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Clinical applications of the mastoid emissary vein
Wei Zhou1, Guangfu Di1, Jun Rong1
1Department of Neurosurgery, The Translational Research Institute for Neurological Disorders of Wannan Medical College, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.
Purpose:
During retrosigmoid craniotomy, the mastoid emissary vein (MEV) can be a source of considerable bleeding during the operation, especially when the larger diameter MEV or sigmoid sinus is torn. In this study, we evaluated the relevant structure of the MEV for their anatomy and applied the data in surgery to summarize their clinical significance.
Methods:
The posterior craniocervical regions of 15 silicon-injected Chinese human cadaver specimens were dissected to expose the MEV and adjacent structures. Fifty-one patients who were scheduled to undergo retrosigmoid craniotomy were selected. All patients underwent preoperative routine CT of the head. The relevant data were collected on cadaveric anatomy and CT. Eventually, all patients underwent retrosigmoid craniotomy and the MEV was observed during the operation.
Results:
In cadaver specimens, the prevalence of the MEV was 90.0%. It originated from the middle and lower parts of the posterior wall of the sigmoid sinus and extended in the posterior direction in the mastoid process, usually having 1-2 external openings (86.7%) and only 1 internal opening. The intraosseous courses of the MEV were classified as straight and curved. The straight type accounted for 57.9%, and the curved type for 42.1%. The mean diameter of the MEV was 1.84 ± 0.85 mm, and the straight length of the MEV inside the mastoid process was 11.93 ± 3.58 mm. In 16.7% and 6.7% of all cadaver specimens, the MEV diameter was greater than 2.5 and 4 mm, respectively. In 51 patients (bilateral), routine head CT scan showed the MEV in 49.0% of the patients, and the MEV diameter was greater than 2.5 and 4 mm, respectively, in 17.6% (18/102) and 3.9% (4/102) of the cases. During surgery (unilateral) in the 51 patients, 48 had the MEV and 3 had no MEV. None of the patients had sigmoid sinus tears or massive bleeding.
Conclusion:
In the process of retrosigmoid craniotomy, detailed anatomical knowledge of the MEV, well-planned CT scan, and meticulous microsurgical techniques are key for successful operation, which can reduce the occurrence of complications.
Insights
Understanding the mastoid emissary vein (MEV) anatomy is crucial for safe retrosigmoid craniotomy. Detailed knowledge and CT scans help surgeons avoid bleeding complications during this procedure.
Area of Science:
- Neurosurgery
- Anatomy
- Radiology
Background:
- The mastoid emissary vein (MEV) can cause significant bleeding during retrosigmoid craniotomy.
- Understanding MEV anatomy is vital for surgical success and complication avoidance.
Purpose of the Study:
- To evaluate the anatomical structures of the MEV.
- To assess the clinical significance of MEV anatomy in retrosigmoid craniotomy.
Main Methods:
- Dissection of 15 Chinese cadaver specimens to expose the MEV and adjacent structures.
- Preoperative CT scans and intraoperative observation of the MEV in 51 patients undergoing retrosigmoid craniotomy.
Main Results:
- MEV prevalence was 90% in cadavers, originating from the sigmoid sinus with 1-2 external openings.
- Mean MEV diameter was 1.84 mm; 16.7% and 6.7% of cadavers had diameters >2.5 mm and >4 mm, respectively.
- CT scans revealed MEV in 49% of patients, with diameters >2.5 mm and >4 mm in 17.6% and 3.9% respectively; no sigmoid sinus tears or massive bleeding occurred during surgery.
Conclusions:
- Detailed anatomical knowledge of the MEV is essential for successful retrosigmoid craniotomy.
- Preoperative CT planning and meticulous microsurgical techniques are key to reducing complications.
- Understanding MEV variations aids in preventing intraoperative bleeding and ensuring patient safety.
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