technical note
Vascularized rotational temporal bone flap for repair of anterior skull base defects: a novel operative technique Frederick A. Zeiler, MD, and Anthony M. Kaufmann, MD Section of Neurosurgery, University of Manitoba, Winnipeg, Manitoba, Canada
Repair of anterior skull base defects with vascularized grafts poses a significant challenge, given the location and small number of adequately sized vessels for free-flap anastomosis. This is particularly the case in the setting of redo surgery or in patients with preexisting soft-tissue trauma. Even more difficult is achieving a vascularized bone flap closure of such bony defects. The authors report a novel technique involving a rotational temporal bone flap with a temporalis muscle vascularized pedicle, which was used to repair an anterior fossa bony and soft-tissue defect created by recurrent malignancy. A 55-year-old man with history of scalp avulsion during a motor vehicle accident, anterior fossa/nasopharyngeal malignant neuroendocrine carcinoma postresection, and bone flap infection presented with a recurrence of his skull base malignancy. The tumor was located in the anterior fossa, extending interhemispherically and down through the cribriform plate, ethmoid air cells, and extending into the nasopharyngeal cavity. Resection of the recurrent tumor was performed. The bony defect in the anterior skull base was repaired with a novel vascularized rotational temporal bone flap, with acceptable separation of the nasopharynx from the intracranial cavity. The vascularized rotational temporal bone flap, in which a temporalis muscle pedicle is used, provides a novel and easily accessible means of vascularized bone closure of anterior skull base defects without the need for microsurgical free-flap grafting. http://thejns.org/doi/abs/10.3171/2014.11.JNS141979
Key Words temporal flap; reconstruction; vascularized bone; skull base
A
graft reconstruction of the skull base poses significant challenges. Using vascularized grafts in the reconstructive process is ideal, although the location and access to such skull defects imposes limitations.2,5 Depending on surrounding anatomy, vascular patency, and the size of the graft site, microsurgical free flaps may provide a solution. However, the availability of suitable graft site vessels is usually limited due to the underlying disease6 and the resections leading to the initial defect. Furthermore, an autologous vascularized bone graft can be even more difficult to find and place in such areas. Anterior fossa defects are particularly difficult to repair with vascularized grafts, given the location and limitautologous
tions of the surrounding vascular anatomy for microvascular free-flap anastomosis. Such cranial base defects are commonly reconstructed using autologous free bone with either rotational temporalis1,4 or free tensor fascia lata grafts.3 We describe a novel technique to acquire a vascularized bone flap that will provide both hard- and soft-tissue closure of anterior fossa defects: the vascularized rotational temporal bone flap.
Methods
We retrospectively reviewed the chart of a patient who underwent a novel technique in the repair of an anterior skull base defect left by a malignancy.
submitted August 29, 2014. accepted November 5, 2014. include when citing Published online May 8, 2015; DOI: 10.3171/2014.11.JNS141979. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. ©AANS, 2015
J Neurosurg May 8, 2015
1
F. A. Zeiler and A. M. Kaufmann
Results
Case Description We report the case of a 55-year-old man with a medical history significant for frontal scalp avulsion secondary to a motor vehicle collision 10 years prior. He presented to neurosurgery initially with headaches, nasal obstruction, and epistaxis. Admission CT and MRI studies demonstrated a large nasopharyngeal mass spanning from the middle turbinate through the frontal floor, and interhemispherically between the frontal lobes of the brain. Results of the metastatic workup were negative. The patient underwent a bifrontal transbasal approach for resection of his anterior skull base tumor. Some tumor was left attached to the anterior cerebral arteries, given its significant adhesion to these vessels on attempted microsurgical dissection. The final pathology findings demonstrated a malignant nasopharyngeal neuroendocrine carcinoma. During the patient’s l-month follow-up visit in the clinic, concerns of bone flap infection were raised, given a fluctuant subgaleal collection. He had not received radiotherapy at this point, and chemotherapy was deemed inappropriate by the medical oncology specialist, given the histological diagnosis. Exploration of the wound demonstrated pus and suspected bone flap infection. The bifrontal craniotomy bone was removed and discarded, with the wound debrided and irrigated. The patient received 8 weeks of intravenous antimicrobial therapy for Staphylococcus aureus. Radiation was delayed until the cessation of antibiotics. Then, while waiting to start radiotherapy, the patient noticed increasing headaches and epistaxis. The MRI studies obtained at that time displayed a significant recurrence of both the nasal and intracranial portions of the tumor (Fig. 1). We elected to attempt repeat resection. The tumor was successfully resected, again with a small residual left attached to the anterior cerebral arteries. The dura mater was closed primarily with a small piece of temporalis fascia graft. A sizable bony defect, approximately 3.5 cm in diameter, was left in the frontal floor, extending through the posterior aspect of the frontal sinus, cribriform plate, ethmoid air cells, and the vomer. Given the concerns of
