By Spencer Cochran, MD

Overview of Nasal Function:
The nose performs seven key functions of the upper airway: respiration, olfaction, humidification, temperature modification, particle filtration, phonation, and possibly as a secondary sex organ [1].  Any of these nasal functions can be altered or impaired by sinonasal disease processes.  Nasal obstruction can result from functional or structural abnormalities of the nose.

Allergic Rhinitis
Allergic rhinitis has been estimated to affect 40 million Americans, with health-care related expenditures in the billions.  Allergic rhinitis is a Type I allergic reaction in which allergen-specific immunoglobulin E (IgE) bound to nasal mast cells interact with an inhalant allergen to produce the symptoms of allergic rhinitis: sneezing, pruritis, congestion, rhinorrhea, and nasal discharge. While allergic rhinitis is still only partially understood, key elements of its pathophysiology have been elucidated. Initially, an individual who is susceptible to the development of allergic disease encounters a potential allergen.  Sensitization refers to the process in which the immune system is triggered to recognize an allergen, ultimately leading to the development of T-lymphocytes, B-lymphocytes, and allergen-specific IgE.  Upon subsequent exposures, the same allergen can simultaneously bind to two adjacent allergen-specific IgE molecules on the surface of the mast cell, triggering degranulation of the cell and release of histamine and other inflammatory mediators.  This reaction is referred to as the early phase response and leads to the immediate onset of symptoms such as sneezing, rhinorrhea, and congestion.  This process, in turn, leads to further recruitment ofneutrophils, lymphocytes, and eosinophils.  Once at the site of the initial degranulation of the mast cell, these inflammatory cells give rise to a self-sustaining inflammatory reaction known as the late phase response, which is less severe but more prolonged than that of the early phase response.
Treatment of allergic rhinitis begins with avoidance, which precludes the formation of antigen-specific IgE and eliminates the initiation point of the allergic cascade.  In reality, avoidance is difficult to achieve, and patients must rely on medical management to treat their allergy symptoms.  Medical management involves both target therapy and immunomodulation.  Targeted forms of therapy (antihistamines, decongestants, mucolytics, anticholinergics, anti-leukotrienes, and mast cell stabilizers) address the mediator effects of allergy, where as immunomodulation (topical or systemic steroids, immunotherapy, and potentially monoclonal antibodies) prevents initiation and down-regulates the allergic response. . 
Allergy may present as a single rhinologic disease, or it may coexist or contribute to other rhinologic disease processes.  For example, allergy produces mucosal edema, which may lead to sinusitis via ostial obstruction and set the stage for secondary bacterial infection.

Nasal Polyposis 
Nasal polyposis is the end result of intranasal inflammation and may present as an isolated phenomenon, idiopathic nasal polyposis, or as a component of other rhinologic diseases such as allergic fungal sinusitis.  Samter's triad refers to nasal polyposis in addition to asthma and aspirin allergy or sensitivity.  Inflammatory nasal polyposis is usually a bilateral disease, and when unilateral may signify a neoplastic process.
Treatment of nasal polyposis entails administration of anti-leukotrienes, topical steroids, systemic corticosteroids, and often debulking in the setting of functional endoscopic sinus surgery. Although steroid nasal sprays are effective in the treatment of small nasal polyps and the prevention of polyp regrowth after nasal and sinus surgery, large polyp masses that essentially block the nasal passage will not generally yield to topical therapy.
 
Rhinitis Medicamentosa
Rhinitis medicamentosa refers to rebound rhinitis and congestion of the nasal mucosa resulting from the sudden cessation of topical decongestants after prolonged use. Treatment is supportive and entails absolute abstinence from further topical decongestants.  Topical steroid sprays and even systemic steroids may be beneficial to attenuate the mucosal hyperemia and edema.

