Aseptic Meningitis after Embolization of Cerebral Aneurysms Using Hydrogel-Coated Coils: Report of Three Cases

Case Reports

Endovascular occlusion of the aneurysm was performed with the patient under general anesthesia, with systemic heparinization. Meticulous aseptic technique was maintained throughout each procedure. Prophylactic intravenous antibiotics were not administered to the patients during the perioperative period. In the presented cases, a combination of bare platinum coils and hydrogel-coated coils was used to maximize the theoretic benefits of each coil type to achieve complete and durable occlusion of large aneurysms. Bare platinum coils were used to frame the aneurysms, whereas hydrogel-coated coils were used to fill the aneurysms.

Discussion

Second-generation new platinum detachable coil systems with biologically active properties are under development to enhance more durable aneurysm occlusion.^1,4 Hydrogel-coated coils are platinum coils coated with polymeric gel composed of cross-linked acrylamide/sodium acrylate that absorbs water by diffusion in an optimal acid-base environment of whole blood, resulting in swelling to improve the volumetric occlusion of aneurysms.¹ Perhaps humans occasionally have an inflammatory reaction to the hydrogel, even though such a reaction has not been demonstrated yet in animals.⁵

Thirty patients with unruptured aneurysms were treated with hydrogel-coated coils in combination with bare platinum coils or PGLA-coated coils in 1 patient, from September 2003 to February 2006. Of these patients, aseptic meningitis developed in 3. Diagnosis of aseptic meningitis was based on the clinical presentation and presence of supportive CSF findings in these patients. Small asymptomatic thrombosis was a complication in 5 patients, and delayed thromboembolic event, a complication in 1 patient. Aseptic meningitis or related hydrocephalus was not identified in 126 patients with 143 intracranial unruptured aneurysms treated with bare platinum coils alone during the same period. Our experience suggests that aseptic meningitis is a complication of HydroCoil use, which is not seen when platinum coils are used alone.

Two cases of aseptic meningitis and related hydrocephalus have been reported as a complication of combined use of hydrogel- and PGLA-coated coils.³ In our patients, aseptic meningitis developed after treatment with hydrogel-coated coils and bare platinum coils. The combined use of hydrogel- and PGLA-coated coils did not cause meningitis in our 1 patient.

HydroCoil-associated chemical meningitis can cause symptomatic hydrocephalus on the basis of our 1 patient. Patients who experience acute meningitis symptoms after use of hydrogel-coated coils should be evaluated by brain CT whenever they have symptoms indicative of hydrocephalus. For a patient showing clinical signs of meningitis shortly after an endovascular treatment procedure, the possibility of aseptic meningitis should be considered in patients treated with hydrogel-coated coils, though thorough evaluation and treatment for presumptive bacterial meningitis is also required in such patients.

Treatment was mainly supportive and included analgesics, antipyretics, and maintenance of fluid balance. Systemic corticosteroid therapy was given to modulate the coil-induced inflammatory response and resulted in good clinical response in all 3 patients. There was no clinical evidence for the presence of bacterial meningitis, and empiric antibiotic therapy was instituted during the interim, pending negative findings on cultures.

Although hydrogel-coated coils were approved by the United States Food and Drug Administration in 2002, studies of their clinical use remain limited. Although hydrogel-coated coils may presumably achieve enhanced volumetric occlusion of the aneurysms, additional risks of these coils should not outweigh the potential added benefits from their clinical use. There were 191 aneurysms treated in the HydroCoil for Endovascular Aneurysm Occlusion (HEAL) study,² with 1 case of aseptic meningitis (H.J. Cloft, personal communication, April 26, 2006). Our report of aseptic meningitis and related hydrocephalus after the use of hydrogel-coated coils suggests that a more judicious clinical use of this new device is warranted and that manufacturers should evaluate these issues during product development.