The role of continuous-wave Doppler sonography in the diagnosis and management of basilar and vertebral artery occlusions, with special reference to its application during local fibrinolysis ("Vertebrobasilar disease. Time for a new strategy." Louis R. Caplan, 1981)

Ultrasound findings in spontaneous extracranial vertebral artery dissection

BACKGROUND AND PURPOSE

In this study we analyzed the value of ultrasound examination for diagnosis of vertebral artery dissection.

METHODS

The vertebrobasilar arterial system was assessed in 14 patients using transcranial and extracranial pulsed-wave Doppler and duplex sonography.

RESULTS

The dissections were verified by angiography (in 1 patient), magnetic resonance imaging (in 5), or both (in 8). The dissected segments were atlantoaxial (V-3) in 6, V-3 and intertransverse (V-2) in 3, V-3 and intracranial (V-4) in 3, and V-2 in 2 patients. Extracranial and transcranial Doppler examination of the atlas loop, involved in 12 patients, showed absent flow signal in 5, low bidirectional flow signal in 1, and poststenotic low blood flow velocities in 3 patients. Seven of these patients had high-grade stenosis or occlusion. The stenotic segment with increased flow signal could be identified directly in 2 patients. Duplex examination of the intertransverse segment confirmed absent flow in 4 patients, making technically insufficient examination unlikely. In the 2 patients with directly detected stenosis, duplex examination showed low flow velocities before the stenosis. The combined use of extracranial and transcranial Doppler and duplex sonography increases the diagnostic yield to detect vertebral artery pathology. If any abnormal sonographic finding was considered, the yield was 86%; relying only on definitively abnormal findings (absent flow signal, severely reduced vertebral artery blood flow velocities, no diastolic flow, bidirectional flow, and a stenosis signal), the yield was 64%.

CONCLUSIONS

In most cases, there is no pathognomonic ultrasound finding for vertebral artery dissection. However, if a patient presents with suggestive symptoms, ultrasound may corroborate the clinical suspicion and aid in the decision regarding early anticoagulant treatment. A definite diagnosis can be made noninvasively when magnetic resonance imaging demonstrates hematoma in the vessel wall. Angiography yields additional information such as nature of underlying vascular disease, site and extent of dissection, intracranial extension, and presence of pseudoaneurysm.

The role of vertebral and internal carotid artery disease in the pathogenesis of vertebrobasilar transient ischemic attacks

Color-coded duplex sonography has improved the evaluation of the hemodynamics of the vertebral arteries (VA). A reliable differentiation between a normal vessel, hypoplasia, stenosis and occlusion of VA can now be made. We studied two groups of patients in a prospective study with isolated carotid artery disease (n = 48), and with a combination of carotid and vertebral artery disease (n = 14), to determine the role of VA in the pathogenesis of transient ischemic attacks (TIAs) in the vertebrobasilar system. Apart from the existing arteriosclerotic changes of the internal carotid arteries, the condition of the VA was of importance for the occurrence of TIAs in the vertebrobasilar territory. We found that 8% of the patients with isolated hemodynamically relevant stenosis or occlusion of one or both internal carotid arteries had a TIA in the vertebrobasilar territory. Patients with combined carotid and vertebral artery disease had an increase of TIAs in the same region in 71%. The high rate of TIAs in this group might be attributed to the combined effect of carotid and vertebral artery disease, as a third group (n = 30) with isolated vertebral artery disease showed TIAs in only 13%.

What have drugs to offer the patient with acute stroke?

1. Drug treatment for acute stroke is designed to salvage neuronal tissue, and to prevent complications of stroke, which are often non-neurological. This review addresses the areas of recent advance in treatment designed to reduce the size of the cerebral infarct. With the exception of cardiac-source embolism, for which anticoagulation in the acute phase is sometimes considered, prevention of recurrent events is not discussed. 2. It is to be hoped that pharmaceutical developments will improve the current bleak picture in which there are no proven treatments for ischaemic stroke or intracerebral haemorrhage. To meet this challenge will require careful, controlled evaluation of treatment early after acute stroke in large scale clinical studies.