prior infection and planned radiotherapy, our goal was to achieve closure of this defect and provide a barrier between the intracranial and nasal cavities. The plastic surgeon harvested a free tensor fascia lata graft with fat from the right thigh, a portion of which was packed beneath the frontal floor. Bone closure was then achieved via a rotated pedicled temporal bone flap from the right calvaria. Details on the vascularized bone flap can be seen in the Operative Technique section. Additional tensor fascia lata with fat was then placed between this and the dura before craniotomy closure with a premolded titanium craniotomy plate. Operative Technique: Vascularized Temporal Bone Flap After lesion removal from the anterior skull base, soft tissue was stripped from the bone edges of the skull base. The anterior fossa defect was exposed until bleeding bone edges were identified. This defect measured approximately 3.5 cm in diameter. Tensor fascia lata graft was packed into the ethmoid space, as described above. The temporal bone donor site was exposed as follows (Fig. 2). First, subgaleal exposure of the temporalis muscle was accomplished with interfascial dissection. This was to expose the posterior portion of the temporalis muscle origin from the superior temporal line, and to allow for a large strip of vascularized temporalis for future rotation. Second, a 3.5-cm-diameter craniectomy was marked for our desired temporal bone graft (Figs. 2A and 3 left). Third, the temporal craniectomy was fashioned with a high-speed bur along the superior and posterior edges of the temporalis muscle origin (Fig. 2A). Fourth, the temporalis muscle was incised inferior to the planned craniectomy and the bone cut was continued (Fig. 2B and C). Fifth, the anterior aspect of the bone cut was performed through a tunnel beneath the temporalis muscle, taking care not to elevate the muscle from the bone graft (Fig. 2D). Sixth, the temporal craniectomy was elevated and mobilized along with the temporalis muscle pedicle that was created with a 3-cm strip of muscle incised parallel to the superior temporal line (Fig. 3 right). The muscle pedicle was then rotated to bring the temporal bone graft to the frontal floor defect (Fig. 4). We also expanded the keyhole bur hole (2 × 2 cm) to accommodate the temporalis muscle pedicle (Fig. 3 right, arrow). The bone graft was secured with a strip of titanium plating. Finally, the bifrontal craniectomy site was covered with a custom titanium plate. Figure 5 displays the postoperative sagittal, axial, and coronal MR images.
Discussion
FIG. 1. Preoperative MRI studies of recurrent neuroendocrine carcinoma. Left: Sagittal T1-weighted MRI study of the brain displaying an iso- and hypointense cystic mass extending from the rostrum of the corpus callosum to the nasal cavity, through the frontal floor. Right: Axial T1-weighted Gd-enhanced MRI study of the brain at the level of the mesencephalon displaying heterogeneous enhancement of interhemispheric lesion and cystic components. 2
J Neurosurg May 8, 2015
Skull base reconstruction has its challenges. Access, location, vascular anatomy for anastomosis, local tissue quality, local microbes, and future treatment of the underlying disease all play a role in the choice of materials for reconstruction. Numerous substrates have been used: autologous tissues, allografts, and synthetics, all with varying degrees of success documented.2,5,6 Ideally, a vascularized graft would be used to repair such defects. Furthermore, a vascularized bone graft would be ideal for repair. These can be quite difficult to acquire and transpose to the skull base.
Vascularized rotational temporal bone flap
FIG. 2. Illustrations of temporal bone flap preparation. A: Temporal bone flap marked at the level of the superior temporal line, with a high-speed drill initiating the craniotomy above the superior temporal line. B: Incision of temporalis muscle with scalpel, allowing the inferior portion of the craniotomy to be completed. C: Craniotomy continued inferiorly with a high-speed drill. D: Temporalis muscle elevated subperiosteally, allowing completion of the bone cut with the drill. Temporalis muscle remained attached to temporal bone flap. Copyright Jon Stepaniuk. Published with permission.
