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Year : 2013  |  Volume : 61  |  Issue : 5  |  Page : 523--525

Retrieval of a microcatheter from arteriovenous malformations after hemorrhage following Onyx embolization

Paritosh Pandey1, Rakshit Shetty2, Paramveer Sabharwal2, HR Aravinda2,  
1 Department of Neurosurgery, NIMHANS, Bengaluru, Karnataka, India
2 Department of Neuroimaging and Interventional Radiology, NIMHANS, Bengaluru, Karnataka, India

Correspondence Address:
Paritosh Pandey
Department of Neurosurgery, NIMHANS, Bengaluru - 560 029, Karnataka


Retained microcatheter is a rare complication during embolization of arteriovenous malformations (AVMs). Following the availability and popularization of Onyx, the incidence of retained catheter has become lesser. Though there have been reports of retained microcatheter during embolization of AVM with Onyx, there has been only one previous report of surgical retrieval of retained microcatheter. We report the second case of retrieval of retained microcatheter following embolization of AVM with Onyx.

How to cite this article:
Pandey P, Shetty R, Sabharwal P, Aravinda H R. Retrieval of a microcatheter from arteriovenous malformations after hemorrhage following Onyx embolization.Neurol India 2013;61:523-525

How to cite this URL:
Pandey P, Shetty R, Sabharwal P, Aravinda H R. Retrieval of a microcatheter from arteriovenous malformations after hemorrhage following Onyx embolization. Neurol India [serial online] 2013 [cited 2022 Jun 29 ];61:523-525
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Embolization of cerebral arteriovenous malformations (AVMs) is an accepted form of treatment and is used either as a curative treatment, or more commonly as an adjunct to surgery or radiosurgery. Recently, embolization with Onyx has improved the total obliteration rates of AVM with embolization. [1],[2] The advantage of Onyx over glue in embolization is that Onyx is hydrophilic and non-adhesive and hence longer injections can be given in the nidus and hence larger portions of AVM can be embolized, leading to better cure rates. Retained microcatheter has been reported during Onyx embolization. [3],[4],[5] However the surgical retrieval of a retained microcatheter has been described only once in the literature. [6] This report presents a case of cerebellar AVM who during Onyx embolization developed intraprocedural hemorrhage with retained microcatheter.

 Case Report

Here we describe a case of a 27-year-old female patient who presented with sudden onset headache, vomiting and worsening of sensorium. Computed tomography (CT) scan done at the other facility showed left cerebellar hemorrhage with intraventricular extension and hydrocephalus. She was managed with placement of an external ventricular drain, mechanical ventilation and decongestants. She was extubated with improvement in sensorium. At 2 months after the bleed, she was asymptomatic, except for mild cerebellar signs. Angiogram revealed a 3.2 cm × 2.2 cm × 1.8 cm AVM, supplied by hemispheric branches of left posterior inferior cerebellar artery (PICA) and draining superiorly into the transverse sinus [Figure 1]a and b. She was planned for embolization of the AVM, followed by surgical excision. Through a groin access, 5F Envoy guiding catheter was placed in the left vertebral artery. An UltraFlow microcatheter was taken with support of a Mirage 008 microguidewire and the catheter was maneuvered into the hemispheric branch of the PICA feeding the AVM [Figure 1]c. During the embolization with Onyx, contrast extravasation was noted from the AVM, suggestive of a bleed. Heparin was immediately reversed with protamine sulfate. Attempts to remove the microcatheter from the nidus were unsuccessful, as there was undue traction on the nidus, which had already ruptured. Hence the microcatheter was not removed and was tied in the groin. A CT scan revealed left cerebellar hematoma, with hydrocephalus [Figure 1]d. Patient's pupils were dilated and not reacting. A right side external ventricular drain was placed immediately and patient was shifted to the operating room. A left paramedian suboccipital craniectomy was performed. Cerebellum was tense and bulging after dural opening, but became lax after hematoma removal which was on the surface of the AVM. There were large dilated and arterialized veins seen on the surface of the AVM. The nidus was identified and circumferential dissection was performed. The main feeding artery was identified and on palpation of the feeder with a forceps, the microcatheter was identified as a hard substance within the soft vessel. After coagulation of the feeder close to the nidus, the nidus was removed. Following this, the distal end of the microcatheter could be seen through the lumen of the feeding artery to which it was stuck. There was no Onyx seen at the distal end of the microcatheter. The groin was then exposed and gentle traction was applied from the groin and the microcatheter was retrieved [Figure 1]h. The feeding artery was then coagulated again and hemostasis was achieved and wound was closed. Post-operatively, the patient was electively ventilated for 2 days. She had persistent hydrocephalus, for which ventriculo-peritoneal shunt was performed. A post-operative angiogram did not reveal any residual AVM [Figure 1]e-g. At 3-month follow-up, she did not have any other deficits except for gait ataxia and is independent for her activities of daily living.{Figure 1}


Entrapment of a microcatheter is a potential problem and has been described more with embolization with N-butylcyanoacrylate, due to the adhesive nature of the embolization agent. However, there are few reports of retained microcatheter during embolization of AVM with Onyx. [3],[4],[7],[8],[9],[10] The presumption is that because of its hydrophilic and non-adhesive nature, embolization with Onyx would eliminate the risk of retained microcatheters. However, because the technique of Onyx embolization involves formation of a proximal plug over the microcatheter and because of this plug, the catheter can give resistance while being pulled following embolization. There can be a large amount of traction on the embolized nidus as well, which can lead to retained microcatheter. The factors that predispose to microcatheters being retained during Onyx embolization are large amount of reflux along the microcatheter, prolonged injection times, tortuosity of the feeding artery and steam-shaping of the catheter. With the availability of detachable-tip microcatheters, this is likely to become less of a complication. In the present case, we believe the microcatheter was retained due to the excessive tortuosity of the feeding vessel that did not allow the transmission of force to the distal end and the rupture occurred due to increased pressure in a small feeding artery.

Various endovascular techniques have been described to retrieve the stuck microcatheter, including over-the-catheter retrieval [9] and monorail snare method. [7] Some interventionalists advocated leaving the catheter in the circulation and treating the patient with anti-platelets. [8] However, there is a small risk of thromboembolism, because of retained foreign body in the circulation. In this patient, this was not an option, because there was AVM rupture and she had to be operated in emergency.

There has been only one previous report of microsurgical retrieval of microcatheter following Onyx embolization. [6] In that patient, the microcatheter was retained following second stage of embolization and the position of the feeding artery was identified with stereotactic guidance. After confirming the position of the microcatheter and resection of the nidus, the microcatheter was pulled from the cranial end. In our view, the microcatheter should be retrieved by pulling it from the groin and not the cranial end, because of undue traction on the small vessels of the brain while pulling from the cranial end. Though there is a very small risk of some Onyx sticking to the open end of the microcatheter and risk of embolism during retrieval of the microcatheter from the caudal end, we believe that the risk if minimal and there is a higher risk of traction and rupture of the catheter because of the tortuosity of the feeding vessel. The caudal retrieval of the catheter is straightforward. The use of stereotactic guidance is also not required, as the identification of the feeding vessel leads one to the position of the catheter.


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