Hadad Flap (Hadad-Bassagasteguy Flap / Nasoseptal Flap)

Definition

Composition

• Composed of nasal septal mucosa with underlying mucoperiosteum and mucoperichondrium
• Tissue layers: respiratory epithelium + lamina propria + periosteum/perichondrium

Vascular Supply

• Pedicle: Posterior septal artery - a branch of the sphenopalatine artery (itself a branch of the internal maxillary artery)
• The pedicle enters at the level of the sphenopalatine foramen, running just below the sphenoid ostium
• This robust axial blood supply makes it reliable for covering large defects

Indications

• Reconstruction of medium to large skull base defects following EEA
• Defects involving the anterior and middle cranial fossa
• High-flow intraoperative CSF leaks
• Cases with planned post-operative radiation (vascularized tissue resists radiation damage better than free grafts)
• Defects at: sella, planum sphenoidale, cribriform plate, clivus

Harvesting Procedure (Steps)

1. Flap is harvested at the start of the operation and tucked into the nasopharynx while the main resection proceeds
2. Superior incision: along the superior nasal septum at the level of the skull base (near the olfactory strip - this is preserved)
3. Inferior incision: along the floor of the nasal cavity
4. Anterior incision: vertical cut on the septum anteriorly to connect superior and inferior incisions
5. Posterior incision: carried to the sphenoid rostrum, protecting the pedicle at the sphenopalatine foramen
6. Flap elevated in a posterior-to-anterior direction using a Cottle elevator
7. After tumor resection and dural repair, the flap is repositioned over the defect and secured with fibrin glue

Clinical Significance

• Prior to its introduction (pre-2006), EEA was associated with CSF leak rates of 20-30%
• After adoption of the H-B flap, rates dropped to less than 5%
• This dramatic reduction in CSF leaks also led to a corresponding drop in postoperative meningitis
• The NSF is now the workhorse flap for endoscopic skull base reconstruction
• Cummings Otolaryngology states: "Its success drastically changed the approach to endoscopic dural reconstruction"

Limitations

• Size of the flap limits coverage of very large defects (>3 cm may need reinforcement with septal cartilage or titanium mesh)
• Cannot be used if prior nasal septectomy or wide sphenoidectomy has damaged the posterior septal artery
• Limited coverage of far-anterior cranial fossa defects
• Leaves a donor site on the nasal septum (heals by secondary intention - crusting, temporary obstruction)
• If a previous NSF was placed, a "nasoseptal flap takedown" technique can reuse it in revision surgery, though the flap is less pliable and may retain the shape of the prior defect

Alternatives When NSF Is Unavailable