Reconstruction of the anterior fossa floor by using free fascial grafts, with or without free fat, has been documented.2,6 However, in previously irradiated and infected sites, these nonvascularized grafts carry a high risk of failure. Pedicled myocutaneous free flaps, typically transposed with the help of a plastic surgeon, provide a vascularized means of closure of such skull base defects and have also been reported.6 Difficulty with recipient vessel availability, caliber, and maintenance of patency with microsurgical anastomosis in the area of the anterior fossa leave these reconstructive tissue flaps as an option, but require significant technical expertise. In the setting of previously irradiated and infected tissue beds, with multiple previ-
ous operations, these pedicled free flaps may fail. Rotational temporalis slings over anterior fossa defects have also been described.2,6 However, the quality of this barrier between the nasal cavity and the anterior fossa is questionable. Finally, synthetic reconstruction in which titanium plating and a variety of bone cements are used has also been documented.2 These nonliving substrates carry a risk of infection in the setting of concomitant or previous irradiation, and provide only a mechanical barrier between the anterior fossa and the nasal cavity, with the hope of a fibrous closure over the graft and defect. With our reported operative technique, we have been able to provide a potential vascularized bone graft option
FIG. 3. Illustrations of lateral skull pre- and postcraniotomy. Left: Lateral skull view with planned temporal bone flap marked out at the level of the superior temporal line. Right: Lateral skull view with pedicled temporal bone flap harvested. The expanded slot drilled in the keyhole for the temporalis muscle is denoted by the arrow. Copyright Jon Stepaniuk. Published with permission.
FIG. 4. Illustrations of temporal bone flap rotation into the anterior skull base. Left: Vertex view of the skull displaying the anterior skull base defect and the pedicled temporal bone flap. Right: Vertex view of the skull displaying the pedicled temporal bone flap placed into the anterior skull base defect. Copyright Jon Stepaniuk. Published with permission. J Neurosurg May 8, 2015
3
F. A. Zeiler and A. M. Kaufmann
FIG. 5. Postresection and reconstruction MRI. A: Sagittal T1-weighted MRI study displaying repair of the anterior skull base defect. Arrow indicates the temporal bone flap plugging the anterior fossa bony defect. The hyperintense signal in the nasal cavity is the tensor fascia lata free graft. B: Axial T1-weighted FLAIR image displaying the anterior skull base with temporal bone flap in situ and secured with a plate (arrow). C: Coronal T1-weighted Gd-enhanced MRI study displaying temporal bone graft in the frontal floor defect (arrow).
for anterior fossa repairs by using a rotational temporal bone flap with a vascularized temporalis muscle pedicle. Although it is not clear how much blood supply will be delivered to our temporal bone flap through the attached temporalis muscle pedicle, we believe this construct will provide better potential for temporal bone flap viability. This technique may have benefits over other reconstructive options. First, the graft donor site is easily accessible through both standard bicoronal and pterional incisions. This reduces the need for a separate access to donor tissues. Second, the technique we have described to harvest the temporal bone is easy and requires standard neurosurgical equipment used for craniotomies. Third, the temporal bone graft may remain vascularized via a temporalis pedicle and provides a living substrate for anterior fossa repairs. It also means that the technical expertise for microvascular free-flap anastomosis is not required to achieve a vascularized graft. Fourth, the temporal graft described is a vascularized hard-tissue graft. This is ideal for repairs of hard-tissue defects such as in the anterior skull base. Fifth, the thickness of the bone graft can be altered to conform to the situation (for example, repair of the orbital roof). Finally, we believe that this technique can be performed by all neurosurgeons, without a significant learning curve. There are limitations to this technique. First, with rotation of the temporalis muscle from the superior temporal line, there exists a temporalis defect that can also be cosmetically undesirable. This can be remedied with implantable material, such as autologous fat injections. Second, it is unclear how well the bone remains vascularized, or how large a bone graft could be reliably sustained by the temporalis muscle rotational flap. Finally, the only evidence that our temporal bone graft is vascularized is the presence of ongoing diploic space hemorrhage after rotation of the flap. Overall, we hope that through the advantages of the described technique, we have provided all neurosurgeons with the ability to provide vascularized bone closure of anterior fossa defects.
