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Minimally invasive retrieval of a bullet from the L5–S1 neural foramina after transperitoneal gunshot wound
The Spine Journal 9 (2009) 169–173
Technical Reviews
Minimally invasive retrieval of a bullet from the L5–S1 neural foramina after transperitoneal gunshot wound Luis M. Tumiala´n, MD*, Raymond R. Walkup, MD, Sanjay K. Gupta, MD Emory University School of Medicine, Grady Memorial Hospital, Department of Neurosurgery, Atlanta, GA, USA Received 6 November 2007; accepted 11 March 2008
Abstract
BACKGROUND CONTEXT: In victims of gunshot wounds with retained bullet fragments in the central nervous system, delayed neurological deficit may result from copper-induced neurotoxicity. The mainstay of therapy involves surgical exploration and retrieval of fragments. PURPOSE: A patient who presented with delayed neurological deficit after a transperitoneal gunshot wound is presented. STUDY DESIGN: Technical report. METHODS: A 25-year-old male, who was the victim of a transperitoneal gunshot wound with a copper-jacketed bullet, presented several weeks after recovering from his abdominal injury. The patient presented with a worsening radiculopathy in the L5 distribution and progressive dorsiflexion weakness. Subsequent imaging demonstrated a bullet lodged lateral to the L5–S1 neural foramina. RESULTS: A minimally invasive approach with the use of a tubular retractor was used to retrieve the retained bullet. The lateral location of the bullet, the proximity of the nerve root to the bullet, and the limited visualization of the operative field from a minimally invasive approach, placed the nerve root at increased risk. Intraoperative myelography and electrophysiological monitoring were used to locate the nerve root in relation to the bullet and guide the extraction of the bullet. Postoperatively, the patient had complete resolution of his preoperative symptoms. CONCLUSIONS: In cases where proximity to neural structures and limited visualization of bony landmarks may increase the risk of injury when extracting a foreign body, intraoperative myelography and electrophysiological monitoring are valuable adjuncts to further elucidate the surgical anatomy for a minimally invasive approach. Ó 2009 Elsevier Inc. All rights reserved.
Keywords:
Bullet; Gunshot wound; Minimally invasive surgery; Spine
Introduction Civilian gunshot wounds account for approximately 13% to 17% of all spine and spinal cord injuries [1,2]. Neurologic deficits resulting from gunshot injury range from radiculopathy to complete spinal cord injury, depending on the level of injury [2]. The role of surgery in patients with no deficit or complete spinal cord injury is limited; however, clear indications exist for patients with FDA device/drug status: approved for this indication (META-RA tubular retractor). The authors do not have a financial relationship that creates, or may be perceived as creating, a conflict related to this article. * Corresponding author. Department of Neurosurgery, The Emory Clinic, 1365-B Clifton Road, N.E. Suite 6100, Atlanta, GA 30322, USA. Tel.: (404) 778-3895; fax: (404) 778-4472. E-mail address: [email protected] (L.M. Tumiala´n) 1529-9430/09/$ – see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.spinee.2008.03.008
incomplete spinal cord injury or progressive neurologic deficits [2–8]. Spinal instability, lead intoxication, copperinduced neural toxicity, and progressive neurologic deficit have been the main indications reported in the literature [9–12]. The reports in the literature of bullet retrieval have been done by laminectomy or vertebrectomy [2,9,12,13]. To date, reports of bullet retrieval by minimally invasive techniques have been limited [14]. The authors report their experience in the management of a patient who suffered a transperitoneal gunshot wound with a copper-jacketed bullet. Over the course of 6 weeks, the patient became progressively symptomatic with an L5 radiculopathy and exhibited dorsiflexion weakness. The authors present the clinical and radiographic findings, discuss the operative technique for bullet retrieval. The relevant literature regarding the operative management of gunshot wounds to the spine is reviewed.
