Keywords

Patient

A 60-year-old female patient with a known medical history of high arterial blood pressure and hypothyroidism, who presented with diplopia, facial pain probably due to a compression of the V1 or V2 root of the 5th cranial nerve, and recurrent episodes of headaches, which had started 1 month before admission. The physical examination revealed a 6th cranial nerve palsy on the left-hand side.

Diagnostic Imaging

Diagnostic MRI/MRA revealed a large saccular aneurysm, related to the carotid-cavernous segment of the left ICA (not shown). A subsequent DSA was carried out, showing a left-hand large saccular aneurysm at the origin of a persistent primitive trigeminal artery (PPTA) (Fig. 1).

Fig. 1
figure 1figure 1

Diagnostic DSA of a patient with a symptomatic, large saccular left ICA aneurysm at the origin of a Saltzman type II PPTA (posterior-anterior projection (a) and lateral projection (b)). Rotational DSA with 3D reconstruction (c) showed the neck of the aneurysm in relation to the ICA and the PPTA trunk with an aneurysm height of 18 mm, a fundus width of 18 mm, and a neck diameter of 9 mm. Contrast medium injection and posterior-anterior projection of the right-hand (d) and left-hand (e) vertebral arteries and lateral projection of the left-hand vertebral artery (f), showing a lack of spontaneous PPTA filling (d, e). Lateral projection with contrast medium injection of the left vertebral artery with manual compression of the left common carotid artery (CCA) (so-called Allcock maneuver) demonstrated the filling of the PTA and its aneurysm (f). Note the complete filling of the basilar trunk during the compression of the left CCA. Both posterior cerebral arteries filled through the posterior communicating artery (PcomA)

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Treatment Strategy

The main treatment goal for this patient was to diminish the mass effect, which would relieve the symptoms arising from the cranial nerve palsy. Considering the size of the aneurysm, its location, and the mass effect, flow diversion therapy was chosen to induce progressive thrombosis of the aneurysm and decrease the transmitted pulsation on the adjacent cranial nerves. Due to the diameter of the PPTA and the presence of a persistent fetal predecessor to the PcomA, it was intended to use an adjuvant deconstruction therapy with coil occlusion of the PPTA to decrease the flow demand into the PPTA and therefore indirectly into the aneurysm.

Treatment

Procedure #1, 01.07.2009: endovascular coil packing of a large, unruptured saccular aneurysm of the left ICA at the origin of a PPTA and occlusion of the PPTA

Anesthesia: general anesthesia; 10,000 IU unfractionated heparin (Riveparin, Rivero) IV. Premedication: 1× 100 mg ASA (Aspirin, Bayer Vital) PO daily and 1× 75 mg clopidogrel (Troken, Laboratorio Bagó) PO daily, both starting 5 days before the intervention

Access: left femoral artery, 7F sheath (Terumo); guide catheter: 6F Envoy (Cordis); microcatheter: Renegade 0.027″ (Boston Scientific); microguidewire: Transend 0.014″ (Stryker)

Implants: 1× Pipeline Embolization Device 4.5/22 mm (Medtronic); 3 coils, 1× microcoil Matrix Ultra Soft SR 3/60 mm, 1× microcoil Matrix Soft SR 2/80 mm, and 1× microcoil Matrix Soft SR 2/60 mm (then Boston Scientific, now Stryker)

Course of treatment: a 7F vascular sheath was placed in the left common femoral artery, and the left ICA was catheterized. Standard posterior-anterior, lateral, and oblique angiographic images were gathered for all vessels involved. Rotational angiography with 3D reconstruction was obtained in order to determine the most suitable working projection. The aneurysm measurements were made using standard methods and included aneurysm height, width, and neck diameter (18 × 18 × 9 mm). A 6F Envoy guide catheter was placed in the cervical segment of the left ICA. A Renegade 0.027″ microcatheter was navigated over the Transend 0.014″ 200 cm microguidewire and placed in the proximal M1 segment of the left MCA. The Pipeline Embolization Device was deployed and positioned from the distal cavernous segment to the proximal cavernous segment of the left ICA, covering the PPTA ostium. Angiography confirmed both the correct position of the device and significant contrast stagnation inside the aneurysm fundus.

