Case of 71 year old female, a retired school teacher from Camarines Sur, Philippines who complained of severe headache. Diagnostic CT cerebral angiogram showed bilobulated aneurysm at the distal end of right ICA.

1. Liza de la Cruz, MD cuddly_9@ymail.com

3. Plain Cranial CT Scan

4. -parenchymal bleed in medial aspect of right temporal lobe -hyperdensities noted in the cortical sulci of both parietal regions -falxcerebri is hyperdense -interventricular fluid is seen with air fluid level of the occipital horn of the lateral ventricle -3rd & lateral ventricles are dilated

6. Circle of Willis

7. ACA

8. Acom

9. Pcom

10. PCA

11. MCA

12. BA

13. VA(DeMyer, 1988)

14. 6.4mm base 8.3mm height R

17. spastic proximal right middle cerebral artery

20. Discussion (Feng, 2005) Hypoplasia - the presence of a patent but very reduced vascular lumen aplasia - associated with vestiges of nonpatent vessels secondary regression following a normal initial phase of development or arrest of development at a certain early embryonic stage is likely

21. compatible with life for an indefinite period of time the development of extensive collateral flows Horner's syndrome - absence of ipsilateral ICA ischemic optic neuropathy & spasmodic torticollis - a dilated vertebral artery related to agenesis of the ICA

22. Limitations of CTA decreased sensitivity for detection of aneurysms measuring <3 mm relatively poor demonstration of perforator decreased sensitivity for detection of AV malformation, dural AV fistulas and vasculitis dependent on the training of the interpreter the postprocessing techniques employed

23. References DeMyer, W. (1988). Neuroanatomy the national medical series for independent study. Pennsylvania: Wiley Medical Publication. Feng, T. (2005). Congenital absence of left internal carotid artery associated with aberrant intracranial arterial circulation . Applied Radiology, 34(6), 44-46

25. Thank you for your kind attention.