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Case report History A 25-year-old man, who was the victim of a transperitoneal gunshot wound, presented to our institution 6 weeks after his injury reporting right lower extremity pain and weakness. At the time of his injury, the patient had undergone an exploratory laparotomy for repair of his multiple enterotomies. Given the patient’s critical condition at the time of the injury, he had no recollection of right lower extremity symptoms at the time of presentation. The patient had been discharged 2 weeks after his injury with the complaint of a mild right lower extremity radiculopathy. The patient was referred to the neurology service after reporting worsening right lower extremity symptoms and was started on gabapentin. Despite this, the patient had progressively worsening symptoms. His gabapentin dose was increased, he was started on methylprednisolone and referred to the neurosurgery service. Physical examination and radiographic findings On presentation to our clinic, the patient was ambulatory with a cane. He reported persistent pain in the L5 distribution, demonstrated 3/5 strength in dorsiflexion, and decreased light touch sensation on the dorsum of the foot. The patient had normal patellar and Achilles reflexes. The remainder of the patient’s neurological exam was without deficit. The patient had a mildly elevated erythrocyte sedimentation rate and C-reactive protein, and a normal white blood cell count. There was no abnormal elevation in his serum lead level. A computed tomography of the lumbosacral spine revealed a bullet lodged on the right anterior superior aspect of the alar wing of the sacrum, lateral to the superior articular process of the sacrum, and beneath the fifth lumbar transverse process (Fig. 1). The bullet appeared lodged immediately anterior to the L5–S1 facet on the right. Coronal reconstructions demonstrated this to be lateral to the L5–S1 neural foramina (Figs. 2 and 3). Operative technique With the patient prone on a Wilson frame, fluoroscopic guidance was used to plan an incision overtop the alar wing and L5 transverse process. A lumbar drain was placed preoperatively to facilitate intraoperative myelography. Using the METRx system (Medtronic, Sofamor Danek, Memphis, TN), a 2.0 cm incision was made and a sequence of dilators was used until a tubular retractor was able to be docked onto the lateral aspect of L5–S1 facet, inferior to the L5 transverse process and above the ala of the sacrum (Fig. 3). Before proceeding, 10 mL of Iohexol 180 mg/mL (Omnipaque, General Electric Company) was injected into the lumbar drain with fluoroscopic imaging. In this way, the L5 nerve root was confirmed to be medial and posterior
Fig. 1. Axial computed tomography image of the lumbosacral spine revealing the bullet lodged into the right alar wing of the sacrum anterior to the L5–S1 facet.
to the bullet. Thus, the decision was made to drill lateral on the transverse process of L5 away from the course of the nerve root established by myelography. The lateral aspect of the facet was also drilled, along with the superior aspect of the ala (Fig. 4). On completion of the bone removal, the neural foramen was entered and the L5 nerve root identified. As demonstrated by the intraoperative myelography, the bullet was identified lateral and anterior to the L5 nerve root. With electrophysiological monitoring following motor evoked potentials (MEPs), somatosensory evoked potentials, and electromyelography (EMG), a bayoneted retractor was used to retract the L5 nerve medially and an attempt was made to remove the bullet. Profound irritation of the L5 nerve root on EMG prompted removal of the retraction and continued removal of bone lateral to the nerve root. After completion of the bone removal, the L5 nerve root was again identified and retracted medially with a bayoneted nerve root retractor. The bullet was removed with direct visualization of the L5 nerve root without EMG demonstrating any irritation of the root. MEPs were monitored closely throughout this portion of the procedure. After removal of the bullet, the L5 nerve root was inspected and found to be intact. There was a significant inflammatory response in the surrounding area where the bullet was lodged. The nerve root itself appeared significantly inflamed. The blood loss for the procedure was estimated at 50 mL. Postoperative course The patient was ambulating without difficulty on the first postoperative day with marked improvement of his preoperative symptoms and was discharged on the second postoperative day. Four weeks after surgery the patient who reported complete resolution of his preoperative symptoms, was completely weaned off of gabapentin, steroids, and
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Fig. 3. A. Intraoperative fluoroscopic image of the tubular retractor system docked on the lateral aspect of the L5–S1 facet, inferior to the L5 transverse process and above the alar wing. After drilling out the lateral aspects of L5–S1 facet, the inferior aspect of the L5 transverse process, and the superior aspect of the ala, the bullet was identified and retrieved.