Intra-arterial thrombolytic therapy improves outcome in patients with acute vertebrobasilar occlusive disease

In this retrospective analysis we report our treatment experience in 65 consecutive patients with clinical signs of severe brainstem ischemia with angiographically demonstrated thrombotic vertebrobasilar artery occlusions who received either local intra-arterial thrombolytic therapy (urokinase or streptokinase) (43 patients) or conventional therapy (antiplatelet agents or anticoagulants) (22 patients). We analyzed the data with respect to cerebral artery occlusion patterns, posttreatment arterial recanalization, and the clinical categories of favorable/unfavorable outcome and survival/death. In subgroup analyses, recanalization in patients who received thrombolytic therapy correlated significantly with clinical outcome; in 19 of 43 patients, recanalization was demonstrated angiographically, while in 24 patients the occlusion persisted. All patients without recanalization died, but 14 of the 19 patients displaying recanalization survived (p = 0.000007), 10 with a favorable clinical outcome. Only three of the 22 patients who received conventional therapy survived, all with a moderate clinical deficit. When we compared the treatment groups, highly significant differences in both outcome quality (p = 0.017) and survival (p = 0.0005) were found to depend on establishing recanalization. Our data support the concept that technically successful thrombolysis of vertebrobasilar artery occlusions is associated with beneficial clinical outcome.

The efficacy of EC-IC anastomoses: evaluation by directional c-w Doppler sonography

We report the results obtained by means of directional c-w Doppler sonography on 33 patients with superficial temporal-to-middle cerebral artery anastomoses. The efficiency of the anastomosis was evaluated by the modified Pourcelot indices (relative end-diastolic flow velocities) of the preauricular superficial temporal artery and of the bypass-supplying branch at the edge of the burr-hole. The influence of intermittent compression of the bypass-supplying branch on the modified Pourcelot index of the ipsilateral common carotid was used as a further criterion in the sonographic evaluation. All efficient anastomoses, defined by a modified Pourcelot index of at least 0.20 at the edge of the burr-hole, exhibited a reduction of the relative end-diastolic flow velocity of 0.08 on the average in the common carotid during compression. In the 18 cases with unilateral occlusion of the internal carotid, bypass surgery was predominantly efficacious in those patients who showed a reduction in the sum of the modified Pourcelot indices of the remaining brain-supplying arteries of at least two standard deviations with respect to the mean of age-matched controls. The subgroups of patent and absent collaterals through the ophthalmic artery did not show any difference with respect to the percentage of efficient anastomoses. In all 4 patients with bilateral internal carotid artery occlusion, bypass surgery was effective, while 50% of the patients with intracranial carotid artery disease exhibited an insufficient anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous-wave Doppler of vertebral arteries in noninvasive diagnosis and management of vertebro-basilar TIAs

Continuous-wave Doppler and angiography of the vertebro-basilar system were used in 38 patients with vertebro-basilar transient ischemic attacks. 63 vertebral arteries were studied. Among 47 normal Doppler parameters, 46 were confirmed by angiography. The sonographic diagnostic procedure showed a very high negative predictive value (97.87%), while the positive predictive value was relatively low (56.25%). Data from literature were reviewed. The authors suggest that when Doppler of vertebral arteries is negative, there is a very low probability that a follow-up angiography will reveal pathologic conditions calling for a surgical approach.

