Noonan Syndrome is an autosomal dominant congenital syndrome that is a multisystem disorder, commonly presenting with craniomaxillofacial, cardiac, and hematologic differences. Anterior mandibular surgery presents a surgical challenge because of potential injury to vessels in the floor of mouth. Inadequately-controlled hemorrhage, particularly in the setting of coagulopathy, may quickly escalate to acute airway obstruction. Additionally, modest hypotension maintained under general anesthesia typically reverses upon wakening, potentially resulting in refractory hemorrhage. In this report, we document a case of rapidly evolving floor of mouth elevation secondary to hemorrhage following alveolar symphyseal reconstruction in a patient with Noonan syndrome. Early recognition and operative re-exploration for hemorrhage control, with airway control, administration of high-dose intravenous steroid, and close monitoring in the intensive care unit resulted in rapid resolution of mouth-floor swelling, safe extubation, and a successful surgical outcome.
Noonan syndrome patients may have increased bleeding tendency.
Violation of the lingual flap in anterior mandibular surgery may cause sublingual hemorrhage with floor of mouth elevation.
Early recognition and airway control are key to preventing a potentially grave airway outcome.
Exploration and hemorrhage control along with the use of corticosteroids may halt or decrease the floor of mouth elevation.
Noonan syndrome is an autosomal dominant congenital syndrome with an estimated prevalence of 1 in 1000 to 1 in 2500 live births [ ]. It is characterized by abnormal craniofacial growth, congenital heart abnormalities and bleeding disorders [ ]. Craniofacial characteristics in Noonan syndrome include widely spaced eyes with down-slanting palpebral fissures, ptosis, and often low-set and posteriorly-rotated ears [ ]. Intraorally, these patients may have high-arched palate, speech articulation difficulties, oligodontia, and micrognathia [ , ]. Cardiac anomalies, such as pulmonary valve stenosis, hypertrophic cardiomyopathy, and atrial septal defects are observed in 50–80% of these patients [ ]. These patients typically have increased bleeding tendency secondary to thrombocytopenia, platelet dysfunction, and coagulation factor deficiencies. These characteristics increase the risk of significant hemorrhage during surgical procedures [ ].
In this report, we present a patient with Noonan Syndrome who presented for extraction of retained primary mandibular central incisors and autogenous block grafting an atrophic anterior mandibular alveolus. Post-operatively the patient developed sublingual hematoma that required urgent return to the operating room for re-exploration and hemorrhage control.
A 19-year-old 61Kg female patient with a history of Noonan Syndrome presented with an atrophic anterior mandibular alveolus, missing mandibular lateral incisors and retained primary central incisors ( Figs. 1 and 2 ) indicated for extractions and ridge augmentation in anticipation for future dental implant placement. She had undergone a Le Fort I osteotomy and bilateral mandibular sagittal split osteotomies previously without complication. She did not take any medications and had no medication allergies. She had a normal mouth opening. On intraoral examination, her tongue was fully mobile, and the floor of mouth was soft, non-elevated. Her mandibular permanent canines were in place of her missing lateral incisors. She had retained mandibular primary central incisors which were associated with an atrophic alveolus at that site ( Fig. 1 ). Pre-operative panoramic radiograph showed vertical and horizontal bone loss associated with her mandibular primary central incisors ( Fig. 2 ). Her pre-operative lab values were notable for hematocrit 32%, platelet 168K, and INR 1.2. A recent echocardiogram demonstrated mild aortic valve thickening with normal left ventricular size and systolic function.
The patient was taken to the operating room for extraction of the retained mandibular primary central incisors, with immediate reconstruction of the alveolus with an autogenous bone graft harvested from the left mandibular ramus. General anesthesia was induced by facemask (patient preference) using Sevoflurane in nitrous oxide and oxygen. Intravenous access was secured after which a rocuronium bolus was administered to facilitate uneventful fiber-optic nasal-intubation of a size 7mm nasal RAE endotracheal tube. She received 8 mg intravenous dexamethasone shortly after intubation. Sevoflurane in air and oxygen, propofol and dexmedetomidine were used for maintenance of anesthesia. Mean arterial pressures were maintained in the range of 50–60 mmHg throughout the duration of the operation.
Surgery commenced with extraction of the retained primary teeth. A crestal incision was made and buccal and lingual full-thickness mucoperiosteal flaps were raised with no tear in the flaps, revealing a 3mm thin anterior alveolus.
A mucosal incision was then made in the left mandibular vestibule, adjacent to the ramus to gain access to the anterior ramus. A block graft was harvested uneventfully and laid on top of the 3mm thin alveolus. Hemostasis was achieved in the left mandibular ramus donor site with gelfoam and primary closure.
Upon making the initial osteotomy through both the block and the anterior alveolus, the bur appeared to perforate the lingual periosteum. We then encountered pulsatile, bright red bleeding from a vessel in the lingual periosteum. The bleeding was managed with electrocautery, gelfoam, and bimanual pressure for 5 minutes, with complete resolution. The block graft was affixed with a single bicortical screw ( Fig. 4 ). The flap was then closed.
At the conclusion of surgery, the patient was extubated uneventfully and transported to the recovery room in stable condition. Approximately 30 minutes later, it was noted that she had difficulty phonating. Intra-oral examination at that time was notable for an expanding floor of mouth hematoma ( Fig. 3 A ). No acute respiratory distress was observed. The patient was immediately returned to the OR for re-exploration. She was induced without difficulty and intubated nasally. The sutures in the anterior mandible were released and the floor of the mouth was explored. Approximately 10 cc of bright red blood was evacuated, though discreet bleeding vessels could not be readily identified for ligation. Hemostasis was achieved with cautery. The site was packed with hemostatic agents, including absorbable gelatin sponge and fibrin glue and then closed with sutures in a water-tight fashion ( Fig. 3 B). Blood loss was estimated at 25 mL.