Fig. 2. Coronal computed tomography (CT) reconstructions demonstrating the position of the bullet relative to the transverse process of L5 and the sacral ala. Arrow demonstrating the neural foramina. (Top) The position of the bullet appears lateral to the exiting nerve root of L5. (Bottom) Three-dimensional volume rendered reconstruction of lumbosacral CT demonstrating the position of the bullet.
narcotics. He was ambulating independently. The bullet was sent to a ballistics laboratory as evidence, where it was confirmed to be a 9-mm copper-jacketed bullet. Discussion The location of the bullet in the patient reported herein, anterior and lateral to the nerve root, lodged in between the
transverse process of L5 and the alar wing of S1, presented several surgical options. Anterior, retroperitoneal, and posterior approaches to the area could be performed to reach the bullet. An anterior or retroperitoneal approach in this case has the advantage of retrieving the bullet from the direction in which it traveled. Thus, the surgeon may identify the bullet first, thereby minimizing the risk of injury to the nerve root, which lay behind it. The disadvantage in the anterior approach is the need for a laparotomy in a patient who has already required a delayed primary closure of his abdominal wound and repair of multiple enterotomies. The anterior exposure also places the iliac vessels at risk for injury when completing the lateral exposure onto the transverse process of L5 and alar wing of S1. The size of the incision and the extent of surgery required for a retroperitoneal approach, on the other hand, are the main detractors for this exposure. Because the bullet traveled transperitoneal prior lodging itself into the alar wing, the main disadvantage of a posterior approach is that the surgeon is approaching and extracting the bullet through a trajectory it did not travel with the nerve root in the path of the extraction. This requires the surgeon to first identify the L5 nerve root, mobilize and retract it, and then retrieve the bullet. The extent of dissection that would be required to accomplish this from a midline approach limits its usefulness. A lateral paraspinal muscle splitting approach as described by Wiltse and colleagues, however, would center the incision on the bullet intended to be retrieved [15,16]. The benefit of such an approach
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dissection, and retraction of the muscle. Although the incision and disruption of the musculature is minimized, it comes at the consequence of the operative view. In such an operation, osseous landmarks are critical to avoiding nerve root injury and safe retrieval of the bullet. The authors compensated for this by adding intraoperative myelography and electrophysiological monitoring. The intraoperative myelography allowed for identification of the nerve root with relation to the bullet before drilling. This directly impacted the authors’ decision on where to begin bone removal. The knowledge of the relative position of the bullet minimized the risk of injury to the nerve root. The electrophysiological monitoring revealed irritation of the nerve root during the initial attempt at bullet extraction and resulted in further removal of bone to minimize retraction on the nerve root. The bullet was successfully removed on the second attempt without nerve root irritation after the extended bone removal. The complete resolution of preoperative symptoms without sensory or motor deficits further demonstrates the value of these adjunctive measures in combination with this minimally invasive approach. Conclusion
Fig. 4. (Top) bone removed reconstruction bone removed
Postoperative computed tomography demonstrating the for the extraction of the bullet. (Bottom) Volume rendered demonstrating the trajectory of the tubular retractor and for the retrieval of the bullet.
is the wide exposure, which facilitates identification of the nerve root as it exits the foramen, followed by extraction of the bullet. The disadvantage is a 7 to 8 cm incision and wide division and retraction of the paraspinal musculature. In light of this, the authors considered retrieval of the bullet in a manner that would combine the benefits of a direct exposure through a minimally invasive approach. The rise of minimally invasive spine surgery over the past decade for elective lumbosacral disckectomies, decompressions, and fusions has decreased intraoperative blood loss, postoperative pain and hospital stays, and improved patient satisfaction [17]. More recently, surgeons have begun applying minimally invasive techniques to trauma, specifically, in the management of thoracolumbar fracture dislocations [18,19]. Although there is a single report of an endoscopic retrieval of a bullet in the subcutaneous tissues near the spine, to our knowledge, the use of a minimally invasive technique for retrieval of a retained bullet from the spine has not been previously reported [14]. The use of a minimally invasive tubular retractor centered over the bullet intended to be retrieved (Fig. 3) minimized the length of incision, the extent of muscle splitting
A symptomatic retained bullet in the lumbosacral spine may be safely removed through a minimally invasive approach. The use of intraoperative myelography and electrophysiological monitoring are valuable adjuncts to further elucidate the surgical anatomy for a minimally invasive approach onto the neural foramen, lateral to midline. In this case, these techniques collectively compensated for the limited field of vision and minimized risk of injury to the nerve root.
