The Middle Vault: Upper Lateral Cartilage Modifications

Anatomy and Physiology

The middle third of the nose is important both cosmetically and functionally. The middle nasal vault encompasses the region bounded superiorly by the rhinion, inferiorly by the cephalic border of the lower lateral cartilages, and laterally at the piriform aperture. The soft tissue envelope is the thinnest over the dorsum of the middle third of the nose, making cartilaginous irregularities difficult to conceal and presenting a challenge to the surgeon, especially in thin-skinned patients. The mucosa lining the middle third of the nose is thin and tightly adherent to the upper lateral cartilage and cartilaginous septum.

The structural framework of the middle third of the nose consists of the cartilaginous septum and the upper lateral cartilages ( Figure 12-1 ). Superiorly, the upper lateral cartilages fuse with the deep surface of the caudal edge of the nasal bones. Caudally, the upper lateral cartilage curves under and articulates with the lower lateral cartilages in the scroll region, which is considered to be a major tip support mechanism. Medially, the upper lateral cartilages fuse with the cartilaginous dorsum via dense fibrous attachments, while inferiorly the medial edge of the cartilage is often free. It is important to note that the cartilaginous septum widens to a T-like shape dorsally where it articulates with the upper lateral cartilages, forming a single unit that defines the dorsal subunit of the nose. The lateral aspect of the upper lateral cartilage is adherent to fibrous tissue that approaches the piriform aperture and, if present, the sesamoid cartilages. Violation of the support for the upper lateral cartilages can cause cosmetic and functional problems, including nasal obstruction and the inverted-V deformity.

The internal nasal valve is an important functional anatomic unit. It is bounded medially by the septum, superiorly by the caudal edge of the upper lateral cartilages and fibrofatty tissue adjacent to the piriform aperture, and inferiorly by the anterior head of the inferior turbinate and nasal floor. It is the point of maximum narrowing of the airway and resistance to airflow on inspiration. In Caucasians, the ideal angle between the upper lateral cartilage and the septum is 10 to 15 degrees. The valve measures between 55 and 83 mm ² .

Examination

A thorough examination of the middle third of the nose is critical for accurate diagnosis and surgical planning. The examination is straightforward and is best achieved in the office during the initial consultation. After a detailed history has established the patient's goals for surgical intervention, the nose is examined in a systematic fashion. With respect to the middle third of the nose, it is important to notice the character of the soft tissue envelope, the relation of the middle third to the patient's midline and the upper and lower thirds of the nose, the brow-tip aesthetic line, and the radix. The surface of the nose should be examined during quiet and deeper inspiration from a frontal and base view, looking for collapse of the internal or external nasal valves. The strength and integrity of the upper lateral cartilages and the character of the cartilaginous dorsum can be ascertained by palpation. Using a nasal speculum and headlight, all three components of the nasal valve (side wall, septum, and turbinate) should be examined. A cerumen curette can be used to identify precisely the site of nasal collapse. Targeted use of the curette provides more detailed information than the traditional Cottle maneuver. Finally, if there is any question of allergic or other mucosal disease, the nose can be sprayed with a topical vasoconstrictor and the examination repeated to determine whether further evaluation for allergic or other sinonasal pathology is warranted. Endoscopy can also be a useful tool in evaluating the internal nasal valve and in documenting valve collapse.

Problems of the Middle Third

The middle third of the nose must be harmonious with the upper and lower thirds of the nose. The brow-tip aesthetic line should be unbroken, and the width between the brow-tip line should fall between the tip-defining points laterally and philtral columns medially. The most frequent request from cosmetic rhinoplasty patients is to take down a dorsal hump. While it is important to respect the patient's wishes, it is also critical that they are aware of the limitations posed by their anatomy and the consequences of overresection including narrowing of the dorsum and nasal obstruction.

Septorhinoplasty may cause collapse of the upper lateral cartilages or excessive narrowing of the dorsum. Destabilization of the upper lateral cartilages can result in cartilaginous collapse, causing the caudal contour of the nasal bones to become visible (the inverted-V deformity). Overly aggressive resection of the cartilaginous dorsum can cause a saddle nose deformity when the septum is lowered or separated from the nasal bones. A twisted or crooked middle third can result from septal deviation or fracture, trauma, or prior surgery.

Functional problems of the middle vault can be caused by a variety of pathologies. Those patients with inherently short nasal bones, a thin soft tissue envelope, and weak cartilages are particularly susceptible to postoperative problems and therefore require careful planning at the time of surgery to maintain the integrity of this critical anatomic region.

Internal nasal valve obstruction can be static or dynamic. Static valve obstruction can be caused by a deviated dorsal septum, mucosal disease, or any other anatomic variation that blocks the valve. Dynamic valve collapse occurs when the strength of the upper lateral cartilages and soft tissue of the valve are unable to withstand the forces of inspiration ( Figure 12-2 ). Even small changes in the radius of the valve can have an impact on nasal airflow as predicted by Poiseuille's law (proportional to the radius to the fourth power).

Materials for Use in the Middle Third

Grafting material used in the middle third falls into two broad categories: structural and camouflage. The ideal structural material in the middle third is biocompatible, strong enough to provide support, soft enough to achieve a natural feel, and able to be shaped or molded in order to obtain a smooth contour. Septal cartilage is readily available in the primary rhinoplasty patient. In patients undergoing revision rhinoplasty or those patients with insufficient septal cartilage, autologous costal cartilage is useful but is associated with donor site morbidity in a small number of patients. Alternatives include irradiated homologous costal cartilage, calvarial bone, porous polyethylene (Medpor; Porex, Newnan, GA), and autologous conchal cartilage. Camouflage grafting materials include GORE-TEX (Gore, Newark, DE), cartilage, fascia, and a wide variety of injectable fillers.