Embolic stroke following carotid radiation angiopathy demonstrated with I-123 IMP brain SPECT

Environmental factors and stroke: A selective review

Despite numerous prior stroke risk factor investigations, much remains unknown about the effect of environmental factor changes on stroke incidence and mortality rates. Yet these data might be important for defining a number of measures to prevent stroke and for developing a greater understanding of the origin and incidence trends of stroke in different regions and populations. In this paper we review the current state of knowledge about certain environmental stroke risk factors.

Detection of radiation-accelerated atherosclerosis of the carotid artery by panoramic radiography

BACKGROUND

The authors review the pathophysiology, epidemiology, course of disease, dental findings and dental treatment of patients who developed atherosclerosis of the carotid artery after having received therapeutic radiation to the neck for squamous-cell carcinoma of the oral cavity, pharynx or larynx; salivary gland tumors; and lymphomas involving the cervical lymph nodes.

TYPE OF STUDIES REVIEWED

The authors conducted a MEDLINE search for 1997 through 2002 using the key terms "radiation therapy," "carotid artery" "atherosclerosis," "cancer" and "dentistry." The articles selected for further review included those published in English in peer-reviewed journals, with preference given to articles reporting randomized, controlled trials.

RESULTS

Recent advances in the delivery of radiation therapy to malignancies of the head and neck have resulted in the prolonged survival of increasing numbers of patients. However, the therapy has been implicated as causing atherosclerotic lesions in the cervical component of the carotid artery, which predisposes patients to an increased risk of developing stroke. Panoramic radiography can identify some of these lesions before they can cause a stroke. Radiation-induced atherosclerosis is common, with approximately 40 percent of patients developing hemodynamically significant carotid artery plaques within 10 years of having received irradiation.

CLINICAL IMPLICATIONS

Dentists treating patients who have received therapeutic radiation to the neck should examine the patients' panoramic radiographs for evidence of atheromalike calcifications, which appear 1.5 to 2.5 centimeters posterior and inferior to the angle of the mandible. Patients with evidence of such lesions should be referred to their physician for an ultrasound examination of their carotid arteries.

Detection of radiation-induced cervical atheromas by panoramic radiography

Therapeutic irradiation of the neck is frequently used to treat patients with head and neck carcinoma. The irradiation, however, has been implicated as the cause of cervical carotid artery atherosclerotic lesions and subsequent stroke. Panoramic radiography previously shown capable of demonstrating isolated lesions was used to assess their development over time. Individuals with a pre-irradiation radiograph free of atheromas were enrolled for study. The prevalence rate of atheroma formation on post-irradiation (bilateral portals at >/=45 Gy) radiographs obtained at an interval of >/=36 months was determined. A control group of non-irradiated patients having similar risk factors for head and neck carcinoma and atherosclerosis and having an initial radiograph free of atheroma formation were likewise enrolled for study. The prevalence rate of atheroma formation on a second radiograph obtained from these individuals at an interval of >/=36 months was determined. The study population consisted of 17 patients, with a mean age of 56.5 (range 21.5-77.8) years who received a mean therapeutic irradiation dose of 53.2 Gy (range 45-71) to each side of their neck. The prevalence rate of atheromas manifested on the post-irradiation radiographs was 53%. These radiographs were obtained, on average, 69.7 (range 37-133) months after completion of radiation therapy. The prevalence rate of atheromas manifested on the second radiograph of patients in the control group was 5.9%. These radiographs were obtained, on average, 53.5 (range 52-55) months after the first. The difference in prevalence rates was statistically significant (p=0.0003). Individuals who have received therapeutic irradiation to the neck are more likely to develop carotid artery atheromas after treatment than are risk-matched control patients who have not been irradiated. These lesions can be detected by panoramic radiography.

Detection of radiation-induced, accelerated atherosclerosis in patients with osteoradionecrosis by panoramic radiography

PURPOSE

Osteoradionecrosis (ORN) of the mandible has long been considered the most destructive complication of head and neck irradiation. Recently, therapeutic irradiation has been implicated as the cause of induced/accelerated atherosclerosis of the cervical carotid artery and subsequent stroke. Panoramic radiography, previously shown to be capable of identifying carotid artery atherosclerosis in nonirradiated individuals, was used to assess the carotid vasculature of patients being treated for ORN.

PATIENTS AND METHODS

The panoramic radiographs of 61 men (mean age, 60.5 years; range, 41 to 77 years) who received therapeutic irradiation to the neck 36 months or more previously were assessed for the presence of carotid artery atherosclerotic lesions. Sixty-one control subjects who never received therapeutic irradiation, but who were similarly susceptible to atherosclerosis by virtue of age, were assessed in a like manner.

