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Traumatic aneurysm of the occipital artery secondary to paintball injury
Clinical Neurology and Neurosurgery 111 (2009) 105–108
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Case report and Review of the literature
Traumatic aneurysm of the occipital artery secondary to paintball injury Neely John a , James L. Leach b , Tyagi Rachana a , Francesco T. Mangano a,∗ a Department of Neurological Surgery, University of Cincinnati College of Medicine, Division of Pediatric Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA b Departments of Radiology, University of Cincinnati College of Medicine and Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
a r t i c l e
i n f o
Article history: Received 23 January 2008 Received in revised form 16 May 2008 Accepted 4 August 2008 Keywords: Traumatic aneurysm Paintball injury Pediatric trauma Occipital artery
a b s t r a c t Paintball is an “extreme sport” that has been steadily growing in popularity since the early 1980s. Although this activity is considered recreational, there are a number of inherent dangers associated. Most notably, the number of head and neck injuries due to paintball participation has been increasing in recent years. In this paper we present the first reported case of occipital artery traumatic pseudoaneurysm resulting from a paintball accident. The presentation, diagnosis and intraoperative findings are detailed. A discussion including a review of the literature is also presented. The authors recommend a re-evaluation of guidelines within the paintball sporting industry, including improvements in protective equipment. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Paintball is a sport that has been steadily gaining popularity since it was first introduced in the early 1980s [1]. Unfortunately, its rise in popularity has been associated with a dramatic rise in the number of head and neck injuries, especially ocular trauma [2–4]. We present the first reported case of a post-traumatic pseudoaneurysm of the occipital artery resulting from a paintball game accident. In the 1990s, the game of paintball began to shift from being played exclusively on professional courses, which enforce the use of safety equipment to protect the eyes and face, to being played in private groups that often neglect the usage of proper safety equipment [3,1]. This transition has been made possible by the increasing availability of non-powder guns, such as paintball guns, in stores. It is now possible to purchase a paintball gun with ammunition for less than 100 US dollars [1]. Further contributing to the growing number of paintball-related injuries is the increasing technological sophistication of paintball equipment. Muzzle velocities of modern paintball guns now range on average from 107 to 290 m/s [5]. Despite their obvious power, the guns are sold to minors as toys.
Abbreviations: CTA, computerized tomographic angiography; VVG, Voerhoeff and Von Geissen; STA, superficial temporal artery. ∗ Corresponding author at: Division of Pediatric Neurosurgery Cincinnati Children’s Hospital Medical Center, MLC 2016, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. Tel.: +1 513 636 4726; fax: +1 513 636 2808. E-mail addresses: [email protected], [email protected] (F.T. Mangano). 0303-8467/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.clineuro.2008.08.006
Low power guns, with muzzle velocities closer to 107 m/s, have a minimum age requirement of 10 years, while high power guns, with velocities closer to 290 m/s, are sold to children as young as 16 [5]. 2. Case report 2.1. Presentation A 16-year-old male presented to Cincinnati Children’s Hospital Medical Center with worsening left sided occipital headaches and a history of trauma to his occiput. He had been shot in the back of the head 6 months prior, during a paintball game. The patient had subsequently developed a steadily enlarging, painful, pulsatile mass in the region of the left occipital artery. The patient did not complain of a subjective bruit or tinnitus. 2.2. Examination The patient’s neurological exam – including cranial nerves, strength, sensation, reflexes and cerebellar findings – was normal. The patient’s only significant clinical finding was a tender, pulsatile, 1 cm × 1 cm × 1 cm compressible mass in his left occipital region. Doppler ultrasound demonstrated a subcutaneous anechoic mass adjacent to the left occipital squama with intrinsic high resistance arterial flow (Fig. 1). Computerized tomographic angiography (CTA) revealed a focal, ellipsoidal collection of contrast, contiguous with the left occipital artery, approximately 6 cm to the left of midline, medial to the left lambdoid suture, measuring
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N. John et al. / Clinical Neurology and Neurosurgery 111 (2009) 105–108
Fig. 1. Doppler ultrasound. Internal color Doppler depicts flow within the lesion with a characteristic “to-and-fro” morphology typical of arterial aneurysms. This results from alternating flow direction during the cardiac cycle (arrows). The occipital artery is identified extending directly into the aneurysm (arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
10 mm × 5 mm × 10 mm (Fig. 2). The occipital bone was normal, without evidence of fracture or periosteal reaction. There were no intracranial abnormalities identified or abnormal foci of contrast enhancement. 2.3. Operation The patient was taken to surgery for resection of the lesion. A traumatic aneurysm of the distal subcutaneous portion of the occipital artery was identified and carefully dissected away from the adherent greater occipital nerve. The lesion was circumferentially mobilized, and the parent occipital artery was ligated and divided both proximal and distal to the lesion. The lesion was resected and submitted for pathological examination. No bony abnormality was noted. 2.4. Histological examination The gross specimen consisted of polypoid rubbery tan/brown tissue measuring 1.5 cm × 1.3 cm × 0.7 cm. Cut sections confirmed the luminal diameter of the lesion to be 5 mm. Light microscope examination showed hyalinization of the arterial wall and edematous changes. The Voerhoeff and Von Geissen (VVG) stain is an elastin staining technique that, in normal vessels, highlights the complete layer of the internal elastic lamina. In this case, the layer was focally disrupted and consistent with the diagnosis of pseudoaneurysm (Fig. 3(a)). The lumen of the artery contained organizing thrombus (Fig. 3(b)).
