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Carotid endarterectomy for nonhemispheric cerebral symptoms: Patient selection with ocular pneumoplethysmography
Carotid endarterectomy for nonhemispheric cerebral symptoms: Patient selection with ocular pneumoplethysmography Kenneth Ouriel, M.D., John J. Ricotta, M.D., Richard M. Green, M.D., and James A. DeWeese, M.D., Rochester, N.Y. Carotid endarterectomy fails to ameliorate nonhemispheric cerebral symptoms in an unacceptably high proportion of patients, specifically those patients with minor, hemodynamically insignificant carotid lesions. Ocular pneumoplethysmography (OPG) has been shown to accurately predict the hemodynamic significance of carotid lesions, but its use has not been applied to the subset of patients with nonhemispheric symptoms. Preoperative OPG studies were obtained in 43 patients with nonhemispheric symptoms. Postoperatively, 72% of patients with OPG suggestive of hemodynamically significant carotid lesions were relieved of symptoms. By contrast, only 32% of patients with normal OPG were asymptomatic after carotid surgery (p < 0.05, life-table methods, 24-month followup). These data suggest that OPG is a useful test to determine which patients with nonhemispheric cerebral symptoms will benefit from carotid revascnlarization. (J VASC SURG 1986; 4:115-8.)
Carotid endarterectomy in patients with transient hemispheric cerebral ischemia is associated with the relief of these symptoms in the vast majority of cases. Indeed, the success of the procedure in ameliorating hemispheric symptoms has been reported to be in the range of 80% to 90%. 1-3 By contrast, the results of carotid surgery for nonhemispheric symptoms have not been so good, with postoperative recurrent symptoms in one third to half of the patients. 4''~The success of carotid endarterectomy for nonhemispheric symptoms may be improved if the operative indications are limited to those patients with hemodynamically significant bifurcation lesions. 5 Relief of nonhemispheric symptoms can be expected in more than 80% of patients with appropriate symptoms and angiographically documented stenoses in excess of 60% diameter reduction. Ocular pneumoplethysmography (OPG) as described by Gee, Oiler, and Wylie6 has been shown to be useful in the determination of the hemodynamic significance of a carotid lesion. The accuracy of OPG in detecting carotid stenoses in excess of 60% diameter reduction is as high as 96%. 7 On the basis of these observations, we evaluated the use of OPG in patients with nonhemispheric symptoms in an effort From the Department of Surge~, The University. of Rochester Medical Center. Reprint requests: Kenneth Ouriel, M.D., Department of Surge~, University of Rochester, 601 Elmwood Ave., Rochester, NY 14642
to discriminate patients with hemodynamically significant carotid lesions and, therefore, to noninvasively select patients with a high probability of relief of symptoms after carotid revascularization. METHODS
Preoperative OPG was undertaken in 43 consecutive patients with transient nonhemispheric cerebral symptoms who presented to the University of Rochester Medical Center between 1981 and 1984. There were 27 male and 16 female patients. The average age at the time of operation was 65 + 4.1 years (mean -+ standard error of the mean). Follow-up was obtained through personal communication with the patients or by review of the medical record and averaged 29 + 3.8 months. The investigators assessing postoperative symptoms had no knowledge of the preoperative OPG results. OPG was performed as described by Gee, Oiler, and Wylie. ~ A test was considered to show abnormality when the pressure difference between the two eyes was greater than 5 mm Hg, or when the unilateral ocular pressure fell below the normal range for the corresponding brachial arterial pressure (normal range defined as greater than 39 + 0.43 × brachial systolic pressure). Our previous studies demonstrated a sensitivity of 97% and a specificity of 95% for OPG when compared with measurements made on the pathologic specimen removed at the time of endarterectomy.7 115
