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July2005 Vol.42 Issue:      2 Table of Contents
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Color Doppler Sonographic Changes of the Vertebral Arteries in Patients with Vertebrobasilar Transient Ischemic Attacks

Ahmed Osama1, M. Refaat Habba2, M. El-Beblawy2
Departments of Neurology1, Radiology2,Suez Canal University

ABSTRACT

 

Objective: To assess the Color Doppler Sonographic changes of the vertebral arteries in-patients with Vertebrobasilar transient ischemic attacks and to evaluate its possible role in those patients. Subjects And Methods: Color Doppler Sonography of the vertebral arteries has been made for 53 patients (106 vertebral arteries) with vertebrobasilar transient ischemic attacks and 53 sex- and age-matched controls. Results: The vertebral artery origin was the difficult segment to visualize among both patients and control subjects.  The left vertebral artery origin (55-60%) was especially more difficult to visualize than the right (75-79%). All the pretransverse and intertransverse segments were visualized on both sides in both groups (100%). The mean left vertebral artery diameter was slightly larger than the right in both groups. Real-time B-mode sonography detected atheromatous plaques in only 4 vertebral arteries in the patients (4%) and in only 1 (1%) in the control group. Color flow mapping detected no flow in two vertebral arteries (2%) in the patients.  Abnormal Doppler spectral wave patterns were found in 51% in patients and in 10% of control. The abnormal wave patterns of the patients were: high velocity flow pattern (35%), spectral broadening (11%) and tardus parvus (5%). Abnormal peak systolic velocities were found in 62% of patients and in 8% of control. The abnormal peak systolic velocities of the patients were high peak systolic velocity (53%) and low peak systolic velocity (9%). The most common site of abnormal Doppler changes was at the vertebral artery origin (41%) followed by the pretransverse segment (31%) and cervical segment (5%). There was a strong positive correlation between peak systolic velocity and Resistive Index and Pulsitility Index. Conclusion: Color Doppler Sonography is a valuable non-invasive diagnostic tool in-patient with vertebrobasilar ischemic diseases. It can provide the physician with a tool for the diagnosis, serial evaluation and follow up. It can also select patients for more invasive diagnostic and therapeutic angiographic procedures. However, its main limitation is the high incidence of non-visualization of vertebral artery origin.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(2): 365-375).

 





INTRODUCTION

 

The vertebrobasilar system provides 20-30% of the intracranial flow in normal subjects and approximately 25% of cerebrovascular strokes occur in its distribution.1 Approximately, 50% of patients suffering infarction in the vertebrobasilar territories, report vertebrobasilar transient ischemic attacks (VB-TIAs) in days or weeks prior to onset of permanent deficit.2 A transient ischemic attack is defined as a focal loss of neurological function caused by ischemia, abrupt in onset, persisting for less than 24 hours and clearing without residual signs.3 The pathogenic process by which TIA occur is the same as that which produces clinical signs and symptoms of persistent stroke; only the size and location of the lesion make a difference.3

Atherosclerosis is a disorder of the larger arteries of the body. It is by far the most common cause of vertebrobasilar ischemic strokes, which may also result from any disease process that has an impact on the arterial supply to the posterior fossa. These include: vertebral artery dissection, arteritis, polycythemia and hypercoagulation syndromes.4

VB-TIAs are a significant diagnostic and therapeutic clinical challenge.5 They may worsen gradually or stepwise over hours or weeks as a progressing stroke. Thus the early detection and treatment of high risk patients with lesions that may predispose to and warn of a more significant stroke seems reasonable.3

The value of a safe, noninvasive and low-coast screening test for conditions that predispose to stroke is therefore great.  Color Doppler Sonography (CDS) is currently the test that best meets these goals.6 It has high sensitivity (93-96%) and specificity (94-97%) for detecting significant stenosis (>50% stenosis) and occlusion.7,8,9  However its value in assessment the vertebral arteries in-patients with VB-TIAs has not been widely studied.  Therefore, this study was undertaken to describe the CDS changes of the vertebral arteries in-patients with VB-TIAs and to evaluate its possible role in those patients.

