Retrospective Analysis of the Differences in the Anatomy of the Nasotracheal Intubation Pathway With Computerized Tomography of Patients With Indication of Maxillary Advancement

A combination of many factors affecting growth and development creates dento-facial deformities. One of these deformities may be defined as maxillary retrusion defined as inadequate maxillary development . The maxilla's sagittal skeletal deficiencies cause functional problems such as respiratory and nutritional difficulties in addition to aesthetic problems and often require surgical treatment.

These surgeries are done under general anesthesia. Nasotracheal intubation is used during these surgeries to provide general anesthesia. During nasotracheal intubation, there are two different pathways (upper and lower) in which the tracheal tube can advance through the nostrils.

The lower tract extends along the nasal floor and lies beneath the lower concha. Concha nasalis inferior is a thin and independent viscerocranium bone and articulates with the face of the maxillary and palatine bone facing the nasal cavity of the vertical lamina. The free lower edge of the concha nasalis inferior is oriented downwards towards the nasal cavity, restricting the meatus inferior. The inferior of the meatus is the largest and extends along the length of the outer wall of the nasal cavity. The area where the part between the first ⅓ and the middle ⅓ meets is the widest area of meatus nasi medius and there is the openness of the nasolacrimal channel. In the lower opening of the nasolacrimal duct, there may be an indeterminate mucosa layer formed by the mucous membrane of the nasal cavity, which is called Hasner cap.

The upper pathway is located just below the middle concha over the lower concha. Concha nasal is medius is a segment extending medially from the ethmoid bone and may sometimes contain one or more of the ethmoid air cells. Concha nasalis medius extends to the posterior and articulates with a vertical laminate of palatine bone. Below Concha nasalis medius is called meatus nasi medius and narrows from front to back. The widest area of the beginning of meatus nasi medius, just above the vestibulum, is called the atrium meatus medii. There are many paranasal sinuses in Meatus nasi medius; frontal sinus, anterior and middle group ethmoid sinuses and maxillary sinus opens here. At the extreme end of the Meatus nasi medius, there are foramen sphenopalatinum, which vessels and nerves related to the nasal cavity enter this gap.

The lower pathway is referred to as a safer road than the upper pathway, since it is located remote from the middle concha and from the cribriform layer. The trauma to the middle concha may cause avulsions and large bleedings. Trauma to the cribriform plate may also cause cerebrospinal fluid rhinoresin or olfactory nerve damage. These conditions will be especially important in anatomic variations, such as in middle concha hypertrophy and concha bullosa.