Journal of VASCULAR SURGERY
116 Ouriel et al.
~_.I00 -'\'-\._.o;%s_,,_._. 80
60 Q_
40
OPG Negatwe
cO
20
'
;
'
12 '
'
18 '
'
24 '
'
3'0
POSTOPERATIVE MONTHS Fig. 1. Life-table analysis of success of carotid endarterectomy in relieving nonhemispheric symptoms with respect to preoperative ocular pneumoplethysmogram (OPG). All patients underwent preoperative four-vessel arteriography with visualization of the extra- and intracranial vasculature. The percentage ofstenosis was determined by measuring the diameter of the radiopaque column at its narrowest point in the internal carotid artery and relating it to the radiopaque border of the first portion of the internal carotid artery distal to the plaque. A lesion was considered to be hemodynamically significant if the degree of stenosis amounted to greater than 60% diameter reduction. Mean arterial pressure proximal and distal to the stenosis was measured before endarterectomy in 17 patients. A 19-gauge needle was inserted into the artery and connected to a mercury manometer. A pressure gradient of greater than or equal to 5 mm Hg was thought to indicate a hemodynamically significant lesion. Postoperative results were assessed with life-table methods, and the statistical significance of differences between groups was determined with the log-rank test. 8 Significance was assumed when p < 0.05. RESULTS Preoperative OPG detected a significant stenosis in 25 patients (58%), whereas the remaining 18 patients (42%) had normal results with OPG. Intemal carotid stenoses documented by angiography aver-
aged 77% + 4% in patients whose OPG showed abnormality, compared with 55% _ 4% in patients with normal results (p < 0.05). Critical intracranial tandem stenoses with an estimated luminal compromise in excess of 60% diameter reduction were present in nine patients, all of whom had abnormal results on OPG. Subclavian or vertebral artery lesions were present in 35 patients (81%), 28 (65%) of which were in excess of 60% diameter reduction. Classic nonhemispheric symptomss were present in 29 patients (67%), whereas nonclassic symptoms were present in the remaining 14 patients (33%). Hemodynamically significant stenoses of the internal carotid artery were detected more frequently in patients with classic symptoms than in patients with nonclassic symptoms, 69% (20 of 29 patients) vs. 36% (5 of 14 patients, p ~< 0.05). No perioperative or late postoperative strokes occurred during the follow-up period; however, one patient died of a myocardial infarction 11 months after operation. Perioperative morbidity consisted of six patients with postoperative hypertension, two patients with transient hypoglossal nerve palsies, and a single patient with a 45-minute episode of mild monoparesis referable to the operated side. At 24 months after operation, 72% of patients with abnormality shown on preoperative OPG were asymptomatic (life-table methods, Fig. 1). By contrast, only
Volume 4 Number 2 August 1986
OPG-Gee in nonhemispheric ischemia 117
32% of patients with normal results of OPG were asymptomatic (p < 0.05). Several factors were evaluated as predictors of successful relief of symptoms (Table I). The presence of a tandem carotid lesion did not exclude success after endarterectomy. O f the nine patients with tandem lesions, six were relieved of their symptoms after the operative correction of the bifurcation lesion alone. Likewise, recurrent symptoms were independent of the presence of a posterior circulation lesion in excess of 60% diameter reduction or the presence of an ulcerated posterior lesion on arteriography. However, the success of operation did appear to be dependent on the character of the patient's symptoms. Patients with classic nonhemispheric symptoms fared significantly better after carotid endarterectomy than patients with nonclassic symptoms (p < 0.05).
Table I. Success of operation in ameliorating nonhemispheric symptoms with respect to angiographic and clinical variables
DISCUSSION
rating nonhemispheric symptoms was significantly greater when the preoperative OPG detected a hemodynamically significant lesion. However, carotid endarterectomy failed to relieve symptoms in five patients whose OPG showed abnormaliw. The explanation for operative failure may have been the prcsencc of a critical siphon lesion in three of the five patients. Other reasons for failure of an operation to alleviate symptoms include a nonvascular origin for the symptoms, posterior circulation emboli as the source of the symptoms, an incomplete circle of Willis without adequate communication between the anterior and posterior cerebral circulation, or a technical problem at the endarterectomy site such that flow limitation is not relieved. In the absence of these complicating circumstances, wc believe that the OPG is a useful preoperative predictor of when carotid endarterectomy will be beneficial in relieving nonhemispheric cerebral symptoms. In this context, the OPG can function as a valuable noninvasive test in patients with nonhemisphcric symptoms. When the OPG yields normal findings, the likelihood of a beneficial result from carotid endarterectomv is small. However, a subgroup of these patients may have symptoms from subclavian or vertebral arteq, disease. Therefore, arteriography is not avoided in the group of patients with classic nonhemispheric symptoms and a normal OPG; rather, careful four-vessel cerebral angiography is directed at the detection of posterior circulation lesions. Operative intervention is not indicated unless the presence of a significant subclavian or vertebral lesion can bc defined. By contrast, when the OPG is abnormal, the probabiliqr of a correctable carotid lesion is great, and arteriography and operation are indicated.
