Craniotomy

A craniotomy is a surgical procedure in which a part of the skull is temporarily removed to expose the brain and perform an intracranial procedure. The most common conditions that can be treated via this approach include brain tumors, aneurysms, arterio-venous malformations, subdural empyemas, subdural hematomas, and intracerebral hematomas. Specialized tools and equipment are used to remove the section of bone, known as the bone flap. The bone flap is temporarily removed, held at the surgical instrument table, and then placed back after the brain surgery has concluded. In some cases, depending on the etiology and indication for the procedure, the bone can be discarded, stored in the abdominal subcutaneous space, or cryopreserved under cold storage conditions. If the bone flap is discarded or not placed back into the skull during the same operation, the procedure is called a craniectomy. In a decompressive craniectomy used for the treatment of malignant brain edema, the bone flap is placed back a few weeks after the brain swelling has improved (see . Decompressive Hemicraniectomy). The surgical procedure to reconstruct and replace the bone flap in the skull during a second intervention is known as cranioplasty. From a historical perspective, cranial interventions ranged from a single burr hole trephine to a larger craniectomy. Modern craniotomies are performed by connecting a series of burr holes. Although trephination is the oldest cranial surgical technique, with ancient reports dating back to 2300 years, our current modern surgical technique for a craniotomy is the final result of the procedure introduced at the end of the 19th century by the self-educated surgeon Wilhelm Wagner. Although the transition from trephination to a tailored resection via craniotomy occurred much later in history, ancient civilizations, eg, the Incas in Peru, likely had some basic familiarity with anatomy and surgical interventions, despite their rudimentary knowledge of pathology. Depending on the type of intracranial lesion, pathology, and surgical approach, some craniotomy procedures can be assisted by neuronavigation guidance based on magnetic resonance imaging (MRI) or computed tomographic (CT) scans to tailor the procedure to the size of the tumor, using the smallest incision possible. Neuronavigation is a modern, computerized technology that helps surgeons localize pathology more precisely by merging a series of craniofacial points in the patient. Neuronavigation offers better guidance, orientation, and localization. It provides the surgeon with greater confidence and improved patient outcomes. The craniotomy approach has evolved, dating back to the Neolithic period. Trepanation, meaning “borer”, became synonymous with trephination because of the French instrument , meaning “3 ends”. Trephination has been found to have been performed by prehistoric people either for magic or religious rituals to release demons and malignant spirits, or to wear them as amulets, as early as 1783. During the Neolithic era, therapeutic drilling was performed by pointed or sharp cutting tools made up of silica or obsidian. The principle of bow drilling was obtained from that of fire-making and was used by the Egyptians around 1400 BC. A sharp rod made of hard stone or metal, which was swiveled rapidly between the hands; later, by a cord and a string of a bow to make a circle of small holes, after which the bony bridges between them were broken down. The approach to craniotomy is attributed to Imhotep, who is believed to have written about it around 2900 BCE. Hippocrates first described the therapeutic use of craniotomy for the management of fractures in the fifth century BC. The instruments were detailed as early as 1518 in “De fractura calvae” by Berengario. Broca had explained the archaeological findings of trepanation of the skull. Celso advocated for trephination, a sequential process involving the external cortex, diploic tissue, and, lastly, the internal cortex, while safeguarding the meninges. William Detmold first operated on an abscess within the lateral ventricle in 1850. Craniotomy evolved in the Renaissance period (firearms and grenades) in the 16th and 17th centuries. The use of angulated manual trephines, equipped with a series of perforating or cutting terminals, was introduced in the 16th century. In 1889, Wagner first performed an osteoplastic bone flap. Gigli's saw was used by Obalinski in 1897. At the beginning of the 19th century, the use of craniotomy declined primarily due to infections, and trephining was limited to exceptional cases. Advancements in antisepsis and general anesthesia in the 19th century led to exponential growth in trephination and craniotomy, even for nontraumatic intracranial lesions.