Conclusions
The vascularized rotational temporal bone flap, with
4
J Neurosurg May 8, 2015
temporalis muscle pedicle, provides a novel and easily acquired vascularized hard-tissue graft for closure of anterior fossa defects.
Acknowledgment
Our thanks go to Jon Stepaniuk for the professional illustrations he provided for the operative technique described.
References
1. Atabey A, Vayvada H, Menderes A, Kirişoğlu U, Barutçu A: A combined reverse temporalis muscle flap and pericranial flap for reconstruction of an anterior cranial base defect: a case report. Ann Plast Surg 39:190–192, 1997 2. Bernal-Sprekelsen M, Rioja E, Enseñat J, Enriquez K, Viscovich L, Agredo-Limos FE, et al: Management of anterior skull base defect depending on its size and location. Biomed Res Int 2014:346873, 2014 3. Jalisi S, O’Gara B, Toshkezi G, Chin L: Local vascularized flap reconstruction of skull base—clinical outcomes and analysis. World Neurosurg 83:87–92, 2015 4. Kwon SG, Kim YO, Rah DK: Anterior cranial base reconstruction with a reverse temporalis muscle flap and calvarial bone graft. Arch Plast Surg 39:345–351, 2012 5. Marcus J, Laufer I, Mehrara B, Kraus D, Singh B, Bilsky MH: Anterior and anterolateral resection for skull base malignancies: techniques and complication avoidance. Neurosurg Clin N Am 24:11–18, 2013 6. Schmalbach CE, Webb DE, Weitzel EK: Anterior skull base reconstruction: a review of current techniques. Curr Opin Otolaryngol Head Neck Surg 18:238–243, 2010
Author Contributions
Conception and design: both authors. Acquisition of data: Zeiler. Analysis and interpretation of data: Zeiler. Drafting the article: both authors. Critically revising the article: both authors. Reviewed submitted version of manuscript: Zeiler. Approved the final version of the manuscript on behalf of both authors: Zeiler. Administrative/technical/material support: Zeiler. Study supervision: Kaufmann.
Correspondence
Frederick A. Zeiler, Section of Neurosurgery, Department of Surgery, University of Manitoba, GB-1 820 Sherbrook St., Winnipeg, MB R3A 1R9, Canada. email: [email protected].
Vascularized rotational temporal bone flap for repair of anterior skull base defects: a novel operative technique Frederick A. Zeiler, MD, and Anthony M. Kaufmann, MD Section of Neurosurgery, University of Manitoba, Winnipeg, Manitoba, Canada
Repair of anterior skull base defects with vascularized grafts poses a significant challenge, given the location and small number of adequately sized vessels for free-flap anastomosis. This is particularly the case in the setting of redo surgery or in patients with preexisting soft-tissue trauma. Even more difficult is achieving a vascularized bone flap closure of such bony defects. The authors report a novel technique involving a rotational temporal bone flap with a temporalis muscle vascularized pedicle, which was used to repair an anterior fossa bony and soft-tissue defect created by recurrent malignancy. A 55-year-old man with history of scalp avulsion during a motor vehicle accident, anterior fossa/nasopharyngeal malignant neuroendocrine carcinoma postresection, and bone flap infection presented with a recurrence of his skull base malignancy. The tumor was located in the anterior fossa, extending interhemispherically and down through the cribriform plate, ethmoid air cells, and extending into the nasopharyngeal cavity. Resection of the recurrent tumor was performed. The bony defect in the anterior skull base was repaired with a novel vascularized rotational temporal bone flap, with acceptable separation of the nasopharynx from the intracranial cavity. The vascularized rotational temporal bone flap, in which a temporalis muscle pedicle is used, provides a novel and easily accessible means of vascularized bone closure of anterior skull base defects without the need for microsurgical free-flap grafting. http://thejns.org/doi/abs/10.3171/2014.11.JNS141979
Key Words temporal flap; reconstruction; vascularized bone; skull base
A
graft reconstruction of the skull base poses significant challenges. Using vascularized grafts in the reconstructive process is ideal, although the location and access to such skull defects imposes limitations.2,5 Depending on surrounding anatomy, vascular patency, and the size of the graft site, microsurgical free flaps may provide a solution. However, the availability of suitable graft site vessels is usually limited due to the underlying disease6 and the resections leading to the initial defect. Furthermore, an autologous vascularized bone graft can be even more difficult to find and place in such areas. Anterior fossa defects are particularly difficult to repair with vascularized grafts, given the location and limitautologous
tions of the surrounding vascular anatomy for microvascular free-flap anastomosis. Such cranial base defects are commonly reconstructed using autologous free bone with either rotational temporalis1,4 or free tensor fascia lata grafts.3 We describe a novel technique to acquire a vascularized bone flap that will provide both hard- and soft-tissue closure of anterior fossa defects: the vascularized rotational temporal bone flap.