In general, the results of carotid surgeH for nonhemispheric cerebral ischemia have been disappointing. The Joint Study of Extracranial Arterial Occlusion reported recurrent symptoms in 51% of 73 patients who had undergone carotid endarterectomy for vertebrobasilar transient ischemic attacks? The recurrence rate in the 63 patients randomized to medical management was 57%, not significantly different from the surgically treated group. More recent studies have confirmed the initial results of the Joint Study, with recurrent symptoms in one third to half of the patients, s'ga° The explanation for these dismal results relates to patient selection. When operation is undertaken for such ill-defined symptoms as dizziness or syncope the results are understandably poor, because most of these complaints are not cerebrovascular in nature. The second problem relates to the hemodynamic significance of the carotid lesion. When operating on the carotid bifurcation for nonhemispheric symptoms, one is making the assumption that these symptoms are hemodynamic as opposed to embolic in origin. Clearly, the operation will only succeed when a flow-limiting stenosis is eliminated. The results of carotid endarterectomy in patients with nonhemispheric symptoms approach the results in patients with carotid territou transient ischemic attacks when the indications are limited to patients with (1) specific vertebrobasilar symptoms and (2) hemodynamically significant bifurcation lesions. Previous work demonstrated that 85% of these patients can be expected to be symptom free 2 years after carotid endarterectolny. ~ The success of carotid endarterectomv in amelio-
Patients asymptommic Tandem carotid lesion Present Absent Posterior circulation stenosis ---60% >60% Posterior ulcerated lesion Present Absent Classic symptoms Present Absent
6/9 (66%) 21/34 (62%)
NS
19/28 (68%) 8/15 (53%)
NS
9/17 (53%) 18/30 (60%)
NS
21/29 (72%) 6/14 (43%)
p < 0.05
NS = no statistical significance.
118
Ouriel et al.
REFERENCES
1. Thompson JE, Talkington CM. Carotid surgery for cerebral ischemia. Surg Clin North Am 1979; 59:539-53. 2. DeWeese JA, Rob CG, Satran R, Marsh DO, Joynt RJ, Summers D, Nichols C. Results of carotid endarterectomies for transient ischemic attacks--five years later. Ann Surg 1973; 178:258-64. 3. Whisnant JP, Snadok BA, Sundt Jr TM. Carotid endarterectomy for unilateral carotid system transient cerebral ischemia. Mayo Clin Proc 1983; 58:171-5. 4. FieldsWS, Maslenikov V, Meyer JS, Hass WK, Remington RD, Macdonald M. Joint Study of Extracranial Arterial Occlusion. V. Progress report of prognosis following surgery or nonsurgical treatment for transient cerebral ischemic attacks and cervical carotid artery lesions. JAMA 1972; 211:19932002. 5. Ouriel K, May AG, Ricotta JJ, DeWeese JA, Green RM. Carotid endarterectomy for nonhemispheric symptoms: Predictors of success. J VASCSURG 1984; 1:339-45.
