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Craniotomy


Craniotomy

Article Author:
Ricardo Fernández-de Thomas
Article Editor:
Orlando De Jesus
Updated:
7/11/2020 7:43:45 AM
For CME on this topic:
Craniotomy CME
PubMed Link:
Craniotomy

Introduction

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, arterio-venous malformations, subdural empyemas, subdural hematomas, and intracerebral hematomas.[2] Specialized tools and equipment are utilized to remove the section of bone, which is called 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.[3] 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.[4][5] The surgical procedure to reconstruct and place the bone flap back into the skull during a second intervention is known as cranioplasty.[6]

From a historical context and perspective, cranial interventions varied 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 cured result of the procedure introduced at the end of the 19th century by the self-educated surgeon Wilhelm Wagner.[1][7][8] Although it was much later in the course of history that the transition from trephination to a tailored resection via craniotomy happened, ancient civilizations, such as the Incas in Peru, must have had some basic familiarity with anatomy and surgical interventions despite their rudimentary knowledge of pathology.[7][9]

Depending on the type of intracranial lesion, pathology, and the surgical approach, some craniotomy procedures can be assisted by neuronavigation guidance based on magnetic resonance imaging or computed tomographic scans to tailor the procedure to the size of the tumor using the smallest incision possible. Neuronavigation is a modern computerized technology that can help surgeons localize the pathology more precisely by merging a series of craniofacial points in the patient. Neuronavigation offers better guidance, orientation, and localization. It provides a higher level of confidence for the surgeon and an improved outcome for the patient.[10]

Anatomy and Physiology

There are many types of craniotomies described in the literature, and a basic understanding of anatomy and physiology is necessary to perform an adequate craniotomy with fewer complications. The type of craniotomy is named depending on the skull bone, which is opened. Typical skull bones targeted for craniotomy include the frontal, parietal, temporal, and occipital bones. Depending on the location of the pathology to be addressed, supratentorial or infratentorial (posterior fossa) craniotomies can be utilized. 

One of the most traditional craniotomies utilized is the pterional craniotomy, a supratentorial craniotomy which can be utilized for aneurysms of the anterior circulation, basilar tip artery aneurysms, direct surgical approaches to the cavernous sinus, frontal and temporal lobe tumors, as well as suprasellar tumors such as pituitary adenomas and craniopharyngiomas.[11][12][13][14] Another type of supratentorial craniotomy is the temporal or subtemporal craniotomy, which can be utilized for temporal lobe biopsy, temporal lobectomy, temporal epilepsy surgery, temporal lobe tumors, as well as access to the floor of the middle cranial fossa.[15][16] 

The frontal craniotomy is used to access the frontal skull base and the frontal lobe of the brain for approaches to the third ventricle or sellar region tumors, craniopharyngiomas, planum sphenoidale meningiomas, frontal lobe tumors, and repair of anterior cerebrospinal fluid fistulas. Other types of craniotomies include parietal, occipital, retrosigmoid, among many others.[17]

Indications

Several conditions require opening the skull for diagnosis and management. The most common conditions for which a craniotomy is used include:

  • Brain aneurysm[18]
  • Vascular malformations (arterio-venous malformation, cavernous angioma, arterio-venous fistula)
  • Brain tumors (meningioma, high-grade and low-grade glioma, epidermoid, ependymoma, oligodendroglioma, metastases)
  • Orbital tumors
  • Pituitary adenomas
  • Cerebellopontine angle tumors[19]
  • Pain treatment (microvascular decompression)[20][21]
  • Brain abscess
  • Subdural empyema
  • Hematomas (intracerebral, epidural, subdural)
  • Decompressive[22][23]
  • Lobectomy[24]
  • Epilepsy surgery[25][26]
  • Craniosynostosis[27][28][29]
  • Depressed skull fractures
  • Intracranial foreign bodies 
  • Cerebrospinal fluid leak repair[30]

