Reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm
- Department of Neurosurgery, Teikyo University Chiba Medical Center, Ichihara, Japan.
Shinya Miyamoto, Department of Neurosurgery, Teikyo University Chiba Medical Center, Ichihara, Japan.
DOI:10.25259/SNI_160_2023Copyright: © 2023 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Shinya Miyamoto, Hajime Nishido, Yasushi Ino, Katsumi Hoya. Reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm. 21-Apr-2023;14:147
How to cite this URL: Shinya Miyamoto, Hajime Nishido, Yasushi Ino, Katsumi Hoya. Reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm. 21-Apr-2023;14:147. Available from: https://surgicalneurologyint.com/surgicalint-articles/12269/
Background: Reversible and multiphasic parenchymal changes in magnetic resonance imaging (MRI) are exceedingly rare. The authors experienced a case of reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm.
Case Description: A 48-year-old woman had a sudden onset of severe headaches and was referred to us for coil embolization. She was alert-oriented and had no neurologic deficits. Her medical history was atopic dermatitis and metal allergy. A head computed tomography (CT) scan demonstrated subarachnoid hemorrhage, and three-dimensional-CT angiography revealed a left internal carotid artery-posterior communicating artery aneurysm. Coil embolization was performed on the next day and seven coils made by three different manufacturers were used for the embolization. Despite no neurologic deficits after the surgery and no abnormal findings in MRI 7 days after the coil embolization, an MRI 2 weeks after embolization demonstrated delayed multiple white matter high intense lesions on T2-weighted image and fluid-attenuated inversion recovery in the left hemisphere. Repeat MRI scans showed multiple high intense lesions at various locations and at different timings. The blood test revealed the elevation of the proportion of EOS up to 9.7%, strongly indicating some allergic response. The MRI scan obtained 3 months after the onset confirmed the complete disappearance of the lesions.
Conclusion: Given her history of metal allergy, and the reversible and multiphasic lesions in the non-vascular territories of the treated aneurysm, metal allergic encephalitis was most likely despite no clear evidence.
Keywords: Metal allergy, Coil embolization, Parenchymal changes, Multiphasic and reversible, Cerebral aneurysm
Delayed leukoencephalopathy (DLE) after coil endovascular surgery is a rare complication but has occasionally been reported.[
A 48-year-old Japanese woman had a sudden onset of severe headaches early in the morning during work and was transported to a local hospital. She was alert-oriented and had no neurologic deficits. She had a medical history of atopic dermatitis and metal allergy that had discouraged her from wearing any jewels.
A head computed tomography (CT) scan demonstrated a subarachnoid hemorrhage (SAH) around the basal cistern with predominant SAH in the left sylvian cistern. A three-dimensional-CT angiography revealed a left internal carotid artery (ICA)-posterior communicating artery (Pcom) aneurysm. Although an emergent aneurysm clipping surgery was scheduled, the patient preferred a coil embolization rather than an open surgery so that she was referred to us for a coil embolization.
On the next day after the onset, a coil embolization was performed using a simple technique under the general anesthesia. The left ICA angiogram confirmed an irregular-shaped aneurysm measuring 7.7 mm in the maximum diameter at the left ICA-Pcom junction. Besides the ICAPcom aneurysm, aneurysms at the bilateral middle cerebral artery (MCA) bifurcations and at the top of the right ICA were also revealed. Given the distribution of SAH as well as the size and the shape of the aneurysm, the left ICA-Pcom aneurysm was believed to be the cause of the SAH.
A guiding sheath (Flexor shuttle 7F × 90 cm ST 0.100”/2.54 mm) was advanced to the pre-petrous portion of the left ICA. A microcatheter (Excelsior SL-10 pre-shaped 90°) was placed in the aneurysm using a manual-shaped intermediate catheter (TACTICS 120 cm STR). Seven coils were used for the complete obliteration of the aneurysm (Raymond-Roy occlusion classification class I) and are listed in
(a) Head computed tomography (CT) scan revealing subarachnoid hemorrhage in the basal cistern and in the left ambient cistern, (b) pre-operative three-dimensional CT angiography depicting the left internal carotid-posterior communicating (IC-PC) aneurysm, (c) pre-operative cerebral angiogram confirming the left IC-PC aneurysm, and (d) post-operative cerebral angiogram showing the complete obliteration of the aneurysm (Raymond-Roy occlusion classification class I) by simple coil embolization.