Methods
We retrospectively reviewed the chart of a patient who underwent a novel technique in the repair of an anterior skull base defect left by a malignancy.
submitted August 29, 2014. accepted November 5, 2014. include when citing Published online May 8, 2015; DOI: 10.3171/2014.11.JNS141979. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. ©AANS, 2015
J Neurosurg May 8, 2015
1
F. A. Zeiler and A. M. Kaufmann
Results
Case Description We report the case of a 55-year-old man with a medical history significant for frontal scalp avulsion secondary to a motor vehicle collision 10 years prior. He presented to neurosurgery initially with headaches, nasal obstruction, and epistaxis. Admission CT and MRI studies demonstrated a large nasopharyngeal mass spanning from the middle turbinate through the frontal floor, and interhemispherically between the frontal lobes of the brain. Results of the metastatic workup were negative. The patient underwent a bifrontal transbasal approach for resection of his anterior skull base tumor. Some tumor was left attached to the anterior cerebral arteries, given its significant adhesion to these vessels on attempted microsurgical dissection. The final pathology findings demonstrated a malignant nasopharyngeal neuroendocrine carcinoma. During the patient’s l-month follow-up visit in the clinic, concerns of bone flap infection were raised, given a fluctuant subgaleal collection. He had not received radiotherapy at this point, and chemotherapy was deemed inappropriate by the medical oncology specialist, given the histological diagnosis. Exploration of the wound demonstrated pus and suspected bone flap infection. The bifrontal craniotomy bone was removed and discarded, with the wound debrided and irrigated. The patient received 8 weeks of intravenous antimicrobial therapy for Staphylococcus aureus. Radiation was delayed until the cessation of antibiotics. Then, while waiting to start radiotherapy, the patient noticed increasing headaches and epistaxis. The MRI studies obtained at that time displayed a significant recurrence of both the nasal and intracranial portions of the tumor (Fig. 1). We elected to attempt repeat resection. The tumor was successfully resected, again with a small residual left attached to the anterior cerebral arteries. The dura mater was closed primarily with a small piece of temporalis fascia graft. A sizable bony defect, approximately 3.5 cm in diameter, was left in the frontal floor, extending through the posterior aspect of the frontal sinus, cribriform plate, ethmoid air cells, and the vomer. Given the concerns of
prior infection and planned radiotherapy, our goal was to achieve closure of this defect and provide a barrier between the intracranial and nasal cavities. The plastic surgeon harvested a free tensor fascia lata graft with fat from the right thigh, a portion of which was packed beneath the frontal floor. Bone closure was then achieved via a rotated pedicled temporal bone flap from the right calvaria. Details on the vascularized bone flap can be seen in the Operative Technique section. Additional tensor fascia lata with fat was then placed between this and the dura before craniotomy closure with a premolded titanium craniotomy plate. Operative Technique: Vascularized Temporal Bone Flap After lesion removal from the anterior skull base, soft tissue was stripped from the bone edges of the skull base. The anterior fossa defect was exposed until bleeding bone edges were identified. This defect measured approximately 3.5 cm in diameter. Tensor fascia lata graft was packed into the ethmoid space, as described above. The temporal bone donor site was exposed as follows (Fig. 2). First, subgaleal exposure of the temporalis muscle was accomplished with interfascial dissection. This was to expose the posterior portion of the temporalis muscle origin from the superior temporal line, and to allow for a large strip of vascularized temporalis for future rotation. Second, a 3.5-cm-diameter craniectomy was marked for our desired temporal bone graft (Figs. 2A and 3 left). Third, the temporal craniectomy was fashioned with a high-speed bur along the superior and posterior edges of the temporalis muscle origin (Fig. 2A). Fourth, the temporalis muscle was incised inferior to the planned craniectomy and the bone cut was continued (Fig. 2B and C). Fifth, the anterior aspect of the bone cut was performed through a tunnel beneath the temporalis muscle, taking care not to elevate the muscle from the bone graft (Fig. 2D). Sixth, the temporal craniectomy was elevated and mobilized along with the temporalis muscle pedicle that was created with a 3-cm strip of muscle incised parallel to the superior temporal line (Fig. 3 right). The muscle pedicle was then rotated to bring the temporal bone graft to the frontal floor defect (Fig. 4). We also expanded the keyhole bur hole (2 × 2 cm) to accommodate the temporalis muscle pedicle (Fig. 3 right, arrow). The bone graft was secured with a strip of titanium plating. Finally, the bifrontal craniectomy site was covered with a custom titanium plate. Figure 5 displays the postoperative sagittal, axial, and coronal MR images.