Fig. 3. A, B-VVG (a) and hemotoxilin and eosin (b) stained microscopic slides, demonstrating the damage to the inner two layers of the occipital artery as a result of the impact of the paintball pellet (70× magnification). IEL, internal elastic lamina; E, elastica; T, thrombus; FN, laminated fibrin with neutrophils.
2.5. Post-operative course The patient was discharged to home on post-operative day 1, after an uneventful course. At 12 months post-operative follow up, a well-healed incision and no evidence of recurrence was demonstrated. 3. Discussion
Fig. 2. CTA with 3D volume rendering demonstrates a 10 mm × 5 mm × 10 mm saccular aneurysm (arrow) contiguous with the occipital artery (arrowheads) overlying the left occipital bone.
Paintball is considered an “extreme sport” with definite risks that are not to be neglected. The tremendously high muzzle velocities that many commercially available paintball guns are now able to generate makes this sport more dangerous than it may initially appear. The current standards, according to the American Society for Testing and Materials International, state that protective equipment must be worn providing eye and adnexal protection from paintballs. No further recommendations have been made to specifically protect other parts of the head [6]. In this report we present the first case in the medical literature to our knowledge of a post-traumatic occipital artery pseudoaneurysm resulting from a paintball injury. We found four cases reported in the literature of traumatic occipital artery pseudoaneurysm, none of which were attributed to paintball injury [7–10]. All prior paintball-related injuries evaluated at Cincinnati Children’s Hospital Medical Center have only involved the orbit (Table 1). In most cases of traumatic aneurysm to superficial arteries of the scalp, blunt trauma causes a disruption of the vessel wall. The
N. John et al. / Clinical Neurology and Neurosurgery 111 (2009) 105–108 Table 1 Summary of all paintball related injuries seen at Cincinnati Children’s Hospital Medical Center from 1991 to 2007 Site of injury
No. of cases
Eye Occiput
4 1a
Total
5
a
Refers to the present case of post-traumatic pseudoaneurysm to the occipital artery.