Contraindications

There are very few contraindications to performing a craniotomy, and most are related to the patient's general condition:

  • Advanced age [31]
  • Poor functional status
  • Severe cardiopulmonary disease
  • Severe systemic collapse (sepsis, multiorgan failure)
  • Pathologies that can be addressed by a single burr hole
  • Altered preoperative coagulation parameters
  • Bleeding disorders

Equipment

A craniotomy is a surgical procedure that requires specific equipment. The following are the requirements for being able to perform a craniotomy:

  • High-speed pneumatic cranial drill (craniotome)
  • Hudson brace handheld manual drill
  • Freer elevator
  • Penfield dissector
  • Cranial plate fixation tray
  • Artificial dura (dural substitute)
  • Head-holder system if necessary, depending on the pathology to be addressed

Personnel

An interprofessional team is required in successfully carrying out a craniotomy. Following are the personnel whose input is mandatory:

  • Neurosurgeon
  • Operating room head nurse
  • Surgical technologist (operating room technologist)
  • Anesthesiologist
  • Anesthetist
  • Intensive care unit nursing personnel (after the procedure)

Preparation

Preoperatively, the patient must be in the best optimal condition possible to tolerate the procedure. The patient must be with an empty stomach or "nil per os" (NPO), a Latin phrase that translates to "nothing through the mouth" in the English language. In emergency cases, this is usually not possible. Blood-thinning medications such as antiplatelet or antithrombotics should be discontinued between 3 to 10 days preoperatively, depending on the drug.[32] Internal medicine or cardiology evaluation for medical clearance should be obtained for recommendations and surgical risk.

Unless otherwise required, most craniotomy procedures are performed under general anesthesia, requiring a case discussion with the anesthesiology team for any pertinent details regarding the etiology to be treated. Sometimes, an awake craniotomy is performed under a local anesthetic agent, to be able to communicate with the patient during surgery involving motor and speech areas.[33][34][35][36] Specific patient preoperative considerations include the patient's procedure informed consent, procedure time-out identifying the correct patient and side of surgical intervention, and blood availability in case it is needed for transfusion during the surgery.[37] 

Routine preoperative antibiotics are administered before the procedure starts for wound infection prophylaxis, jointly with other medications that could be necessary, such as anticonvulsant medications or corticosteroids. Initial setup of equipment such as neuronavigation system, surgical microscope, and neuromonitoring are performed. Intensive care unit availability should be discussed preoperatively, as most patients do require this level of care after a craniotomy.

Technique

Once the patient is under anesthesia, the correct position of the head is fixed depending on the approach to be utilized. It is of utmost importance to avoid any pressure points on vulnerable body areas by adequately padding throughout. The location of the incision for the craniotomy depends on the part of the brain to be operated. If the surgical craniotomy is assisted by neuronavigation, anatomical points are confirmed before the incision at this time.

For surgery in the supratentorial area, the incision is usually made over the frontal, temporal, parietal, or occipital bones, or over a combination of bones. For surgery in the infratentorial area, the incision is usually made over the back portion of the skull below the transverse sinus. After the desired location of the incision is chosen on the skin, the hair in the area may be shaved off.[38] The incision should preferably be behind the hairline for cosmetic reasons. Once the incision is confirmed, the surgical area is cleaned with the preferred antiseptic agent followed by routine sterile draping techniques. A local anesthetic with epinephrine is usually injected on the marked skin incision to help with hemostasis. 

After the skin incision is made, the muscles below the scalp are dissected to expose the skull. Retractors can be placed on the edges of the incision to have adequate exposure to the surgical area to be focused on. Alternatively, fish hook retractors or sutures can be used to hold the scalp flap. The pericranium can be separated to be used as a dural substitute if necessary during the closure. Several burr holes are made into the skull utilizing the craniotome or cranial drill.[38] The caution has to be employed to avoid plunging the craniotome into the brain tissue. The holes are cleaned from any bone fragment, and the dura is separated with a Freer elevator or Penfield dissector. The burr holes are connected with a craniotome saw, and a bone flap is elevated after carefully separating it from the dura matter below. The bone flap is held in the surgical instrument table until the closure portion of the surgery. For the intradural procedure, the dura is cut and retracted, exposing the brain.