Despite no neurologic deficits after the surgery and no abnormal findings on a MRI 7 days after the coil embolization, an MRI study performed 24 days after the embolization demonstrated a round lesion beside the posterior horn of the left lateral ventricle, as shown in
(a) Diffusion-weighted imaging (DWI) on postoperative day (POD) 7 showing no high signals, (b and c) fluid-attenuated inversion recovery (FLAIR) on POD7 showing no abnormal findings, (d) DWI on POD24 showing no high intense lesions, whereas (e and f) FLAIR on POD24 demonstrating a strange round high intense lesion beside the posterior horn of the left lateral ventricle. (g) DWI on POD44 showing no high signals, whereas, (h and i) FLAIR on POD44 depicting scattered small high intense lesions in the left frontal lobe, (j) DWI on POD146 showing no abnormal findings, and (k and l) FLAIR on POD146 confirming the complete disappearance of the high intense lesions.
Meanwhile, the ratio of eosinophils (EOS) among the leukocytes was 3.0% (0.0–7.0%) before the surgery, and it elevated up to 9.7% 16 days after the coil embolization and got back to 2.6% 147 days after the surgery, as shown in
Despite the MRI findings, the patient showed no neurologic deficits and complained of only mild headaches throughout the course. No specific treatments were performed, and the headaches gradually subsided and finally resolved completely.
The patient subsequently underwent a metal skin patch test that showed positive against only zinc though the patch test covered neither titanium, tungsten, nor molybdenum, as shown in
Coil embolization has emerged as the mainstay treatment for cerebral aneurysms. The prognosis and outcome after a coil embolization has proved to be as favorable as those after a clipping surgery in SAH patients. Nowadays, a wide range of coils for cerebral aneurysms have been produced and provided from many manufacturers worldwide.
Small scattered cerebral infarcts are not rare on a post-surgical MRI after a coil embolization. High intense lesions on DWI and FLAIR of the MRI study after coil embolization are mostly cerebral infarcts related to the surgery. First, we suspected scattered embolization associated with the surgery, though the patient had only headaches. However, we found that one of the presented high intense lesions showed atypical appearance such as a round and homogeneously high intensity located near the posterior horn that was in the nonvascular territory of the treated aneurysm. Moreover, those lesions disappeared in a few weeks without any treatments, and similar lesions appeared at separate locations in the same hemisphere. The patient never had neurologic deficits and had only mild headaches throughout the course, but these lesions continued for a few months after the surgery.
Delayed atypical white matter lesions after coiling have been documented. Metal allergy, acute disseminated encephalomyelitis (ADEM)-like reaction due to contrast medium,[
ADEM is mostly seen in young children who are infected with viruses or after vaccination shots. Since symptoms of ADEM are acute and severe, ADEM-like reactions due to contrast medium are unlikely to have occurred in our patient.
Although PGLA coils were not used for our patient, PVP is used in most of the catheters for hydrophilic coating. The detachment of PVP from the surface of a catheter has recently been reported to occur due to the friction between a catheter and a guidewire,[
A few past articles reported PVP allergies; however, they were all anaphylaxis.[
Many symptomatic patients received a corticosteroid regimen and recovered almost fully after treatment.[
Metal hypersensitivity reactions are usually manifested as a T-cell-mediated delayed type 4 reaction with characteristic cutaneous pruritic lesions.[
A delivery wire is generally made of stainless steel that is an alloy of iron, nickel, and molybdenum plus some plastic, even though the wire is only used during a surgery. Although a minute amount of nickel ion is released when the coils are detached from the delivery wire, the amount should be far below the acceptable level of safety.[
Coils for cerebral aneurysms are generally made of an alloy that contained 92% platinum and 8% tungsten. Platinum is a precious metal that is widely used for jewels and its allergy is rare. However, dermatitis caused by metal allergy after coil embolization for unruptured cerebral aneurysm was reported.[
Tungsten is known to have some metabolic and toxicity profiles. Despite this, tungsten and its compounds are not considered very toxic for humans. Most existing human toxicology information comes from chronic occupational exposure. However, in a previous case of urticaria after percutaneous varicocele coil embolization, the patient was found to be allergic to tungsten on the immunological tests.[
As far as the coil embolization systems that we used are concerned, it is notable that only the axium prime detachable coil system uses the stainless steel for coils, which means nickel stays in the body even after a simple coil embolization without stent-assistance. As most stents are made of nitinol that is an alloy made of 45% of titanium and 55% of nickel in general, there has been a great deal of concern regarding the release of nickel.[
The authors experienced a rare case of reversible parenchymal changes in the MRI after coil embolization for the ruptured cerebral aneurysm. Despite no clear evidence, given the medical history of metal allergies, no high signals on DWI, and delayed, reversible, and multiphasic lesions in the nonvascular territories of the treated aneurysm, metal-induced encephalitis was most likely in our case.
The authors certify that they have obtained all appropriate patient consent.
There are no conflicts of interest.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.
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