Acknowledgments The authors are grateful for the editorial assistance rendered by Andrea J. Porter and Rhonda Everett. References [1] Mirovsky Y, Shalmon E, Blankstein A, Halperin N. Complete paraplegia following gunshot injury without direct trauma to the cord. Spine 2005;30:2436–8. [2] Benzel EC, Hadden TA, Coleman JE. Civilian gunshot wounds to the spinal cord and cauda equina. Neurosurgery 1987;20:281–5. [3] Gupta S, Senger RL. Wandering intraspinal bullet. Br J Neurosurg 1999;13:606–7. [4] Karim NO, Nabors MW, Golocovsky M, Cooney FD. Spontaneous migration of a bullet in the spinal subarachnoid space causing delayed radicular symptoms. Neurosurgery 1986;18:97–100. [5] Kitchel SH. Current treatment of gunshot wounds to the spine. Clin Orthop Relat Res 2003;408:115–9. [6] Kuijlen JM, Herpers MJ, Beuls EA. Neurogenic claudication, a delayed complication of a retained bullet. Spine 1997;22:910–4. [7] Mariottini A, Delfini R, Ciappetta P, Paolella G. Lumbar disc hernia secondary to gunshot injury. Neurosurgery 1984;15:73–5.
L.M. Tumiala´n et al. / The Spine Journal 9 (2009) 169–173 [8] Soges LJ, Kinnebrew GH, Limcaco OG. Mobile intrathecal bullet causing delayed radicular symptoms. AJNR Am J Neuroradiol 1988;9:610. [9] Bono CM, Heary RF. Gunshot wounds to the spine. Spine J 2004;4: 230–40. [10] Tindel NL, Marcillo AE, Tay BK, Bunge RP, Eismont FJ. The effect of surgically implanted bullet fragments on the spinal cord in a rabbit model. J Bone Joint Surg Am 2001;83-A:884–90. [11] Messer HD, Cerza PF. Copper jacketed bullets in the central nervous system. Neuroradiology 1976;12:121–9. [12] Waters RL, Sie IH. Spinal cord injuries from gunshot wounds to the spine. Clin Orthop Relat Res 2003;408:120–5. [13] Arasil E, Tascioglu AO. Spontaneous migration of an intracranial bullet to the cervical spinal canal causing Lhermitte’s sign. Case report. J Neurosurg 1982;56:158–9. [14] Haramoto U, Kobayashi S, Okazaki M, Sekiguchi J. Endoscopic management of subcutaneous gunshot wound with irrigation technique. Ann Plast Surg 1998;40:646–9.
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[15] Wiltse LL, Bateman JG, Hutchinson RH, Nelson WE. The paraspinal sacrospinalis-splitting approach to the lumbar spine. J Bone Joint Surg Am 1968;50:919–26. [16] Wiltse LL. The paraspinal sacrospinalis-splitting approach to the lumbar spine. Clin Orthop Relat Res 1973;91:48–57. [17] Fessler RG, O’Toole JE, Eichholz KM, Perez-Cruet MJ. The development of minimally invasive spine surgery. Neurosurg Clin N Am 2006;17:401–9. [18] Wild MH, Glees M, Plieschnegger C, Wenda K. Five-year follow-up examination after purely minimally invasive posterior stabilization of thoracolumbar fractures: a comparison of minimally invasive percutaneously and conventionally open treated patients. Arch Orthop Trauma Surg 2007;127:335–43. [19] Rampersaud YR, Annand N, Dekutoski MB. Use of minimally invasive surgical techniques in the management of thoracolumbar trauma: current concepts. Spine 2006;31(11 Suppl):S96–S102; discussion S4.