Journal of VASCULAR SURGERY
6. Gee W, OUerDW, WylieEJ. Noninvasivediagnosisof carotid occlusion by ocular pneumoplethysmography. Stroke 1976; 7:18-23. 7. Ricotta JJ, Fiore WM, Holen J, Gramiak RA, Green RM, DeWeese JA. Definition of extracranialcarotid disease: Comparison of oculopneumoplethysmography, continuous wavc Doppler angiography and measurement at operation. In: Rose FC. Progress in stroke research, ed 2. London: Pitman Publishers, 1983:91-102. 8. Anderson S, Auguier A, Hauck WW. Statisticalmethods for comparative studies. New York: John Wiley and Sons, 1980:205-14. 9. Ford Jr JJ, Baker WH, Ehrenhaft JL. Carotid endarterectomy for nonhemispheric transient ischemic attacks. Arch Surg 1975; 110:1314-7. 10. McNamara JO, Heyman A, Silver D, Mandel ME. The value of carotid endarterectomy in treating transient cerebral ischemia of the posterior circulation. Neurology 1977; 27: 682-4.
Carotid endarterectomy in patients with transient hemispheric cerebral ischemia is associated with the relief of these symptoms in the vast majority of cases. Indeed, the success of the procedure in ameliorating hemispheric symptoms has been reported to be in the range of 80% to 90%. 1-3 By contrast, the results of carotid surgery for nonhemispheric symptoms have not been so good, with postoperative recurrent symptoms in one third to half of the patients. 4''~The success of carotid endarterectomy for nonhemispheric symptoms may be improved if the operative indications are limited to those patients with hemodynamically significant bifurcation lesions. 5 Relief of nonhemispheric symptoms can be expected in more than 80% of patients with appropriate symptoms and angiographically documented stenoses in excess of 60% diameter reduction. Ocular pneumoplethysmography (OPG) as described by Gee, Oiler, and Wylie6 has been shown to be useful in the determination of the hemodynamic significance of a carotid lesion. The accuracy of OPG in detecting carotid stenoses in excess of 60% diameter reduction is as high as 96%. 7 On the basis of these observations, we evaluated the use of OPG in patients with nonhemispheric symptoms in an effort From the Department of Surge~, The University. of Rochester Medical Center. Reprint requests: Kenneth Ouriel, M.D., Department of Surge~, University of Rochester, 601 Elmwood Ave., Rochester, NY 14642
to discriminate patients with hemodynamically significant carotid lesions and, therefore, to noninvasively select patients with a high probability of relief of symptoms after carotid revascularization. METHODS
Preoperative OPG was undertaken in 43 consecutive patients with transient nonhemispheric cerebral symptoms who presented to the University of Rochester Medical Center between 1981 and 1984. There were 27 male and 16 female patients. The average age at the time of operation was 65 + 4.1 years (mean -+ standard error of the mean). Follow-up was obtained through personal communication with the patients or by review of the medical record and averaged 29 + 3.8 months. The investigators assessing postoperative symptoms had no knowledge of the preoperative OPG results. OPG was performed as described by Gee, Oiler, and Wylie. ~ A test was considered to show abnormality when the pressure difference between the two eyes was greater than 5 mm Hg, or when the unilateral ocular pressure fell below the normal range for the corresponding brachial arterial pressure (normal range defined as greater than 39 + 0.43 × brachial systolic pressure). Our previous studies demonstrated a sensitivity of 97% and a specificity of 95% for OPG when compared with measurements made on the pathologic specimen removed at the time of endarterectomy.7 115
