The Keros classification is a system used to categorize the depth of the olfactory fossa within the ethmoid bone. This classification is important for surgical planning, particularly in endoscopic sinus and skull base surgery, as a deeper olfactory fossa increases the risk of complications such as cerebrospinal fluid (CSF) leak.
Details of the Keros Classification
The Keros classification divides the depth of the olfactory fossa (also known as the lateral lamella) into three types:
- Type I: Shallowest, with a depth of 1-3 mm.
- Type II: Intermediate depth, with a depth of 4-7 mm.
- Type III: Deepest, with a depth of 8-16 mm. This type poses the highest risk during surgery.
Significance in Surgical Planning
Understanding the Keros classification is crucial for surgeons because:
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A deeper olfactory fossa (Keros Type III) means that the cribriform plate (the bone separating the nasal cavity from the brain) is longer and more exposed within the nasal cavity. This makes it more susceptible to damage during endoscopic procedures.
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Surgeons can use preoperative imaging, like CT scans, to determine the Keros type and plan their surgical approach accordingly, minimizing the risk of complications such as CSF leak, meningoencephalocele (a sac of brain tissue protruding through a defect in the skull), or injury to the olfactory nerve fibers (potentially causing anosmia, or loss of smell).
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Knowledge of the Keros classification helps the surgeon to anticipate potential challenges and select appropriate surgical techniques and instruments.
In summary, the Keros classification provides a standardized way to assess the depth of the olfactory fossa, which is an important anatomical consideration in endoscopic sinus and skull base surgery for preventing iatrogenic injuries.
