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A craniotomy involves temporarily removing a portion of the skull, known as a bone flap, to access the brain for diagnostic or therapeutic procedures such as tumor excision, aneurysm clipping, hematoma evacuation, or treatment of vascular malformations. Depending on the clinical indication, the bone flap may be replaced, discarded, or stored for later reconstruction during cranioplasty. This course reviews modern craniotomy techniques, which have evolved from early trephination practices dating back thousands of years, with significant advancements in surgical precision, infection control, anesthesia, and neuro-navigation. Image-guided systems based on imaging studies now enable surgeons to localize lesions with high accuracy while minimizing healthy tissue disruption and improving patient outcomes. This activity explores craniotomy procedures, including indications, contraindications, operative principles, and perioperative management. Participants will gain an enhanced understanding of modern surgical innovations, patient positioning, wound closure, and postoperative care strategies. This activity for healthcare professionals is designed to enhance the learner's competence in performing a craniotomy, integrating cranial anatomy and physiology into clinical decision-making, determining appropriate candidates for the procedure, and implementing an appropriate interprofessional approach to improve patient safety within neurosurgical practice. Objectives: Identify the indications for craniotomy procedures. Apply modern neuronavigation techniques during craniotomy to minimize disruption of healthy brain tissue. Evaluate perioperative complications to guide timely interventions in patients undergoing craniotomy. Collaborate with interprofessional teams to ensure coordinated, patient-centered neurosurgical care when performing a craniotomy. Access free multiple choice questions on this topic.

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.[1] The most common conditions that can be treated via this approach include brain tumors, aneurysms, arteriovenous malformations, subdural empyemas, subdural hematomas, and intracranial hematomas.[2] Specialized tools and equipment are used to remove the section of bone, known as the bone flap. The bone flap is temporarily removed, placed on the surgical instrument table, and then reapplied back after the brain surgery has been concluded. In some cases, depending on the indication for the procedure, the bone can be discarded, stored in an abdominal subcutaneous space, or cryopreserved under cold storage conditions.[3] If the bone flap is discarded or not replaced 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 several weeks after the brain swelling has resolved (see Image. Decompressive Hemicraniectomy).[4][5] The surgical procedure to reconstruct and replace the bone flap in the skull during a second intervention is known as a cranioplasty.[6] From a historical perspective, cranial interventions have ranged from a single burr hole trephine to a much larger craniectomy. Modern craniotomies are performed by connecting a series of burr holes. Although trephination is the oldest known cranial surgical technique, with ancient reports dating back 2300 years, our modern surgical technique for a craniotomy is the result of a procedure introduced at the end of the 19th century by the self-educated surgeon Wilhelm Wagner.[1][7][8] Although the transition from trephination to a tailored intracranial resection via craniotomy that occurred much later in history, ancient civilizations, eg, the Incas in Peru, likely had some basic familiarity with brain anatomy and surgical interventions, despite their rudimentary knowledge of pathology.[7][9]

From a historical perspective, cranial interventions have ranged from a single burr hole trephine to a much larger craniectomy. Modern craniotomies are performed by connecting a series of burr holes. Although trephination is the oldest known cranial surgical technique, with ancient reports dating back 2300 years, our modern surgical technique for a craniotomy is the result of a procedure introduced at the end of the 19th century by the self-educated surgeon Wilhelm Wagner.[1][7][8] Although the transition from trephination to a tailored intracranial resection via craniotomy that occurred much later in history, ancient civilizations, eg, the Incas in Peru, likely had some basic familiarity with brain anatomy and surgical interventions, despite their rudimentary knowledge of pathology.[7][9] Depending on the type of intracranial lesion, pathology that was present, and surgical approach, some craniotomy procedures can be aided by neuronavigation guidance based on magnetic resonance imaging (MRI) or computed tomographic (CT) scans to customize the procedure to the size of the mass lesion, using the smallest incision that is required. Neuronavigation is a modern, computerized technology that helps surgeons localize pathology more precisely by merging a series of craniofacial points present in the patient located in the surgical field. Neuronavigation offers improved surgical guidance, orientation, and localization that provides the surgeon with greater technical confidence and improved patient outcomes.[10] Historical Background

