In a retrospective review of all the PICA aneurysms operated at Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, and Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India. in the past 10 years along with the site, presentation, and approach used for the same. Preoperative World Federation of Neurosurgical Society scores and follow-up modified Rankin scores (mRS) were also evaluated. During the same period, data for intervention cases of PICA aneurysm were also collected with follow-ups for a comparative analysis.

A total of 20 patients with 21 PICA aneurysms were reviewed. All the reviewed cases presented with subarachnoid hemorrhage, and the most common location was the lateral medullary segment and vertebral artery (VA)-PICA junction. Midline approaches were used for distal PICA cases, with far-lateral approach reserved for anterior medullary/VA-PICA junction. No lower cranial nerve palsies were recorded at follow-up. Four cases needed Cerebrospinal fluid shunt and two developed cerebellar infarctions. All cases were mRS 0 to 2 at follow-up.

These series compares well with some of the larger surgical series of PICA aneurysms. This may be due to early referral patterns and early surgery (<24 hours) policy at the institution. Anatomical knowledge of PICA anatomy and sound perioperative management are keys to good outcomes in these cases ¹⁾.

94 patients treated for PICA aneurysms between 2000 and 2015 at three large tertiary referral centers were retrospectively reviewed. Purkynje University, Masaryk Hospital, Labem, Czech Republic. Mayo Clinic, Rochester, MN, USA. Medical University Innsbruck, Innsbruck, Austria.

Eighty-three patients met inclusion criteria and of these, two died before treatment, leaving 81 treated patients (43 underwent endovascular and 38 surgical treatment). Among patients treated endovascularly, procedure-related complications occurred in four cases (11.8%). Six patients (19.4%) suffered from complications directly associated with surgery. Recurrences occurred in 0% of surgical and in 16.3% of endovascularly treated patients, requiring treatment. Patients with unruptured asymptomatic aneurysms had good outcomes. In the group of 67 ruptured aneurysms, 16 endovascularly (47.1%) and 15 surgically (48.4%) treated patients had modified Rankin scale (mRS) scores of 3-6. Of patients in poor neurological condition (Hunt & Hess (H&H) IV-V at admission), 84.6% suffered a poor clinical outcome. Fifty percent of patients with distal and 31.9% patients with proximal ruptured PICA aneurysms suffered a poor neurological outcome.

This study of PICA aneurysms demonstrates that results of both treatment modalities are comparable. However, endovascular treatment is associated with higher risks of recurrence, requiring additional treatment. Outcomes were mostly impacted by clinical state at admission ²⁾.

During a 17-year period in which 129 PICA aneurysms in 125 patients were treated microsurgically, 35 IC-IC bypasses were performed as part of PICA aneurysm management, including in situ p3-p3 PICA-PICA bypass in 11 patients (31%), PICA reimplantation in 9 patients (26%), reanastomosis in 14 patients (40%), and 1 V3 VA-to-PICA bypass with an interposition graft (3%). All aneurysms were completely or nearly completely obliterated, 94% of bypasses were patent, 77% of patients were improved or unchanged after treatment, and good outcomes (modified Rankin Scale ≤ 2) were observed in 76% of patients. Two patients died expectantly. Ischemic complications were limited to 2 patients in whom the bypasses occluded, and permanent lower cranial nerve morbidity was limited to 3 patients and did not compromise independent function in any of the patients.

PICA aneurysms receive the application of IC-IC bypass better than any other aneurysm, with nearly one-quarter of all PICA aneurysms treated microsurgically requiring bypass without a single EC-IC bypass. The selection of PICA bypass is almost algorithmic: trapped aneurysms at the PICA origin or p1 segment are revascularized with a PICA-PICA bypass, with PICA reimplantation as an alternative; trapped p2 segment aneurysms are reanastomosed, bypassed in situ, or reimplanted; distal p3 segment aneurysms are reanastomosed or revascularized with a PICA-PICA bypass; and aneurysms of the p4 segment that are too distal for PICA-PICA bypass are reanastomosed. Interposition grafts are reserved for when these 3 primary options are unsuitable. A constructive approach that preserves the PICA with direct clipping or replaces flow with a bypass when sacrificed should remain an alternative to deconstructive PICA occlusion and endovascular coiling when complete aneurysm occlusion is unlikely ³⁾.

Data relating to clinical presentation, radiological findings, operative approaches and outcomes were analyzed in 27 consecutive patients surgically treated for PICA aneurysms in a single hospital between January 1991 and December 2010.

