Three-Dimensional Packing with Complex Orbit Coils for the Endovascular Treatment of Intracranial Aneurysms

Population

Between January and February 2004, 20 consecutive patients with intracranial aneurysms were referred to our department for endovascular treatment. As shown in the Table, there were 12 women and eight men, with a mean age of 48 years (range, 31–73 years). Fourteen patients presented with subarachnoid hemorrhage (SAH) and were classified according to the Hunt and Hess (HH) scale (9): 12 patients were grade I or II, and two were grade IV. In six patients, the aneurysm was asymptomatic. Aneurysms were located in the anterior circulation in 17 cases and in the posterior circulation in three. Mean size of aneurysms was 5 mm (range, 3–11 mm) and two had an unfavorable neck size (>4 mm) or neck-to-sac ratio (>0.7). All patients underwent conventional angiography of both carotid arteries and vertebral arteries. Therapeutic alternatives were discussed between neurosurgical and neurointerventional teams.

Orbit Coils

The Orbit Coil consists of a shaped 0.012-inch platinum coil attached to a delivery tube. It is designed for use with the detachment syringe that is required to purge the system properly and detach the coil through a hydraulic detachment mechanism. Orbit coils are the evolution of the Trufill detachable coil system and present a reduced system profile to allow for compatibility with 0.014-inch microcatheters.

These coils are available in both 3D (Orbit complex and mini-complex coils according to their size) and helical shapes (Orbit helical coil). The complex coils present a 3D structure that is designed to fill the outer circumference of the aneurysm while leaving the inner space open for subsequent coils (Fig 1). All sizes from 2 to 20 mm are presently available.

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Fig 1.

The 3D configuration of the complex Orbit coil.

Endovascular Procedure

In all patients, the endovascular treatment was performed under general anesthesia and systemic heparinization. The adequacy of systemic anticoagulation was monitored by frequent measurements of the activated clotting time (ACT). A baseline ACT was obtained before the bolus infusion of heparin (50–75 IU/kg body weight), and hourly thereafter. The bolus infusion of heparin was followed by a continuous drip (1,000–1,500 IU/h), with the purpose of doubling the baseline ACT. In most patients, systemic heparinization was stopped at the end of the procedure. For wide-neck aneurysms or in cases with periprocedural complications, systemic heparinization was prolonged for 48–72 hours. Patients were treated by selective embolization with Orbit coils; we have tried to obtain a 3D packing of the aneurysms by forming a basket with a complex coil that was subsequently filled concentrically with smaller complex coils in an “onion-like” fashion. An Excelsior 10 microcatheter (Target Therapeutics, Fremont, CA) was used to deliver coils within the aneurysm. In two cases with unfavorable neck-to-sac ratio, the remodeling technique (10, 11) was used to avoid coil protrusion into the parent artery. Failure of endovascular treatment was defined as an impossibility to completely occlude an aneurysm with complex Orbit coils alone. In these cases, helical Orbit coils or Guglielmi detachable coils (GDC) were used to achieve aneurysm obliteration. After endovascular treatment, patients were transferred to the intensive care unit, and fluid balance, neurologic status, and blood pressure were carefully monitored.

Immediate Outcome

Patients were evaluated by angiography to document aneurysm obliteration. Angiographic results were classified as complete occlusion (no contrast filling the aneurysmal sac), neck remnant (residual contrast filling the aneurysmal neck), or residual flow (residual contrast filling the aneurysmal body). A senior neurosurgeon (J.-P.L.) recorded the clinical course, including worsening of symptoms and death. Clinical outcome was graded according to a modified Glasgow outcome scale (GOS) (12), as follows: excellent (neurologically intact); good (mild hemiparesis, cranial nerve palsy, or other deficit that does not interfere with daily functioning or work); fair (significant hemiparesis, aphasia, confusion, or other deficit that interferes with daily activities or prevents a return to work); and poor (coma or severe neurologic deficit rendering the patient dependent on family or nursing staff).

Patient Follow-up

Imaging follow-up included MR examination and MR angiography (MRA) at 6 months. We assessed both brain tissue by using axial spin-echo T1-weighted sequence, T2-weighted sequence, fluid-attenuated inversion recovery sequence and the intracranial vessels by using time-of-flight and gadolinium-enhanced angiography. Clinical examination by a senior neurosurgeon (J.-P.L.) was simultaneously obtained with the imaging control. No patient was lost, and follow-up MRAs were compared with immediate postembolization angiograms and then assigned to one of three categories: (1) further thrombosis, when the amount of contrast agent filling the aneurysm decreased; (2) unchanged, when a similar degree of aneurysm occlusion in multiple projections was found; and (3) recanalization, when an increase of the amount of contrast filling in the aneurysm was observed. Conventional angiography, MRA, and MR imaging were reviewed for all patients by two senior neuroradiologists together (B.L., X.L.).

Illustrative Cases

Case 1

A 37-year-old woman (patient 12) presented with a SAH (HH grade I), and conventional angiography (Fig 2A) revealed an anterior communicating artery aneurysm. The patient was treated by selective embolization with Orbit coils alone. Five complex coils were delivered within the aneurysm lumen, including a 9 mm/25 cm coil (Fig 2B), a 7 mm/21 cm coil (Fig 2C), a 5 mm/15 cm coil (Fig 2D), a 3 mm/3 cm coil (Fig 2E), and a 2 mm/2 cm coil. Conventional angiograms (Figs 2F, -G) at the end of the procedure showed a neck remnant. The patient made an excellent recovery and was discharged 12 days after the treatment. MRA at 6 months showed complete occlusion of the aneurysm (Fig 2H).