resultant hemorrhage is retained in a sac formed by the surrounding soft tissues, and a fibrous wall develops. In some instances, part of the arterial wall is retained in the sac, while a further possibility may be a shearing of the adventitia and muscle coats to leave an unsupported intima, which bulges to form an aneurysm [10]. Usually the presentation consists of an enlarging, pulsatile mass, in the superficial scalp region, that is sometimes painless but usually tender to touch, and a previous history of trauma to the scalp will further suggest the diagnosis [9]. The traumatic aneurysm reported here developed as a result of the blunt force delivered to the scalp by the impact of an airborne paintball pellet. Zwann et al. suggested that because paintball pellets are designed to rupture on impact, there is no exit wound, and thus the pellet’s total energy is released at the site of impact [11]. Therefore, tissue damage is proportional to the product of projectile mass and the square of impact velocity. The small size, high mass and extremely high velocities of paintball pellets fired from non-powder guns explains their ability to cause such severe ocular and vascular damage [3,11]. While the moment of inertia of paintball pellets rupturing on impact may be not high enough to cause intracranial brain damage, significant soft tissue damage is likely in the case of injury to an unprotected scalp. In this case, the impact and resulting shock waves caused mechanical disruption of the arterial wall, producing a transmural rent that subsequently led to the development of a pseudoaneurysm. The occipital artery is at an increased risk for the development of blunt force injuries specifically where it approaches bone edges that are poorly covered by muscle. The occipital artery has been conceptualized as having three segments from proximal to distal: the digastric, sub-occipital and sub-galeal segments, respectively [12]. In the region of the superior nuchal line, the sub-occipital segment of the artery crosses a sagittal plane, which intersects the midpoint of the lambdoid suture on that side [7]. This section of the occipital artery is vulnerable to trauma, with little underlying muscle tissue to provide cushioning between vessel and bone. As the occipital artery courses over the superior nuchal ridge, it crosses over, contacts and indents the greater occipital nerve in the nuchal subcutaneous layer. This anatomic relationship has been cited as a cause of neurovascular compression syndromes resulting in occipital neuralgia [13]. In our patient, we found direct contact between the aneurysm and the greater occipital nerve at surgery, emphasizing the potential risk of nerve damage associated with injury in this anatomic region. The literature also presents a useful review of imaging techniques used in the diagnosis of aneurysms to the scalp area. Modern neuroimaging techniques allow elegant non-invasive assessment of post-traumatic abnormalities of the distal branches of the external carotid artery [14,9]. Ultrasound is a rapid technique that allows identification of internal flow characteristics within a palpable subcutaneous lesion by the use of color Doppler techniques. The typical “to-and-fro” flow characteristics of aneurysms can be identified, and the artery of origin can be demonstrated. This test can be performed at the bedside, can definitively diagnose the lesion as vascular in origin, and requires no contrast injection or radiation
107
exposure. CTA is the most definitive non-invasive technique for the diagnosis of these lesions. The vessel of origin, exact luminal morphology, and relationship to adjacent osseous and soft tissue structures can be demonstrated well, particularly with the use of modern surface and volume rendering techniques—all valuable information for therapeutic decision-making [14]. Treatment options for traumatic pseudoaneurysm include simple resection of the aneurysm, proximal ligation of the parent artery or trapping of the aneurysm [9]. Direct thrombin injections have also been employed, though inducing embolism is a possible complication [8]. Yang et al. suggest using N-butyl-2-cyanoacrlyate for percutaneous embolization, instead of thrombin, as the previous results in rapid casting, thus making it easier to terminate the injection at the appropriate time. For superficially located, large pseudoaneurysms, such as the one reported here, surgical resection may be the first therapeutic option [9]. As noted, our literature review uncovered only four cases reporting aneurysm to the occipital artery, all reports being pseudoaneurysms specifically. Of these pseudoaneurysms, blunt force trauma was the cause attributed in each case, though none by way of paintball injury [7–10]. Given the rarity of traumatic aneurysm in the occipital artery, we felt this particular case report was indicative of the elevated risk inherent in the sport of paintball. Based on the severity of this and other paintball-related injuries, we suggest that the paintball sporting industry re-evaluate its safety precautions for paintball play by considering the introduction of protective equipment for the entire head, such as a soft helmet or a padded cap [1,5,15]. We also recommend the education of parents as to the potential for injury inherent in the use of paintball guns. Greater awareness of such risks would temper the incorrect yet prevalent impression that paintball guns are merely harmless toys. Lastly, prevention