C h a l l e n g e s i n Pe d i a t r i c N e u ro a n e s t h e s i a Awake Craniotomy, Intraoperative Magnetic Resonance Imaging, and Interventional Neuroradiology Craig D. McClain,
MD, MPH*,
Mary Landrigan-Ossar,
MD, PhD
KEYWORDS Pediatric Intraoperative magnetic resonance imaging Awake craniotomy Neurointerventional Neuroendovascular Pediatric neuroanesthesia KEY POINTS There are many complexities to the care of children undergoing awake craniotomies. The anesthesiologist must be prepared to deal with a variety of urgent and emergent intraoperative scenarios. When the techniques of cortical mapping are combined with an awake, responsive patient, optimal outcomes can be realized. Intraoperative magnetic resonance imaging offers high-resolution intraoperative images that can assess the extent of resection in pseudoreal time. Angiography and embolization are frequent procedures performed in the neurointerventional suite to address a variety of pediatric neurovascular lesions.
INTRODUCTION
Anesthesiologists involved in caring for children undergoing neurosurgical procedures are required to have an intimate understanding of normal neurocognitive development, the effects of anesthetics on the developing nervous system, the fundamental differences between children and adults, and the implications of these surgical approaches to children. Several surgical approaches such as image-guided procedures and awake craniotomies add to the complex environment faced by the anesthesiologist. In addition, the neurointerventional suite has become increasingly used as
Disclosures: the authors have no disclosures to make. Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Bader 3, Boston, MA 02115, USA * Corresponding author. E-mail address: [email protected] Anesthesiology Clin 32 (2014) 83–100 http://dx.doi.org/10.1016/j.anclin.2013.10.009 anesthesiology.theclinics.com 1932-2275/14/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved.
84
McClain & Landrigan-Ossar
children with a variety of neurovascular lesions present for often lengthy and complicated procedures for definitive diagnosis or treatment. Planning and executing safe, age-appropriate perioperative care in these environments is challenging. This article offers some insight into the complexities of care of children undergoing awake craniotomies as well as procedures in intraoperative magnetic resonance imaging (iMRI) suites and neurointerventional radiology. AWAKE CRANIOTOMY History of Awake Craniotomy
Evidence of craniotomy predates the invention of surgical anesthesia by several millennia. There is evidence of trepanation (creating a hole through the skull and dura) in human skulls unearthed in France from approximately 6500 BC.1 In addition, it is clear that several pre-Columbian societies in Mesoamerica practiced trepanation, most notably, the Incas.2,3 During the Middle Ages and Renaissance in western Europe, trepanation was performed to alleviate headaches and seizures.4 Dutch painter Hieronymus Bosch famously captured this practice in his painting, The Extraction of the Stone of Madness, from the late fifteenth century. The modern use of awake craniotomy (AC) began in the second half of the nineteenth century, when local anesthetics became widely available. With good local anesthesia, Horsley was able to perform ACs.5 However, the modern understanding of the benefit of AC began in 1951, when Wilder Penfield, the first director of the famous Montreal Neurologic Institute, published his landmark monograph, Epilepsy and the Functional Anatomy of the Human Brain.6 Penfield described the use of craniotomy performed under local anesthesia only to facilitate resection of epileptogenic foci. Before resection, Penfield stimulated various locations of the cortex and observed the responses in the awake patient. This practice allowed him to generate cortical maps of motor and sensory areas, which result in cortical homunculus. The 1960s brought the advent of neuroleptic anesthetic techniques, which continued to provide a responsive patient but offered some degree of analgesia and sedation in order to tolerate prolonged awkward positions.7 A combination of drugs such as droperidol and fentanyl were commonly used to facilitate a patient who was drowsy and comfortable, yet still able to arouse to stimulation and follow commands. The downside of prolonged use of dopaminergic drugs became apparent when the occurrence of side effects, including extrapyramidal effects and dysphoria, was noted. AC as a method of treating seizure foci and tumors became popular again in the 1990s and early 2000s, with the widespread use of shorter-acting hypnotic agents and opioids, such as propofol and remifentanil.8,9 Current anesthetic techniques use a wide range of agents. Dexmedetomidine, an a2 agonist with sedating and analgesic properties, is a relatively newer drug that offers some distinct advantages over other techniques using sedative hypnotics and opioids.10,11 One of the most advantageous aspects of dexmedetomidine is its ability to offer mild analgesia and good sedation without compromising the airway. AC in Children Equipment