Journal of VASCULAR SURGERY
116 Ouriel et al.
~_.I00 -'\'-\._.o;%s_,,_._. 80
60 Q_
40
OPG Negatwe
cO
20
'
;
'
12 '
'
18 '
'
24 '
'
3'0
POSTOPERATIVE MONTHS Fig. 1. Life-table analysis of success of carotid endarterectomy in relieving nonhemispheric symptoms with respect to preoperative ocular pneumoplethysmogram (OPG). All patients underwent preoperative four-vessel arteriography with visualization of the extra- and intracranial vasculature. The percentage ofstenosis was determined by measuring the diameter of the radiopaque column at its narrowest point in the internal carotid artery and relating it to the radiopaque border of the first portion of the internal carotid artery distal to the plaque. A lesion was considered to be hemodynamically significant if the degree of stenosis amounted to greater than 60% diameter reduction. Mean arterial pressure proximal and distal to the stenosis was measured before endarterectomy in 17 patients. A 19-gauge needle was inserted into the artery and connected to a mercury manometer. A pressure gradient of greater than or equal to 5 mm Hg was thought to indicate a hemodynamically significant lesion. Postoperative results were assessed with life-table methods, and the statistical significance of differences between groups was determined with the log-rank test. 8 Significance was assumed when p < 0.05. RESULTS Preoperative OPG detected a significant stenosis in 25 patients (58%), whereas the remaining 18 patients (42%) had normal results with OPG. Intemal carotid stenoses documented by angiography aver-
aged 77% + 4% in patients whose OPG showed abnormality, compared with 55% _ 4% in patients with normal results (p < 0.05). Critical intracranial tandem stenoses with an estimated luminal compromise in excess of 60% diameter reduction were present in nine patients, all of whom had abnormal results on OPG. Subclavian or vertebral artery lesions were present in 35 patients (81%), 28 (65%) of which were in excess of 60% diameter reduction. Classic nonhemispheric symptomss were present in 29 patients (67%), whereas nonclassic symptoms were present in the remaining 14 patients (33%). Hemodynamically significant stenoses of the internal carotid artery were detected more frequently in patients with classic symptoms than in patients with nonclassic symptoms, 69% (20 of 29 patients) vs. 36% (5 of 14 patients, p ~< 0.05). No perioperative or late postoperative strokes occurred during the follow-up period; however, one patient died of a myocardial infarction 11 months after operation. Perioperative morbidity consisted of six patients with postoperative hypertension, two patients with transient hypoglossal nerve palsies, and a single patient with a 45-minute episode of mild monoparesis referable to the operated side. At 24 months after operation, 72% of patients with abnormality shown on preoperative OPG were asymptomatic (life-table methods, Fig. 1). By contrast, only
Volume 4 Number 2 August 1986
OPG-Gee in nonhemispheric ischemia 117
32% of patients with normal results of OPG were asymptomatic (p < 0.05). Several factors were evaluated as predictors of successful relief of symptoms (Table I). The presence of a tandem carotid lesion did not exclude success after endarterectomy. O f the nine patients with tandem lesions, six were relieved of their symptoms after the operative correction of the bifurcation lesion alone. Likewise, recurrent symptoms were independent of the presence of a posterior circulation lesion in excess of 60% diameter reduction or the presence of an ulcerated posterior lesion on arteriography. However, the success of operation did appear to be dependent on the character of the patient's symptoms. Patients with classic nonhemispheric symptoms fared significantly better after carotid endarterectomy than patients with nonclassic symptoms (p < 0.05).
Table I. Success of operation in ameliorating nonhemispheric symptoms with respect to angiographic and clinical variables
DISCUSSION
rating nonhemispheric symptoms was significantly greater when the preoperative OPG detected a hemodynamically significant lesion. However, carotid endarterectomy failed to relieve symptoms in five patients whose OPG showed abnormaliw. The explanation for operative failure may have been the prcsencc of a critical siphon lesion in three of the five patients. Other reasons for failure of an operation to alleviate symptoms include a nonvascular origin for the symptoms, posterior circulation emboli as the source of the symptoms, an incomplete circle of Willis without adequate communication between the anterior and posterior cerebral circulation, or a technical problem at the endarterectomy site such that flow limitation is not relieved. In the absence of these complicating circumstances, wc believe that the OPG is a useful preoperative predictor of when carotid endarterectomy will be beneficial in relieving nonhemispheric cerebral symptoms. In this context, the OPG can function as a valuable noninvasive test in patients with nonhemisphcric symptoms. When the OPG yields normal findings, the likelihood of a beneficial result from carotid endarterectomv is small. However, a subgroup of these patients may have symptoms from subclavian or vertebral arteq, disease. Therefore, arteriography is not avoided in the group of patients with classic nonhemispheric symptoms and a normal OPG; rather, careful four-vessel cerebral angiography is directed at the detection of posterior circulation lesions. Operative intervention is not indicated unless the presence of a significant subclavian or vertebral lesion can bc defined. By contrast, when the OPG is abnormal, the probabiliqr of a correctable carotid lesion is great, and arteriography and operation are indicated.