is the best treatment for paintball related injuries. We therefore suggest that the industry consider increasing the minimum age requirements for both low and high power paintball guns. Acknowledgments The authors would like to thank Lili Miles M.D., of the University of Cincinnati and Cincinnati Children’s Hospital Medical Center, Department of Pathology, for her assistance in preparing and presenting the histopathology slides for the purpose of publication. References [1] Arman KF, Sharon F. Eye injuries associated with paintball guns. Int Ophthalmol 1999;22:169–73. [2] Agrawal V, Li C, Minhas S, Ralph D. Paint ball injury resulting in penoscrotal lymphedema. Urology 2006;67:1288–9. [3] Fineman MS, Fischer DH, Jeffers JB, Buerger DG, Repke C. Changing trends in paintball sport-related ocular injuries. Arch Ophthalmol 2000;118(1):60–4. [4] Joudi JN, Lux MM, Sandlow JI. Testicular rupture secondary to paint ball injury. J Urol 2004;171(2):797. [5] Laraque D. Injury risk of nonpowder guns. Pediatrics 2004;114(5):1357–61. [6] ASTM International. Standard specification for eye protective devices for paintball sports; 2006. [7] Aquilina K, Carty F, Keohane C, Kaar GK. Pseudoaneurysm of the occipital artery: an unusual cause of persisting headache after minor head injury. Ir Med J 2005;98(7):215–7. [8] Yang H-J, Choi Y-H. Postraumatic pseudoaneurysm in scalp treated by direct puncture embolization using N-butyl-2-cyanoacrylate: a case report. Korean J Radiol 2005;6:37–40. [9] Mendez JC, Sendra J, Poveda P, Garcia-Leal R. Endovascular treatment of traumatic aneurysm of the occipital artery. Cardiovasc Intervent Radiol 2006;29:486–7. [10] Boles DM, van Dellen JR, van de Heever CM, Lipschitz R. Traumatic aneurysms of the superficial temporal and occipital arteries: case reports and review. S Afr Med J 1977;51(10):313–4. [11] Zwann J, Bybee L, Casey P. Eye injuries during training exercises with paint balls. Mil Med 1996;161:720–2.
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[12] Alvernia JE, Fraser K, Lanzino G. The occipital artery: a microanatomical study. Neurosurgery 2006;58(1 Suppl):114–22. [13] Shimizu S, Oka H, Osawa S, Fukushima Y, Utsuki S, Tanaka R, et al. Can proximity of the occipital artery to the greater occipital nerve act as a cause of idiopathic greater occipital neuralgia? An anatomical and histological evaluation of the artery-nerve relationship. Plast Reconstr Surg 2007;119(7):2029–34.
[14] Walker MT, Liu BP, Salehi SA, Badve S, Batjer HH. Superficial temporal artery pseudoaneurysm: diagnosis and preoperative planning with CT angiography. Am J Neuroradiol 2003;4:147–50. [15] Mason JO, Feist RM, White MF. Ocular trauma from paintball-pellet war games. South Med J 2002;95(2):218–22.
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Case report and Review of the literature
Traumatic aneurysm of the occipital artery secondary to paintball injury Neely John a , James L. Leach b , Tyagi Rachana a , Francesco T. Mangano a,∗ a Department of Neurological Surgery, University of Cincinnati College of Medicine, Division of Pediatric Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA b Departments of Radiology, University of Cincinnati College of Medicine and Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
a r t i c l e
i n f o
Article history: Received 23 January 2008 Received in revised form 16 May 2008 Accepted 4 August 2008 Keywords: Traumatic aneurysm Paintball injury Pediatric trauma Occipital artery
a b s t r a c t Paintball is an “extreme sport” that has been steadily growing in popularity since the early 1980s. Although this activity is considered recreational, there are a number of inherent dangers associated. Most notably, the number of head and neck injuries due to paintball participation has been increasing in recent years. In this paper we present the first reported case of occipital artery traumatic pseudoaneurysm resulting from a paintball accident. The presentation, diagnosis and intraoperative findings are detailed. A discussion including a review of the literature is also presented. The authors recommend a re-evaluation of guidelines within the paintball sporting industry, including improvements in protective equipment. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Paintball is a sport that has been steadily gaining popularity since it was first introduced in the early 1980s [1]. Unfortunately, its rise in popularity has been associated with a dramatic rise in the number of head and neck injuries, especially ocular trauma [2–4]. We present the first reported case of a post-traumatic pseudoaneurysm of the occipital artery resulting from a paintball game accident. In the 1990s, the game of paintball began to shift from being played exclusively on professional courses, which enforce the use of safety equipment to protect the eyes and face, to being played in private groups that often neglect the usage of proper safety equipment [3,1]. This transition has been made possible by the increasing availability of non-powder guns, such as paintball guns, in stores. It is now possible to purchase a paintball gun with ammunition for less than 100 US dollars [1]. Further contributing to the growing number of paintball-related injuries is the increasing technological sophistication of paintball equipment. Muzzle velocities of modern paintball guns now range on average from 107 to 290 m/s [5]. Despite their obvious power, the guns are sold to minors as toys.