Technical Reviews
Minimally invasive retrieval of a bullet from the L5–S1 neural foramina after transperitoneal gunshot wound Luis M. Tumiala´n, MD*, Raymond R. Walkup, MD, Sanjay K. Gupta, MD Emory University School of Medicine, Grady Memorial Hospital, Department of Neurosurgery, Atlanta, GA, USA Received 6 November 2007; accepted 11 March 2008
Abstract
BACKGROUND CONTEXT: In victims of gunshot wounds with retained bullet fragments in the central nervous system, delayed neurological deficit may result from copper-induced neurotoxicity. The mainstay of therapy involves surgical exploration and retrieval of fragments. PURPOSE: A patient who presented with delayed neurological deficit after a transperitoneal gunshot wound is presented. STUDY DESIGN: Technical report. METHODS: A 25-year-old male, who was the victim of a transperitoneal gunshot wound with a copper-jacketed bullet, presented several weeks after recovering from his abdominal injury. The patient presented with a worsening radiculopathy in the L5 distribution and progressive dorsiflexion weakness. Subsequent imaging demonstrated a bullet lodged lateral to the L5–S1 neural foramina. RESULTS: A minimally invasive approach with the use of a tubular retractor was used to retrieve the retained bullet. The lateral location of the bullet, the proximity of the nerve root to the bullet, and the limited visualization of the operative field from a minimally invasive approach, placed the nerve root at increased risk. Intraoperative myelography and electrophysiological monitoring were used to locate the nerve root in relation to the bullet and guide the extraction of the bullet. Postoperatively, the patient had complete resolution of his preoperative symptoms. CONCLUSIONS: In cases where proximity to neural structures and limited visualization of bony landmarks may increase the risk of injury when extracting a foreign body, intraoperative myelography and electrophysiological monitoring are valuable adjuncts to further elucidate the surgical anatomy for a minimally invasive approach. Ó 2009 Elsevier Inc. All rights reserved.
Keywords:
Bullet; Gunshot wound; Minimally invasive surgery; Spine
Introduction Civilian gunshot wounds account for approximately 13% to 17% of all spine and spinal cord injuries [1,2]. Neurologic deficits resulting from gunshot injury range from radiculopathy to complete spinal cord injury, depending on the level of injury [2]. The role of surgery in patients with no deficit or complete spinal cord injury is limited; however, clear indications exist for patients with FDA device/drug status: approved for this indication (META-RA tubular retractor). The authors do not have a financial relationship that creates, or may be perceived as creating, a conflict related to this article. * Corresponding author. Department of Neurosurgery, The Emory Clinic, 1365-B Clifton Road, N.E. Suite 6100, Atlanta, GA 30322, USA. Tel.: (404) 778-3895; fax: (404) 778-4472. E-mail address: [email protected] (L.M. Tumiala´n) 1529-9430/09/$ – see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.spinee.2008.03.008
incomplete spinal cord injury or progressive neurologic deficits [2–8]. Spinal instability, lead intoxication, copperinduced neural toxicity, and progressive neurologic deficit have been the main indications reported in the literature [9–12]. The reports in the literature of bullet retrieval have been done by laminectomy or vertebrectomy [2,9,12,13]. To date, reports of bullet retrieval by minimally invasive techniques have been limited [14]. The authors report their experience in the management of a patient who suffered a transperitoneal gunshot wound with a copper-jacketed bullet. Over the course of 6 weeks, the patient became progressively symptomatic with an L5 radiculopathy and exhibited dorsiflexion weakness. The authors present the clinical and radiographic findings, discuss the operative technique for bullet retrieval. The relevant literature regarding the operative management of gunshot wounds to the spine is reviewed.
