Case report

A 29-year-old male bricklayer, with no known co-morbidities, suffered an episode of ‘heat stroke’ while returning home on foot from a building site. He was found lying unconscious on the roadside with twitching limbs, and an initial Glasgow Coma Scale score of 3/15 was recorded. After transfer to a nearby tertiary hospital, a clinical, biochemical, and radiographic assessment indicated that he had suffered an anoxic brain injury with severe cognitive deficits. He was immediately intubated, ventilated, and transferred to the intensive care unit (ICU) and a tracheostomy was performed to protect the airway.

Subsequently, he developed multi-organ failure and required renal dialysis. Further biochemical studies confirmed a diagnosis of DIC with a poor prognosis. However, after 2 months, his condition improved and he was transferred to a rehabilitation centre in his home state to manage his neurological deficits, which included dysarthria, impulsive behaviour, poor memory, and a gait disturbance. Brain magnetic resonance imaging (MRI) demonstrated marked bi-frontal, cerebral, and cerebellar atrophy.

After 6 months of rehabilitation therapy, his attending physicians noted that his nasal dorsum appeared to be slowly collapsing and that his maxillary anterior teeth were ‘intruding’. Presuming an infective cause, he was referred to the maxillofacial surgery unit for assessment. Clinically, a saddle nose deformity was evident with obstruction of his nasal airways, greater on the left side ( Fig. 1 A) . His maxillary anterior teeth, previously in occlusion, were noted to be mobile and had displaced superiorly ( Fig. 1 B). A 3D computed tomography (CT) scan demonstrated lysis of the anterior portion of the maxilla ( Fig. 1 C) causing collapse of the cartilaginous nasal septum. It was concluded that a process of bony necrosis was occurring, and although he remained afebrile and asymptomatic, subsequent blood cultures confirmed the presence of Candida albicans, Aspergillus fumigatus aspergillosis and beta-haemolytic Staphylococcus aureus , but without any markers of an acute infection. An area of occipital alopecia, inconsistent with male pattern baldness, was also observed and presumed to be secondary to scalp pressure and circulatory compromise while the patient was unconscious in the ICU. A diagnosis of avascular necrosis of the midface secondary to DIC was made.

(A) Lateral facial view demonstrating a ‘saddle nose’ deformity. (B) Anterior open bite due to osteonecrosis of the anterior maxilla. (C) Three-dimensional CT scan showing bony lysis around the anterior teeth.

A treatment plan was then devised that commenced with extraction of the compromised maxillary teeth and debridement of the necrotic maxilla and associated structures. This was to be followed by a staged reconstruction of the maxilla–nasal complex.

In the first procedure, under antibiotic cover, all maxillary teeth from second premolar to second premolar were extracted together with debridement of the associated non-vital bone. No purulence was present and an attempt at closure of a large anterior oronasal fistula was undertaken. The wound broke down in the early postoperative phase and was obturated with a temporary maxillary prosthesis.

Six months later, the maxillary defect was reconstructed with a deep circumflex iliac artery bone flap. The donor fragment was osteotomized into three segments to shape a new maxillary complex, and access to the recipient facial vessels was achieved via an incision parallel to the right nasolabial fold. The pedicle was orientated posteriorly on the graft to facilitate the anastomoses.

After a further 5 months, a costochondral graft was harvested from the seventh rib to reconstruct the nasal deformity. The graft was shaped to restore the dorsal contours by creating a peg on the cephalic end to insert into a bony tunnel prepared in the naso-frontal region midline as far as the antero-inferior wall of the frontal sinus. This enabled the graft to be cantilevered to elevate the nasal tip. The caudal end was contoured to enable the collapsed lower lateral cartilages to be raised by suturing to the costal cartilage. A third procedure was performed 2 months later in which six dental implants were inserted into the grafted segment, which was noted to be firmly united to the native bone posteriorly. After osseointegration was confirmed, an implant-retained bar and overdenture prosthesis was constructed and inserted enabling a return to normal function ( Fig. 2 ). Finally, a rotational scalp flap was performed to excise an area of alopecia on the scalp to restore hair-bearing continuity. His neurological function has improved slowly with respect to speech and motor skills. Close monitoring and maintenance of his implant-supported prosthesis will be required.

(A) Lateral facial view post-reconstruction. (B) Frontal facial view with overdenture in situ. (C) Lateral cephalogram demonstrating implants and framework in the free vascularized graft.

Discussion

DIC is a complex systemic disorder characterized by widespread activation of the coagulation cascade, resulting in thrombosis and ischaemia of organs and soft tissues. The depletion of clotting factors, fibrinogen, and platelets leads to extensive haemorrhage and secondary activation of the plasminogen pathway. This can occur through the extrinsic pathway via the activation of thromboplastin on factor VII. Tissue factor, or thromboplastin, is found in high concentrations in the heart and lungs. It is released following trauma, head injury, infection, and metastatic disease. With regard to oral and maxillofacial surgery, DIC has been described in the literature also following head trauma, infection, and metastatic disease. DIC can also be initiated by the intrinsic pathway following the activation of factor XII and has been associated with vascular damage, Gram-negative septicaemia, and local tissue damage.