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Fig 2.

Subarachnoid hemorrhage in a 37-year-old woman.

Left ICA angiogram (A) shows an anterior communicating artery aneurysm with a length of 11 mm and a width that varied from 5 to 7 mm.

Selective embolization with complex Orbit coils only: five coils were delivered within the aneurysm lumen including a 9 mm/25 cm coil (B), a 7 mm/21 cm coil (C), a 5 mm/15 cm coil (D), a 3 mm/3 cm coil. (E), and a 2 mm/2 cm coil.

Conventional nonsubstracted (F) and substracted (G) angiograms at the end of the procedure show a neck remnant.

Follow-up MRA (H) at 6 months shows a complete aneurysm occlusion.

Case 2

A 44-year-old woman (patient 10) presenting with chronic headaches underwent brain imaging. An unruptured internal carotid artery (ICA) aneurysm was discovered, and the patient was referred to our department for embolization. Conventional angiography revealed a left ICA bifurcation aneurysm (Fig 3A). Selective coiling was performed with four complex coils delivered in a concentric fashion, including a 7 mm/21 cm coil (Fig 3B), a 4 mm/7 cm coil (Fig 3C), a 3 mm/4 cm coil (Fig 3D), and a 2 mm/2 cm coil (Fig 3E). Final result consisted of a complete occlusion and the patient was discharged 4 days after the treatment. MRA at 6 months showed a slight recanalization of the neck (Fig 3F).

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Fig 3.

Incidental cerebral aneurysm in a 44-year-old woman.

A, Left ICA angiogram shows a round 7 mm aneurysm of the ICA bifurcation.

Selective coiling with complex Orbit coils only: four coils were delivered in a concentric fashion within the aneurysmal sac including a 7 mm/21 cm coil (B), a 4 mm/7 cm coil (C), a 3 mm/4 cm coil (D), and a 2 mm/2 cm coil.

E, Conventional angiogram at the end of the embolization shows a complete occlusion.

F, Follow-up MRA at 6 months shows a slight recanalization of the neck (arrow).

Reliability of the Material

Endovascular treatment with complex Orbit coils alone was successfully performed in 16 patients. In four patients (patients 6, 7, 9, and 15), additional helical Orbit coils or GDC were required to complete aneurysm occlusion. In patients 6 and 15, the last 2 mm/1.5 cm complex coil could not be delivered because of its stiffness, and a 2 mm/2 cm helical coil (patient 6) and a 2 mm/3 cm Ultra-Soft GDC (patient 15) were placed instead to occlude the aneurysm neck. In a 73-year-old woman (patient 7) with a tortuous ICA, the microcatheter kicked back during delivery of the first complex coil. In this case, only Ultra-Soft GDCs were used allowing to occlude the aneurysmal sac with correct stabilization of the microcatheter. In a 50-year-old woman (patient 9) with a middle cerebral artery bifurcation aneurysm, a 4 mm/3 cm complex coil placed within the aneurysmal sac did not adapt a 3D configuration. Because of the nonoptimal basket, the coil was not detached and was retrieved. A 4 mm/4 cm 3D GDC was then delivered allowing to bridge the aneurysm neck. These four patients (20%) were judged as failure of endovascular treatment with complex Orbit coils.

In a most of cases (round-shape aneurysms), a 3D packing could be achieved by filling the aneurysms in a concentric fashion (Fig 3). In two cases of aneurysms with an unusual shape (length ≫ width), however, it was judged safer to fill the aneurysm in “segments” (Fig 2) to prevent from high tension on the aneurysmal sac.

A total of 55 complex Orbit coils were used and easily passed through the microcatheter without any friction in all cases. In all aneurysms, from two to five complex coils were placed to obtain good packing. During the delivery process, the first complex coils were adapted smoothly to the aneurysm wall without any tendency to move in a tumbling manner. These coils automatically assumed their configuration upon deployment except the 4 mm/3 cm complex coil that did not behave like a 3D coil. Smaller complex coils were then added and densely packed the aneurysms without any compartmentalization. At the end of the procedure, the last complex coil (2 mm/2 cm or 2 mm/1.5 cm) could be delivered in all cases but two (patients 6 and 15) despite their stiffness that is superior to that of helical coils. No stretching of complex coils was encountered during their repositioning.

The detachment of all coils immediately occurred except for two 5 mm/15 cm complex coils that could not be detached and were retrieved and then exchanged. There was no coil rupture or involuntary coil detachment. In two cases of wide-neck aneurysms treated with the remodeling technique (10, 11), all Orbit coils were easily delivered during balloon inflation. No technical complication occurred in the present series.

Anatomic and Clinical Outcome

Endovascular treatment—with complex Orbit coils alone—in 16 patients resulted in 14 complete occlusions and two neck remnants. The modified GOS was excellent in 14 patients and good in two. One patient (patient 13) with a grade IV SAH kept a mild hemiparesis despite uneventful and effective endovascular treatment. In one patient (patient 19) with a ruptured AcomA aneurysm, a thromboembolic complication resulted in an anterior cerebral artery infarct. The patient kept a mild lower limb weakness. Follow-up MRA at 6 months were obtained in all 16 patients and showed 14 complete occlusions, one neck remnant, and only one slight recanalization.