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Case report History A 25-year-old man, who was the victim of a transperitoneal gunshot wound, presented to our institution 6 weeks after his injury reporting right lower extremity pain and weakness. At the time of his injury, the patient had undergone an exploratory laparotomy for repair of his multiple enterotomies. Given the patient’s critical condition at the time of the injury, he had no recollection of right lower extremity symptoms at the time of presentation. The patient had been discharged 2 weeks after his injury with the complaint of a mild right lower extremity radiculopathy. The patient was referred to the neurology service after reporting worsening right lower extremity symptoms and was started on gabapentin. Despite this, the patient had progressively worsening symptoms. His gabapentin dose was increased, he was started on methylprednisolone and referred to the neurosurgery service. Physical examination and radiographic findings On presentation to our clinic, the patient was ambulatory with a cane. He reported persistent pain in the L5 distribution, demonstrated 3/5 strength in dorsiflexion, and decreased light touch sensation on the dorsum of the foot. The patient had normal patellar and Achilles reflexes. The remainder of the patient’s neurological exam was without deficit. The patient had a mildly elevated erythrocyte sedimentation rate and C-reactive protein, and a normal white blood cell count. There was no abnormal elevation in his serum lead level. A computed tomography of the lumbosacral spine revealed a bullet lodged on the right anterior superior aspect of the alar wing of the sacrum, lateral to the superior articular process of the sacrum, and beneath the fifth lumbar transverse process (Fig. 1). The bullet appeared lodged immediately anterior to the L5–S1 facet on the right. Coronal reconstructions demonstrated this to be lateral to the L5–S1 neural foramina (Figs. 2 and 3). Operative technique With the patient prone on a Wilson frame, fluoroscopic guidance was used to plan an incision overtop the alar wing and L5 transverse process. A lumbar drain was placed preoperatively to facilitate intraoperative myelography. Using the METRx system (Medtronic, Sofamor Danek, Memphis, TN), a 2.0 cm incision was made and a sequence of dilators was used until a tubular retractor was able to be docked onto the lateral aspect of L5–S1 facet, inferior to the L5 transverse process and above the ala of the sacrum (Fig. 3). Before proceeding, 10 mL of Iohexol 180 mg/mL (Omnipaque, General Electric Company) was injected into the lumbar drain with fluoroscopic imaging. In this way, the L5 nerve root was confirmed to be medial and posterior
Fig. 1. Axial computed tomography image of the lumbosacral spine revealing the bullet lodged into the right alar wing of the sacrum anterior to the L5–S1 facet.
to the bullet. Thus, the decision was made to drill lateral on the transverse process of L5 away from the course of the nerve root established by myelography. The lateral aspect of the facet was also drilled, along with the superior aspect of the ala (Fig. 4). On completion of the bone removal, the neural foramen was entered and the L5 nerve root identified. As demonstrated by the intraoperative myelography, the bullet was identified lateral and anterior to the L5 nerve root. With electrophysiological monitoring following motor evoked potentials (MEPs), somatosensory evoked potentials, and electromyelography (EMG), a bayoneted retractor was used to retract the L5 nerve medially and an attempt was made to remove the bullet. Profound irritation of the L5 nerve root on EMG prompted removal of the retraction and continued removal of bone lateral to the nerve root. After completion of the bone removal, the L5 nerve root was again identified and retracted medially with a bayoneted nerve root retractor. The bullet was removed with direct visualization of the L5 nerve root without EMG demonstrating any irritation of the root. MEPs were monitored closely throughout this portion of the procedure. After removal of the bullet, the L5 nerve root was inspected and found to be intact. There was a significant inflammatory response in the surrounding area where the bullet was lodged. The nerve root itself appeared significantly inflamed. The blood loss for the procedure was estimated at 50 mL. Postoperative course The patient was ambulating without difficulty on the first postoperative day with marked improvement of his preoperative symptoms and was discharged on the second postoperative day. Four weeks after surgery the patient who reported complete resolution of his preoperative symptoms, was completely weaned off of gabapentin, steroids, and
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Fig. 3. A. Intraoperative fluoroscopic image of the tubular retractor system docked on the lateral aspect of the L5–S1 facet, inferior to the L5 transverse process and above the alar wing. After drilling out the lateral aspects of L5–S1 facet, the inferior aspect of the L5 transverse process, and the superior aspect of the ala, the bullet was identified and retrieved.
