Pica Bypass and Trapping in Ruptured Fusiform Vertebro-Pica Origin Aneurysms. Rationale and Case Illustrations

Background: Fusiform ruptured aneurysms of the vertebral artery involving PICA or the PICA origin are challenging aneurysms to treat. Many surgical approaches including wrapping techniques as well as various bypass procedures with aneurysm trapping have been described. Endovascular techniques currently do not offer acceptable solutions for these aneurysms, particularly in the ruptured state. Deconstructive procedures (occlusion of the fusiform segment) will result in PICA stroke and may involve the brain stem. Flow diversion is controversial in ruptured cases because of the need for dual antiplatelet agents and the lack of immediate aneurysm obliteration.

Methods: A total of two illustrative cases are described of aneurysms involving PICA origin and the vertebral artery at PICA treated with PICA bypass and trapping of the aneurysm.

Case 1: This 52-year-old female patient presented with neck pain followed by severe headache and loss of consciousness. She was found to have a Fischer grade 4, Hunt and Hess grade 3 SAH. CTA showed a possible left PICA origin saccular aneurysm, however angiography revealed a small serpentine fusiform recanalization within the larger aneurysm dome. The patient was taken for suboccipital craniotomy, partial left condylectomy, and midline PICA–PICA side-to-side anastomosis followed by trapping of the aneurysm at the origin of PICA. The patient had a small asymptomatic distal left PICA stroke. She was eventually discharged to rehab with no neurologic deficit but significant deconditioning. A 6-month follow-up angiogram showed patency of the bypass and the patient had returned to her neurologic baseline with no deficit.

Case 2: This 42-year-old female patient presented after sudden onset worst headache of her life. On arrival, she was intubated, weakly following commands in the upper extremities with no significant movement in the lower extremities. Angiogram showed a fusiform dissecting aneurysm of the left vertebral artery involving the origin of PICA as well as the origin of the anterior spinal artery (ASA). The PICA was recognized to be a bihemispheric variant with aplasia of the contralateral PICA. The patient was taken for suboccipital craniotomy, partial left condylectomy, and occipital artery to PICA anastomosis. The vertebral artery was then clipped just proximal to the dilated segment. No distal clip was applied to allow retrograde filling of the anterior spinal artery. Follow-up angiography revealed patency of the bypass filling the bihemispheric PICA, patency of the ASA, and a small amount of slow filling of the aneurysm at the ASA level. She developed vasospasm and required balloon angioplasty to the right vertebral artery. She had a prolonged recovery with pneumonia and meningitis and required tracheostomy and PEG tube. She has progressed to the point of following commands in all extremities but remains in long-term acute care at 1-month follow-up.

Discussion: Ruptured fusiform vertebral/PICA origin aneurysms are challenging to treat and do not have a good endovascular solution at this point. Surgical treatment often requires one of a variety of bypass techniques that will be dictated by an understanding of the anatomy and potential anatomic variants.