The clinical presentation of DIC depends on the site of intravascular coagulation, the severity of the disease process, and whether haemodynamic instability occurs predominantly from vascular obstruction or haemorrhage. End-organ damage occurs due to local fibrin thrombus formation that may embolize and obstruct the microcirculation. If the occlusion is proximal and no collateral circulation exists, ischaemia may lead to end-organ failure. Since the distal portion of the infarct has no blood supply, local inflammation does not occur and the organ is fixed and preserved initially.

Patients may present with signs of spontaneous bleeding and purpura from wounds, operative sites, or venipuncture sites. With regard to end-organ dysfunction, the kidneys are most commonly affected, followed by hepatic, respiratory, and central nervous systems. The diagnosis of DIC can be made by a combination of platelet count, international normalized ratio (INR), and D-dimer and fibrinogen levels on biochemistry. In the patient described, there was generalized bruising, and mechanical ventilation was required together with renal dialysis. Coagulation studies supported the diagnosis of DIC.

Avascular necrosis is a pathological state where a reduced vascular supply leads to ischaemia and eventual necrosis of the bone. This has been thoroughly described in the orthopaedic literature, particularly affecting the hip. The interruption of vascular supply may have several causes, of which the most common is trauma. Vascular occlusion of arterioles has also been attributed to corticosteroids, alcohol, fat emboli, immune complexes in vasculitic diseases, and sickle cells. It has been suggested that unless there is a collateral circulation, osteoblasts and osteocytes become hypoxic and undergo apoptosis leading to osteonecrosis.

To the authors’ knowledge, this is the first reported case of avascular necrosis of the midface secondary to DIC. This is inherently due to the rich collateral vascular supply to the midface. The maxilla is supplied by multiple branches of the external carotid artery, including greater and lesser palatine arteries, the ascending palatine branch of the facial artery, the anterior branch of the ascending pharyngeal artery, and alveolar branches of the maxillary artery. The nasal cavity is vascularized by an anastomosis of both internal and external carotid arteries. The internal carotid artery terminal branches include the anterior and posterior ethmoidal vessels, while the sphenopalatine, pharyngeal, and greater palatine arteries are terminal branches of the maxillary artery that also supply the nasal cavity. In the present study, given the severity of the patient’s DIC, it is proposed that multiple fibrin thrombi embolized and obstructed the vascular network to the midface leading to avascular osteonecrosis of the maxillo–nasal complex.

Osteonecrosis may be categorized as either septic or aseptic. Septic osteonecrosis can occur from a bacterial, fungal, or viral source. Fungal infections include mucormycosis and aspergillosis and viral infections include herpes zoster. These conditions can occur in immunocompromised patients including those on long-term corticosteroids and immunosuppressants for lung transplants and malignancies. While the patient described had positive blood cultures, an infective clinical picture was not demonstrated.

Trauma has been described as a cause of osteonecrosis of the maxilla on three occasions. Two cases involved Le Fort I–II level fractures and the third case involved right maxillary sinus fractures that led to clinical and radiographic signs of osteonecrosis. The patient described in the current study was severely dehydrated and had an unwitnessed collapse. While he may have fallen onto his face, the clinical assessment and initial CT scans revealed no signs of facial injury, and trauma was therefore excluded as the cause of the maxillary osteonecrosis.

Other known causes of osteonecrosis include orthognathic surgery, bisphosphonates, radiation therapy, and Gorham’s disease. Orthognathic surgery has become a routine and safe surgical procedure with predictable results for the management of dentofacial deformities. The Le Fort I osteotomy is designed to separate the tooth-bearing segment of the maxilla from the superior part of the maxilla with complete pterygomaxillary dysjunction. Ischaemia is a known but rare complication of this operation. A recent study of 1000 patients reported a 1% incidence of ischaemic complications. Of the 10 patients, eight required critical surgical revision and two experienced aseptic necrosis of the alveolar process. Since 2003, bisphosphonate-related osteonecrosis of the jaws (BRONJ) has been well documented in patients being treated for various bone-related conditions, and is the most common cause of osteonecrosis in the maxillofacial region, with an incidence of up to 27.5%. Patients who have had malignancies often receive adjunctive radiotherapy to the head and neck region. The irradiated tissues are permanently hypovascular and hypoxic and at risk of osteonecrosis. Osteoradionecrosis (ORN) has been described as a long-term complication following dental extractions or minor trauma, with an incidence of up to 10%. Gorham’s disease has been described as an idiopathic destructive process causing bone resorption and locally aggressive lymphovascular infiltration.

Functional maxillary reconstruction is a challenge for the maxillofacial surgeon, as the contours of resorbed or resected bone are difficult to reproduce. The deep circumflex iliac artery flap has been recommended for maxillary defects and was considered the best source and volume of vascularized bone to adequately restore the defect in our patient. Access for the anastomoses was facilitated by a trans-facial access incision despite the pedicle being superficial and at risk within the oral cavity. This procedure was performed first to provide the necessary foundation for the subsequent nasal reconstruction to close the oronasal communication and to anticipate dental implants for restoration of the maxillary arch.