Basilar artery disease--clinical outcome and Doppler sonographical follow-up

In the past 5 years we have investigated 29 patients with symptomatic basilar artery stenoses (14 cases) and occlusions (14) and a patent primitive trigeminal artery with thin-calibered basilar and vertebral arteries (1) using directional continuous-wave Doppler sonography of the vertebral arteries. A total of 19 patients survived, and 17 of them were clinically and sonographically reexamined after 40.4 +/- 15.8 months (mean +/- SD). Among the 8 patients with basilar stenoses, 6--with no further transient ischemic attacks (TIAs) in the interval--exhibited an increase in the summed modified Pourcelot indices (relative end-diastolic flow velocities) of the vertebrals by 0.18 +/- 0.16; the other 2 showed a decrease by 0.26 each, in 1 case temporally related to a TIA, in the 2nd case without further clinical deterioration. In the 8 survivors with basilar occlusions, 5 remained--by sonographic criteria--unchanged with summed modified Pourcelot indices of the vertebrals of 0.00, while 3 patients exhibited a slight increase in the summed modified Pourcelot indices of 0.13 +/- 0.03. While the difference between the outcome of subsets of patients treated with regimens of 30,000-40,000 units heparin/day or phenprocoumon and less radical drugs were statistically not significant, the former regimen appeared clinically more efficacious in preventing further deterioration in approximately two-thirds of the patients affected. Due to the potential recurrence of neurological symptoms, a treatment period with phenprocoumon of 6 months after discharge from hospital appears justified. Due to these therapeutic efforts, approximately half of the patients initially affected survived with no or only a mild neurological deficit.(ABSTRACT TRUNCATED AT 250 WORDS)

Vertebral artery Doppler sonography

We have examined the vertebral and subclavian arteries in 1,205 patients using directional continuous-wave (c-w) Doppler sonography, and compared the sonographic findings with the results of unilateral or bilateral retrograde brachial arteriographies in the same patients. Doppler sonography revealed 33 false positives among 909 cases with normal angiographic findings. Some types of vertebral artery (VA) lesions allowed an excellent, others a fairly good differentiation by Doppler sonography: the complete subclavian steal syndrome with constant reversal of VA flow was reliably detected (16 cases). In the incomplete steal syndrome (5 cases) sonography was superior to angiography. Two bilateral distal VA occlusions and seven basilar artery occlusions - six in the proximal third and one in the rostral third - were detected sonographically; four basilar occlusions sparing the caudal third and one case exhibiting rete mirabile anastomoses were not identified by Doppler sonography. Our acoustically defined sonographic criteria did not permit an unequivocal assignment to an anatomical variant or a vascular lesion. The sensitivity in the detection of a severe stenosis at the VA origin amounted to 16 out of 31, and to 12 of 25 in cases with a proximal VA occlusion and reconstitution of the distal VA through cervical collaterals. Our results confirm that the conventional hand-held c-w Doppler sonography cannot replace angiography in the evaluation of vertebro-basilar insufficiency. It rather serves as an aid to the decision for or against angiography, and in the follow-up of angiographically proven lesions. However, several therapeutically important lesions are readily diagnosed by sonography.

Vascular recanalizing techniques in the hind brain circulation

Percutaneous transluminal angioplasty (PTA) was performed in 45 patients with a manifest subclavian steal syndrome. Thirty-five of those patients were subjected to follow up examinations over a period of 6 to 18 months. Five patients suffered from severe restenosis and were treated again. Two thirds of the patients benefited from the treatment. PTA of the proximal vertebral artery was performed in 15 patients with bilateral occlusive lesions of the extracranial vertebral arteries. In 13 of these cases the neurological and the vascular states of the patients were regularly reexamined, 8 showed a marked improvement. During the 2 to 25 month observation period (average 15 months post-PTA) reocclusion was observed in only two cases. These showed no recurrent neurological sequelae. Forty-three consecutive patients with acute vertebro-basilar or basilar occlusion received intraarterial fibrinolytic therapy with streptokinase or urokinase. Twenty-three of these had presented severe deficits at the beginning of therapy (e.g. complete tetraplegia, comatous state for more than 6 hours). None of this group survived. By contrast the 20 other patients in this group presented with incomplete fluctuating or progressive motor deficits. None was comatous for more than 6 hours. Fourteen patients (33% in this group) survived. Local intraarterial fibrinolytic therapy is the only therapy successful in the treatment of progressive stroke from vertebro-basilar thrombosis.

Validity of continuous-wave Doppler sonography of the vertebrobasilar system

To assess the value of continuous-wave Doppler sonography for detection and exclusion of lesions in the vertebrobasilar system, the ultrasonic and angiographic findings were compared in a prospective study. Altogether, 200 vertebral arteries in 176 patients were evaluated by both methods. Insonation of the vertebral arteries was performed at the mastoid slope and at the origin of the vessel. Of 62 angiographically proven lesions, 45 were detected by ultrasound. Of 138 normal vertebral arteries, 129 were correctly diagnosed. Sensitivity for all lesions was 72.5%, and for hemodynamically relevant lesions it was 91%. Overall specificity was 93.5%. A positive predictive value of 83.3% and a negative predictive value of 88.4% for all lesions shown by angiography demonstrate the high reliability and accuracy of doppler ultrasound of the vertebrobasilar system.