 

SUBJECTS AND METHODS

 

Fifty three (53) patients with clinical diagnosis of VB-TIAs were selected from the Neurology out-patient clinic, Suez Canal University Hospital. They were 32 (60%) males and 21 (40%) females. Their age ranging from 34 to 74 years (Mean 56.7±10.7 years). The diagnosis of VB-TIAs depends mainly on the presence of symptoms of focal loss of neurological function caused by ischemia of the territories of vertebrobasilar circulation, abrupt in onset, persisting for less than 24 hours and clearing without residual signs.3 The most common transient symptom was vertigo (92%) followed by motor weakness (38%), body sensory loss (28%), Tinnitus (25%), Diplopia (21%), Facial sensory loss (13%), Dysphagia (9%), Dysarthria (9%), Visual field defects (8%) and Ataxia (4%). The most common risk factor for VB-TIAs was hypertension (60%) followed by diabetes mellitus (38%), hypercholesterolemia (39.5%) and smoking (21%). Patients with benign paroxysmal positional vertigo and otological causes of vertigo and patients with manifestations of persistent cerebrovascular stroke were excluded from the study.     

Computed tomographic brain scan was done for all the patients using the Tomoscan LX/C Philips CT Machine. All of them showed no abnormality (no infarction, hemorrhage or tumor).

A similar number (53) of healthy volunteers of same age and sex distribution were included in the study as a control group. They were 34 (64%) males and 19 (36%) females. Their age ranging from 35 to 71 years (Mean 55.3±11.2 years). 

Color Doppler Sonography (CDS) of the vertebral arteries was done for the 53 patients (106 vertebral arteries) and control subjects by using Acuoson 128 XP10 ultrasound system with a 7.5 MHz linear array probe, located in department of Radiology, Suez Canal University Hospital. Patients and controls were examined in the supine position. The lower neck was examined first for the origin (ostium) and Pretransverse (prevertebral) segments of the artery, then the Intertransverse (vertebral) (cervical) segment was examined. CDS findings were divided into:

Real-time B-mode:

-               Measurement of Vertebral artery diameter.

-               Characterization of atheromatous plaques.

Color Flow Mapping:

-               Detection of direction of blood flow.

-               Detection of occluded vertebral artery.

Pulsed wave Doppler analysis: 

-       Detection of abnormal Doppler spectral wave-patterns e.g. spectral broadening, High-velocity flow pattern, Tardus parvus or subclavian steal waveform.

-       Calculation of the following Doppler flow measurements at the three segments of the vertebral arteries:10

.     Peak systolic velocity (PSV) (cm/s).

.     End diastolic velocity (EDV) (cm/s).

.     Mean Flow Velocity (MFV) (cm/s)

.     Resistive index (RI): (PSV-EDV) / PSV.

.     Pulsatility index (PI): (PSV-EDV)/ MFV.

.     Systolic/Diastolic Ratio (S/D ratio): PSV/ EDV

     According to PSV, patients were subdivided into three groups:11 

Group A: Patients with normal PSV:

                                      (PSV=20-60 cm/s)

Group B: Patients with high PSV:

                                      (PSV > 60 cm/s)

Group C: Patients with low PSV:

                                      (PSV < 20 cm/s)

 

Mean values ± Standard Deviation were calculated for Doppler values and indices. Level of significance was determined at P value <0.05. Level of high significance was determined at P value <0.01.

 

RESULTS

 

The origin of the vertebral artery was the most difficult segment to visualize among both VB-TIA patients and control subjects.  The left vertebral artery origin was especially more difficult to visualize. In the patients, it was seen in 55% and 75% at left and right sides respectively. In the control group it was seen in 60% and 79%. All pretransverse and intertransverse segments were visualized on both sides in both groups (100%) (Table 1).    

The mean left vertebral artery diameter at the pretransverse segment was slightly larger than the right vertebral artery in both patient (3.53±0.62 mm & 3.51±0.36 mm) and control (3.50±0.57 mm & 3.48±0.34 mm) groups. However, this difference was statistically non-significant (P>0.05) (Table 2).

