Diagnosis

NOE fractures

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 Introduction
 Type I
 Type II
 Type III
 Clinical examination
 Radiographic findings
 Make sure to rule out CSF leak
 Evaluation of lacrimal apparatus
Introduction
Diagnosis of NOE fractures

The nasoorbitoethmoidal (NOE) fracture refers to injuries involving the area of confluence of the nose, orbit, ethmoids, the base of the frontal sinus, and the floor of the anterior cranial base. The area includes the insertion of the medial canthal tendon(s). NOE fractures, by definition, are a different entity than isolated nasal bone fractures. However, they are often associated with fractures of the nasal bones.

NOE fractures are most commonly classified according to Markowitz BL, Manson PN, Sargent L, et al (1991) Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment. Plast Reconstr Surg. 87(5):843-53:

  • Type I
  • Type II
  • Type III

These can be unilateral or bilateral injuries.


Diagnosis of NOE fractures

Involvement of buttresses
NOE complex fractures involve the medial vertical (nasomaxillary) buttresses of the facial skeleton. Click here for further details on buttresses.


Diagnosis of NOE fractures

Association with frontal sinus fractures
NOE fractures are often associated with frontal sinus fractures.


Type I
Diagnosis of NOE fractures

In unilateral Markowitz type I fractures, there is a single large NOE fragment bearing the medial canthal tendon.


Diagnosis of NOE fractures

Involvement of the nasal bone
The nasal bone may also be involved and, in cases of comminution, may not provide adequate dorsal support to the nasal bridge.


Type II
Diagnosis of NOE fractures

In unilateral type II fractures, there is often comminution of the NOE area, but the canthal tendon remains attached to a fragment of bone, allowing the canthus to be stabilized with wires or a small plate on the fractured segment.


Diagnosis of NOE fractures

Involvement of the nasal bone
The nasal bone may also be involved and, in cases of comminution, may not provide adequate dorsal support to the nasal bridge.


Diagnosis of NOE fractures

Bilateral type II fracture with nasal bone involvement
The illustration shows a bilateral NOE type II fracture. In bilateral fractures the nasal bones are commonly involved. In some instances, bone grafting of the nasal dorsum may be necessary.


Type III
Diagnosis of NOE fractures

In type III fractures, there is often comminution of the NOE area (as in type II fractures) and a detachment of the medial canthal tendon from the bone.


Diagnosis of NOE fractures

Involvement of the nasal bone
The nasal bones are usually involved and might not provide adequate dorsal support to the nasal bridge. In such cases bone graft reconstruction often is indicated.


Diagnosis of NOE fractures

Bilateral type III fracture with nasal bone involvement
The illustration shows a bilateral NOE type III fracture. The nasal bones are usually involved. Bone graft of the nasal dorsum is usually necessary.


Clinical examination
Diagnosis of NOE fractures

The patient often has swelling in the medial canthal area and pain and crepitation with palpation.


Diagnosis of NOE fractures

The nose can be retruded and impacted at the nasofrontal suture area with lack of support for the nasal septum and cartilages.


Diagnosis of NOE fractures

Intercanthal distance
There will be a lack of definition of the bony anatomy in the medial canthal area and possible lateral splaying of the medial canthus with increased intercanthal distance (the normal distance varies depending on the ethnic group, e.g., in Caucasians more than 35 mm intercanthal distance is considered abnormal.)

A thorough ophthalmological examination should be performed.

This illustration demonstrates widening on the left with the medial canthus positioned lateral to the position of the lateral nasal alar margin.


Diagnosis of NOE fractures

Bow string test
The surgeon may be able to grab the eyelid or use a forceps to grab the skin in the medial canthal area and pull it laterally (“bow-string” test).

In the bow-string test the lid is pulled laterally while the tendon area is palpated to detect movement of fracture segments. A lack of resistance or movement of the underlying bone is indicative of a fracture.


Diagnosis of NOE fractures

Bimanual palpation
Another test is to place an instrument in the nose and push laterally in the medial canthal area to test for instability and crepitation, which suggests an unstable NOE fracture.


Radiographic findings
Diagnosis of NOE fractures

A surgeon can often distinguish between a type I NOE fracture versus a type II / III fracture by the degree of comminution noted on the CT.

It is generally very difficult to distinguish between a type II and a type III NOE fracture based on radiographic examination. The finding of an avulsed medial canthal tendon from its insertion on the bone often has to be determined intraoperatively.

CT shows a sagittal view of a bilateral NOE type II fracture. Note the depression of the nasal root.


Diagnosis of NOE fractures

Coronal view of the same patient.


Diagnosis of NOE fractures

Axial views of the same patient. The axial view shows the involvement and potential compromise of the lacrimal system.


Diagnosis of NOE fractures

Note the depression of the nasal bone complex.


Diagnosis of NOE fractures

A 3D CT, as shown, can help assessing the severity of the injury but the final diagnosis requires clinical findings and is usually made intraoperatively. This 3D CT shows a bilateral NOE type II with involvement of the nasal bones.

Be aware that a 3D CT often underestimates the severity of the injury.


Make sure to rule out CSF leak
Diagnosis of NOE fractures

The following diagnostic procedures can be performed if there is a suspected CSF leak (clinical sign: straw-colored or clear nasal drainage):

  • Tilt test with positive halo sign (as illustrated)
  • CT scan with thin coronal cuts (0.5 mm) of the cribriform plate
  • Comparison of the concentration of glucose between fluid and patient’s serum
  • Laboratory analysis for beta-transferrin
  • Application of fluorescent dyes and direct visualization of the leak via transnasal endoscopy. (Note: in many countries the use of intrathecal dyes is not approved and, therefore, special permission from the patient may be necessary.)

Evaluation of lacrimal apparatus

The lacrimal drainage system is intimately related to the NOE region and can be damaged during the trauma. The surgeon should assess the patency/continuity of the nasolacrimal system at the time of surgical treatment.

If there is a discontinuity in the nasolacrimal system repair should be considered at the time of fracture treatment. Click here for a detailed description of repair of the lacrimal system.