Clip slippage is a rare occurrence, and the scissoring or torsional failure of aneurysm clips is rarer still. Titanium clips have been implicated in a few such reported cases. The authors report its occurrence while using a fenestrated cobalt alloy clip for an internal carotid artery aneurysm which was identified by intraoperative angiography and rectified by re-applying a non-fenestrated cobalt alloy clip. The possible mechanism of this complication, and measures that may prevent its occurrence, including meticulous dissection, decompression when possible, proper clip selection, and intraoperative angiogram are described. 

Kariyattil, Rajeev

Panikar, Dilip

Sultan Qaboos University Medical Journal [SQUMJ]

English

PubMed

Sultan Qaboos University Scientific Journals

Sultan Qaboos University Med J, February 2013, Vol. 13, Iss. 1, pp. 179-182, Epub. 27th Feb 13Submitted 21ST Apr 12Revision Req. 7TH Aug 12, Revision Recd. 1ST Sep 12Accepted 6TH Oct 121Sultan Qaboos University Hospital, Muscat, Oman; 2Amrita Institute of Medical Sciences, Kochi, Kerala, India*Corresponding Author e-mail: rajeevkariyattil@gmail.com  انزالق مشابك سبائك الكوبالت أثناء جراحة متدد األوعية الدموية الدماغية تقرير حالة ومراجعة املنشوراتراجيف كاريتيل،ديليب بانيكارالدموية ما يزال نادرا. وقد  نتجت  معظم هذه  التواء م�صابك متدد الأوعية  اأو  امللخ�ض: انزلق امل�صابك ظاهرة نادرة احلدوث، وتداخل احلالت من م�صابك التيتانيوم.  وا�صفو التقرير اأبلغوا عن  حدوثه اأثناء ا�صتخدام م�صابك   �صبيكة الكوبالت املنخلة يف جراحة  متدد الأوعية الدموية يف  ال�رسيان ال�صباتي الداخلي التي مت حتديدها خالل العملية با�صتخدام الأ�صعة امل�صبغة  لالأوعية  وت�صحيحه من خالل اإعادة و�صع  م�صبك �صبيكة الكوبالت الغري املنخل. الآلية املحتملة لهذه امل�صاعفات، والتدابري التي قد حتول دون حدوثه، مبا يف ذلك الت�رسيح احلذر، اإزالة اأو تخفيف ال�صغط عندما يكون ذلك ممكنا، اختيار امل�صبك املنا�صب، والأ�صعة امل�صبغة اأثناء العملية.مفتاح الكلمات: متدد الأوعية الدموية الدماغية، ف�صل امل�صبك؛ الأ�صعة امل�صبغة ؛ تقرير حالة؛ الهند.abstract: Clip slippage is a rare occurrence, and the scissoring or torsional failure of aneurysm clips is rarer still. Titanium clips have been implicated in a few such reported cases. The authors report its occurrence while using a fenestrated cobalt alloy clip for an internal carotid artery aneurysm which was identified by intraoperative angiography and rectified by re-applying a non-fenestrated cobalt alloy clip. The possible mechanism of this complication, and measures that may prevent its occurrence, including meticulous dissection, decompression when possible, proper clip selection, and intraoperative angiogram are described.Keywords: Cerebral aneurysm; Clip failure; Intra-operative angiogram; Case report; India.Scissoring of a Cobalt Alloy Aneurysm Clip causing Slippage during Cerebral Aneurysm SurgeryCase report and review of literature*Rajeev Kariyattil1 and Dilip Panikar2case reportSecure clip placement is the key to successful aneurysm surgery. Clip failure after application, caused by twisting of the blades or scissoring rarely has been described in the literature.1–3 The failures that have been reported have followed the use of titanium clips. In these cases, the tensile property of the metal itself was suspected to be the main cause.However, other factors related to the aneurysm itself and clip application techniques may play an equally important role.Case ReportA 53-year-old hypertensive male presented with a good grade sub-arachnoid haemorrhage (SAH) of 3 days’ duration. A computed tomography (CT) scan of the brain showed a Fischer grade 4 SAH with ventriculomegaly. A digital subtraction angiogram (DSA) showed a 1.47 cm trilobed internal carotid artery (ICA) aneurysm of the communicating segment with a 2.7 mm wide neck. There was irregular narrowing of the ICA, suggestive of atherosclerosis [Figure1].The patient was admitted to Amrita Institute of Medical Sciences, Cochin, India, for clipping of the aneurysm through a right pterional approach. Exposure of the region showed the ICA to have Scissoring of a Cobalt Alloy Aneurysm Clip causing Slippage during Cerebral Aneurysm Surgery Case report and review of literature180 | SQU Medical Journal, February 2013, Volume 13, Issue 1atheromatous changes extending into the aneurysm neck and sac. After the neck was sufficiently exposed, a parallel clipping was achieved with a 10 mm bayonet-shaped fenestrated cobalt alloy Yasargil aneurysm clip (B. Braun Melsungen AG, Meslungen, Germany) with the fenestra enclosing