Anatomy
 The nose is comprised of a soft tissue envelope and an osseocartilaginous framework.  The soft tissue envelope is made up of the skin, SMAS, and fibrofatty tissue of the ala.  The osseocartilaginous vault provides the nose with its shape and structural support and is made up of the paired nasal bones, upper lateral cartilages, lower lateral cartilages, and the septum.
 The structures making up the nasal septum include the quadrangular cartilage, vomer, and perpendicular plate of the ethmoid.  The maxillary crest runs centrally along the floor to the nasal spine, which projects anteriorly from the premaxilla.  Septal deviation can occur in a variety of configurations including, concave (cephalad-caudad or anterior-posterior), dorsal deviation, S-shaped (cephalad-caudad or anterior posterior) or inferior spurs (boney or cartilaginous). 
Septal perforations most frequently are caused iatrogenically during septoplasty or can arise secondary to intranasal cocaine or topical decongestant abuse.  Systemic diseases (e.g. Wegener's Granulomatosis and Sarcoidosis) may have septal perforations a part of their myriad of symptoms.
Because airflow through the nasal passages is laminar, either of these septal abnormalities can impede airflow during inspiration and cause symptoms of nasal obstruction.
The turbinates, nasolacrimal system, and the nasal valves are components of the lateral nasal wall. Of particular importance in regards to nasal airflow are two discrete areas referred to as the nasal valves.  The external nasal valve represents the soft tissue surrounding the nostril opening and is defined by the membranous septum, soft tissue ala, and nasal sill.
The internal nasal valve represents an area bound by the caudal edge of the upper lateral cartilage, the septum, and the head of the inferior turbinate.  The normal angle of the internal nasal valve is greater than 15 degrees and the internal nasal valve accounts for one-half of nasal resistance.  Both of these areas are prone to collapse and can result in symptoms of nasal obstruction.  Additionally, nasal valve incompetency negatively affects quality of life, sleep apnea symptoms, and nasal aesthetics.

NASAL ANALYSIS
  Nasal analysis begins with a thorough intranasal exam.  The character and quality of the nasal mucosa should be noted.  Turbinate size, septal deviation, or the presence of intranasal masses or polyps are important findings.  The exterior nasal form should be analyzed in a systematic fashion. Key elements include: symmetry, shape, tip definition, tip projection, and tip rotation.
 Symmetry
 The various areas of the nose (boney base, mid-vault, and tip) should be examined for any asymmetries.  The dorsum may be deviated due to displaced nasal bones from congenital or post-traumatic causes.  The midvault may appear deviated or asymmetric due to abnormalities of the upper lateral cartilages and manifest as asymmetric dorsal lines, which represent an imaginary curve from the medial head of the brow to the tip defining points.  Tip asymmetries can result from irregularities of the lower lateral cartilages or from asymmetric domes.  The nasal base should be examined for nostril size or shape discrepancies.

Shape
 The overall nasal shape is the second key aspect of nasal analysis. The radix position should lie at the level of the supratarsal crease.  The length of the nose is defined as the length between the radix and tip defining points.  The dorsum may be straight, convex or concave.  On frontal view, the width of the boney base and midvault should be assessed
 Analysis of the nasal tip should reveal several important features.  The overall lobule shape is best appreciated on frontal view.  A supratip break is a slight depression immediately cephalad to the domes and should be more pronounced in women.   The nasolabial angle is formed by the junction of the upper lip with the columella.  The columellar-lobular angle is located the junction of the columella and the infratip lobule and is commonly referred to as the "double-break".   The alar-columelar relationship refers to the amount of "columellar show" and nostril height on profile view.
 On basal view, the width of the soft tissue ala should be noted.  The nostrils should comprise two-thirds of the length of the base and should be angulated approximately 50-60% from the midline. The width of the nose at the base should equal the intercanthal distance.  The presence of any alar collapse should be evaluated at rest and with quiet respiration.

Tip Projection
 Tip projection refers to the distance that the nose protrudes from the face.  Several methods of assessing tip projection have been described over the years.  The Goode method utilizes a line drawn from the alar-facial groove to the tip defining points and should measure .55 to .60 of the distance from the nasion to the tip.  Simons method relates the tip projection to the length of the upper lip.  Byrd defined the desired tip projection as measuring 2/3 of the nasal length.

 Rotation
 Tip rotation refers to the inclination of the columella and nasal tip and is defined by the nasolabial angle, which is the angle formed by the junction of the columella with the upper lip.  For women, tip rotation should be between 95 and 110 degrees.  For men, less rotation is desired and should be closer to 90 degrees.  
 
Tip Deformities
 There are several common anatomic variants and abnormalities that can give the nasal tip a distinct shape.  Recognizing these key tip deformities are important because correction of the different types of tip deformities uses varied techniques.

 Boxy Tip
  The boxy tip has a broad rectangular or trapezoidal appearance that is often best appreciated on basal view.  This type of tip deformity is often caused by a wide angle (>30 degrees) of divergence of the tip defining points and a wide domal arc (> 4mm).  These patients often have structurally strong lower cartilages and thin skin.  This combination of attributes contributes to the pronounced appearance.