No special equipment is needed for the performance of AC. The anesthesiologist should have the operating room (OR) prepared for the same problems that may be encountered during a craniotomy under general anesthesia. Invasive blood pressure monitoring is useful. The anesthesiologist should be prepared to convert to a general anesthetic if needed. Airway management while the patient is in head pins can be
Challenges in Pediatric Neuroanesthesia
particularly problematic. It can be lifesaving to have properly sized supraglottic airway devices within easy reach. More advanced airway tools may be necessary to provide definitive airway management. The anesthesiologist must be prepared to deal with a variety of urgent and emergent intraoperative scenarios. This strategy applies to any surgical case, but may be more important for an AC. Seizures, which can occur during cortical mapping in an AC, must be quickly and effectively controlled to prevent patient injury. Seizures are more common in younger patients with frontal lobe lesions.12 Generalized tonic clonic movements can be devastating to a patient who is fixed in head pins. Injuries that may result can range from scalp lacerations to skull fractures and even cervical spine injuries. Anesthesiologists should always have a heightened sense of concern with an unrelaxed patient fixed in head pins (awake or under general anesthesia). Indications
The benefits of having a responsive patient during surgery performed near eloquent cortex are legion. Most commonly, AC is performed on patients with lesions located near, adjacent to, or even within eloquent cortex. Intraoperative cortical mapping can be used to identify areas that are dysfunctional as well as those cortical areas that control important functions such as speech and motor movements. When the techniques of cortical mapping are combined with an awake, responsive patient, optimal outcomes can be realized. A prospective comparison in 201113 of AC versus craniotomies performed under general anesthesia for resection of supratentorial lesions found a statistically significant improvement in resection quality and better neurologic outcome in the awake patients. Certainly a useful technique in adults, AC in pediatric neurosurgical patients presents the anesthesiologist with a tremendous challenge, because of the differences in level of cognitive development of children. The youngest patient reported in the literature to have successfully undergone an AC is a 9-year-old boy, who underwent resection of a glioblastoma in the left frontotemporal region using propofol sedation.14 Despite this reported success, it is unlikely that many children younger than 10 years are emotionally mature enough to tolerate such a procedure. Contraindications
Proper patient selection is probably the single most important factor in achieving an optimal outcome for an AC. Relative contraindications include patient’s age (
MD, MPH*,
Mary Landrigan-Ossar,
MD, PhD
KEYWORDS Pediatric Intraoperative magnetic resonance imaging Awake craniotomy Neurointerventional Neuroendovascular Pediatric neuroanesthesia KEY POINTS There are many complexities to the care of children undergoing awake craniotomies. The anesthesiologist must be prepared to deal with a variety of urgent and emergent intraoperative scenarios. When the techniques of cortical mapping are combined with an awake, responsive patient, optimal outcomes can be realized. Intraoperative magnetic resonance imaging offers high-resolution intraoperative images that can assess the extent of resection in pseudoreal time. Angiography and embolization are frequent procedures performed in the neurointerventional suite to address a variety of pediatric neurovascular lesions.
INTRODUCTION
Anesthesiologists involved in caring for children undergoing neurosurgical procedures are required to have an intimate understanding of normal neurocognitive development, the effects of anesthetics on the developing nervous system, the fundamental differences between children and adults, and the implications of these surgical approaches to children. Several surgical approaches such as image-guided procedures and awake craniotomies add to the complex environment faced by the anesthesiologist. In addition, the neurointerventional suite has become increasingly used as
Disclosures: the authors have no disclosures to make. Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Bader 3, Boston, MA 02115, USA * Corresponding author. E-mail address: [email protected] Anesthesiology Clin 32 (2014) 83–100 http://dx.doi.org/10.1016/j.anclin.2013.10.009 anesthesiology.theclinics.com 1932-2275/14/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved.