Real-time B-mode sonography detected atheromatous plaques in only 4 (4%) vertebral arteries in the patients and in only 1 (1%) in the control group. Color flow mapping detected no flow in only 2 arteries (2%) of the patients (Figure 2). Abnormal Doppler spectral wave patterns were found in 51% in patients and in 10% of control. The most common abnormal wave pattern of the patients was high velocity flow pattern (35%) (Fig. 3), followed by spectral broadening (11%) and tardus parvus wave pattern (5%) (Fig. 4). Abnormal peak systolic velocities were found in 62% of patients, (in 53% the PSV was >60 cm/sec and in 9% PSV was < 20 cm/sec), and in 8% of control subjects (Table 3).

The most common site of abnormal Doppler changes was at the vertebral artery origin (41%) followed by the pretransverse (31%) and cervical (5%) segments (Table 4). 

Table (5) shows the mean pulsed-wave Doppler parameters (PSV, EDV, MFV, RI, PI and S/D ratio) at different segments of the vertebral arteries. There was a statistically significant difference (P<0.05) of some parameters between control group and both patients with high peak systolic velocity (PSV>60) (Group B) and patients with low peak systolic velocity (PSV<20) (Group C). Also in patients with high peak systolic velocity (Group B), there was a strong positive correlation between PSV & RI and PI (Table 6).


 

Table 1. Visualizing success of different vertebral artery segments detected by Color Doppler sonography among VB-TIAs and control groups.

 

Visualized segment                            VB-TIA group                                          Control group

of Vertebral artery                       Rt. VA               Lt. VA                            Rt. VA               Lt. VA

                                                        (n=53)               (n=53)                             (n=53)                (n=53)                                

 

Origin (Ostium)                           40 ( 75%)           29 ( 55%)                          42 (79%)          32 ( 60%)

 

Pretransverse (Prevertebral)        53 (100%)          53 (100%)                         53 (100%)        53 (100%)

 

Intertransverse (Cervical)            53 (100%)          53 (100%)                         53 (100%)        53 (100%)

 

VB-TIAs:  vertebrobasilar transient ischemic attacks, Rt. VA: Right vertebral artery, Lt. VA: Left vertebral artery.

Table 2. Mean diameter of vertebral artery detected by Real-time B-mode sonography among VB-TIA and control groups.

 

Vertebral artery                                       VB-TIA group                                  Control group

Diameter (mm)                                            Mean±S.D.                                        Mean±S.D.

Rt. VA                                                            3.51±0.36                                          3.48±0.34

Lt. VA                                                            3.53±0.62                                          3.50±0.57

VB-TIA:  vertebrobasilar transient ischemic attacks, Rt. VA: Right vertebral artery, Lt. VA: Left vertebral artery, P value>0.05

 

 

Table 3. Prevalence of abnormal results detected by B-mode sonography, color flow mapping and pulsed wave Doppler analysis in the vertebral arteries (at any segment) among VB-TIA and control groups.

 

                                                                                      VB-TIA group                      Control group

                                                                                         n=106 (%)*                           n=106 (%)*

 

B-mode Sonographic Results:

    Atheromatous Plaque                                                        4 (4%)                                     1 (1%)

Color Flow Mapping Results: 

    No Blood Flow (Occluded)                                               2 (2%)                                     0 (0%)

Pulsed Wave Doppler Analysis Results:

    Abnormal Spectral Wave Patterns (Total)                 54 (51%)*                               11 (10%)

           Spectral Broadening                                                 12 (11%)                                   5 (5%)

           High Velocity Flow Pattern                                     37 (35%)**                                     4 (4%)

           Tardus Parvus (Dampened waveform)                       5 ( 5%)                                                2 (2%)

    Abnormal Peak Systolic Velocity (total):                   66 (62%)**                                 8 (8%)         

           PSV > 60 cm/s                                                         56 (53%)**                                8 (8%)

           PSV < 20 cm/s                                                           10 (9%)*                                  0 (0%)

 

VB-TIA:  vertebrobasilar transient ischemic attacks, n= 106: number of vertebral arteries in 53 patients and 53 control subjects. (*): P<0.05 Significant, (**): P<0.01 Highly Significant. 

