Naso- orbital- ethmoid (NOE) fracture
The naso- orbital- ethmoid complex is a delicate anatomical structure which is three dimensional. Facial dysfunction and severe malformation may occur due to damage to this complex. If a patient has suffered from trauma of the NOE complex, a clinical examination should be performed by the doctor comprehensively and radiographic analysis should be done to assess the extent and the type of fracture. The results of the tests can help the doctor to formulate a customized treatment plan for the patient which can help in restoration of the patient’s appearance to as normal as possible and also prevent post-operative complications.
Since the anatomy of the naso-orbital- ethmoid complex is quite complicated any trauma to this region poses a great challenge for the surgeons. Eve minimal damage to this region may cause major malfunctioning of face and may cause abnormal appearance. Since the NOE complex separates the orbital and nasal cavity from the cranial cavity it has an intricate relationship with the brain and eyes. After the fracture, once the vital signs are stabilized a complete physical examination along with radiographic assessment by CT scan in both 2D and 3D should be done.
The anatomy of the NOE complex
The NOE complex comprises of the frontal process of the maxilla, nasal process of the frontal bone, nasal bones, lamina papyracea, lacrimal bone, sphenoid bone, nasal septum and ethmoid bone. All these act as a barrier between the cranial cavity and the orbital and nasal cavity. The blowout fracture can easily occur on the medial orbital wall which is made up of the lamina papyracea of the ethmoid bone and the lacrimal bone.
Medial Canthal Tendon (MCT)
MCT is an important soft tissue in the NOE complex which acts as a support to the canthus, performs the job of lacrimal pump and enables proper apposition between the eyelid and globe. However there is controversy on the number of tendon’s limbs in the MCT.
NLD or nasolacrimal duct extends through the nasal cavity through the inferior meatus underneath the inferior turbinate. It is situated in the bone of the lateral nasal wall. It acts as a drain for tears.
The horizontal buttress consists of the frontal bone, inferior orbital rims and superior orbital rims. It is divided in to inferior horizontal buttress and superior horizontal buttress. The medial vertical buttress is made up of the maxilla’s bilateral frontal process and the internal angular process of the frontal bone.
The branches of the internal and external carotid arteries acts as the blood supply carriers to the nasal region and the mid face. The posterior as well as anterior ethmoid arteries descend from the internal carotid artery.
The NOE complex consists of maxillary and ophthalmic nerves derived from the trigeminal nerves.
Symptoms of the NOE fracture
The symptoms of the fracture of the NOE complex depend upon the severity of the fracture as well as its location. In the early stages of fractures, gross facial edema may be present, which distorts the soft tissue landmarks. The symptoms may be followed in the nose and eyes. Ophthalmic symptoms originating due to NOE fracture could be telecanthus, Epiphora, enophthalmos, and as result of malformation of medial canthal tendon and orbital wall the shortening of palpebral fissure.
Nasal symptoms may cause anosmia due to damage to the cribform plate, retrusion of the nasal bridge, deformity of bone or cartilage, septal hematoma and secondary nasal congestion.
With a combination of physical examination and imaging techniques, a comprehensive diagnosis should be made about the extent, location and the displacement of the fractures. Pictures of the patient taken before the trauma can also help in assessing the damage.
For physical examination for location of the fracture, palpation is an effective way. Whether the central nasal drum has been fractures can be determined by its palpation. There is a possibility of fracture in the medial wall if the intercanthal distance is greater than 35 mm. In case the distance is greater than 40 mm there could be a possibility of displacement fracture. If the damage is severe, a misdiagnosis can occur due to extreme pain and also because the initial symptoms may mask the actual fracture characteristics. Physical examination in isolation is not completely accurate and should be combined with radiographic imaging.
According to the type of fracture the treatment begins with the stabilization of the vertical, horizontal and inferior horizontal buttress. This is done with screws and junctional plates. For fracture in the medial wall titanium mesh and microplates can be used. The type III type of fractures are the most complicated to repair and the focus of the repair should be reconstruction of the orbital wall and the restoration of the MCT to its pre trauma state.