84
McClain & Landrigan-Ossar
children with a variety of neurovascular lesions present for often lengthy and complicated procedures for definitive diagnosis or treatment. Planning and executing safe, age-appropriate perioperative care in these environments is challenging. This article offers some insight into the complexities of care of children undergoing awake craniotomies as well as procedures in intraoperative magnetic resonance imaging (iMRI) suites and neurointerventional radiology. AWAKE CRANIOTOMY History of Awake Craniotomy
Evidence of craniotomy predates the invention of surgical anesthesia by several millennia. There is evidence of trepanation (creating a hole through the skull and dura) in human skulls unearthed in France from approximately 6500 BC.1 In addition, it is clear that several pre-Columbian societies in Mesoamerica practiced trepanation, most notably, the Incas.2,3 During the Middle Ages and Renaissance in western Europe, trepanation was performed to alleviate headaches and seizures.4 Dutch painter Hieronymus Bosch famously captured this practice in his painting, The Extraction of the Stone of Madness, from the late fifteenth century. The modern use of awake craniotomy (AC) began in the second half of the nineteenth century, when local anesthetics became widely available. With good local anesthesia, Horsley was able to perform ACs.5 However, the modern understanding of the benefit of AC began in 1951, when Wilder Penfield, the first director of the famous Montreal Neurologic Institute, published his landmark monograph, Epilepsy and the Functional Anatomy of the Human Brain.6 Penfield described the use of craniotomy performed under local anesthesia only to facilitate resection of epileptogenic foci. Before resection, Penfield stimulated various locations of the cortex and observed the responses in the awake patient. This practice allowed him to generate cortical maps of motor and sensory areas, which result in cortical homunculus. The 1960s brought the advent of neuroleptic anesthetic techniques, which continued to provide a responsive patient but offered some degree of analgesia and sedation in order to tolerate prolonged awkward positions.7 A combination of drugs such as droperidol and fentanyl were commonly used to facilitate a patient who was drowsy and comfortable, yet still able to arouse to stimulation and follow commands. The downside of prolonged use of dopaminergic drugs became apparent when the occurrence of side effects, including extrapyramidal effects and dysphoria, was noted. AC as a method of treating seizure foci and tumors became popular again in the 1990s and early 2000s, with the widespread use of shorter-acting hypnotic agents and opioids, such as propofol and remifentanil.8,9 Current anesthetic techniques use a wide range of agents. Dexmedetomidine, an a2 agonist with sedating and analgesic properties, is a relatively newer drug that offers some distinct advantages over other techniques using sedative hypnotics and opioids.10,11 One of the most advantageous aspects of dexmedetomidine is its ability to offer mild analgesia and good sedation without compromising the airway. AC in Children Equipment
No special equipment is needed for the performance of AC. The anesthesiologist should have the operating room (OR) prepared for the same problems that may be encountered during a craniotomy under general anesthesia. Invasive blood pressure monitoring is useful. The anesthesiologist should be prepared to convert to a general anesthetic if needed. Airway management while the patient is in head pins can be
Challenges in Pediatric Neuroanesthesia
particularly problematic. It can be lifesaving to have properly sized supraglottic airway devices within easy reach. More advanced airway tools may be necessary to provide definitive airway management. The anesthesiologist must be prepared to deal with a variety of urgent and emergent intraoperative scenarios. This strategy applies to any surgical case, but may be more important for an AC. Seizures, which can occur during cortical mapping in an AC, must be quickly and effectively controlled to prevent patient injury. Seizures are more common in younger patients with frontal lobe lesions.12 Generalized tonic clonic movements can be devastating to a patient who is fixed in head pins. Injuries that may result can range from scalp lacerations to skull fractures and even cervical spine injuries. Anesthesiologists should always have a heightened sense of concern with an unrelaxed patient fixed in head pins (awake or under general anesthesia). Indications
The benefits of having a responsive patient during surgery performed near eloquent cortex are legion. Most commonly, AC is performed on patients with lesions located near, adjacent to, or even within eloquent cortex. Intraoperative cortical mapping can be used to identify areas that are dysfunctional as well as those cortical areas that control important functions such as speech and motor movements. When the techniques of cortical mapping are combined with an awake, responsive patient, optimal outcomes can be realized. A prospective comparison in 201113 of AC versus craniotomies performed under general anesthesia for resection of supratentorial lesions found a statistically significant improvement in resection quality and better neurologic outcome in the awake patients. Certainly a useful technique in adults, AC in pediatric neurosurgical patients presents the anesthesiologist with a tremendous challenge, because of the differences in level of cognitive development of children. The youngest patient reported in the literature to have successfully undergone an AC is a 9-year-old boy, who underwent resection of a glioblastoma in the left frontotemporal region using propofol sedation.14 Despite this reported success, it is unlikely that many children younger than 10 years are emotionally mature enough to tolerate such a procedure. Contraindications
Proper patient selection is probably the single most important factor in achieving an optimal outcome for an AC. Relative contraindications include patient’s age (