Fig. 2. Coronal computed tomography (CT) reconstructions demonstrating the position of the bullet relative to the transverse process of L5 and the sacral ala. Arrow demonstrating the neural foramina. (Top) The position of the bullet appears lateral to the exiting nerve root of L5. (Bottom) Three-dimensional volume rendered reconstruction of lumbosacral CT demonstrating the position of the bullet.
narcotics. He was ambulating independently. The bullet was sent to a ballistics laboratory as evidence, where it was confirmed to be a 9-mm copper-jacketed bullet. Discussion The location of the bullet in the patient reported herein, anterior and lateral to the nerve root, lodged in between the
transverse process of L5 and the alar wing of S1, presented several surgical options. Anterior, retroperitoneal, and posterior approaches to the area could be performed to reach the bullet. An anterior or retroperitoneal approach in this case has the advantage of retrieving the bullet from the direction in which it traveled. Thus, the surgeon may identify the bullet first, thereby minimizing the risk of injury to the nerve root, which lay behind it. The disadvantage in the anterior approach is the need for a laparotomy in a patient who has already required a delayed primary closure of his abdominal wound and repair of multiple enterotomies. The anterior exposure also places the iliac vessels at risk for injury when completing the lateral exposure onto the transverse process of L5 and alar wing of S1. The size of the incision and the extent of surgery required for a retroperitoneal approach, on the other hand, are the main detractors for this exposure. Because the bullet traveled transperitoneal prior lodging itself into the alar wing, the main disadvantage of a posterior approach is that the surgeon is approaching and extracting the bullet through a trajectory it did not travel with the nerve root in the path of the extraction. This requires the surgeon to first identify the L5 nerve root, mobilize and retract it, and then retrieve the bullet. The extent of dissection that would be required to accomplish this from a midline approach limits its usefulness. A lateral paraspinal muscle splitting approach as described by Wiltse and colleagues, however, would center the incision on the bullet intended to be retrieved [15,16]. The benefit of such an approach
172
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dissection, and retraction of the muscle. Although the incision and disruption of the musculature is minimized, it comes at the consequence of the operative view. In such an operation, osseous landmarks are critical to avoiding nerve root injury and safe retrieval of the bullet. The authors compensated for this by adding intraoperative myelography and electrophysiological monitoring. The intraoperative myelography allowed for identification of the nerve root with relation to the bullet before drilling. This directly impacted the authors’ decision on where to begin bone removal. The knowledge of the relative position of the bullet minimized the risk of injury to the nerve root. The electrophysiological monitoring revealed irritation of the nerve root during the initial attempt at bullet extraction and resulted in further removal of bone to minimize retraction on the nerve root. The bullet was successfully removed on the second attempt without nerve root irritation after the extended bone removal. The complete resolution of preoperative symptoms without sensory or motor deficits further demonstrates the value of these adjunctive measures in combination with this minimally invasive approach. Conclusion
Fig. 4. (Top) bone removed reconstruction bone removed
Postoperative computed tomography demonstrating the for the extraction of the bullet. (Bottom) Volume rendered demonstrating the trajectory of the tubular retractor and for the retrieval of the bullet.
is the wide exposure, which facilitates identification of the nerve root as it exits the foramen, followed by extraction of the bullet. The disadvantage is a 7 to 8 cm incision and wide division and retraction of the paraspinal musculature. In light of this, the authors considered retrieval of the bullet in a manner that would combine the benefits of a direct exposure through a minimally invasive approach. The rise of minimally invasive spine surgery over the past decade for elective lumbosacral disckectomies, decompressions, and fusions has decreased intraoperative blood loss, postoperative pain and hospital stays, and improved patient satisfaction [17]. More recently, surgeons have begun applying minimally invasive techniques to trauma, specifically, in the management of thoracolumbar fracture dislocations [18,19]. Although there is a single report of an endoscopic retrieval of a bullet in the subcutaneous tissues near the spine, to our knowledge, the use of a minimally invasive technique for retrieval of a retained bullet from the spine has not been previously reported [14]. The use of a minimally invasive tubular retractor centered over the bullet intended to be retrieved (Fig. 3) minimized the length of incision, the extent of muscle splitting
A symptomatic retained bullet in the lumbosacral spine may be safely removed through a minimally invasive approach. The use of intraoperative myelography and electrophysiological monitoring are valuable adjuncts to further elucidate the surgical anatomy for a minimally invasive approach onto the neural foramen, lateral to midline. In this case, these techniques collectively compensated for the limited field of vision and minimized risk of injury to the nerve root.
