new microinspection tool QEVO^® that serves as a plug-in feature for the recently launched KINEVO 900 digital visualization platform (CARL ZEISS MEDITEC, Oberkochen, Germany). For illustration purposes, we offer video footage. Methods: The handling, workflow, and visualization patterns of the QEVO^® microinspection tool were critically evaluated in cadaver specimens by simulating four standardized neurosurgical approaches: (1) pterional, (2) retrosigmoidal, (3) transsphenoidal, (4) and transcallosal. Similarly, we evaluated the QEVO^® tool in corresponding clinical cases of (1) aneurysm clipping, (2) removal of cerebellar cavernoma, (3) and pituitary adenomectomy. Results: In both the cadaveric study and clinical case series, the QEVO^® tool was found to be beneficial in terms of high-quality visualization of fine structures and for displaying hidden anatomical details (“looking around the corner”). The handling was good, and the workflow was easy. However, the use of this tool was restricted by the lack of an external fixation and a working channel, the shortness of the tool, and the impossibility to switch to a 0° or 30° optic. Conclusion: Despite some restrictions, the QEVO^® microinspection tool is an innovative, handheld, endoscopic tool that allows excellent additional visualization of the surgical field. In our opinion, this tool effectively enhances the modern neurosurgical armamentarium.

(1) Background: The radial forearm flap (RFF) has evolved as the flap of choice for intraoral mucosal reconstructions, providing thin and pliable skin with a safe blood supply. Perforator flaps such as the anterolateral thigh (ALT) flap are increasingly being discussed for the same applications. (2) Methods: Patient history, treatment details, and outcome of 12 patents with moderate to extended defects of the lip and/or nose area that were reconstructed by a folded radial forearm flap were retrospectively evaluated for oncologic and functional outcomes. (3) Results: The mean oncologic and functional follow-up were 21.1 (min. 3.8; max. 83.3) and 31.2 (min. 6; max. 96) months, respectively. All flaps survived without revision. In eight cases, major lip defects were reconstructed by an RFF; in six patients, the palmaris longus tendon was included for lip suspension. The functional results in terms of eating, drinking, and mouth opening were good in five cases, while three patients were graded as fair due to moderate drooling. In seven cases, the major parts of the nose were reconstructed with two good and five fair (nostril constriction in three cases) functional results. (4) Conclusions: The folded RFF remains a unique free flap option for complex three-dimensional lip and nose reconstructions in terms of flexibility, versatility, and robustness.

To date, there is no approved local therapeutic agent for the treatment of epistaxis due to hereditary hemorrhagic telangiectasia (HHT). Several case reports suggest the topical use of timolol. This monocentric, prospective, randomized, placebo-controlled, double-blinded, cross-over study investigated whether the effectiveness of the standard treatment with a pulsed diode laser can be increased by also using timolol nasal spray. The primary outcome was severity of epistaxis after three months, while the main secondary outcome was severity of epistaxis and subjective satisfaction after one month. Twenty patients were allocated and treated, of which 18 patients completed both 3-month treatment sequences. Timolol was well tolerated by all patients. Epistaxis Severity Score after three months, the primary outcome measure, showed a beneficial, but statistically nonsignificant (p = 0.084), effect of additional timolol application. Epistaxis Severity Score (p = 0.010) and patients’ satisfaction with their nosebleeds after one month (p = 0.050) showed statistically significant benefits. This placebo-controlled, randomized trial provides some evidence that timolol nasal spray positively impacts epistaxis severity and subjective satisfaction in HHT patients when additively applied to standard laser therapy after one month. However, the effect of timolol was observed to diminish over time. Trials with larger sample sizes are warranted to confirm these findings.