The left VA was catheterized with a coaxial system, using the 6F Envoy guide catheter and placed in the V2 segment. The left PPTA was catheterized with an Excelsior SL10 microcatheter over a Transend 0.014″ 200 cm microguidewire, and coil occlusion of the PPTA was carried out. The final angiogram confirmed the occlusion of the left PPTA and complete filling of the basilar trunk, while all posterior circulation vessels remained patent. XperCT was performed immediately after the procedure, and no hemorrhagic or ischemic complications were encountered (Fig. 2).

Fig. 2
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Treatment of an unruptured, symptomatic, large saccular ICA aneurysm at the origin of a Saltzman type II PPTA. DSA immediately after deployment of the PED in the early arterial phase (a) and the late parenchymal angiographic phase (b) revealed contrast stagnation inside the aneurysm. Occlusion of the PPTA with road map visualization of the posterior circulation (c) showed the catheterization of the PPTA. DSA after the coil occlusion of the left-hand PPTA with injection of the left VA in frontal (d) and lateral projection (e) with complete occlusion of the PPTA distal to the BA (cast of coils (f)). Final follow-up DSA of the left ICA (g, h) and VasoCT (i) confirmed the adequate opening and position of the PED in the ICA

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Duration: 1st–23rd DSA run: 60 min; fluoroscopy time, 41 min

Complications: none

Post medication: 1× 100 mg ASA PO daily for life and 1× 75 mg clopidogrel for 6 months

Clinical Outcome

Procedure #1 was well tolerated, and the patient was discharged home 3 days later, with no change in clinical condition. At the 3-month clinical follow-up, an improvement in the left-hand trigeminal neuralgia and headache was seen; however, the 6th cranial nerve palsy was still persisting on the left-hand side.

Follow-Up Examinations

DSA follow-up was performed at 3 months, showing partial thrombosis of the PPTA aneurysm with an aneurysm remnant (Raymond-Roy III). The flow diverter device was well positioned, and no in-stent stenosis was seen (Fig. 3).

Fig. 3
figure 3

Follow-up DSA 3 months after the treatment of a left ICA/PPTA aneurysm with flow diversion (left ICA) and parent vessel occlusion with coils (left PPTA) (posterior-anterior view (a), lateral view (b)) showed a small aneurysm remnant of the PTA aneurysm. The flow diverter stent was patent and well positioned with good wall apposition, and there was no in-stent stenosis

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Treatment Strategy

The hemodynamic effect of the single implanted flow diverter was considered insufficient to induce complete aneurysm occlusion, especially since the 6th cranial nerve palsy had only partially improved. For this reason, the patient underwent a second endovascular procedure.

Treatment

Procedure #2, 03.10.2009: telescopic deployment of a second flow diverter to occlude an aneurysm remnant of the PPTA

Anesthesia: general anesthesia; 10,000 IU unfractionated heparin (Riveparin, Rivero) IV

Medication: 1× 100 mg ASA (Aspirin, Bayer Vital) PO daily and 1× 75 mg clopidogrel (Troken, Bagó) PO daily; the patient had been taking this medication for the last 3 months

Access: left femoral artery, 7F sheath (Terumo); guide catheter: 6F Envoy (Cordis); microcatheter: Renegade 0.027″ (Boston Scientific); microguidewire: Transend 0.014″ 200 cm (Stryker).

Implant: 1× Pipeline Embolization Device 4.5/18 mm (Medtronic).

Course of treatment: a 7F vascular sheath was placed in the left common femoral artery, and the left ICA was catheterized. Standard posterior-anterior, lateral, and oblique angiographic images were gathered for all vessels involved. Rotational angiography with 3D reconstruction was obtained in order to determine the most suitable working projection.

The aneurysm remnant measurements were made using standard methods and included aneurysm height, width, and neck diameter (10 × 7 × 5 mm). After the diagnostic DSA, a 6F Envoy guide catheter was placed in the cervical portion of the left ICA. A Renegade 0.027″ microcatheter was navigated over a Transend 0.14 microguidewire through the first flow diverter device and placed in the proximal M1 segment of the left MCA. The second Pipeline Embolization Device was positioned from the distal cavernous segment to the proximal cavernous segment of the left ICA and overlapped with the first flow diverter, covering the PPTA ostium. DSA confirmed the correct position of the device and the contrast medium stagnation inside the aneurysm remnant. All access devices were retrieved (Fig. 4). XperCT was performed immediately after the procedure, and no hemorrhagic or ischemic lesions were observed.

