Single-Stage Reconstruction of Maxillectomy and Midfacial Defects in Cases of Covid Associated Mucormycosis

Covid associated mucormycosis [CAM] may involve the nose, paranasal sinuses, orbit, cranium and palate which is challenging in terms of management. The most critical aspect in having a favourable outcome is prompt diagnosis. It is known that diplopia, ophthalmoplegia, proptosis, periocular cellulitis, ocular pain, acute vision loss, nasoantral or cutaneous eschar in a predisposed host carry a potentially high predictive value.[5] Along with L-AmB, radical surgical debridement must be expeditious to eradicate the fungal reservoir by acting aggressively until bleeding tissue, bone, and periosteum is well perfused with the antifungal agent.

It is vital to provide these patients with a good outcome in terms of survival, quality of life, speech, feeding and aesthetics [7]. The appropriate technique for reconstruction depends primarily on the type of anatomical defect. There are several classification systems for maxillary defects [8], although the Brown classification system has been widely adopted. [9] Although these are more pertinent for maxillary tumours, similar principles may be extrapolated for cases of CAM as well. The reconstruction may be done by the use of prosthesis or flap reconstruction.

Historically, maxillectomy defects were reconstructed with a skin graft to revive a mucosal barrier followed by use of an obturator. [6] Obturator can be used when the defect is limited, patients are poor surgical candidates with an advantage that it is a cheaper reconstructive option, causing less surgical morbidity but with a disadvantage of giving persistent crusting and pain, subjective to wear and tear over time, require daily maintenance and may require frequent visits for adjustments. It may demand a level of manual dexterity for insertion, removal and cleaning which can be challenging for elderly and people with failing dexterity. [10]

Depending of the size and volume of defect, either free flaps or pedicled flaps may be employed. With free flap reconstruction, there are several options like fasciocutaneous flap from anterolateral thigh, radial forearm, myocutaneous flaps from latissimus dorsi or rectus abdominis, or osseocutaneous flaps - fibular free flap, scapular flaps with either thoracodorsal artery or circumflex scapular artery, radial forearm osseocutaneous flap and iliac crest free flap. All types of flaps have their pros and cons and the ultimate decision rests with the reconstructive surgeon based on the type and size of the defect along with convenience and expertise. [11] The algorithms proposed by Cordeiro and Chen serve as valuable guides in decision making [12].

Perforator free flaps allow surgeons to reap large areas of skin and subcutaneous tissue, supplied by vessels perforating the underlying muscle, without harvesting denervated muscle. In so doing, surgeons can minimize postoperative pain, muscle weakness, and therefore the risk of hernia formation after muscle harvest. Surgeons can also better predict flap bulk by not including denervated muscle during a flap which will significantly atrophy over time. [13] The anterolateral thigh (ALT) flap for example, can be harvested as a perforator flap for midface reconstruction. It provides significant tissue bulk and an extended pedicle (10–15 cm), allows for primary closure of the donor [13]. site, and can be sensate. Further, when two separate perforators are harvested, then the ALT can provide two separate skin flaps allowing for intraoral and skin reconstruction. Other perforator flaps include the deep inferior epigastric perforator flap, the anteromedial thigh perforator flap, the arteria glutes perforator flap, the thoracodorsal artery perforator flap, peroneal artery perforator flap, submental perforator flap, and others [13].

Previous studies have demonstrated the feasibility of flap reconstruction in maxilla defects. [14] The reconstruction may also be either immediate or delayed. A large proportion of cases from older series underwent delayed reconstruction. [14] The apprehension with immediate reconstruction is that of recurrence of local disease and failure of the flap which may render the whole surgery futile and lead to tremendous patient morbidity. However, it has been demonstrated that if the margins are clear of the disease, then simultaneous flap reconstruction is also a valid option. [14, 15]

The management of CAM during the deadly second wave of COVID 19 was a challenge not just in terms of medical and surgical management but also in terms of logistics. The volume of cases was unprecedented. Health facilities and intensive care were completely saturated with COVID cases. There were also issues with availability of Liposomal Amphotericin. This series highlights that despite these mitigating factors it was still possible to provide satisfactory patient outcome with single-stage surgical debridement and autologous flap reconstruction.

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