Once the surgery on the brain concludes, the bone is reattached in position with plates and screws. Adequate hemostasis should be obtained before closing the scalp. The overlying tissues are reattached, and the scalp is then sutured in anatomical layers. Depending on the surgeon’s preference, a subdural or subgaleal drain can be left in place to drain the accumulated blood products.

Complications

Like all other surgical procedures, craniotomy can also lead to certain complications. The following are some of the complications that the surgeons should be aware of in order to achieve the best outcomes:

  1. Intraoperative blood loss during the craniotomy
  2. Dural sinus perforation[39]
  3. Intracerebral, epidural, or subdural hematomas
  4. Dural laceration with the craniotome
  5. Seizure
  6. Stroke
  7. Coma
  8. Death
  9. Hydrocephalus
  10. New neurologic deficit related to the area of surgery
  11. Wound infection[40]
  12. Osteomyelitis of the bone flap
  13. Bacterial, viral, fungal meningitis
  14. Post craniotomy headache[2]
  15. Drill perforator plunge into the brain with cerebral contusion[39]
  16. Air embolism

Clinical Significance

The surgical procedure of a craniotomy has become one of the essential procedures in modern healthcare for neurological disorders. Before the advent of this procedure, many patients were not able to survive conditions that today are treated daily. Disorders ranging from brain tumors, vascular pathologies, and trauma are routinely treated, which could produce devastating damage to the patient if access to the intracranial cavity was limited. The procedure itself has been modernized and will continue to do so with the advent of new technology as it is developed. Since its beginnings, it has produced a revolution for neurosurgical and neurological patient care.

Depending on the specific type of pathology to be addressed and the clinical judgment of the physician, it is determined if a craniotomy is necessary for the patient. Even with the new endovascular techniques to treat intracranial vascular disorders and the radiosurgery technique to treat intracranial tumors, the craniotomy remains the primary tool for the treatment of the majority of neurosurgical pathologies.

Enhancing Healthcare Team Outcomes

To enhance healthcare team outcomes, measures should aim to provide the safest yet effective intervention for the patient. Different improvement strategies aiming to improve patient care and healthcare team outcomes can be implemented and can be divided into preoperative, intraoperative, and postoperative. 

Preoperative measures start in the emergency department once the patient arrives, or in the outpatient clinic. An interprofessional approach to patient care after successful communication between the neurosurgeon, emergency department physician, internal medicine physician, or cardiologist improves outcomes.

Intraoperatively, effective communication between the team members in the operating room is needed at all times. This communication will ensure the correct patient is operated, and the correct procedure is performed on the right side, minimizing potential errors or mistakes. Patient safety should be the top priority at all times. All personnel need to know the procedure to be performed and how it is performed. For intraoperative neuromonitoring, technicians become part of the essential team that will provide the best care for the patient. For those complicated and rare cases, experienced neurosurgeons provide the patient with the best result and outcomes. Neuroanesthesiologists are very important during the wake-up process to avoid coughing or agitation to prevent hemorrhage into the surgical area.[41][42]

During the postoperative period, once the patient wakes up from anesthesia, nursing personnel from the recovery room and intensive care unit communicate to transfer and receive the patient. Pharmacists will also become an integral part of the team needed for the essential care of the patient by providing treatment recommendations and modifications.

Nursing, Allied Health, and Interprofessional Team Interventions

Team-based practices are necessary for performing a successful craniotomy procedure. Interaction between the neurosurgeon and the anesthesiologist usually happens even before the patient is in the operating room by discussing 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, and in some cases, speech pathologists, physical medicine and rehabilitation physician, practical nurses, physical therapists, respiratory therapists, and even discharge planning team and social work team personnel.[43]


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