RESULTS

The irradiated individuals sustained a dose of 40 to 72 Gy to the area of the carotid bifurcation. Seventeen individuals (27.9%) with an irradiation dosage to the carotid bifurcation that averaged 59.2 Gy had a panoramic radiograph with a carotid atheroma (11 with unilateral lesions and six with bilateral lesions). The radiographs of the control subjects showed that three individuals (4.9%) had calcified carotid lesions. The mean age of these subjects was 66.1 years; two had unilateral lesions, and one had bilateral lesions. The difference in the proportion of individuals with ORN who manifested carotid artery atherosclerosis on their panoramic radiographs was statistically significant (P = .001) when compared with the nonirradiated control subjects. The lesions seen in both populations had a similar morphologic appearance and were radiographically located within the soft tissues of the neck 1.5 to 4.0 cm inferior-posterior to the angle of the mandible.

CONCLUSIONS

Individuals with radiation doses sufficient to cause osteoradionecrosis of the mandible are at significantly higher risk of developing carotid artery atherosclerotic lesions than age-matched, nonirradiated controls.

The role of panoramic radiography in determining an increased risk of cervical atheromas in patients treated with therapeutic irradiation

PURPOSE

Therapeutic irradiation of the neck is a common component of treatment for those with carcinoma of the oral cavity, pharynx, and larynx. Such irradiation, however, has been implicated as the cause of accelerated atherosclerosis of the cervical carotid artery and subsequent stroke. Panoramic radiography, previously shown to be capable of identifying carotid artery atherosclerosis in non-irradiated individuals, was used to assess the carotid vasculature of patients who had been treated for cancer with therapeutic irradiation.

METHODS

The panoramic radiographs of 33 male subjects who had received therapeutic irradiation (> or = 50 Gy) to the neck 30 or more months previously were assessed for the presence of calcified carotid artery atherosclerotic lesions. Age-matched controls, similarly liable for oropharyngeal malignancy and atherosclerosis by virtue of their medical and habitual risk factors (hypertension, smoking, obesity) were assessed in a like manner.

RESULTS

The panoramic radiographs of the irradiation-treated subjects (age range, 32 to 84 years; mean age, 66.1 years) showed that 21% (7 of 33 subjects) had calcified atherosclerotic lesions. The mean age of these seven subjects was 64.6 years; four had unilateral lesions and three had bilateral lesions. The radiographs of the control subjects showed that 4.7% (5 of 107 subjects) had calcified atherosclerotic lesions. The mean age of these five subjects was 67; three had unilateral lesions and two had bilateral lesions. The lesions seen in the two populations had similar morphologic appearances. The discrete radiopaque calcifications were located within the soft tissues of the neck, approximately 2.5 cm inferior-posterior to the angle of the mandible.

CONCLUSIONS

Subjects who had received therapeutic irradiation of the neck had a statistically higher risk (p = 0.007, according to Fisher's Exact Test) of the development of calcified carotid artery atherosclerotic lesions than age-matched, risk-matched, non-irradiated control subjects. These lesions can be detected on routine panoramic radiographs.

Radiation-induced injury to the carotid artery: a longitudinal study

Therapeutic radiation can lead to damage of arterial walls. In the present investigation, we studied prospectively 16 patients without pre-existing vascular disease (13 males, three females; mean age = 59.75 ± 11.9 years) who had undergone surgery and post-operative radiation therapy (cumulative dose = 56.2 ± 10.2 Gy) for the treatment of carcinoma of the head and neck. The carotid arteries were examined every 3 months for 19.9 ± 8.7 months using Doppler ultrasound and B-mode sonography. The thickness of the arterial walls was determined using an index (outer:inner mean arterial wall), and it was compared to a group of age-matched control subjects (n = 16) with healthy arteries. The index of the common carotid artery (CCA) was initially 1.14 ± 0.04 in both the right and left CCA in the radiation-treated subjects. By the end of the study, this index had increased significantly to 1.37 ˙ 0.14 in both right and left CCA in the radiation-treated subjects (p < 0.01). There was a significant difference in arterial wall thickness between the radiation-treated and control subjects (p < 0.001). Frequent and extensive smooth-surfaced plaques indicative of arterial thickening in the area of the common carotid and internal carotid arteries were seen in the irradiated patients. Four patients developed > 50% atherosclerotic stenosis of the internal carotid artery. These data suggest that arterial damage may occur following radiation treatment of the head and neck area. Modification of radiation therapy for the post-surgical treatment of head tumors coupled with the continuous monitoring of the carotid arteries using B-mode sonography could minimize this arterial damage.