Trepanation

TREPANATION (from Greek trepao—I bore, I drill), an operation of drilling a hole in one or another membrane of the human body (e.g., trepanation of the cornea, trepanation of bone in osteomyelitis, trepanation of the mastoid process, trepanation of the skull). It is used mainly for opening the cranial cavity for the purpose of stopping bleeding from damaged vessels (a. meningea media) or performing one or another intervention on the brain. Trepanation of the skull is one of the oldest operations, which, judging by findings from excavations, was used as early as prehistoric times. Prunières and Broca in 1873 particularly enriched the history of this operation with the discovery of a number of trepanned skulls, proving through research that the operated subjects continued to live after the operation. Hippocrates perfectly mastered the technique of trepanation and described it. He used a number of very ingeniously constructed instruments for it. However, the founders of modern methods of trepanation and operations on the skull and brain in general should be considered the German surgeons Bergmann, Krause, and the American Cushing. Trepanation can for the most part be performed completely painlessly under local anesthesia. Many surgeons perform trepanation with the patient in a sitting position (see Operating tables) to avoid the leakage of cerebrospinal fluid. Skin incisions for trepanation are recommended to be made in a direction that spares large vessels (e.g., a. temporalis), although usually it is still not possible to avoid bleeding in this case due to the great richness of vascular anastomoses. To combat bleeding from the outer integuments during trepanation, a number of measures have been proposed (tourniquets, bandages compressing the vessels leading to the upper integuments of the skull, special clamps compressing the edges of the incision, etc.), of which the method of suturing around the wound has gained the greatest prevalence. The opening of the bone itself is performed by drilling with various boring, drilling instruments (burs, cutters, trephines), set in motion by hand (manual trephines) or with the help of electric motors (Borchardt's device, de Martel's, etc.). However, the osteoplastic trepanation proposed in 1889 by Wagner, in which the cranial cavity is opened temporarily, and upon completion of the operation the hole in the skull is again closed with a bone flap (see Cerebellum, surgery), has gained the greatest prevalence. To enlarge the hole in the bone, various instruments that bite off bone are used (Borchardt's, Dahlgren's rongeurs, etc.). When opening the skull, significant bleeding from the veins of the diploë usually occurs, which must be stopped by compressing the bone with special forceps, or by plugging the bone with wax, pieces of bone, or muscle. The opening of the cranial cavity itself (especially during operations on the posterior cranial fossa) is sometimes accompanied by a sharp, sudden drop in blood pressure, forcing the interruption of the operation (two-stage trepanation) (see Cerebellum, surgery).