Abbreviations: CTA, computerized tomographic angiography; VVG, Voerhoeff and Von Geissen; STA, superficial temporal artery. ∗ Corresponding author at: Division of Pediatric Neurosurgery Cincinnati Children’s Hospital Medical Center, MLC 2016, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. Tel.: +1 513 636 4726; fax: +1 513 636 2808. E-mail addresses: [email protected], [email protected] (F.T. Mangano). 0303-8467/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.clineuro.2008.08.006
Low power guns, with muzzle velocities closer to 107 m/s, have a minimum age requirement of 10 years, while high power guns, with velocities closer to 290 m/s, are sold to children as young as 16 [5]. 2. Case report 2.1. Presentation A 16-year-old male presented to Cincinnati Children’s Hospital Medical Center with worsening left sided occipital headaches and a history of trauma to his occiput. He had been shot in the back of the head 6 months prior, during a paintball game. The patient had subsequently developed a steadily enlarging, painful, pulsatile mass in the region of the left occipital artery. The patient did not complain of a subjective bruit or tinnitus. 2.2. Examination The patient’s neurological exam – including cranial nerves, strength, sensation, reflexes and cerebellar findings – was normal. The patient’s only significant clinical finding was a tender, pulsatile, 1 cm × 1 cm × 1 cm compressible mass in his left occipital region. Doppler ultrasound demonstrated a subcutaneous anechoic mass adjacent to the left occipital squama with intrinsic high resistance arterial flow (Fig. 1). Computerized tomographic angiography (CTA) revealed a focal, ellipsoidal collection of contrast, contiguous with the left occipital artery, approximately 6 cm to the left of midline, medial to the left lambdoid suture, measuring
106
N. John et al. / Clinical Neurology and Neurosurgery 111 (2009) 105–108
Fig. 1. Doppler ultrasound. Internal color Doppler depicts flow within the lesion with a characteristic “to-and-fro” morphology typical of arterial aneurysms. This results from alternating flow direction during the cardiac cycle (arrows). The occipital artery is identified extending directly into the aneurysm (arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
10 mm × 5 mm × 10 mm (Fig. 2). The occipital bone was normal, without evidence of fracture or periosteal reaction. There were no intracranial abnormalities identified or abnormal foci of contrast enhancement. 2.3. Operation The patient was taken to surgery for resection of the lesion. A traumatic aneurysm of the distal subcutaneous portion of the occipital artery was identified and carefully dissected away from the adherent greater occipital nerve. The lesion was circumferentially mobilized, and the parent occipital artery was ligated and divided both proximal and distal to the lesion. The lesion was resected and submitted for pathological examination. No bony abnormality was noted. 2.4. Histological examination The gross specimen consisted of polypoid rubbery tan/brown tissue measuring 1.5 cm × 1.3 cm × 0.7 cm. Cut sections confirmed the luminal diameter of the lesion to be 5 mm. Light microscope examination showed hyalinization of the arterial wall and edematous changes. The Voerhoeff and Von Geissen (VVG) stain is an elastin staining technique that, in normal vessels, highlights the complete layer of the internal elastic lamina. In this case, the layer was focally disrupted and consistent with the diagnosis of pseudoaneurysm (Fig. 3(a)). The lumen of the artery contained organizing thrombus (Fig. 3(b)).
Fig. 3. A, B-VVG (a) and hemotoxilin and eosin (b) stained microscopic slides, demonstrating the damage to the inner two layers of the occipital artery as a result of the impact of the paintball pellet (70× magnification). IEL, internal elastic lamina; E, elastica; T, thrombus; FN, laminated fibrin with neutrophils.
2.5. Post-operative course The patient was discharged to home on post-operative day 1, after an uneventful course. At 12 months post-operative follow up, a well-healed incision and no evidence of recurrence was demonstrated. 3. Discussion
Fig. 2. CTA with 3D volume rendering demonstrates a 10 mm × 5 mm × 10 mm saccular aneurysm (arrow) contiguous with the occipital artery (arrowheads) overlying the left occipital bone.