Directional C-W Doppler sonography in the diagnosis of basilar artery disease

Using directional continuous-wave Doppler sonography of the vertebral arteries, we have investigated 1,540 patients during the past 5 years. On the basis of unilateral and bilateral retrograde brachial angiograms in the same patients (a total of 1,989 angiograms) we have developed sonographic criteria for demonstrating a significant increase in the peripheral resistance of both distal vertebral arteries and/or the basilar artery. All 11 cases of basilar artery stenosis of at least 60% reduction in lumen diameter (as shown by angiography) exhibited an approximately 40% or higher reduction in the sum of the modified Pourcelot indices of both vertebral arteries with respect to age-matched controls. All 3 stenoses of less than 60% reduction in lumen diameter were not detected by sonography. Even a good collateral circulation through rete mirabile anastomoses did not normalize the modified Pourcelot indices. One case of a persistent primitive trigeminal artery with thin-calibered vertebral arteries was also detected by sonography. The high percent of patients with one hypoplastic vertebral artery in the group with basilar artery stenoses indicates an increased risk for atherosclerosis of the basilar and/or distal vertebral artery in these patients. All 14 angiographically verified occlusions of the basilar artery were detected by sonographic criteria independent of the occlusion localization. Thus, we believe that directional continuous-wave Doppler sonography is a reliable technique for detecting basilar artery stenoses of at least 60% reduction in lumen diameter and basilar artery occlusions.

[Doppler sonographic diagnosis of basilar stenoses and obliterations]

We have examined 10,162 patients during the past 5 years using directional continuous-wave Doppler sonography of the vertebral arteries. On the basis of 1,989 retrograde brachial angiograms, we have developed sonographic criteria for demonstrating a significant increase in the peripheral resistance of both distal vertebral arteries and/or the basilar artery. All 11 cases of basilar artery stenosis of at least 60% reduction in lumen diameter (as shown by angiography) exhibited an approximately 40% or higher reduction in the sum of the modified Pourcelot indices of both vertebral arteries in comparison with age-matched controls. The 3 stenoses below 60% reduction in lumen diameter were not detected by sonography. Even a good collateral circulation through rete-mirabile anastomoses did not normalize the modified Pourcelot indices. One case of persistent primitive trigeminal artery with thin-calibred vertebral arteries was also detected by sonography. The high percentage of patients with one hypoplastic vertebral artery in the group of basilar artery stenoses indicates an increased risk for atherosclerosis of the basilar and/or the distal vertebral artery in these patients. All 14 angiographically verified occlusions of the basilar artery were detected by sonographic criteria independent of the occlusive localization. Thus, we believe that directional continuous-wave Doppler sonography is a reliable technique for detecting basilar artery stenoses of at least 60% reduction in lumen diameter and basilar artery occlusions.

[Doppler ultrasonic evaluation of the efficiency of extra-intracranial anastomoses]

We report on the results obtained by means of directional continuous-wave Doppler sonography in 33 patients with superficial temporal-to-middle cerebral artery anastomoses. Recurrent transient ischaemic attacks or a recent mild neurological deficit were considered as justification for bypass surgery in cases of angiographically proven occlusions of one or both internal carotids, severe intracranial carotid artery disease, or stenoses and occlusions of the M-1 segment of the middle cerebral artery. The efficiency of the anastomosis was evaluated by the modified Pourcelot indices (relative end-diastolic flow velocity) of the preauricular superficial temporal artery and of the bypass-supplying branch at the edge of the burr-hole. The influence of intermittent compression of the bypass-supplying branch on the modified Pourcelot index of the ipsilateral common carotid was used as a further criterion for sonographic evaluation. All efficient anastomoses, defined by a modified Pourcelot index of at least 0.20 at the edge of the burr-hole, exhibited an average reduction of 0.08 in the relative end-diastolic flow velocity in the common carotid during compression. In the 18 patients with unilateral occlusion of the internal carotid, bypass surgery was predominantly efficacious (by the above criterion) in those patients who showed a reduction in the sum of the modified Pourcelot indices of the remaining brain-supplying arteries of at least 10% as compared with age-matched controls. The subgroups of existing and absent collaterals through the ophthalmic artery did not show any differences with respect to the percentage of efficient anastomoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive diagnosis of intracranial lesions in the vertebrobasilar system. A comparison of Doppler sonographic and angiographic findings

