Historical Perspective on Evolution in Management o f L a t e r a l Sk u l l B a s e Tu m o r s Theodore R. McRackan,
MD,
Derald E. Brackmann,
MD*
KEYWORDS Lateral skull base tumors Lateral skull base lesions Acoustic neuroma Schwannoma Glomus jugulare Jugular paraganglioma Meningioma Stereotactic radiosurgery KEY POINTS During the first 100 years of lateral skull base surgery, the mortality has decreased from 80% to the current rate of less than 0.5% through the efforts of Cushing, Dandy, House, and numerous others. The invention of modern imaging techniques (eg, MRI) has allowed a better understanding of the natural history of lateral skull base lesions. Modern deescalated radiosurgery doses of 12 to 13 Gy have maintained excellent tumor control rates (>90%) with decreased associated morbidity. Surgical resection has become less aggressive, favoring preserved facial nerve function rather than complete tumor resection.
INTRODUCTION
The history of lateral skull base tumor management is best understood through the history of acoustic neuroma (AN) surgery. Like most lateral skull base lesions, ANs were initially thought to be unresectable. Surgical resection of lateral skull base tumors had a tumultuous course before arriving at the extremely low mortalities seen with modern surgery. As understanding of these lesions continues to advance so does our treatment algorithm. This article describes the major turning points in the treatment of lateral skull base lesions and how treatment strategies continue to evolve. EARLY HISTORY OF ACOUSTIC NEUROMA SURGERY
ANs were among the first lesions to be anatomically localized based on symptomatology alone. ANs therefore played a major role in neurosurgical history. The earliest
Disclosures: None. House Ear Clinic, 2100 West 3rd Street, Los Angeles, CA 90057, USA * Corresponding author. House Ear Clinic, 2100 West 3rd Street, Suite 111, Los Angeles, CA 90057. E-mail address: [email protected] Otolaryngol Clin N Am 48 (2015) 397–405 http://dx.doi.org/10.1016/j.otc.2015.02.002 0030-6665/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
oto.theclinics.com
398
McRackan & Brackmann
Abbreviations AN Acoustic neuroma GK Gamma Knife WRS Word recognition scores
descriptions of cerebellopontine angle lesions causing deafness and facial numbness date back to the mid–nineteenth century.1,2 However, it was not until the later part of that century that the first attempts at AN resection were made. The first reported surgical attempt was by Charles McBurney in 1891, who opened a suboccipital plate with a mallet and chisel.3 Because of excessive cerebellar swelling, no tumor could be removed and the patient died 12 days later. Soon thereafter (1894), an account from Charles Ballance described the first successful complete removal of an AN.4 Exposure was performed through a suboccipital approach and tumor was removed using blunt finger dissection. During this earliest era of AN surgery, the surgical mortality approached 80%, with high operative morbidity affecting the few patients who survived.5 It is clear that if posterior fossa surgery were to continue, significant advances would be needed. More modern surgical techniques were ushered in during the Harvey Cushing era (early 1900s). His technique included using an extended bilateral suboccipital approach and a belief that only the core of the tumor could be safely resected.6 He postulated that, by leaving the tumor capsule intact, cranial nerve function would be preserved and the brainstem vasculature would be left undisturbed. Cushing also advocated for the use of delicate and meticulous surgical technique, decreased cerebellar retraction, and the importance of relieving cerebrospinal fluid pressure to improve operative space. Along with the use of bone wax and electrocautery for hemostasis, this allowed him to decrease the surgical mortality to 20% in his lifetime.6–8 Although there was significant overlap with Cushing, the Walter Dandy era saw the increased use of diagnostic imaging to guide surgical technique. In 1918, Dandy invented ventriculography, which allowed neurosurgeons to identify the approximate location and size of brain tumors for the first time.6,9 This ability was further advanced 1 year later by his development of pneumoencephalography.6 In addition, Dandy, developed the more modern unilateral suboccipital approach using a smaller bone flap. He also created a schism between himself and Cushing by advocating and successfully performing total tumor excision.10,11 Improving on Cushing’s advances, Dandy was able to advance the modern surgical era. The introduction of the operative microscope by William House12 in 1961 changed neurosurgery forever. This microscope allowed improved viewing of the cranial nerves and blood vessels, permitting more complete tumor resection with decreased morbidity. It made facial nerve preservation with tumor resection possible for the first time. This improved vision paved the way for House to fully develop the translabyrinthine approach; unknown to House, this had been described by Panse13 (1904) and Quix14 (1911) decades earlier.15 The microscope also allowed the development of the transcochlear approach as well as hearing preservation surgery in the form of the middle cranial fossa and the modern retrosigmoid approach. Before William House’s era, there was no cooperation between otologists and neurosurgeons in posterior fossa surgery. They were often vehemently opposed to their counterparts performing these surgeries. This lack of cooperation changed when William House invited William Hitselberger to join forces in treating posterior fossa lesions. The two spent countless hours together in the temporal bone laboratory cross-training