Headache was the most common presentation (100%) followed by gait ataxia (14.8%) and lower cranial nerve dysfunction (7.4%). SAH was seen in 20 patients, intraventricular hemorrhage in 22 patients, and 3 had evidence of intracerebellar hematoma. Eighteen aneurysms were located proximally and 9 were located distally. The 25 saccular and 2 fusi-saccular aneurysms were secured by direct clipping (24 cases) or aneurysmorrhaphy (3 cases) using a far-lateral suboccipital (without condylar resection) or midline/ paramedian suboccipital approach. Overall outcome at the time of hospital discharge was excellent or good in 88.9% of the patients.

PICA aneurysms, by virtue of their rarity and strategic location pose a unique technical challenge. Depending on the PICA segment affected, variations in the surgical corridor and clipping strategy were major contributors to good outcomes ⁴⁾.

Singh et al. study focuses on surgical considerations during clipping of saccular PICA aneurysms in a Tertiary care hospital, It was a retrospective study in 20 patients.

CT angiogram/digital substraction angiogram was used to correlate the site and anatomical variations of aneurysms located on different segments of PICA with the approach selected, the difficulties encountered and the final outcome.

The location was: vertebral artery/basilar artery (VA/BA)-PICA (n=5); anterior medullary (n=4); lateral medullary (n=3); tonsillomedullary (n=4); and, telovelotonsillar (n=4) segments. The Hunt and Hess grade distribution was I in 15; II in 2; and, III in 3 patients (mean ictus-surgery interval: 23.5 days; range: 3-150 days). Eight patients had hydrocephalus. Anatomical variations included giant, thrombosed aneurysms; 2 PICA aneurysms proximal to an arteriovenous malformation; bilobed or multiple aneurysms; low PICA situated at the foramen magnum with a hypoplastic VA; and fenestrated PICA. The approaches included a retromastoid suboccipital craniectomy (n=9); midline suboccipital craniectomy (n=6); and far-lateral approach (n=5). At a follow-up (range 6 months-2.5 years), 13 patients had no deficits (modified Rankin score (mRS) 0); 2 were symptomatic with no significant disability (mRS1); 1 had mild disability (mRS2); 1 had moderately severe disability (mRS4); and 3 died (mRS6). Three mortalities were caused by vasospasm (2) and, rupture of unclipped second VA-BA junctional aneurysm (1).

PICA aneurysms may present with only IV(th) ventricular blood without subarachnoid hemorrhage. PICA may have multiple anomalies and its aneurysms may be missed on CT angiograms. Surgical approach is influenced by VA-BA tortuosity and variations in anatomy, location of the VA-BA junction and the PICA aneurysm relative to the brain-stem, and the pattern of collateral supply. The special category of VA-PICA junctional aneurysms and its management; and, the multiple anatomical variations of PICA aneurysms, merit special surgical considerations and have been highlighted in this study ⁵⁾.

Of 2169 aneurysms treated between January 1995 and March 2007 in St. Elisabeth Ziekenhuis, Tilburg, the Netherlands, 60 were located on the PICA (incidence, 2.8%). Forty-seven proximal PICA aneurysms in 46 patients were treated with endovascular techniques, 37 ruptured (79%) and 10 unruptured (21%). Four patients presented with lower cranial nerve palsies. Mean aneurysm size was 6.8 mm (median, 6 mm; range, 2-32 mm). Forty-three aneurysms were occluded with coils (6 including the PICA origin), and 4 were treated with proximal vertebral artery (VA) occlusion.

Four aneurysms treated with proximal VA occlusion were not occluded. Procedural rupture occurred in 9 aneurysms leading to death in 2 patients and to permanent disability in 1 patient. One patient developed lateral medullary and cerebellar infarctions after PICA occlusion. Combined mortality and morbidity was 8.6% (4 of 46). Outcome at 6 months in 38 surviving patients was good in 35 and moderate in 3. No hemorrhage occurred during 109 patient-years of follow-up. Symptoms of mass effect resolved in all 4 patients.

PICA aneurysms were challenging lesions, prone to procedural rupture. In some instances, endovascular treatment required occlusion of the parent PICA; usually this was well tolerated. In other instances, treatment required occlusion of the VA. Although this was effective in alleviation of symptoms of mass effect, it was not effective in causing thrombosis of the aneurysm ⁶⁾.