Letter: Risk of Bone Wax Migration During Retrosigmoid Craniotomy for Microvascular Decompression: Case-Control Study

This is the authors' abstract. We don't add key points for this paper.

To the Editor: We have read with great interest the paper by Hashikata et al1 highlighting the potential risks associated with bone wax migration during retrosigmoidal microvascular decompression surgery, particularly in patients with large mastoid emissary canals. We agree with the authors' conclusion that excessive bone wax application should be avoided during microvascular decompression procedures. The principle of “less is more” should be applied to bone wax usage, ensuring that it is used sparingly to control bleeding without compromising hemostasis or increasing the risk of migration. Beyond the immediate risk of migration, we would like to emphasize the significance of minimizing bone wax usage because of its inherent drawbacks. Bone wax, being a nonabsorbable hemostatic agent, remains in the body indefinitely, potentially leading to a range of adverse effects. Several histologic reports described foreign body reactions, granuloma formation, fibrosis, and/or chronic inflammation after application of bone wax in neurosurgical procedures.2-9Figure illustrates foreign body reactions to bone wax after removal in secondary surgery.FIGURE.: H&E staining of bone wax removed after secondary neurosurgery. A, Multiple macrophages visible with multinucleated foreign body giant cells throughout the slice (not visible). B, Presence of oedema and congestive, dilated blood vessels. There is an increased number of lymphocytes, plasma cells and neutrophils visible in the stroma. Neutrophils for scale (12-15 µm).Infection risk is always present, and the application of bone wax is not an exception.10 A rabbit model demonstrated diminished clearance of staphylococcal bacteria with bone wax on site.10,11 This aligns with the observation that Staphylococcus Aureus is a predominant pathogen in bone wax–related infections.10,12 Different fungal infections have also been reported.12 It is hypothesized that the malleable bone wax is manipulated by the surgeon later in surgery, when the probability of contamination is higher.10 In addition, the effect of bone wax on inhibiting bone healing and osteogenesis has been consistently demonstrated in various animal and human studies.13-15 Furthermore, the literature is replete with reports of rare but serious clinical complications associated with bone wax usage. These include paraplegia,16 iatrogenic quadriplegia,17 ptosis and diplopia,18 venous sinus thrombosis,5,19 skull osteohypertrophy,3 peripheral facial palsy with trigeminal neuropathy,4 elevated intraorbital and intraocular pressure,20 swelling around the eye,6,20 wound extrusion,5 and speech and orientation deficits21 because of bone wax deployment. These complications further reinforce the principle of “less is more” when it comes to bone wax usage. Surgeons must exercise judicious restraint in using bone wax, using only as much as is necessary to achieve hemostasis. In addition, precise and targeted application of bone wax in the bleeding bone openings is essential. In doing so, one avoids placing bone wax in epidural or subdural spaces including venous sinuses. In other words, if the bone wax is placed on the exact bleeding point, the risks and complications are minimized. In our experience, excess bone wax is often found in the epidural space during redo surgeries. Bone wax is not a hemostatic agent for the epidural space. Tacking sutures and/or topical hemostats from oxidized cellulose or gelatin do a much better job in the epidural space. In addition, the exploration of alternative hemostatic agents should be embraced whenever possible. Ostene (Ceremed, Inc), a water-soluble bone wax alternative, is commercially available. Similar to bone wax, Ostene is pliable and can be manipulated manually before application. It adheres effectively to bleeding bone as a tamponade. It dissolves within 24–48 hours at the implant site, facilitating the initial stages of bone healing. Its solubility offers the possibility of addressing adverse reactions commonly associated with inert bone wax.13 The authors are congratulated for bringing this important topic to the readers of operative neurosurgery.