Paintball is considered an “extreme sport” with definite risks that are not to be neglected. The tremendously high muzzle velocities that many commercially available paintball guns are now able to generate makes this sport more dangerous than it may initially appear. The current standards, according to the American Society for Testing and Materials International, state that protective equipment must be worn providing eye and adnexal protection from paintballs. No further recommendations have been made to specifically protect other parts of the head [6]. In this report we present the first case in the medical literature to our knowledge of a post-traumatic occipital artery pseudoaneurysm resulting from a paintball injury. We found four cases reported in the literature of traumatic occipital artery pseudoaneurysm, none of which were attributed to paintball injury [7–10]. All prior paintball-related injuries evaluated at Cincinnati Children’s Hospital Medical Center have only involved the orbit (Table 1). In most cases of traumatic aneurysm to superficial arteries of the scalp, blunt trauma causes a disruption of the vessel wall. The
N. John et al. / Clinical Neurology and Neurosurgery 111 (2009) 105–108 Table 1 Summary of all paintball related injuries seen at Cincinnati Children’s Hospital Medical Center from 1991 to 2007 Site of injury
No. of cases
Eye Occiput
4 1a
Total
5
a
Refers to the present case of post-traumatic pseudoaneurysm to the occipital artery.
resultant hemorrhage is retained in a sac formed by the surrounding soft tissues, and a fibrous wall develops. In some instances, part of the arterial wall is retained in the sac, while a further possibility may be a shearing of the adventitia and muscle coats to leave an unsupported intima, which bulges to form an aneurysm [10]. Usually the presentation consists of an enlarging, pulsatile mass, in the superficial scalp region, that is sometimes painless but usually tender to touch, and a previous history of trauma to the scalp will further suggest the diagnosis [9]. The traumatic aneurysm reported here developed as a result of the blunt force delivered to the scalp by the impact of an airborne paintball pellet. Zwann et al. suggested that because paintball pellets are designed to rupture on impact, there is no exit wound, and thus the pellet’s total energy is released at the site of impact [11]. Therefore, tissue damage is proportional to the product of projectile mass and the square of impact velocity. The small size, high mass and extremely high velocities of paintball pellets fired from non-powder guns explains their ability to cause such severe ocular and vascular damage [3,11]. While the moment of inertia of paintball pellets rupturing on impact may be not high enough to cause intracranial brain damage, significant soft tissue damage is likely in the case of injury to an unprotected scalp. In this case, the impact and resulting shock waves caused mechanical disruption of the arterial wall, producing a transmural rent that subsequently led to the development of a pseudoaneurysm. The occipital artery is at an increased risk for the development of blunt force injuries specifically where it approaches bone edges that are poorly covered by muscle. The occipital artery has been conceptualized as having three segments from proximal to distal: the digastric, sub-occipital and sub-galeal segments, respectively [12]. In the region of the superior nuchal line, the sub-occipital segment of the artery crosses a sagittal plane, which intersects the midpoint of the lambdoid suture on that side [7]. This section of the occipital artery is vulnerable to trauma, with little underlying muscle tissue to provide cushioning between vessel and bone. As the occipital artery courses over the superior nuchal ridge, it crosses over, contacts and indents the greater occipital nerve in the nuchal subcutaneous layer. This anatomic relationship has been cited as a cause of neurovascular compression syndromes resulting in occipital neuralgia [13]. In our patient, we found direct contact between the aneurysm and the greater occipital nerve at surgery, emphasizing the potential risk of nerve damage associated with injury in this anatomic region. The literature also presents a useful review of imaging techniques used in the diagnosis of aneurysms to the scalp area. Modern neuroimaging techniques allow elegant non-invasive assessment of post-traumatic abnormalities of the distal branches of the external carotid artery [14,9]. Ultrasound is a rapid technique that allows identification of internal flow characteristics within a palpable subcutaneous lesion by the use of color Doppler techniques. The typical “to-and-fro” flow characteristics of aneurysms can be identified, and the artery of origin can be demonstrated. This test can be performed at the bedside, can definitively diagnose the lesion as vascular in origin, and requires no contrast injection or radiation
