[Conservative and reconstructive surgery of the superior longitudinal sinus].

Neurosurgeons are confronted with the superior longitudinal sinus (SLS) in three circumstances: following injuries; compression or invasion of the sinus by tumors, particularly parasagittal meningiomas; and other less common occasions such as measuring pressure in the SLS or in the presence of a ventriculosinusal shunt or phlebitis of the SLS. Anatomical and physiological features of the sinus can be summarized as follows. The emissary veins open directory into the sinus at different angles according to whether they are anteriorly, medially, or posteriorly located. Their orifices are protected by willis cords, provoking laminar flow in the sinus. Pacchionian bodies are found mainly in the parasinusal blood lakes. To ensure an effective cerebral blood flow, pressure in the sinus must be less than that of the cerebrospinal fluid which itself must be at a lower pressure than that in the cortical veins. The anatomical structure of the sinuses in the rigid dural folds explains why they are compressed little or not at all by increased intracranial pressure. Surgery on the sinus should therefore include conservation or re-establishment of its two fold structure; internal venous, perfectly visible under the operating microscope, and external dura mater structure. Based on these anatomophysiological considerations, experimental sinus surgery was performed in the dog: either replacement of one or two sinus walls by a venous autograft doubled with dura mater. These techniques have been employed in humans mainly for parasagittal meningiomas, but they can be used for sinus injuries. A provisional shunt is necessary only when there is cerebral edema with venous turgescence, particularly posterior to the rolandic veins. Suturing of wounds, or their repair by means of a vein graft is employed whether they are associated or not with hematomas. Sinus invasion of meningiomas is diagnosed from the venous time of bilateral carotid angiography employing the subtraction process.