Management of Lateral Skull Base Tumors
to gain from each other’s expertise. Over time, they created the modern collaborative neurosurgeon/neuro-otologist relationship that is now used across the world. It is easy to take this working relationship for granted in the modern era, but it is important to remember that it arose from the hard work and dedication of these two men. The surgical treatment of meningiomas, glomus tumors, facial nerve schwannomas, petrous apex lesions, and other lateral skull base lesions was also similarly affected by the surgical advances discussed earlier. The modernization and adaptation of these surgical approaches, along with use of the operative microscope, allowed surgeons to surgically address these lesions with improved outcomes. IMAGING
Without radiological advances, our current understanding of the size and growth characteristics of lateral skull base lesions would be deficient. It became possible to identify moderate-sized tumors with the use of positive contrast cisternography.16 Later, the development of the Polytome Pantopaque technique allowed the diagnosis of smaller lesions confined to the internal auditory canal.6 Although all these advances were helpful at their time, the widespread use of computer tomography and eventually MRI in the 1980s greatly improved the characterization of these lesions and ultimately became the primary diagnostic imaging study.17 The improved identification of AN, along with improved MRI resolution, allowed physicians to better understand the natural history of skull base lesions and intervene at an earlier stage than was previously possible. NATURAL HISTORY OF SKULL BASE LESIONS
Perhaps the greatest breakthrough in the management of lateral skull base tumors has been a better understanding of the natural growth rates of these lesions. Before this, nearly all lesions were surgically resected on diagnosis regardless of symptoms. It is now known that meningiomas, facial nerve schwannomas, and glomus tumors follow similar slow growth patterns to AN. Multiple studies have reported the overall growth rates of ANs to vary widely, between 6% and 73%.18 However, when data have been collected in metaanalyses, 51% of ANs show no growth, 43% to 54% grow, and 4% to 8% regress in size.19–21 Data from the Denmark Prospective Observational Study show that 17% of intrameatal and 28.9% of extrameatal ANs showed growth (P
MD,
Derald E. Brackmann,
MD*
KEYWORDS Lateral skull base tumors Lateral skull base lesions Acoustic neuroma Schwannoma Glomus jugulare Jugular paraganglioma Meningioma Stereotactic radiosurgery KEY POINTS During the first 100 years of lateral skull base surgery, the mortality has decreased from 80% to the current rate of less than 0.5% through the efforts of Cushing, Dandy, House, and numerous others. The invention of modern imaging techniques (eg, MRI) has allowed a better understanding of the natural history of lateral skull base lesions. Modern deescalated radiosurgery doses of 12 to 13 Gy have maintained excellent tumor control rates (>90%) with decreased associated morbidity. Surgical resection has become less aggressive, favoring preserved facial nerve function rather than complete tumor resection.
INTRODUCTION
The history of lateral skull base tumor management is best understood through the history of acoustic neuroma (AN) surgery. Like most lateral skull base lesions, ANs were initially thought to be unresectable. Surgical resection of lateral skull base tumors had a tumultuous course before arriving at the extremely low mortalities seen with modern surgery. As understanding of these lesions continues to advance so does our treatment algorithm. This article describes the major turning points in the treatment of lateral skull base lesions and how treatment strategies continue to evolve. EARLY HISTORY OF ACOUSTIC NEUROMA SURGERY
ANs were among the first lesions to be anatomically localized based on symptomatology alone. ANs therefore played a major role in neurosurgical history. The earliest
Disclosures: None. House Ear Clinic, 2100 West 3rd Street, Los Angeles, CA 90057, USA * Corresponding author. House Ear Clinic, 2100 West 3rd Street, Suite 111, Los Angeles, CA 90057. E-mail address: [email protected] Otolaryngol Clin N Am 48 (2015) 397–405 http://dx.doi.org/10.1016/j.otc.2015.02.002 0030-6665/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
oto.theclinics.com
398
McRackan & Brackmann
Abbreviations AN Acoustic neuroma GK Gamma Knife WRS Word recognition scores