107
exposure. CTA is the most definitive non-invasive technique for the diagnosis of these lesions. The vessel of origin, exact luminal morphology, and relationship to adjacent osseous and soft tissue structures can be demonstrated well, particularly with the use of modern surface and volume rendering techniques—all valuable information for therapeutic decision-making [14]. Treatment options for traumatic pseudoaneurysm include simple resection of the aneurysm, proximal ligation of the parent artery or trapping of the aneurysm [9]. Direct thrombin injections have also been employed, though inducing embolism is a possible complication [8]. Yang et al. suggest using N-butyl-2-cyanoacrlyate for percutaneous embolization, instead of thrombin, as the previous results in rapid casting, thus making it easier to terminate the injection at the appropriate time. For superficially located, large pseudoaneurysms, such as the one reported here, surgical resection may be the first therapeutic option [9]. As noted, our literature review uncovered only four cases reporting aneurysm to the occipital artery, all reports being pseudoaneurysms specifically. Of these pseudoaneurysms, blunt force trauma was the cause attributed in each case, though none by way of paintball injury [7–10]. Given the rarity of traumatic aneurysm in the occipital artery, we felt this particular case report was indicative of the elevated risk inherent in the sport of paintball. Based on the severity of this and other paintball-related injuries, we suggest that the paintball sporting industry re-evaluate its safety precautions for paintball play by considering the introduction of protective equipment for the entire head, such as a soft helmet or a padded cap [1,5,15]. We also recommend the education of parents as to the potential for injury inherent in the use of paintball guns. Greater awareness of such risks would temper the incorrect yet prevalent impression that paintball guns are merely harmless toys. Lastly, prevention is the best treatment for paintball related injuries. We therefore suggest that the industry consider increasing the minimum age requirements for both low and high power paintball guns. Acknowledgments The authors would like to thank Lili Miles M.D., of the University of Cincinnati and Cincinnati Children’s Hospital Medical Center, Department of Pathology, for her assistance in preparing and presenting the histopathology slides for the purpose of publication. References [1] Arman KF, Sharon F. Eye injuries associated with paintball guns. Int Ophthalmol 1999;22:169–73. [2] Agrawal V, Li C, Minhas S, Ralph D. Paint ball injury resulting in penoscrotal lymphedema. Urology 2006;67:1288–9. [3] Fineman MS, Fischer DH, Jeffers JB, Buerger DG, Repke C. Changing trends in paintball sport-related ocular injuries. Arch Ophthalmol 2000;118(1):60–4. [4] Joudi JN, Lux MM, Sandlow JI. Testicular rupture secondary to paint ball injury. J Urol 2004;171(2):797. [5] Laraque D. Injury risk of nonpowder guns. Pediatrics 2004;114(5):1357–61. [6] ASTM International. Standard specification for eye protective devices for paintball sports; 2006. [7] Aquilina K, Carty F, Keohane C, Kaar GK. Pseudoaneurysm of the occipital artery: an unusual cause of persisting headache after minor head injury. Ir Med J 2005;98(7):215–7. [8] Yang H-J, Choi Y-H. Postraumatic pseudoaneurysm in scalp treated by direct puncture embolization using N-butyl-2-cyanoacrylate: a case report. Korean J Radiol 2005;6:37–40. [9] Mendez JC, Sendra J, Poveda P, Garcia-Leal R. Endovascular treatment of traumatic aneurysm of the occipital artery. Cardiovasc Intervent Radiol 2006;29:486–7. [10] Boles DM, van Dellen JR, van de Heever CM, Lipschitz R. Traumatic aneurysms of the superficial temporal and occipital arteries: case reports and review. S Afr Med J 1977;51(10):313–4. [11] Zwann J, Bybee L, Casey P. Eye injuries during training exercises with paint balls. Mil Med 1996;161:720–2.
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N. John et al. / Clinical Neurology and Neurosurgery 111 (2009) 105–108
[12] Alvernia JE, Fraser K, Lanzino G. The occipital artery: a microanatomical study. Neurosurgery 2006;58(1 Suppl):114–22. [13] Shimizu S, Oka H, Osawa S, Fukushima Y, Utsuki S, Tanaka R, et al. Can proximity of the occipital artery to the greater occipital nerve act as a cause of idiopathic greater occipital neuralgia? An anatomical and histological evaluation of the artery-nerve relationship. Plast Reconstr Surg 2007;119(7):2029–34.
[14] Walker MT, Liu BP, Salehi SA, Badve S, Batjer HH. Superficial temporal artery pseudoaneurysm: diagnosis and preoperative planning with CT angiography. Am J Neuroradiol 2003;4:147–50. [15] Mason JO, Feist RM, White MF. Ocular trauma from paintball-pellet war games. South Med J 2002;95(2):218–22.