 

 

Table 4. Site of abnormal Doppler Peak Systolic Velocity* according to segment of vertebral arteries detected by Pulsed-Wave Doppler analysis among VB-TIA and control groups.

 

                                                                                        VB-TIA Group                      Control Group                                                                    

Origin (Ostium)                                                               28/69 (41%)                             5/74 (7%)                 

Pretransverse  (prevertebral)               33/106 (31%)                          2/106 ( 2%)                

Intertransverse (Cervical)                      5/106 (5%)                            1/106 ( 1%)                 

VB-TIA:  Vertebrobasilar Transient Ischemic Attacks.

Fifty-three (53) subjects have a total of 106 vertebral arteries. The origin was visualized in 69 vertebral arteries in VB-TIA Group and in 74 vertebral arteries in the Control Group,

* Peak systolic velocity >60 or <20 cm/s           

 

Table 5. Mean Pulsed-Wave Doppler (PW-D) parameters at different vertebral artery  segments (Origin, Pretransverse, and Intertransverse) of control and VB-TIA groups.

 

    Segments of          PW-D                Control                                      VB-TIA Groups

Vertebral Artery                                  Group                Group (A)            Group (B)           Group (C)        

                                                                                  PSV=20-60              PSV>60              PSV <20

                                                      Mean+SD            Mean+SD              Mean+SD           Mean+SD

                                                            cm/s                     cm/s                       cm/s                    cm/s

 

 Origin                         PSV               46 + 9                  43 + 8                  74 + 18*                15 + 7*

                                    EDV              15 + 3                  14 + 5                    15 + 5                    7 + 3*

                                    MFV              24 + 5                  24 + 6                   29 + 7*                 12 + 5*

                                    RI             0.64 + 0.005         0.67 + 0.009         0.80 + 0.006*        0.69 + 0.13

                                    PI                1.18 + 0.2            1.28 + 0.4             2.11 + 0.6*            1.58 + 0.9                                  

                                    S/D            3.03 + 0.48          3.33 + 1.18           5.85 + 3.04*          4.27 + 3.24

 

Pretransverse               PSV              46 + 10                43 + 7                71 + 22*                  18 + 11*

                                    EDV             16 + 4                  14 + 5                15 + 6                         7 + 3*

                                    MFV             25 + 6                  24 + 5                 27 + 9                       12 +4*

                                    RI            0.65 + 0.005          0.67 + 0.01         0.78 + 0.008*           0.73 + 0.1*

                                    PI              1.21 + 0.2             1.29 + 0.5           2.14 + 0.7*              1.88 + 0.8*                                   

                                    S/D          2.92 + 0.43            3.33 + 1.28         5.39 + 2.62*            4.46 + 2.43*

 

Intertransverse            PSV             39 + 11                  41 + 10               48 + 18*                 12 + 12*

                                   EDV             15 + 4                   14 + 5                   13 + 4                      5 + 3*

                                   MFV             22 + 6                   22 + 6                   21 + 6                     10 + 4*

                                   RI              0.63 + 0.004        0.66 + 0.009        0.71 + 0.007*           0.72 + 0.13*

                                   PI                1.15 + 0.2            1.27 + 0.4             1.65 + 0.7*              1.72 + 0.8*

                                   S/D             2.71 + 0.28          2.73 + 1.17          3.78 + 1.36*            4.67 + 2.88*

 

VB-TIA:  Vertebrobasilar Transient Ischemic Attacks, PW-D: Pulsed-WaveDoppler, PSV: Peak Systolic Velocity, EDV: End Diastolic Velocity, MFV: Mean Flow Velocity, RI: Resistive Index, PI: Pulsatility Index, S/D: Systolic/Diastolic ratio. (*): Significant at the p < 0.05 level as compared to the control.

 

Table 6. Correlation of Peak Systolic Velocity with other Doppler Parameters among control and VB-TIA groups.