the middle cerebral artery (MCA). There was evidence of parent vessel compromise which was corrected by readjusting the clip distally along the neck. The dome was aspirated to confirm satisfactory clipping.An intraoperative angiogram was then performed. The initial fluoroscopy images showed scisssoring of the blades and the angiogram showed refilling of the aneurysm [Figure 2]. On returning back to the operative field, it was found that the aneurysm had refilled with blood, which was leaking through the puncture site. Additionally, the clip was found to have rotated clockwise with the inner surface of one of the blades exposed [Figure 3].Temporary clipping was not considered due to the extensive atheromatous changes in the ICA. Instead the clip was gently de-rotated and removed. There was considerable distortion of the aneurysm neck, ICA, and MCA during this manoeuvre. Clipping was then achieved after a more complete dissection around the aneurysm neck, with a perpendicularly placed 9 mm curved cobalt alloy Yasargil aneurysm  clip. The check angiogram was found to be satisfactory [Figure 4 ].The postoperative course was complicated by a delayed left sided hemiparesis due to multiple MCA territory infarcts secondary to vasospasm, which  Figure 1: Preoperative angiogram showing internal carotid artery (ICA) aneurysm. Figure 2: Intraoperative angiogram showing scissoring of clip and filling of aneurysm. Figure 3: Intraoperative view showing rotated clip. Figure 4: Final intraoperative angiogram showing complete clipping and vasospasmRajeev Kariyattil and Dilip PanikarCase Report | 181improved with medical measures. DiscussionThe phenomenon of a “slipped” aneurysm following routine postoperative angiograms, although first described by Charles Drake, has been documented infrequently in the literature, and failure due to twisting of the blades or scissoring is rarer still.1–5The stability of an aneurysm clip during surgery depends on various factors operating simultaneously, most of which cannot be predicted based on the mechanical properties of the clip alone. Additionally, the current data are from in vitro testing and hardly mimic the real life situation.6-12 Of these, only one study shows the effect of torque on the twisting of clip blades.11Of the several factors that are responsible for the stability of the clip, the one most commonly reported is that of the clip’s mechanical properties. Pure titanium and titanium alloy clips have been implicated in all the reported cases of scissoring malfunction so far.1–3 Although there are several studies which show reliable closing forces and the stability of these clips, one of these showed inferior stability of titanium clips to torque forces compared to cobalt alloy clips.9–13 There are also concerns in using titanium clips for larger aneurysms due to the decreased opening of the clip blades.14 For cobalt alloy clips, the make, length, and geometry of the clips have all been shown to influence the closing forces.7,8,10 In particular, bayonet and fenestrated clips have been shown to have weaker closing forces when compared to standard straight clips.8 The clip used in our patient was a fenestrated bayonet-shaped cobalt alloy clip. This is an alpha-type clip with a single box lock mechanism for stability. Other similar clips like the Sugita (Mizuho Medical Co., Tokyo, Japan) have stabilisation bars to prevent scissoring.The next most important factor is aneurysm-related. Large complex aneurysms, especially those with a neck wider than 2 mm, require greater closing forces, which is often not achievable with a single clip. The presence of atherosclerosis further adds to the complexity by increasing wall thickness and stiffness.2,3,14 Both these factors were present in this case. But the nature of failure, (i.e. the rotation and scissoring occurring in a slightly delayed manner), cannot be explained by size and wall thickness alone. However, if the atheroma is non-uniformly distributed around the neck, one of the clip blades may gradually slide over a rigid part of the plaque, resulting in their scissoring over a short period of time after the clip placement, as occurred in this patient.The third—and probably most important factor—is procedure-related. A good neck exposure freeing all adhesions, decreasing intra-luminal pressure, and choosing the right clip and final placement, all contribute to clip stability.14 Torsional forces created while re-adjusting a clip in a large atheromatous