COLOR DOPPLER CHANGES OF THE VERTEBRAL ARTERIES IN PATIENTS WITH VERTEBROBASILAR INSUFFlClENCY

Abstract

BACKGROUND: The vertebrobasilar arterial sistem provides from 20-30% of the entire intracranial blood flow in normal subjects. A transient ischemic attack in the vertebrobasilar territory is referred to as vertebrobasilar insufficiency (VBI). Basilar artery occlusion is a devastating disease. with a mortality rate of > 75%. Until fairly recently, arteriography was the only widely available diagnostic tool to evaluate VB!, however, its high cost and potential morbidity may outweigh its benefit. Thus the role of a safe, noninvasive, and /ow-cost screening test in patients with a high-risk of developing VB! is therefore great. Co/or-coded Doppler sonography (CCDSj is currently the test that best meets these criteria, and it possesses a high sensitivity and specificity for detecting lesions or hemodynamic flow abnormalities in the vertebrobasilar arterial system.

OBJECTIVE: The objective of our study was to describe the CCDS changes of the vertebral arteries in patients with the clinical diagnosis of VB!, and to characterize normal and abnormal pulsed-wave Doppler waveforms and parameters of the vertebral arteries. We also correlated CCDS changes in patients clinically diagnosed with VB!, with the occurrence of cervical spine spondylo-degenerative changes.

METHODOLOGY: We studied 53 patients with the clinical diagnosis of vertebrobasilar insufficiency (VB/ group) and 53 healthy control subjects (control group) by color-coded Doppler sonography using a 7.5 MHz linear transducer. Each patient within the VB! group was subjected to lateral t-ray cervical spine to detect the presence ofspondylo•degenerative changes, brain CT to detect the presence of cerebral infarction and its location, and CCDS to detect abnormal hemodynamic changes within the vertebral arteries. CCDS findings were subdivided into B-mode grayscale imaging fmdings, color flow mapping findings, and pulsed-wave Doppler spectral analysis findings. Each vertebral artery was evaluated at three main standardized sites: the vertebral artery origin, prevertebral segment, and cervical segment. CCDS fmdings were then correlated with epidemiological and clinical data, lateral x-ray cervical spine findings, and brain CT fmdings of the VB!and control groups, to determine if there was a difference between the two groups.

RESULTS: The mean age of the VB/ group was 56.7 ;t 10.7 years, and 55.3 :t 11.2 years in the control group. The most corrunon symptom among the VB! group of patients was vertigo (92%), followed by motor weakness (38%), body sensory loss (28%), tinnitus (25%), diplopia (21%) and facial sensory loss (13%). Among the VB/ group, the most common risk factor was hypertension (60%), fullowed by diabetes mellitus (38%), and finally smoking habit (15%). Fifty-one percent (51%) of the VB/ group had spondylo-degenerative changes of the cervical spine, in comparison to ll% among the control group (p value< 0.05). A total of 23% of the VB/ group patients had significant brain infarctions detected by brain CT. Overall, significant "abnormal" CCDS findings in the vertebral arteries were detected in 62% afthe VBI group patients. in comparison to only 8% among the control group (p value< 0.05). Among the VB/ group, the most common site of abnonnal CCDS findings was at the vertebral artery origin (41%), followed by the prevertebral segment of the vertebral artery (31%). Among the VB/ group, atheromatous plaques/thrombi were clearly visible by 8- mode sonography in 4% of patients. The most cormnon abnormal Doppler spectral waveform was the high-velocity (high-resistance) flow pattern, seen in 35% of VB/ patients in comparison to 4% among the control group (p value < 0.05). The most significant abnormal CCDS findings highly suggestive of the presence of vertebral anery stenosis included: (1) a visible stenosis (atheromatous plaque or thrombus) on 8-mode grays-scale imaging, (2) absent or markedly reduced color flow on color flow mapping, (3) or a striking tradus­ parvus ("dampened') vertebral artery wavepattern on pulsed-wave Doppler spectral analysis (4), or a focal increase m velocity of at least 50% on pulsed­ wave spectral analysis. It was noted that abnormal CCDS findings were most prevalent among elderly males. with presence of long-standing hypertension or diabetes mellitus. and with spondylo-degenerarive changes of the cervical spine.

CONCLUSIONS: Color-coded Doppler sonography (CCDS) is a safe, noninvasive, relatively inexpensive and reliable tool, and is a good screening test in the evaluation of patients with the clinical diagnosis of vertebrobasilar insufficiency.