 

                                      Control                                                      VB-TIA Groups

                                                                            Group A                      Group B                         Group C

                                  R              P                     R             P                    R             P                     R             P

 

EDV                                        0.864       0.267                       0.378       0.052                       0.540       0.109                       0.070      0.911

MFV                                       0.855       0.578                       0.762       0.343                       0.572       0.235                       0.460      0.435

RI                                            0.243       0.169                       0.290       0.142                       0.426       0.003*                     0.720      0.170

PI                                            0.229       0.065                       0.140       0.487                       0.293       0.008*                     0.537      0.351

S/D                         0.079       0.529                       0.170       0.397                       0.122       0.545                       0.471      0.424

 

VB-TIA:  Vertebrobasilar Transient Ischemic Attacks, R value:  Correlation Coefficient, * P value = Correlation is significant at the p<0.05

 

 

Fig. (1): (A) Color flow mapping of a normal right vertebral artery (cervical segment) and vertebral vein. (B) Pulsed wave Doppler analysis of the artery demonstrates a normal low resistance waveform pattern, with broad systolic component, gradual plateau and continuous flow throughout diastole. There is no spectral broadening or obliteration of the spectral window. The peak systolic velocity is 49 cm/s.

 

 

 

 

Fig. (2): (A) Color flow mapping of a right vertebral artery (cervical segment). There is no color flow could be seen within the lumen of the vertebral artery (VA) although the vertebral vein (VV) is well visualized anterior to the artery. (B) Pulsed wave Doppler analysis of the artery demonstrates absent Doppler signal.

 

 

 

Fig. (3): (A) Pulsed wave Doppler analysis of  a left vertebral artery (origin) demonstrates relatively narrow systolic waveform and sharp systolic upstroke and down stroke with high peak systolic velocity (98cm/sec). (B) Pulsed wave Doppler analysis of  a left vertebral artery (pretransverse segment) demonstrates marked increase of peak systolic velocity (130 cm/sec) and obliteration of spectral window.

 

Fig. (4): Pulsed wave Doppler analysis of a right vertebral artery (cervical segment) demonstrates reduction of peak systolic velocity (15 cm/s) diminished diastolic flow and dampened appearance of spectral wave (Tardus parvus).

 


DISCUSSION

 

The vertebral artery was evaluated by CDS at three standardized sites: the origin (V0), pretransverse (V1) and intertransverse (V2) segments. The origin was the most difficult segment to visualize among both VB-TIAs patients and control subjects. The left vertebral artery origin (55-60%) was especially more difficult to visualize than the right (75-79%). All pretransverse and intertransverse segments were visualized on both sides in both groups (100%). Similar difficulties were reported in previous studies.12-16 Trattnig et al.12, could visualize the origin in 71% on the left side and in 87% on the right side in 86 patients with vertebrobasilar insufficiency. Touboul et al.13, visualized the left origin in 60% and the right in 94% in 100 normal subjects. Lovrencic et al.14, reported that visualization of V1 and V2 segments were possible in 100% and of the origin (V0) in 81.7% on the right, and 80.7% on the left side in 596 normal persons. Kuhl et al.15, visualized the origin in 92% on the right side and in 86% on the left side in 50 normal subjects. Trattnig et al.12, attributed difficulties in visualization of the origin to (1) Variation in tissue echogenicity depending on the individual subjects and their age.  (2) The depth of the structure examined in relation to the skin. Thus it seems that the deeper and more posterior location of the left vertebral artery origin explains its non-visualization in 40 – 45% of our subjects.

The mean left vertebral artery diameter at the pretransverse segment was slightly larger than the right vertebral artery in both the patients (3.53±0.62 mm & 3.51±0.36 mm) and control subjects (3.50±0.57 mm & 3.48±0.34 mm). However this difference was statistically non-significant. Similar results were reported by Bendick and Glover1 when they evaluated 1500 patients with vertebrobasilar insufficiency by duplex sonography. They found that the mean left vertebral artery diameter (4.58+0.76 mm) was slightly larger than the right (4.43+0.75mm). Lovrencic et al.14, also reported that the left vertebral artery diameter (3.55+0.61 mm) was slightly larger than the right (3.37+0.6 mm).  