 Bulbous Tip
 Like the boxy tip, the bulbous tip is broad and is often caused by a wide angle of divergence.  However, patients with this type of tip deformity often have thick skin and weaker lower lateral cartilages.  As a result, the bulbous tip is more rounded and has ill-defined tip defining points compared to the boxy tip.

 Parenthesis Tip
 The parenthesis tip is characterized by the appearance of "( )" on frontal view.  Typically, these patients have a flat, broad tip.  Alar retraction is frequently associated with this tip deformity.  The parenthesis tip results from cephalically-oriented lower lateral cartilages (also termed alar cartilage malposition) in which the long axis of the lateral crura are rotated cephalically > 45 degrees relative to the alar rim.  Patients with alar cartilage malposition are prone to external valve collapse, which is often exacerbated when not corrected during rhinoplasty.

 Pinched Tip
  The pinched nasal tip is manifested by depression or collapse of the lateral crura proximal to the tip.  It is frequently seen in patients who have undergone rhinoplasty in which the lateral crura were over-resected.
 
 Plunging Tip
 The plunging tip, also known as the "ptotic tip" is characterized by elongated lateral crura and a nasolabial angle < 90 degrees.  It is often seen in older patients who have a loss of tip support.

 Bifid Tip
 The bifid tip has prominent tip defining points and a visible depression between the intermediate crura due in part to a wide angle of divergence.  Thin skin exacerbates the appearance of this tip deformity.

 Amorphous Tip
 The amorphous tip demonstrates no recognizable anatomy and lack of tip defining points.  Patients typically have thick skin which obscures the cartilaginous framework.

DORSAL DEFORMITIES
 C-Shaped Dorsal Deviation
 This dorsal deviation can be a result of boney or cartilaginous displacement to one side causing a lateral concavity and asymmetric dorsal aesthetic lines.  The C-shaped dorsal deviation is often the result of prior trauma.  Not only does the external nose appear deviated, but there is often multiple areas of septal deviation.  Dorsally, the septum deviates to the side of the nasal root, and caudally, the septum typically deviates to the opposite side.  Thus, there are multiple areas of deviation that give rise to symptoms of nasal obstruction.

 S-Shaped Dorsal Deviation
 This dorsal deformity is often the result of multiple or severe nasal trauma, giving the nose a twisted or "S-shaped" appearance.  Usually significant septal deformities are seen.

 Saddle Deformity
 The saddle nose deformity describes the appearance of a depressed mid-vault that results from loss of dorsal support secondary to trauma or over aggressive resection of the dorsal septum.  "L-strut" fractures can cause the dorsal segment of the septum to rotate posteriorly with a concomitant loss of dorsal support.  Other causes of loss of support include cartilage necrosis secondary to cocaine abuse, septal hematoma, or septal abscess.

 Dorsal Hump
 The dorsal hump is usually caused by both a boney and cartilaginous prominence, giving the dorsum a convex shape.  Patients typically have a narrow appearance on frontal view with narrowed internal nasal valves.  As result, these patients often have symptoms of nasal obstruction.

 Pollybeak Deformity
 The pollybeak, or supratip deformity, occurs with the lower dorsal septum projects beyond the nasal tip.  This can arise as a primary nasal deformity.  However, it is most frequently seen secondary to excessive dorsal hump resection with inadequate tip support and projection, or paradoxically from soft tissue ingrowth in the supratip area.

 Inverted "V" Deformity
 This dorsal deformity describes the appearance of an inverted "V" appearance of the nasal bone edges and interrupted dorsal aesthetic lines along the mid-vault.  It can occur when the upper lateral cartilages are not adequately reattached to the dorsal septum during rhinoplasty or from trauma causing the upper lateral cartilages to separate from the nasal bone edges.  Functionally, this deformity manifests as internal valve collapse with resultant nasal obstruction.

 "Tension Nose" Deformity
 The tension nose deformity results from an over-projecting septum.  Patients may have a prominent dorsal or exhibit caudal septum excess.  The nasal spine is often prominent.  These factors give the impression of a  hanging columella, blunted subnasale, and short upper lip.

CONCLUSION
 Essential elements of nasal analysis include a thorough medical history and physical exam.  Adequate patient photographs are requisite and should include frontal, oblique, profile, and basal views. Finally, analysis of the various components of the nose should proceed via a systematic approach.