Discussion
FIG. 1. Preoperative MRI studies of recurrent neuroendocrine carcinoma. Left: Sagittal T1-weighted MRI study of the brain displaying an iso- and hypointense cystic mass extending from the rostrum of the corpus callosum to the nasal cavity, through the frontal floor. Right: Axial T1-weighted Gd-enhanced MRI study of the brain at the level of the mesencephalon displaying heterogeneous enhancement of interhemispheric lesion and cystic components. 2
J Neurosurg May 8, 2015
Skull base reconstruction has its challenges. Access, location, vascular anatomy for anastomosis, local tissue quality, local microbes, and future treatment of the underlying disease all play a role in the choice of materials for reconstruction. Numerous substrates have been used: autologous tissues, allografts, and synthetics, all with varying degrees of success documented.2,5,6 Ideally, a vascularized graft would be used to repair such defects. Furthermore, a vascularized bone graft would be ideal for repair. These can be quite difficult to acquire and transpose to the skull base.
Vascularized rotational temporal bone flap
FIG. 2. Illustrations of temporal bone flap preparation. A: Temporal bone flap marked at the level of the superior temporal line, with a high-speed drill initiating the craniotomy above the superior temporal line. B: Incision of temporalis muscle with scalpel, allowing the inferior portion of the craniotomy to be completed. C: Craniotomy continued inferiorly with a high-speed drill. D: Temporalis muscle elevated subperiosteally, allowing completion of the bone cut with the drill. Temporalis muscle remained attached to temporal bone flap. Copyright Jon Stepaniuk. Published with permission.
Reconstruction of the anterior fossa floor by using free fascial grafts, with or without free fat, has been documented.2,6 However, in previously irradiated and infected sites, these nonvascularized grafts carry a high risk of failure. Pedicled myocutaneous free flaps, typically transposed with the help of a plastic surgeon, provide a vascularized means of closure of such skull base defects and have also been reported.6 Difficulty with recipient vessel availability, caliber, and maintenance of patency with microsurgical anastomosis in the area of the anterior fossa leave these reconstructive tissue flaps as an option, but require significant technical expertise. In the setting of previously irradiated and infected tissue beds, with multiple previ-
ous operations, these pedicled free flaps may fail. Rotational temporalis slings over anterior fossa defects have also been described.2,6 However, the quality of this barrier between the nasal cavity and the anterior fossa is questionable. Finally, synthetic reconstruction in which titanium plating and a variety of bone cements are used has also been documented.2 These nonliving substrates carry a risk of infection in the setting of concomitant or previous irradiation, and provide only a mechanical barrier between the anterior fossa and the nasal cavity, with the hope of a fibrous closure over the graft and defect. With our reported operative technique, we have been able to provide a potential vascularized bone graft option
FIG. 3. Illustrations of lateral skull pre- and postcraniotomy. Left: Lateral skull view with planned temporal bone flap marked out at the level of the superior temporal line. Right: Lateral skull view with pedicled temporal bone flap harvested. The expanded slot drilled in the keyhole for the temporalis muscle is denoted by the arrow. Copyright Jon Stepaniuk. Published with permission.