In general, the results of carotid surgeH for nonhemispheric cerebral ischemia have been disappointing. The Joint Study of Extracranial Arterial Occlusion reported recurrent symptoms in 51% of 73 patients who had undergone carotid endarterectomy for vertebrobasilar transient ischemic attacks? The recurrence rate in the 63 patients randomized to medical management was 57%, not significantly different from the surgically treated group. More recent studies have confirmed the initial results of the Joint Study, with recurrent symptoms in one third to half of the patients, s'ga° The explanation for these dismal results relates to patient selection. When operation is undertaken for such ill-defined symptoms as dizziness or syncope the results are understandably poor, because most of these complaints are not cerebrovascular in nature. The second problem relates to the hemodynamic significance of the carotid lesion. When operating on the carotid bifurcation for nonhemispheric symptoms, one is making the assumption that these symptoms are hemodynamic as opposed to embolic in origin. Clearly, the operation will only succeed when a flow-limiting stenosis is eliminated. The results of carotid endarterectomy in patients with nonhemispheric symptoms approach the results in patients with carotid territou transient ischemic attacks when the indications are limited to patients with (1) specific vertebrobasilar symptoms and (2) hemodynamically significant bifurcation lesions. Previous work demonstrated that 85% of these patients can be expected to be symptom free 2 years after carotid endarterectolny. ~ The success of carotid endarterectomv in amelio-
Patients asymptommic Tandem carotid lesion Present Absent Posterior circulation stenosis ---60% >60% Posterior ulcerated lesion Present Absent Classic symptoms Present Absent
6/9 (66%) 21/34 (62%)
NS
19/28 (68%) 8/15 (53%)
NS
9/17 (53%) 18/30 (60%)
NS
21/29 (72%) 6/14 (43%)
p < 0.05
NS = no statistical significance.
118
Ouriel et al.
REFERENCES
1. Thompson JE, Talkington CM. Carotid surgery for cerebral ischemia. Surg Clin North Am 1979; 59:539-53. 2. DeWeese JA, Rob CG, Satran R, Marsh DO, Joynt RJ, Summers D, Nichols C. Results of carotid endarterectomies for transient ischemic attacks--five years later. Ann Surg 1973; 178:258-64. 3. Whisnant JP, Snadok BA, Sundt Jr TM. Carotid endarterectomy for unilateral carotid system transient cerebral ischemia. Mayo Clin Proc 1983; 58:171-5. 4. FieldsWS, Maslenikov V, Meyer JS, Hass WK, Remington RD, Macdonald M. Joint Study of Extracranial Arterial Occlusion. V. Progress report of prognosis following surgery or nonsurgical treatment for transient cerebral ischemic attacks and cervical carotid artery lesions. JAMA 1972; 211:19932002. 5. Ouriel K, May AG, Ricotta JJ, DeWeese JA, Green RM. Carotid endarterectomy for nonhemispheric symptoms: Predictors of success. J VASCSURG 1984; 1:339-45.
Journal of VASCULAR SURGERY
6. Gee W, OUerDW, WylieEJ. Noninvasivediagnosisof carotid occlusion by ocular pneumoplethysmography. Stroke 1976; 7:18-23. 7. Ricotta JJ, Fiore WM, Holen J, Gramiak RA, Green RM, DeWeese JA. Definition of extracranialcarotid disease: Comparison of oculopneumoplethysmography, continuous wavc Doppler angiography and measurement at operation. In: Rose FC. Progress in stroke research, ed 2. London: Pitman Publishers, 1983:91-102. 8. Anderson S, Auguier A, Hauck WW. Statisticalmethods for comparative studies. New York: John Wiley and Sons, 1980:205-14. 9. Ford Jr JJ, Baker WH, Ehrenhaft JL. Carotid endarterectomy for nonhemispheric transient ischemic attacks. Arch Surg 1975; 110:1314-7. 10. McNamara JO, Heyman A, Silver D, Mandel ME. The value of carotid endarterectomy in treating transient cerebral ischemia of the posterior circulation. Neurology 1977; 27: 682-4.