Depending on the type of intracranial lesion, pathology that was present, and surgical approach, some craniotomy procedures can be aided by neuronavigation guidance based on magnetic resonance imaging (MRI) or computed tomographic (CT) scans to customize the procedure to the size of the mass lesion, using the smallest incision that is required. Neuronavigation is a modern, computerized technology that helps surgeons localize pathology more precisely by merging a series of craniofacial points present in the patient located in the surgical field. Neuronavigation offers improved surgical guidance, orientation, and localization that provides the surgeon with greater technical confidence and improved patient outcomes.[10] Historical Background The craniotomy approach has evolved, dating back to the Neolithic period. Trepanation, meaning “borer”, became synonymous with trephination because of the French instrument tres fines, meaning “3 ends”.[11] Trephination has been performed by prehistoric peoples either for magic or religious rituals to release demons and malignant spirits, or to wear the skull bone as an amulet. During the Neolithic era, therapeutic drilling was performed by pointed or sharp cutting tools made up of silica or obsidian.[12] The principle of bow drilling originated in fire-making and was used by the Egyptians around 1400 BC. A sharp rod made of hard stone or metal was swiveled rapidly between the hands and later by a cord and the string of a bow to make a circle of small holes where the bony bridges between them were connected.[13] The approach to craniotomy is attributed to Imhotep, who is believed to have described it around 2900 BCE.[12] Hippocrates first reported the therapeutic use of craniotomy for the management of fractures in the fifth century BC.[13][14] The instruments were detailed as early as 1518 in “De fractura calvae” by Berengario. Broca also related the archaeological findings of trepanation of the skull.[14] Celso advocated for trephination, a sequential process involving the external cortex, diploic space, and the internal cortex, while safeguarding the meninges.[13] William Detmold first operated on a brain abscess within the lateral ventricle in 1850.[13] Craniotomy evolved in the Renaissance, when firearms and grenades were used, 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. The Gigli saw was used by Obalinski in 1897. At the beginning of the 19th century, the use of craniotomy declined primarily due to the development of infections, and trephining was limited to exceptional cases.[13] Advancements in antisepsis and general anesthesia in the 19th century led to an exponential growth in the use of trephination and craniotomy, even for nontraumatic intracranial lesions.[13][12][14]

Complications of Head Fixation Devices Complications of cranial fixation devices include: Scalp laceration Skull fractures Pin site infections and osteomyelitis (see Image. Osteomyelitis) Venous air embolism Acute epidural, subdural hematoma, and brain contusions Specific Complications to Individual Flaps Flap-specific complications include: Scalp flap necrosis Frontal flaps Cosmetic deformity Cerebrospinal fluid (CSF) leak Injury of the superior sagittal sinus Retraction-induced bilateral frontal lobe injury.[12] Temporal flaps The vein of Labbe injury with subsequent venous infarction[12] Temporal muscle hollowing (preserving the temporalis origin and avoiding dissection between the leaflets of the deep temporal fascia or intermediate fat pad minimizes temporal hollowing risk) [62] Parietal flaps Injury to the vein of the Trolard with subsequent venous infarction Injury to the superior sagittal sinus and overlying cortical veins, sinus or cortical vein bleeding or thrombosis Injury to the motor cortex [12] Pterional flaps The frontal sinus may be violated The frontalis branches of the facial nerve may be injured Osteotomy involving the sphenoid bone may extend into the optic canal.[12] Orbitzygomatic flaps Fractures of the orbital roof and rim can lead to injury of the optic nerve Fractures of the sphenoid and ethmoid sinuses can cause CSF leaks Retrosigmoid flaps Injury to the lesser occipital and greater auricular nerves, causing postoperative headache and dysesthesia Retraction injury to the cerebellum Injury to the transverse, sigmoid, occipital venous sinuses, and torcula Damage to the cranial nerves and brainstem CSF leaks and pseudomeningocele formation The mastoid emissary vein can cause substantial bleeding and can be a source of air embolism Injury to the vertebral artery Bone-dust-induced meningitis [12] Suboccipital: Pooling of the blood within the operative bed limits surgical visibility in prone positioning Pressure on the eyes and face in prone positioning can cause visual impairment or loss The sitting position has the risk of venous air embolism and hemodynamic instability Injury to the transverse, sigmoid, occipital venous sinuses, and torcula CSF leak and pseudomeningocele formation Cerebellar mutism Burr Holes, Craniotomy, and Durotomy Complications Complications of burr holes, craniotomy, and durotomy include:

