REPEAT ANGIOGRAPHY AND MAGNETIC-RESONANCE-IMAGING (MRI) OF DISSECTING ANEURYSMS OF THE INTRACRANIAL VERTEBRAL ARTERY

We here present 4 cases with dissecting aneurysm (DA) of the intracranial vertebral artery, who were followed up by repeat cerebral angiography and MRI. The patients consisted of 2 males and 2 females, and the mean age was 43 years. Two cases were associated with polyarteritis nodosa (PN) and hypertension, respectively. Three of the cases developed subarachnoid haemorrhage (SAH), while the other one suffered from lateral medullary syndrome. In cerebral angiography, ''pearl and string'' signs were revealed in all cases, while a ''double lumen'' indicating a true diagnostic sign of DA was demonstrated in only one case. Repeat angiography showed that a bleb formation with a bulging of the aneurysmal sac was seen in 2 cases, and an irregularity of the wall in one case. On the other hand in one case, the ectatic part shrank, while the stenotic part was restored. In magnetic resonance imaging (MRI), a hyperintensity mass on T1-weighted image (T1-WI) adjacent to flow void suggesting either an intramural haematoma or a linear shape hyperintensity on T1-WI were demonstrated in 3 cases. In the follow up MRI done in 2 cases, a serial change in the intensity from iso-intensity to hyperintensity on T1-WI was observed in one case suggesting intramural haemorrhage, while an enlargement of the ectatic flow void was seen in the other case. Three of 4 cases were operated on by trapping of the aneurysms. One, who had systemic vascular diseases due to PN, and repeat angiography showed a regression of the aneurysm, was conservatively treated. The outcome was excellent in the 3 surgical cases, whilst the one medically treated case was also excellent without any rebleeding. In conclusion, repeat neuro-imaging procedures are strongly recommended to clarify the possibility of a spontaneous repair of the dissection, and to consider the surgical strategy for the lesion.