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PERIPHERAL VASCULAR ULTRASOUND
POSSIBLE SYMPTOMS OF CAROTID AND
VERTEBRAL ARTERY DISEASE
Patients with carotid artery stenosis may suffer from transient ischemic attack (TIA) or amaurosis fugax, a form of visual disturbance. Symptoms of TIA may only last a few minutes and the patient will make a full recovery within 24 hours, whereas patients suffering from a stroke will have symptoms lasting more than 24 hours and may not make a full recovery. Symptoms include single or multiple episodes of loss of power or sensation in an arm or leg (monoparesis), in both (hemiparesis), or in one side of the face; slurring or loss of speech (dyspha- sia); or visuospatial neglect (Box 8.1). As the right side of the brain controls the left-hand side of the body and the converse, the symptoms will relate to the contralateral carotid artery. The speech is usually controlled by the dominant side of the brain (i.e., a right-handed patient’s speech will typically be con- trolled by the left side of the brain). Patients suffer- ing from episodes of amaurosis fugax often complain of ‘a curtain drawing across one eye’ lasting for a few minutes, which is due to emboli within the retinal circulation. In this situation, the symptoms in the eye will relate to the ipsilateral carotid artery. Typical
vertebrobasilar symptoms are shown in Box 8.1. Vague symptoms, such as dizziness and blackout, are not usually associated with carotid artery dis- ease. Subclavian steal syndrome does not usually cause significant symptoms. Patients with symp- toms of TIA are thought to have a risk of stroke of the order of 7–8% per year for the first 2–3 years following a TIA. Patients suffering from crescendo TIA (i.e., very frequent TIA) may require urgent surgery and should be scanned, as a matter of pri- ority, to assess the severity of any carotid disease.
Symptoms similar to TIA can also be caused by other neurological problems, such as epilepsy, intracranial tumor, multiple sclerosis or migraine. Asymptomatic carotid disease is usually discovered clinically by the presence of a carotid bruit, heard as a murmur when listening to the neck with a stethoscope. However, the presence of a carotid bruit may not be due to an ICA stenosis, but could instead relate to an ECA or aortic stenosis or to no stenosis at all. A large proportion of patients with a 70% stenosis will not have a carotid bruit, and therefore its presence or absence is not accurate enough to predict the presence of disease.
Only about 15% of patients suffer symptoms of TIA prior to a stroke. Fifty per cent of ischemic strokes are due to thromboembolism of the ICA or MCA or both, whereas 25% are due to small vessel disease and 15% are due to emboli originating from the heart. Only 1–2% of all strokes are hemodynamic strokes (i.e., due to flow-limiting stenoses) (Naylor et al 1998).
Trauma to the neck can lead to dissection of the carotid artery wall, possibly causing the vessel to occlude. This condition may be suspected in patients suffering a stoke following a neck injury. Ultrasound examination may also be requested in the presence of a pulsatile swelling in the neck to identify the presence of a carotid aneurysm or carotid body tumor, both of which are quite rare.
SCANNING
Objectives and preparation
The purpose of the carotid scan is to identify the extent of any atheroma within the CCA and extra- cranial ICA and ECA and to determine the degree of narrowing of the vessels. The examination should
Box 8.1 Typical carotid territory and vertebrobasilar symptoms (after Naylor et al 1998, with permission)
Typical carotid territory symptoms
● Hemimotor/hemisensory signs
● Monocular visual loss (amaurosis fugax)
● Higher cortical dysfunction (dysphasia—
incomplete language function, visuospatial neglect, etc.)
Typical vertebrobasilar symptoms
● Bilateral blindness
● Problems with gait and stance
● Hemi- or bilateral motor/sensory signs
● Dysarthria
● Homonymous hemianopia (loss of visual field
in both eyes)
● Diplopia, vertigo and nystagmus (provided it is
not the only symptom)