Article written by Dr. Cristina Herțea – neurology specialist
Benefits of extra-transcranial examination
1. Why is it important for the patient to perform a cervical (extracranial) investigation and complete the examination with the transcranial evaluation?
The cervical vessels, through the carotid and vertebral arteries, represent the arterial blood supply to the brain. These are 4 in number – a pair of common carotid arteries (left / right) and a pair of vertebral arteries (left / right). At the neck zone and above in the brain, some of them branch off into their terminal branches (the carotid system that irrigates the anterior part of the brain – also called the anterior circulation), others join to form a single arterial vascular trunk that later bifurcates. in its collateral and terminal branches (this is called the posterior circulation that vascularizes the brain in its posterior region). The 2 arterial systems (anterior and posterior) function in the brain on the principle of communicating vessels, so that blood can be directed where necessary, this being possible due to the fact that the blood vessels at this level do not have valves to direct the blood in one direction. The anatomical name of this system is Willis polygon, and functionally it is known as cerebral hemodynamics.
Examination of the neck (cervical-extracranial) can only assess this complex system of communicating vessels in the brain in terms of indirect criteria that provide limited information.
Transcranial evaluation is important because:
- it can detect the presence of intracranial stenoses (cerebral vessels). This can change the patient’s treatment schedule as well as his subsequent monitoring. Intracranial stenoses are likely to precipitate a stroke as are stenoses detected in the cervix. Treatment is different for intracranial stenoses compared to cervical stenoses;
- the incidence of intracranial stenoses, in the case of a patient who requires carotid surgery can adapt the operating protocol according to cerebral hemodynamics;
- to a lesser extent, cerebral aneurysms can be detected by transcranial ultrasonography. Depending on the size and location, the suspicion of an aneurysm can be detected, which can later be confirmed by superior imaging techniques;
- transcranial ultrasonography comes as a complement to the extracranial examination and raises a suspicion of cerebral venous thrombosis (occlusion of the veins in the brain). This suspicion can be raised on clinical or imaging criteria (eg: on MRI-MRV investigation when a defect in filling the cerebral veins is detected), when cranial ultrasonography can certainly differentiate between a venous dominance (physiological / normal aspect ) or a venous thrombosis (pathological aspect / patient requiring specific neurological treatment);
- stroke in young people is a special chapter in neurology. A common cause in young people is the presence of a heart defect called patent foramen ovale. This requires confirmation by echocardiographic examination and cardiological examination, but transcranial examination may appreciate 100% if the venous blood has an aberrant bypass pathway that may be cardiac or pulmonary;
- another example in which transcranial examination is beneficial is the evaluation of pulsatile tinnitus. Pulsating tinnitus is a noise that the patient hears in the ear and is synchronous with the pulse. Transcranial examination may determine whether it is caused by the presence of a dural arterio-venous fistula (which is a condition that may require imaging follow-up and / or neurosurgical evaluation) or by a less dangerous pathology such as a vascular-nervous conflict. Prior to performing the imaging investigation, the doctor will ask the patient several questions to detect the arterial or venous source of tinnitus;
- other applications of transcranial exploration are the examination of the central retinal artery (CRA) in patients with amaurosis fugax (temporary loss of vision in the presence of an eye) and which may be suggestive of a transient stroke. It requires ultrasound evaluation and adjustment of the treatment schedule according to the results. Less well known and being evaluated (due to the lack of expert consensus) are the evaluation of the substantia nigra in patients with Parkinson’s disease, the evaluation of the ventricle III in patients with dementia and the measurement of raffia in patients with depressive syndrome;
- last but not least, the indication is for extra and transcranial examination because it is the only one that is correct and complete from a neurological point of view;
2. Does extra-transcranial examination require special training?
This type of examination does not require additional training, but given that 2 segments are examined, the duration of the investigation is approximately one hour.
3. Is the examination harmful in any way?
No, the examination is not harmful (it is non-invasive). It does not use X-rays and is completely painless. It can be performed whenever needed (in principle, re-evaluation is required at 3 or 6 months depending on the results of the initial evaluation).
The only safety restriction is related to the trans-orbital examination, the indication being to reduce the power of the device and respecting the ALARA principle (as low as reasonably achievable).
4. Is it possible for this investigation to be performed on pregnant women?
Yes, this investigation can be performed safely in pregnant women. It is similar to any other ultrasound investigation that is performed during pregnancy for fetal morphology.
5. Who has an indication for this type of investigation?
Vascular disease is currently one of the leading causes of mortality and morbidity in the world. Stroke ranks 3rd in conditions that can cause death or disability after cancer and myocardial infarction. Cervical-cerebral ultrasonographic examination gives us information about vascular status. Performed early allows the patient to take measures to control the evolution of vascular disease by changing lifestyle and adjusting drug therapy where appropriate.
In conclusion, we can conclude that the cervico-cerebral ultrasonographic examination is a non-invasive, painless investigation that can be performed by anyone, whenever needed and that gives us valuable information about vascular status, information that can be used effectively in the prevention of vascular disease, respectively in the prevention of stroke and myocardial infarction.