descriptions of cerebellopontine angle lesions causing deafness and facial numbness date back to the mid–nineteenth century.1,2 However, it was not until the later part of that century that the first attempts at AN resection were made. The first reported surgical attempt was by Charles McBurney in 1891, who opened a suboccipital plate with a mallet and chisel.3 Because of excessive cerebellar swelling, no tumor could be removed and the patient died 12 days later. Soon thereafter (1894), an account from Charles Ballance described the first successful complete removal of an AN.4 Exposure was performed through a suboccipital approach and tumor was removed using blunt finger dissection. During this earliest era of AN surgery, the surgical mortality approached 80%, with high operative morbidity affecting the few patients who survived.5 It is clear that if posterior fossa surgery were to continue, significant advances would be needed. More modern surgical techniques were ushered in during the Harvey Cushing era (early 1900s). His technique included using an extended bilateral suboccipital approach and a belief that only the core of the tumor could be safely resected.6 He postulated that, by leaving the tumor capsule intact, cranial nerve function would be preserved and the brainstem vasculature would be left undisturbed. Cushing also advocated for the use of delicate and meticulous surgical technique, decreased cerebellar retraction, and the importance of relieving cerebrospinal fluid pressure to improve operative space. Along with the use of bone wax and electrocautery for hemostasis, this allowed him to decrease the surgical mortality to 20% in his lifetime.6–8 Although there was significant overlap with Cushing, the Walter Dandy era saw the increased use of diagnostic imaging to guide surgical technique. In 1918, Dandy invented ventriculography, which allowed neurosurgeons to identify the approximate location and size of brain tumors for the first time.6,9 This ability was further advanced 1 year later by his development of pneumoencephalography.6 In addition, Dandy, developed the more modern unilateral suboccipital approach using a smaller bone flap. He also created a schism between himself and Cushing by advocating and successfully performing total tumor excision.10,11 Improving on Cushing’s advances, Dandy was able to advance the modern surgical era. The introduction of the operative microscope by William House12 in 1961 changed neurosurgery forever. This microscope allowed improved viewing of the cranial nerves and blood vessels, permitting more complete tumor resection with decreased morbidity. It made facial nerve preservation with tumor resection possible for the first time. This improved vision paved the way for House to fully develop the translabyrinthine approach; unknown to House, this had been described by Panse13 (1904) and Quix14 (1911) decades earlier.15 The microscope also allowed the development of the transcochlear approach as well as hearing preservation surgery in the form of the middle cranial fossa and the modern retrosigmoid approach. Before William House’s era, there was no cooperation between otologists and neurosurgeons in posterior fossa surgery. They were often vehemently opposed to their counterparts performing these surgeries. This lack of cooperation changed when William House invited William Hitselberger to join forces in treating posterior fossa lesions. The two spent countless hours together in the temporal bone laboratory cross-training
Management of Lateral Skull Base Tumors
to gain from each other’s expertise. Over time, they created the modern collaborative neurosurgeon/neuro-otologist relationship that is now used across the world. It is easy to take this working relationship for granted in the modern era, but it is important to remember that it arose from the hard work and dedication of these two men. The surgical treatment of meningiomas, glomus tumors, facial nerve schwannomas, petrous apex lesions, and other lateral skull base lesions was also similarly affected by the surgical advances discussed earlier. The modernization and adaptation of these surgical approaches, along with use of the operative microscope, allowed surgeons to surgically address these lesions with improved outcomes. IMAGING
Without radiological advances, our current understanding of the size and growth characteristics of lateral skull base lesions would be deficient. It became possible to identify moderate-sized tumors with the use of positive contrast cisternography.16 Later, the development of the Polytome Pantopaque technique allowed the diagnosis of smaller lesions confined to the internal auditory canal.6 Although all these advances were helpful at their time, the widespread use of computer tomography and eventually MRI in the 1980s greatly improved the characterization of these lesions and ultimately became the primary diagnostic imaging study.17 The improved identification of AN, along with improved MRI resolution, allowed physicians to better understand the natural history of skull base lesions and intervene at an earlier stage than was previously possible. NATURAL HISTORY OF SKULL BASE LESIONS
Perhaps the greatest breakthrough in the management of lateral skull base tumors has been a better understanding of the natural growth rates of these lesions. Before this, nearly all lesions were surgically resected on diagnosis regardless of symptoms. It is now known that meningiomas, facial nerve schwannomas, and glomus tumors follow similar slow growth patterns to AN. Multiple studies have reported the overall growth rates of ANs to vary widely, between 6% and 73%.18 However, when data have been collected in metaanalyses, 51% of ANs show no growth, 43% to 54% grow, and 4% to 8% regress in size.19–21 Data from the Denmark Prospective Observational Study show that 17% of intrameatal and 28.9% of extrameatal ANs showed growth (P