neck can also result in scissoring, especially if the plaque is hard and eccentric, thereby preventing proper apposition of the blades. Temporary clip occlusion of the ICA and aspiration of the aneurysm provide the best conditions for a satisfactory clipping in such circumstances; however, these were not considered due to the presence of gross atheromatous changes in the parent vessel as seen in the angiogram as well as during surgery. Parallel clipping was initially performed to avoid kinking of the ICA. An additional clip, parallel and distal to the first after collapsing the sac, might have prevented the slipping. In the end, a simpler clipping solution with a standard clip in a perpendicular direction was found to be effective.The role of the intraoperative angiogram in achieving satisfactory clipping has been highlighted previously and cannot be over-emphasised.15,16ConclusionClip failure is a rare but distinct possibility and occurs when the clip is made to function in situations beyond its design parameters, irrespective of its make and mechanical properties. A good technique adhering to the basic principles of aneurysm surgery and choosing the right clip(s) for the right aneurysm are the keys to a successful outcome.The intraoperative angiogram is a valuable tool in identifying various unexpected and correctable problems, especially in complex aneurysms.Scissoring of a Cobalt Alloy Aneurysm Clip causing Slippage during Cerebral Aneurysm Surgery Case report and review of literature182 | SQU Medical Journal, February 2013, Volume 13, Issue 1References1. Hirashima Y, Kurimoto M, Kubo M, Endo S. Blade crossing of a pure titanium clip applied to a cerebral aneurysm: Case report. Neurol Med Chir (Tokyo) 2002; 42:123–4.2. Horiuchi T, Li Y, Seguchi T, Sato A, Aoyama T, Hanaoka Y, Hongo K. Clip blade scissoring with titanium bayonet clip in aneurysm surgery. Neurol Med Chir (Tokyo) 2012;52:84–6.3. Carvi y Nievas MN, Hollerhage HG. Risk of intraoperative aneurysm clip slippage: A new experience with titanium clips. J Neurosurg 2000; 92:478–80.4. Drake CG, Allcock JM. Postoperative angiography and the "slipped" clip. J Neurosurg 1973; 39:683–9.5. Asgari S, Wanke I, Schoch B, Stolke D. Recurrent hemorrhage after initially complete occlusion of intracranial aneurysms. Neurosurg Rev 2003; 26:269–74.6. Takayasu M, Nagatani T, Noda A, Shibuya M, Yoshida J. Clinical safety and performance of Sugita titanium aneurysm clips. Acta Neurochir (Wien) 2000; 142:159–63.7. Atkinson JL, Anderson RE, Piepgras DG. A comparative study in opening and closing pressures of cerebral aneurysm clips. Neurosurgery 1990; 26:80–5.8. Ooka K, Shibuya M, Suzuki Y. A comparative study of intracranial aneurysm clips: Closing and opening forces and physical endurance. Neurosurgery 1997; 40:318–23.9. Papadopoulos MC, Apok V, Mitchell FT, Turner DP, Gooding A, Norris J. Endurance of aneurysm clips: Mechanical endurance of Yasargil and Spetzler titanium aneurysm clips. Neurosurgery 2004; 54:966–72.10. Dujovny M, Kossovsky N, Kossowsky R, Perlin A, Segal R, Diaz FG, et al. Intracranial clips: An examination of the devices used for aneurysm surgery. Neurosurgery 1984; 14:257–67.11. Horiuchi T, Hongo K, Shibuya M. Scissoring of cerebral aneurysm clips: Mechanical endurance of clip twisting. Neurosurg Rev 2012; 35:219–25.12. Lawton MT, Ho JC, Bichard WD, Coons SW, Zabramski JM, Spetzler RF. Titanium aneurysm clips: Part I--Mechanical, radiological, and biocompatibility testing. Neurosurgery 1996; 38:1158–64.13. Lawton MT, Heiserman JE, Prendergast VC, Zabramski JM, Spetzler RF. Titanium aneurysm clips: Part III--Clinical application in 16 patients with subarachnoid hemorrhage. Neurosurgery 1996; 38:1170–5.14. Schmid-Elsaesser R, Steiger HJ. Aneurysm clip slippage. J Neurosurg 2000; 93:371–3.15. Tang G, Cawley CM, Dion JE, Barrow DL. Intraoperative angiography during aneurysm surgery: A prospective evaluation of efficacy. J Neurosurg 2002; 96:993–9.16. Chiang VL, Gailloud P, Murphy KJ, Rigamonti D, Tamargo RJ. Routine intraoperative angiography during aneurysm surgery. J Neurosurg 2002; 96:988–92.

Scissoring of a Cobalt Alloy Aneurysm Clip causing Slippage during Cerebral Aneurysm Surgery : Case report and review of literature

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Scissoring of a Cobalt Alloy Aneurysm Clip causing Slippage during Cerebral Aneurysm Surgery : Case report and review of literature

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