FIG. 4. Illustrations of temporal bone flap rotation into the anterior skull base. Left: Vertex view of the skull displaying the anterior skull base defect and the pedicled temporal bone flap. Right: Vertex view of the skull displaying the pedicled temporal bone flap placed into the anterior skull base defect. Copyright Jon Stepaniuk. Published with permission. J Neurosurg May 8, 2015
3
F. A. Zeiler and A. M. Kaufmann
FIG. 5. Postresection and reconstruction MRI. A: Sagittal T1-weighted MRI study displaying repair of the anterior skull base defect. Arrow indicates the temporal bone flap plugging the anterior fossa bony defect. The hyperintense signal in the nasal cavity is the tensor fascia lata free graft. B: Axial T1-weighted FLAIR image displaying the anterior skull base with temporal bone flap in situ and secured with a plate (arrow). C: Coronal T1-weighted Gd-enhanced MRI study displaying temporal bone graft in the frontal floor defect (arrow).
for anterior fossa repairs by using a rotational temporal bone flap with a vascularized temporalis muscle pedicle. Although it is not clear how much blood supply will be delivered to our temporal bone flap through the attached temporalis muscle pedicle, we believe this construct will provide better potential for temporal bone flap viability. This technique may have benefits over other reconstructive options. First, the graft donor site is easily accessible through both standard bicoronal and pterional incisions. This reduces the need for a separate access to donor tissues. Second, the technique we have described to harvest the temporal bone is easy and requires standard neurosurgical equipment used for craniotomies. Third, the temporal bone graft may remain vascularized via a temporalis pedicle and provides a living substrate for anterior fossa repairs. It also means that the technical expertise for microvascular free-flap anastomosis is not required to achieve a vascularized graft. Fourth, the temporal graft described is a vascularized hard-tissue graft. This is ideal for repairs of hard-tissue defects such as in the anterior skull base. Fifth, the thickness of the bone graft can be altered to conform to the situation (for example, repair of the orbital roof). Finally, we believe that this technique can be performed by all neurosurgeons, without a significant learning curve. There are limitations to this technique. First, with rotation of the temporalis muscle from the superior temporal line, there exists a temporalis defect that can also be cosmetically undesirable. This can be remedied with implantable material, such as autologous fat injections. Second, it is unclear how well the bone remains vascularized, or how large a bone graft could be reliably sustained by the temporalis muscle rotational flap. Finally, the only evidence that our temporal bone graft is vascularized is the presence of ongoing diploic space hemorrhage after rotation of the flap. Overall, we hope that through the advantages of the described technique, we have provided all neurosurgeons with the ability to provide vascularized bone closure of anterior fossa defects.
Conclusions
The vascularized rotational temporal bone flap, with
4
J Neurosurg May 8, 2015
temporalis muscle pedicle, provides a novel and easily acquired vascularized hard-tissue graft for closure of anterior fossa defects.
Acknowledgment
Our thanks go to Jon Stepaniuk for the professional illustrations he provided for the operative technique described.
References
1. Atabey A, Vayvada H, Menderes A, Kirişoğlu U, Barutçu A: A combined reverse temporalis muscle flap and pericranial flap for reconstruction of an anterior cranial base defect: a case report. Ann Plast Surg 39:190–192, 1997 2. Bernal-Sprekelsen M, Rioja E, Enseñat J, Enriquez K, Viscovich L, Agredo-Limos FE, et al: Management of anterior skull base defect depending on its size and location. Biomed Res Int 2014:346873, 2014 3. Jalisi S, O’Gara B, Toshkezi G, Chin L: Local vascularized flap reconstruction of skull base—clinical outcomes and analysis. World Neurosurg 83:87–92, 2015 4. Kwon SG, Kim YO, Rah DK: Anterior cranial base reconstruction with a reverse temporalis muscle flap and calvarial bone graft. Arch Plast Surg 39:345–351, 2012 5. Marcus J, Laufer I, Mehrara B, Kraus D, Singh B, Bilsky MH: Anterior and anterolateral resection for skull base malignancies: techniques and complication avoidance. Neurosurg Clin N Am 24:11–18, 2013 6. Schmalbach CE, Webb DE, Weitzel EK: Anterior skull base reconstruction: a review of current techniques. Curr Opin Otolaryngol Head Neck Surg 18:238–243, 2010
Author Contributions
Conception and design: both authors. Acquisition of data: Zeiler. Analysis and interpretation of data: Zeiler. Drafting the article: both authors. Critically revising the article: both authors. Reviewed submitted version of manuscript: Zeiler. Approved the final version of the manuscript on behalf of both authors: Zeiler. Administrative/technical/material support: Zeiler. Study supervision: Kaufmann.
Correspondence
Frederick A. Zeiler, Section of Neurosurgery, Department of Surgery, University of Manitoba, GB-1 820 Sherbrook St., Winnipeg, MB R3A 1R9, Canada. email: [email protected].