Acknowledgments The authors are grateful for the editorial assistance rendered by Andrea J. Porter and Rhonda Everett. References [1] Mirovsky Y, Shalmon E, Blankstein A, Halperin N. Complete paraplegia following gunshot injury without direct trauma to the cord. Spine 2005;30:2436–8. [2] Benzel EC, Hadden TA, Coleman JE. Civilian gunshot wounds to the spinal cord and cauda equina. Neurosurgery 1987;20:281–5. [3] Gupta S, Senger RL. Wandering intraspinal bullet. Br J Neurosurg 1999;13:606–7. [4] Karim NO, Nabors MW, Golocovsky M, Cooney FD. Spontaneous migration of a bullet in the spinal subarachnoid space causing delayed radicular symptoms. Neurosurgery 1986;18:97–100. [5] Kitchel SH. Current treatment of gunshot wounds to the spine. Clin Orthop Relat Res 2003;408:115–9. [6] Kuijlen JM, Herpers MJ, Beuls EA. Neurogenic claudication, a delayed complication of a retained bullet. Spine 1997;22:910–4. [7] Mariottini A, Delfini R, Ciappetta P, Paolella G. Lumbar disc hernia secondary to gunshot injury. Neurosurgery 1984;15:73–5.
L.M. Tumiala´n et al. / The Spine Journal 9 (2009) 169–173 [8] Soges LJ, Kinnebrew GH, Limcaco OG. Mobile intrathecal bullet causing delayed radicular symptoms. AJNR Am J Neuroradiol 1988;9:610. [9] Bono CM, Heary RF. Gunshot wounds to the spine. Spine J 2004;4: 230–40. [10] Tindel NL, Marcillo AE, Tay BK, Bunge RP, Eismont FJ. The effect of surgically implanted bullet fragments on the spinal cord in a rabbit model. J Bone Joint Surg Am 2001;83-A:884–90. [11] Messer HD, Cerza PF. Copper jacketed bullets in the central nervous system. Neuroradiology 1976;12:121–9. [12] Waters RL, Sie IH. Spinal cord injuries from gunshot wounds to the spine. Clin Orthop Relat Res 2003;408:120–5. [13] Arasil E, Tascioglu AO. Spontaneous migration of an intracranial bullet to the cervical spinal canal causing Lhermitte’s sign. Case report. J Neurosurg 1982;56:158–9. [14] Haramoto U, Kobayashi S, Okazaki M, Sekiguchi J. Endoscopic management of subcutaneous gunshot wound with irrigation technique. Ann Plast Surg 1998;40:646–9.
173
[15] Wiltse LL, Bateman JG, Hutchinson RH, Nelson WE. The paraspinal sacrospinalis-splitting approach to the lumbar spine. J Bone Joint Surg Am 1968;50:919–26. [16] Wiltse LL. The paraspinal sacrospinalis-splitting approach to the lumbar spine. Clin Orthop Relat Res 1973;91:48–57. [17] Fessler RG, O’Toole JE, Eichholz KM, Perez-Cruet MJ. The development of minimally invasive spine surgery. Neurosurg Clin N Am 2006;17:401–9. [18] Wild MH, Glees M, Plieschnegger C, Wenda K. Five-year follow-up examination after purely minimally invasive posterior stabilization of thoracolumbar fractures: a comparison of minimally invasive percutaneously and conventionally open treated patients. Arch Orthop Trauma Surg 2007;127:335–43. [19] Rampersaud YR, Annand N, Dekutoski MB. Use of minimally invasive surgical techniques in the management of thoracolumbar trauma: current concepts. Spine 2006;31(11 Suppl):S96–S102; discussion S4.