Fig. 4
figure 4

Deployment of a second PED inside the first PED to treat an aneurysm remnant of the PPTA. A digital radiograph showed the flow-diverter position and that it had expanded (a). DSA in the working projection after the deployment of the PED during the early arterial (b) and late parenchymal (c) angiographic phases demonstrated the contrast stagnation inside the aneurysm remnant, which was now covered by two flow diverters

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Duration: 1st–20th DSA run: 44 min; fluoroscopy time, 32 min

Complications: none

Post medication: 11 × 100 mg ASA PO daily for life and 11 × 75 mg clopidogrel PO daily for 6 months

Clinical Outcome

Procedure #2 was also well tolerated, and no hemorrhagic or ischemic complications occurred. Three days later the patient was discharged home with no change in her clinical condition. The clinical follow-up at 6 months after the procedure showed an improvement in the left trigeminal neuralgia and the headaches, and it was ascertained that the left-hand 6th cranial nerve palsy had resolved. The patient’s mRS score was now 0, without any other procedure-related complications.

Follow-Up Examinations

Follow-up DSA was performed at 6 months after the second procedure and MRI at 4 and 10 years, showing complete occlusion of the PPTA aneurysm (Raymond-Roy I). The Pipeline Embolization Devices were patent and well positioned, and there was no evidence of in-stent stenosis. The coil cast in the left PPTA was stable, and there was no recanalization of the left PPTA. In the 4- and 10-year follow-up MRIs, no ischemic or hemorrhagic lesions were found (Fig. 5).

Fig. 5
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Follow-up examinations after staged endovascular treatment of a large left-hand ICA aneurysm at a PPTA origin. DSA with contrast medium injection of the left ICA 6 months after the second procedure (posterior-anterior view (a), lateral views (b, c)) confirmed the complete occlusion of the aneurysm. Injections of the left VA (lateral views, without (d) and with (e) simultaneous compression of the left CCA) confirmed the occlusion of the PPTA. MRI was carried out 10 years after the first treatment and showed that the previously large left-hand ICA aneurysm had disappeared

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Discussion

A persistent primitive trigeminal artery (PPTA) is an embryonic remnant of fetal circulation still present in adulthood and is one of the most common vertebrobasilar anastomoses, with an incidence of 0.06–0.6%, more frequent in women (Vasović et al. 2012). Most of the time, a PPTA is an incidental finding, but it may be associated with other cerebrovascular abnormalities, of which aneurysms are the most common. Other cerebrovascular disorders possibly related are arteriovenous malformations and carotid-cavernous fistulas (Weon et al. 2011). The PPTA originates from the pre-cavernous ICA, just proximal to the meningohypophyseal trunk. Its course can run medially (sphenoidal) or laterally (petrosal) between the ICA and basilar artery; the laterally variant course runs through the cavernous sinus, just next to the 5th and 6th cranial nerves. The 6th cranial nerve is superior and medial to the 5th cranial nerve and does not have a dural cover. Therefore, 6th cranial nerve palsy is more frequent in aneurysmal dilatations of the lateral PPTA variant due to their close proximity (Luh et al. 1999).

The PPTA is anatomically classified according to Saltzman in three different variants. Type I encompasses 67% of all PPTAs. In this type, the anastomosis between the PPTA and the basilar trunk is below the superior cerebellar artery (SCA) and above the anterior inferior cerebellar artery (AICA). In this vascular disposition, the distal part of the basilar trunk is mainly supplied by the PPTA and is associated with either a hypoplastic or missing PcomA. Type II is found in 20% of all PPTA cases, and the anastomosis on the BA is above the SCA, and the posterior cerebral arteries (PCA) are supplied by the PcomA. Type III represents about 13% of all PPTA cases and is a combination of the two previously described configurations. In this configuration, both SCAs and the contralateral PCA receive flow through the PPTA; the ipsilateral PCA is supplied by the PcomA. There are some variations, as anastomosis of PPTA to the SCA (IIIa), to the AICA (IIIb), or to the PICA (IIIb) (Alonso-Vanegas et al. 2017; Weon et al. 2011).

