Post. Circulation aneurysms M.MOLAVI MD

10-15% of all intracranial aneurysms Most challenging aspect of cerebrovascular surgery Situated close to the BS

Ans. Arising from intracranial VA (PICA) Ans. of vb junction Ans. of AICA & mid basilar trunK Ans. of SCA Ans. of Basilar tip Ans. of PCA

Major challenges of treating VB ans. Achieving adequate exposure Avoiding cranial nerves inj. Maintaining vascular integrity

VA, BA, PICA, AICA, SCA,& PCA perforating branches supply the Ant. & Lat, aspect of BS 2/3 of perforating branches of BA arise from cephalic portion; thus the caudal portion is the prefered site for cross- clamping

CLINICAL PRESENTATION Headache Coma BS symptoms 3 rd nerve palsy (basilar-SCA an. Rupture) 6 th nerve palsy( basilar – AICA an.) Lower cranial nerve dysfunction ( vertebral & vertebro-basilar an.) Unruptured ans. May cause dysfunction of BS & cranial nerves by local effects of the mass lesion

VB Anatomy

DIAGNOSIS CT MRI MR Angiography Standard 4-vessel angiography DSA

Surgical Considerations Surgical clipping Wrapping Trapping Ligation of VA extra or intracranially Endovascular techniques ( Balloons or coils)

General principles for operation Careful choice of the appropriate approach Adequate positioning Maximal decompression of brain w CSF diversion & drugs Use of magnification Thorough intraoperative monitoring Wide selection of clips

Intraoperative rupture prevention Systemic hypotension Temporary clipping of the parent vessel or Temporary balloon occlusion Deep hypothermia Cardiac arrest

Surgical approaches Suboccipital app: entire intracranial VA, PICA, & lower part of BA up to the level of AICA Sub temporal or Trans oral app: ans. Along the upper2/3 of the clivus Subtemporal transtentorial or suboccipital app: mid basilar trunk ans. & AICA origin ans.