The sitting position has the risk of venous air embolism and hemodynamic instability Injury to the transverse, sigmoid, occipital venous sinuses, and torcula CSF leak and pseudomeningocele formation Cerebellar mutism Burr Holes, Craniotomy, and Durotomy Complications Complications of burr holes, craniotomy, and durotomy include: Opening into an air sinus is repaired by removing the sinus mucosa, packing the sinus with betadine-shocked gel foam, and covering the repair with bone wax or a vascularized flap Bone bleeding is controlled with bone wax packing Dural venous sinus injury is controlled with hemostatic agent packing or by being sewn closed Dural lacerations are sewn closed Injuries to the cortical draining veins are coagulated until closed The drill perforator plunges into the brain, causing a cerebral contusion that is treated with hemostatic agents.[63] The following factors increase the risk of complications: Prone/lateral prone positioning Emergency procedure Anesthesia fluctuation Increased length of the operation Thin scalp [64] Postprocedure Complications of Craniotomy Complications that may occur following craniotomy include: Postcraniotomy headache [2] Postcraniotomy emergence hypertension [65] Extraxial hematomas Seizures: Levetiracetam is superior to phenytoin for de novo seizures following craniotomy [66] Electrolyte abnormalities: the most common being hyponatremia and hypernatremia Tension pneumocephalus Postoperative infection: The incidence of postoperative meningitis is 2.2%, most commonly caused by gram-negative organisms, with an overall mortality rate of 5%. Intracranial hemorrhage (ICH) Ventilator-associated pneumonia (VAP) diagnosed by bronchoalveolar lavage and endotracheal tube aspiration Cerebral edema Cerebral ischemia Vasospasm Pneumocephalus CSF leak (studies demonstrate that dural sealants do not reduce the number of CSF leaks but minimize the risk of surgical-site infection) [67][68] Hydrocephalus Infection (eg, soft tissue infections, extradural abscess, empyema, and bone flap infection) [69][70] Instrument failure, eg, drill bit breakage [71] Incidental dropping of the craniotomy bone flap on the floor [72] Temporalis muscle atrophy [73] Myositis ossificans [74] Craniectomy itself can induce an inflammatory response, inhibit autophagy, and disrupt the blood-brain barrier.[75] One study has shown that significant variables for surgical site infections include: American Society of Anesthesiologists (ASA) score (>2)

Incidental dropping of the craniotomy bone flap on the floor [72] Temporalis muscle atrophy [73] Myositis ossificans [74] Craniectomy itself can induce an inflammatory response, inhibit autophagy, and disrupt the blood-brain barrier.[75] One study has shown that significant variables for surgical site infections include: American Society of Anesthesiologists (ASA) score (>2) The presence of other infections Duration of the operation >4 hours Sinus entry CSF leak (OR 7.817) CSF drainage Surgical drain placement Number of previous operations Implants present [76][77][78] A meta-analysis has shown that prophylactic antibiotics significantly reduce the risk of meningitis after craniotomy.[79] The reported incidence of significant complications is 8.3%, while minor complications occur in up to 60% of cases. Mortality owing to major complications is reportedly 22% (0.5% in minor complications).[78] Variables associated with significant complications include: Age An abnormal neurological examination after the end of the surgery Intraoperative desaturation [78]

Craniotomy is a surgical procedure that involves temporarily removing a portion of the skull to access the brain for treatment of tumors, vascular lesions, traumatic injuries, infections, or functional disorders. Modern techniques integrate neuronavigation, advanced imaging, and minimally invasive approaches to enhance precision, reduce healthy tissue disruption, and optimize patient outcomes. Perioperative management, including patient positioning, bone flap handling, dural repair, and postoperative care, is critical for safety, recovery, and functional outcomes. Historical evolution from trephination to contemporary craniotomy demonstrates continual advancement in surgical skill, technology, and evidence-based practices, enabling more effective and safer interventions. Effective care requires coordinated skills and responsibilities across the healthcare team. In the preoperative phase, communication among neurosurgeons, emergency physicians, internists, and cardiologists ensures appropriate risk assessment and preparation. Intraoperatively, neurosurgeons, neuroanesthesiologists, and neuromonitoring technicians collaborate closely, ensuring procedural accuracy, patient safety, and timely intervention. Postoperatively, nurses, intensivists, and pharmacists coordinate care, monitor recovery, and manage medications, fostering patient-centered outcomes. Strong interprofessional communication, strategy, and shared responsibility enhance team performance, safety, and overall quality of neurosurgical care.

Team-based practices are necessary for performing a successful craniotomy procedure. Interaction between the neurosurgeon and the anesthesiologist typically occurs even before the patient enters the operating room, through discussion of the case and the desired approach. Discussing the necessary equipment with the operating room head nurse is essential. A discussion of non-anesthetic agents to be administered by the anesthetist takes place before commencing the incision. Once the patient is under general anesthesia, effective communication between the anesthesia team and the neurosurgeon during the procedure minimizes complications and unexpected events. Postoperative care for a patient who has undergone a craniotomy also involves an interprofessional team, including intensive care unit nursing personnel, as well as speech pathologists, physical medicine and rehabilitation physicians, practical nurses, physical therapists, respiratory therapists, and occasionally, personnel from the discharge planning team and social work team.[81]