Aneurysms arising from the PPTA are not frequent. Aneurysm formation is thought to be due to the turbulent flow near the bifurcation of the PPTA and ICA. Approximately 15–29% of cases of PPTA have an associated aneurysm (Ajeet and John 2016; O’uchi and O’uchi 2010), with the most common location being the bifurcation of the cavernous segment of the ICA and the PPTA. Aneurysms that originate from the PPTA trunk are exceptionally rare and have been reported in 1–2% of cases (Ajeet and John 2016; Tubbs et al. 2011). The pathogenesis of the PPTA aneurysm could be related to hemodynamic stress and structural dysfunction of the vessel wall (Kwon et al. 2007). PPTA aneurysms are often asymptomatic. When they become symptomatic, the first cause is subarachnoid hemorrhage, as these aneurysms have a high propensity to rupture. Furthermore, mass effect on the adjacent cranial nerves often calls for urgent treatment (Ladner et al. 2014). Most commonly, it is the 3rd, 4th, and 5th cranial nerves which are compromised, a situation which manifests through nerve palsy and – more rarely – the trigeminal neuralgia (V1 and V2) (Meckel et al. 2013). If these aneurysms rupture, they may cause a carotid-cavernous sinus fistula (Kim et al. 2010; Yoshida et al. 2011).

Open surgery is difficult in these aneurysms because the cavernous segment of the ICA is too deeply located. The cavernous segment of the ICA is located in front of the brainstem and in close proximity to the cranial nerves and perforating vessels (Kwon et al. 2007; Mohammed et al. 2002). Endovascular ICA occlusion is another therapeutic option; however, this technique may cause ischemic injury to the brain stem by occluding the perforator vessels. Furthermore, the patient needs to have developed communicating arteries (Ajeet and John 2016; Ladner et al. 2014).

Aneurysm coil occlusion through the PPTA is an option; however, there are reports of embolus migration to the anterior and posterior circulation by thrombus formation at the afferent and efferent stumps of the trunk related to the aneurysm.

It is important to develop an appropriate treatment strategy. In the above case, the aneurysm had a wide neck. An elevated risk of coil protrusion into the anterior or posterior circulation was anticipated (Onizuka et al. 2006). Coiling of the aneurysm does not immediately decrease the mass effect like surgical clipping would do. Rather, coiling eliminates high-velocity pulsatile flow through the aneurysm across the surface of the compressed nerve and can quickly relieve symptoms. Stent-assisted coil embolization has been widely used for wide-necked aneurysms. This technique is safer and more effective in the occlusion of the carotid-basilar anastomosis aneurysms (Ajeet and John 2016; Zenteno et al. 2018).

Endovascular flow diverter treatment of lateral ICA aneurysms has been widely studied, with a reported occlusion rate of 96.3% with an mRS <2 (Becske et al. 2017).

Kan et al. (2016) reported on four cases of PcomA aneurysms with fetal vessel configuration treated with a PED. None of the four cases resulted in complete obliteration. The fetal PcomA like the PPTA is an end vessel with no distal collaterals. The flow demand of this vessel will keep the aneurysm patent even after a flow diverter has been inserted because of the pressure gradient across the ostium (Kan et al. 2016). In a report of 29 PcomA aneurysms treated with PEDs, a total of four patients had a fetal configuration, and complete occlusion could not be achieved in any of those four cases. The authors attributed the treatment failure to the continuous sump blood from the ICA across the device resulting in a diminished flow- diverting effect (Tsang et al. 2015). This explains why there was a need for a second procedure in our case in which a second PED was inserted to support the first. This increased the flow diversion effect, allowing a good angiographic and clinical outcome to be achieved.

Therapeutic Alternatives

  • Coil Occlusion

  • Microsurgical Clipping

  • Parent Vessel Occlusion

  • Stent-assisted Coil Occlusion