Real-time B-mode sonography detected atheromatous plaques at the origin of only 4 (4%) vertebral arteries in the patients and in only 1 (1%) in the control group.  These results are less than those reported by Trattnig et al.12 (8%), who stressed on the importance of high resolution Real-time B-mode sonography in detection of atheromatous plaque of the proximal vertebral artery and analysis of plaque surface and structure. This may be of some importance for identifying a possible source of local (artery to artery) embolism.

Color flow mapping could easily detect flow in the vertebral artery. If no flow is detected; this is diagnostic of vertebral artery occlusion.17 In the VB-TIAs patients only two vertebral arteries (2%) had no flow detected by Color flow mapping (Fig. 2), suggesting complete occlusion of this vertebral artery. In the control group, all the subjects demonstrated a cephalic direction of blood flow. These results are less than those reported by Trattnig et al.12, and Schneider et al.11, who had found 4% and 6.6%  occlusion respectively in their patients with vertebrobasilar insufficiency. The difference could be attributed to the type of patients. As we select only patients with transient ischemic attacks persisting for less than 24 hours and clearing without residual signs.

Normal vertebral artery spectral wave pattern exhibit low-resistance characteristics (Fig. 1) identical to those seen in the internal carotid artery. In normal circumstances, good flow is maintained throughout the cardiac cycle.1 Thus, a large volume of flow is present throughout diastole and systolic waveform is relatively broad.18 Atheromatous plaques projecting to arterial lumen disturbs the normal smooth laminar flow of erythrocytes. The erythrocytes move with a wide range of velocities, so the spectral line becomes wider. Spectral broadening increases in proportion to the severity of stenosis. Therefore, obliteration of the spectral window indicates turbulence of blood flow associated with more sever stenosis.17 With significant stenosis (>50% diameter reduction) the velocity of erythrocytes increase. This can be recorded as an increase in Doppler shift frequencies. As the severity of stenosis increases the velocity elevation increases.17 At critical stenosis (>95%) the velocity measurements actually decrease and the waveform becomes dampened (Tardus Parvus). The waveform pattern becomes monophasic low velocity flow with prolonged, rounded, poorly defined systolic peak systolic reversal, and little or no flow during diastole.1

We studied the prevalence of abnormal Doppler wave patterns of the vertebral arteries among patients and control groups. Abnormal Doppler spectral wave patterns were found in 51% of patients and in 10% of control. The most common abnormal wave pattern of the patients was high velocity flow pattern (35%) (Fig. 3), followed by spectral broadening (11%) and lastly tardus parvus waveform pattern (5%) (Fig. 4).

Velocity is an important factor in calculating the severity of vertebral artery stenosis.  Velocity increases are focal and most pronounced in and immediately distal to a stenosis.17 A focal increased PSV exceeding 43+17 cm/s, accompanied by disturbed flow in the adjacent portion of the vessel, suggests vertebral stenosis with a diameter reduction of at least 50%.11 At critical stenosis (>95%), velocity may decrease. This is diagnostic of severe proximal  stenosis.19-21 Fujita et al.22, reported decreased blood flow along the vertebral arteries in 32% of patients with vertigo. They attributed this reduction of blood flow velocity to sever proximal stenosis of the vertebral arteries at the origin. 

Sixty-two percent (62%) of the patients had an abnormal peak systolic velocity and in 8% of control. The abnormal peak systolic velocities of the patients were high peak systolic velocity (53%) (Fig. 3) and low peak systolic velocity (9%) (Fig. 4). The most common site of abnormal Doppler PSV was at the origin (41%) followed by the pretransverse segment (31%), and least in the inter-transverse segment (5%). This finding indicates that the proximal segment of the artery is the most commonly involved segment. Easton and colleagues23, reported that atherothrombotic lesions of the vertebral artery have the predilection for the first and fourth segments of the vertebral artery. Kuhl et al.15, stated that proximal vertebral arteries lesions probably occur in about 30% of stroke patients and considered atherosclerotic disease at the origin of the vertebral arteries is one of the most important risk factors for vertebrobasilar ischemic disease.

