Dear Editor,

Orbital cavernous venous malformation (OCVM) represents a prevalent orbital pathology in adult patients. The primary treatment for this condition is surgical removal, beneficial for patients with visual complications or proptosis. While generally successful, surgery varies in postoperative complications, including vision loss (2%-32% of cases). For larger OCVMs, lesion def lation is useful for dissection, particularly with a medial approach [1]. In this case study, we detail the removal of an exceptionally large OCVM, employing a cavitron ultrasonic surgical aspirator (CUSA) to effectively reduce the size of lesion. Written informed consent for publication of the research details and clinical images was obtained from the patient.

A 47-year-old man presented with a 1-year history of proptosis and visual disturbance in his right eye. He exhibited 10 mm of proptosis compared to the opposite eye, with a visual acuity of 20 / 40 in the right eye and 20 / 20 in the left (Fig. 1A, 1B). A diffuse visual field defect was observed, and magnetic resonance imaging (MRI) revealed a 3.2 × 2.5 × 3.3-cm cavernous venous malformation (CVM) that completely filled the entire right orbit (Fig. 1C-1E). He exhibited restricted extraocular motility in all directions, accompanied by marked diplopia in every direction. Despite the deterioration observed in his ophthalmic examinations, there was no relative afferent pupillary defect or abnormal light reflex. Surgical removal of orbital CVM was decided with lateral orbitotomy under general anesthesia. Despite careful dissection around the CVM, extracting the mass without complications, such as pupil dilation, was challenging. CUSA was applied to debulk the mass and relieve the pressure exerted by the mass on adjacent critical structures, such as the optic nerve. Minimal bleeding was well controlled with bipolar cautery. After applying the CUSA to the mass, the CVM became significantly softer, and its size was remarkably reduced. Further dissection of the CVM was performed with a cotton applicator, and successfully removed from the orbit using a cryoprobe, with little resistance. The surgical techniques are depicted in Fig. 1F-1M. Two months after surgery, the patient exhibited normal vision and visual field with no complications, except for a persistently dilated pupil, which persisted 12 months after surgery (Fig. 1N-1R).

While OCVM generally presents as a surgeon-friendly lesion, its extensive size can pose surgical challenges and potentially result in unwanted complications. Especially, although rare, there is a risk of visual loss or deterioration postsurgery, particularly associated with the apical extensions of the OCVM. OCVM which is located at the lateral aspect of the orbit, may increase the risk of permanent tonic pupil and efferent defects as well [1]. In such circumstances, the CUSA emerges as a valuable tool for overcoming surgical hurdles and enhancing patient outcomes. The ultrasonic energy provided by CUSA facilitates effective debulking of the malformation, significantly reducing its size and pressure on surrounding structures. This debulking effect not only improves surgical visibility and access but also minimizes the risk of damage to vital tissues like the optic nerve, which is particularly vulnerable in extensive OCVM cases.

Compared to conventional techniques, CUSA offers several advantages in the context of OCVM removal [2,3]. The ultrasonic energy allows for precise debulking of the lesion with minimizing the risk of blood loss and subsequent complications. Additionally, the ability to selectively target and remove tumor tissue while preserving surrounding structures further enhances the safety and efficacy of the procedure. Moreover, CUSA’s ability to soften the malformation facilitates its extraction, simplifying the surgical approach and potentially reducing operative time [4].

The persistent postoperative pupil dilation observed in this case requires further investigation. While the exact cause remains unclear, potential contributing factors include manipulation of the oculomotor nerve, direct damage of ciliary ganglion or short ciliary nerves during surgery. Additionally, the patient’s history of long-standing extensive OCVM or existing medical conditions such as compressive damage on adjacent tissues could play a role [5].

This case report highlights the promising potential of CUSA as a tool for facilitating the safe and effective removal of extensive OCVM. However, further research and large-scale clinical studies are warranted to validate its efficacy and establish its role as a standard surgical technique in this context. Such studies should encompass a larger patient population with varying OCVM sizes and locations to provide comprehensive evidence of CUSA’s safety profile and long-term outcomes. Additionally, exploring and refining surgical techniques utilizing CUSA can further optimize its effectiveness and minimize potential complications.