The accuracy and the reliability of extracranial vertebral Doppler flow (continuous wave Doppler sonography) for the detection of intracranial vertebrobasilar lesions was studied prospectively in twenty-one patients with brainstem disturbances and/or coma. The Doppler findings were compared with cerebral angiography. Doppler sonography was highly reliable for both detection and exclusion of high grade intracranial vertebrobasilar lesions. The pathognomonic Doppler finding was an abrupt deceleration of the blood column during systole and stoppage or even reflux during diastole. The same blood flow alterations were found in two additional illustrative cases having therapeutically or brain-death induced blockages of the vertebral arteries. The pathophysiologic mechanisms of flow disturbances and the limitations of Doppler sonography in this area are discussed.

Doppler sonography in basilar artery occlusion

We have investigated 6,972 patients with directional continuous-wave Doppler sonography within the last three and a half years, and have derived criteria for the sonographic diagnosis of basilar artery occlusion or tight stenosis in conjunction with 1,071 retrograde brachial angiograms. By sonographic patterns, we have suspected obstruction of the basilar artery or of both distal vertebral arteries in nine cases. Either bilateral sonographic silence or the absence of a diastolic flow component of the vertebral arteries served as criteria in the sonographic evaluation. Angiography of the vertebro-basilar system, performed in eight cases, showed near or complete occlusion in the distal vertebrals or in the proximal basilar artery. Degrees of stenosis less than an 80 percent reduction in lumen diameter could not be detected sonographically. Two further basilar artery occlusions were detected by means of angiography despite negative Doppler sonography: one of these patients showed an extensive collateral circulation between the posterior inferior and the superior cerebellar arteries, and one patient had an occlusion only of the middle and rostral thirds of the basilar artery, the proximal third and the anterior inferior cerebellar arteries being widely patent. Thus, we believe that directional CW Doppler sonography is very useful in the diagnosis of near or complete occlusion of both distal vertebral arteries or of the proximal basilar artery.

Vascular recanalizing techniques in interventional neuroradiology

Vascular recanalizing techniques only recently became methods of some clinical importance. Angioplasty of the subclavian artery in cases with subclavian steal syndrome has now been performed in so many instances that it can be judged safe. Angioplasty at the origin of the vertebral artery has not yet been performed in as many cases. However, even there this method is obviously less hazardous than surgery. Local intraarterial fibrinolytic therapy is the only therapy providing some success in progressive stroke from vertebrobasilar thrombosis. In contrast to the vertebrobasilar territory local fibrinolytic therapy within the carotid territory has to be strictly limited to some special indications.

[Doppler sonogram in basilar artery thromboses]

We have investigated 6,380 patients with directional c-w Doppler sonography within the last 3 1/2 years, and have suspected obstruction of the basilar artery or of both distal vertebral arteries in 7 cases. Either bilateral sonographic silence or an absent diastolic flow component of the vertebral arteries were employed as criteria in the sonographic evaluation. Angiography of the vertebro-basilar system, performed in 6 cases, confirmed the diagnoses: basilar artery occlusion was found in 4 patients, 1 patient revealed tight stenosis of the basilar artery in its entire length, and 1 patient exhibited occlusion of both distal vertebral arteries. Three further basilar artery occlusions were detected by means of angiography despite initially negative Doppler sonography within the same period of time; 1 of those patients, however, met the above criteria for basilar artery occlusion upon sonographic reevaluation on the following day. Thus, we believe that directional c-w Doppler sonography is very useful in the diagnosis of basilar artery obstruction.