Doppler flow analysis allows the detection of two types of arterial flow, a high resistance and a low resistance pattern. The high resistance pattern has a high systolic peak and a low diastolic flow. Low resistance pattern demonstrate a relatively high level of flow in diastole. Vascular resistance is defined as the opposition to blood flow in a vascular bed.24 When the pressure is abnormally increased, as in arterial stenosis, a high resistance flow pattern develops. High resistance flow pattern can be normal in some locations, such as in the external carotid and femoral arteries.24 If a high resistance pattern is seen where there is normally a low resistance pattern (like vertebral artery) vessel narrowing is present. Resistance is commonly calculated by the formula for resistive index (RI). An alternative technique, known as pulsitility index (PI), evaluated the diastolic flow in a different fashion.18 Quantifying the severity of the resistance helps in determining the degree of vessel stenosis.18 Therefore quantification of RI and PI could be used as an indicator of the presence of vertebral artery stenosis.

We studied the relationship between PSV and other Doppler parameters (EDV, MFV, RI, PI and S/D ratio) among patients and control groups. In patients with high PSV (>60 cm/s) (Group B), PSV showed a strong positive correlation value with RI and PI (P<0.05), i.e., an increased PSV was associated with increased RI and PI. This finding confirms the importance of measuring RI and PI in diagnosis of vertebral artery stenosis.

Conventional intra-arterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery. It is considered as a mandatory test prior to any operative intervention and before Balloon angioplasty and endo-luminal stent placement.25,26 However, it has been inconsistently applied because of the cost and the potential morbidity may outweigh the benefit, particularly in patients where the probability of negative study is high. Therefore noninvasive modalities such as CDS, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and playing an increasingly important role in diagnosing vertebral artery pathology.27

CDS is the most widespread diagnostic procedure used in diagnosis of obstructive diseases of the arteries supplying the brain.28 The combined non-invasive information on morphology and function makes it the procedure of choice in screening and follow-up of carotid and vertebral artery diseases.29,30 It should be proposed first in all patients with clinical symptoms or signs of vertebrobasilar ischemic disease to select patients for more invasive diagnostic angiographic procedures before surgery and angioplasty.15 However, its main limitation of use is the high incidence of non-visualization of vertebral artery origin. This limitation could be overcome by detection of flow velocity changes consistent with sever proximal stenosis.28

 

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الملخص العربي

 

متغيرات الدوبلر الملون في الشريان الفقاري لدي مرضي القصور العابر للشرايين الفقارية القاعدية

 

تم إجراء فحص الدوبلر الملون علي الشرايين الفقارية لعدد 53 مريضا يعانون من مرض القصور العابر للشرايين الفقارية القاعدية (106 شريان) بالإضافة إلي 53 فردا صحيحا للمجموعة المقارنة؛ بهدف معرفة التغيرات الحادثة في الدوبلر الملون للشريان الفقاري لتقييم دور هذا الفحص في هؤلاء المرضى.

ولقد أثبتت النتائج التالي:

-     بداية الشريان الفقاري هو أصعب جزء في الشريان يتم فحصة مقارنة بالأجزاء الأخرى من الشريان، وكانت الصعوبة أكثر في الشريان الفقاري الأيسر.

-            قطر الشريان الفقاري الأيسر أكبر قليلا من قطر الشريان الفقاري الأيمن.

-            62% من شرايين المرضى كان فحص الدوبلر الملون غير طبيعي.

-            أكثر جزء في الشريان بة اضطراب هو بداية الشريان الفقاري.

-            أكثر التغيرات الحادثة في الدوبلر الملون للشريان الفقاري شيوعا هي: زيادة سرعة تدفق الدم.

 

وتوصى هذه الدراسة باستخدام فحص الدوبلر الملون علي الشرايين الفقارية لتقييم مرضي القصور العابر للشرايين الفقارية القاعدية عند بدء الشكوى بهذا المرض، وبالتالي يمكن التعرف علي المرضى الذين يحتاجون إلي فحوصات أخرى أكثر دقة مثل الأشعة بالصبغة علي الشرايين الفقارية القاعدية.



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