Deviated nasal septum (DNS)

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Clinical Pathology: Deviated Nasal Septum (DNS)

High-Yield Revision Notes for NEET PG / NEXT

A Deviated Nasal Septum (DNS) is a physical shift of the osteofibrocartilaginous partition away from the midline. While minor deviations are common and asymptomatic in up to 80% of the population, severe deviations impair nasal airflow, alter sinus ventilation, and can induce secondary mucosal changes.

1. Etiology & Structural Variants

The development of DNS typically traces back to three fundamental mechanisms:

  • Trauma: Direct impact (lateral or frontal blows) shifts the cartilage out of its bony grooves. In children, micro-fractures during birth or play can manifest as severe deviation later during pubertal growth spurts.
  • Developmental Error: An evolutionary mismatch between the growth of the bony palate and the skull base. If the vertical space for the septum is compressed, the quadrilateral cartilage must buckle to fit the space. This is classically seen in patients with a **high-arched palate** (e.g., adenoid facies or mouth-breathers).
  • Genetic Factors: Familial tendencies running parallel with specific craniofacial structural traits.

Morphological Patterns:

  • C-shaped Deviation: A simple, uniform bowing to one side, causing unilateral narrowing.
  • S-shaped Deviation: A bidirectional curvature that typically causes bilateral nasal airway obstruction.
  • Septal Spur: A sharp, shelf-like bony projection or ridge usually located at the junction of the vomer and the quadrilateral cartilage.
  • Caudal Dislocation: The anterior-inferior edge of the septal cartilage slips completely out of the maxillary midline groove, projecting directly into one of the nasal vestibules.

2. Clinical Features & Associated Signs

Symptoms vary based on the location and severity of the deviation:

  • Nasal Obstruction: The primary presenting complaint. It is typically worse on the side of the deviation, though it can become bilateral due to secondary mucosal adaptations.
  • Compensatory Hypertrophy: Long-standing DNS leaves a large airway gap in the opposite, patent nostril. To prevent excessive drying and to maintain optimal air humidification, the contralateral inferior turbinate undergoes marked bony and mucosal hypertrophy.
  • Sluder’s Neuralgia (Contact Point Headaches): A sharp septal spur can press directly into the mucosa of the lateral nasal wall. This mechanical compression irritates the branches of the anterior ethmoidal or sphenopalatine nerves, triggering referred facial pain or chronic headaches.
  • Epistaxis: Airflow becomes highly turbulent as it passes over the sharpest point of the deviation. This localized drying crusts the overlying mucosa, leading to erosions and bleeding from the capillaries of Kiesselbach’s plexus.
  • Sinusitis: A high deviation can impinge upon the middle turbinate, blocking the infundibulum or osteomeatal complex and impairing the drainage of the anterior ethmoid, maxillary, and frontal sinuses.

3. Surgical Management Matrix

Asymptomatic DNS requires no intervention. Symptomatic cases are managed surgically via two distinct procedural archetypes:

Feature Submucous Resection (SMR) Septoplasty (Conservative Approach)
Age Criteria Strictly performed only after 17–18 years of age (after mid-facial skeletal maturity). Can be safely performed at younger ages if severe obstruction impairs development.
Surgical Concept Radical procedure. Elevates mucosal flaps and **removes a massive central piece** of the cartilaginous and bony septum, leaving only a structural perimeter. Conservative procedure. Focuses on remodeling, scoring, and repositioning the cartilage while **retaining as much structural matrix as possible**.
Incision Used Killian’s Incision
(Made 5mm superior-posterior to the caudal border of the cartilage).		 Freer’s / Freer-He先进 (Caudal) Incision
(Made directly at the caudal reflex margin).
Flap Elevation Bilateral mucoperichondrial flaps are fully elevated. Unilateral flap elevation is preferred; tissues on the opposite side remain attached to preserve the blood supply.

4. Post-Surgical Complications

  • Septal Hematoma / Abscess: Occurs when blood accumulates in the dead space between the elevated flaps. This cuts off nutrition to the remaining cartilage, predisposing the patient to rapid ischemic necrosis.
  • Septal Perforation: Occurs if matching tears are inadvertently made in both the left and right mucoperichondrial flaps during the operation.
  • Saddle Nose Deformity: A classic hazard of over-aggressive SMR. If the surgeon fails to preserve a 1.5 cm strip of cartilage along both the dorsal and caudal borders (the **strut or structural frame**), the nasal bridge will collapse.
  • Retraction of the Columella: Loss of adequate caudal cartilaginous support allows the columella to pull backward and upward, altering the nasolabial profile.