The common frontal sinusotomy, modified endoscopic Lothrop procedure (MELP), or Draf III procedure, is an adaptation of the technique first described by Dr. Harold Lothrop in 1914. Wolfgang Draf popularized the operation in the 1990s; it has since become an important surgical procedure used in the treatment of a variety of disease processes.

The fundamental concept of the common frontal sinusotomy is that it converts the complex and limited frontal sinus outflow tracts into a simple common cavity by removing the frontal sinus floor and nasofrontal beak.

Maximally opening the frontal sinus minimizes the issues of access inherent to the design of the frontal sinus and has been shown to improve the delivery of topical therapies to the frontal sinus when compared to more limited dissections.

Additionally, the Draf III procedure permits the surgeon to endoscopically access almost the entire frontal sinus, thereby increasing the number of neoplastic lesions involving the frontal sinus or rostral skull base that are amenable to a purely endoscopic resection.

Traditionally, the MELP has been described as an inside-out approach whereby the surgeon first performs frontal sinus dissections and then commences drilling from the frontal recess. This can be challenging if the frontal recess has significant disease burden, neo-osteogenesis, or scarring from prior surgery. The outside-in approach, which is discussed here, avoids this issue altogether as dissection is not related to frontal recess anatomy. As a result, the outside-in approach offers an efficient, safe, and reliable option to the traditional technique.

One of the primary benefits of the common frontal sinusotomy is improved access to the frontal sinus and anterior skull base. This offers advantages in numerous clinical situations; consequently, the common frontal sinusotomy is used alone or in conjunction with other surgical procedures to treat a variety of pathologies.

Inflammatory sinus disease: A mainstay in the management of inflammatory sinus disease is the ability to deliver topical medications—namely, corticosteroids—to the affected sinuses. The common frontal sinusotomy maximally exteriorizes the frontal sinus and allows for a more effective delivery of topical therapies. As our understanding of the pathophysiology of chronic rhinosinusitis (CRS) has evolved, we have become more assertive in our treatment algorithm and use the common frontal sinusotomy as a primary surgical intervention and as a salvage procedure. The common frontal sinusotomy procedure should be considered in the following scenarios:

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  Primary surgery for patients with eosinophilic CRS, the Samter triad, aspirin-exacerbated airway disease, and extensive nasal polyposis, especially in patients with concurrent lower airway inflammatory disease

  
  
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  Patients with recalcitrant frontal sinus disease who have failed prior endoscopic sinus surgery or those who have developed iatrogenic frontal sinus disease

  
  
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  Salvage for failed osteoplastic flap with sinus obliteration

Sinonasal and skull base neoplasms: Many frontal sinus neoplasms can be surgically accessed through the Draf III cavity. The lateral orbital roof is an exception, but the common frontal sinusotomy can be expanded with an orbital transposition to access more laterally based lesions. Additionally, the common frontal sinusotomy is an important surgical adjunct during resections of anterior skull base neoplasms because it improves exposure and the angle of surgical access. The common frontal sinusotomy is beneficial for the treatment of neoplastic processes for the following reasons:

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  Enhanced surgical access for tumors involving the frontal sinus, anterior ethmoids, and rostral skull base

  
  
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  Improved postoperative surveillance

  
  
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  Simplified posttreatment care after surgery and radiotherapy

The common frontal sinusotomy can also be used in selected cases for surgical access in the management of cerebrospinal fluid (CSF) leaks, encephaloceles, mucoceles, and postcraniofacial trauma.

A general contraindication for the common frontal sinusotomy is in the setting of very active inflammatory airway disease that requires systemic steroids. These patients are unlikely to improve with the addition of topical therapy and often heal poorly if there is suboptimal control of their underlying inflammatory condition. As such, wait until the inflammatory airway state has reached a stage at which topical therapies are likely to be the primary modality for disease control before performing a common frontal sinusotomy.

An extremely narrow anterior-posterior dimension of the frontal recess is often stated as a contraindication, but the outside-in approach negates this issue and the only instances in which anatomy precludes the common frontal sinusotomy is if the posterior table is less than 5 mm to the skin anterior to the nasofrontal beak. This is only rarely seen in instances of prior trauma or craniofacial abnormalities.