The Lateral Mesencephalic Vein: Surgical Anatomy and its Role in the Drainage of Tentorial Dural Arteriovenous Fistulae
Background: The lateral mesencephalic vein (LMV) represents an important connection between the infra- and the supratentorial compartments. It joins the basal vein of Rosenthal and the petrosal system. In our experience with diagnosis and treatment of tentorial dural arteriovenous fistulas (DAVFs), we have often noted the involvement of the LMV in the venous drainage of these fistulas.
Methods: We reviewed the clinical and angiographic findings of 26 consecutive patients with tentorial dural AVFs to study the incidence of drainage through the LMV and pattern of venous drainage in the patients. In addition, we reviewed the pertinent literature on the anatomy of the LMV.
Results: The LMV participated to the venous drainage of 31% (8/26) of patients with tentorial DAVFs. The direction of venous drainage through the LMV is more commonly from the infra- to the supra-tentorial compartment. There were no specific clinical symptoms/signs associated with tentorial DAVFs involving the LMV compared with those without LMV involvement. When involved in the drainage of the DAVF, the LMV could be invariably identified on noninvasive imaging studies. We present different clinical/angiographic cases and provide a detailed review of the pertinent clinical anatomy of this important but often neglected intracranial vein.
Conclusion: The LMV is the most important and constant venous anastomosis between the supra- and the infratentorial compartment. Detailed knowledge of the surgical and radiological anatomy and of the most common variations of the LMV has important clinical implications. This important vein (which can be easily recognized on noninvasive imaging) is an important anatomical landmark during surgery of midbrain lesions. It is also often involved in the drainage of dural AVFs of the tentorium and it is critical (due to the connections between the LMV and the petrosal venous system) in understanding some “unexpected” venous complications during surgery for posterior fossa lesions.