The vascular patient, occlusive pathology of cerebral arteries and cerebral ischemic infarction

Definition

Ischemic stroke is the most frequent pathology affecting the diabetic patient, the hypertensive patient, the dyslipidemic, but it is not possible to make the watertight compartments between these types of patients, as the internist prefers to talk about "vascular patient", meaning with this term define a patient with very varied and complex problems.

The ischemic stroke, due to the passage of a blood clot, that is of coagulated blood that circulates and which suddenly obstructs the vessel or, sometimes, caused by the breaking of an atherosclerotic plaque, affects the extra-cranial cerebral arteries, ie those that originate from the aortic arch. While posteriorly the two vertebral arteries merge into the basilar artery and provide the posterior part of the brain. In reality we speak of the supra-aortic branches of the aortic arch:
- brachiocephalic trunk, a. subclavian, a. vertebral, a. common and internal carotid (elective site: carótidea bifurcation). The most frequently involved artery is the internal carotid artery (50% of cases). In fact, at the base of the brain forms, so to speak, a ring, that is an interweaving of vessels (continues to read Willis's polygon), which has the aim of guaranteeing the cerebral circulation, even if one or the supporting vessels it is partially or totally occluded. The writer, for example, recently dealt with the case of a diabetic patient, in oral therapy, an elderly gentleman, about 70 years old, who even in the slightest thought of having decompensated blood sugar on 500 mg% and pass! Well, this gentleman, suddenly had accused a malaise and had been accompanied to the PS for the care of the case. Here, the soluble encephalous CT scan, which at first glance is always negative, was treated for glycometabolic decompensation with IV fluids and the like, including small insulin boluses. And so far in the act of pleading.

At our insistence, however, he had performed an ecocolordoppler of the supra-aortic trunks, which had shown complete occlusion of the left internal carotid. In fact, with hindsight, the patient, who once operated on PTA, ie TSA angioplasty, was fine, referred to sudden dizzying syndrome that he needed as soon as he turned his head on the trunk! Fortunately, the intra-cranial cerebral arteries constitute the famous arterial polygon circle of the Willis + its ramifications; the most frequently involved artery is the average cerebral (25% of cases).

In case of embolism of these vessels you can have:

· An ischemic cerebral infarction, ie an irreversible damage of brain tissue by localized acute circulatory disorder, which is the basis of 80% of all acute cerebrovascular accidents (stroke, apoplexy);
· The most frequent cause of disability in patients over sixty-five
· The death of the patient who is the third cause after death due to ischemic heart disease and neoplasia
related link : ictus stroke1 stroke2 stroke3 stroke4 paziente confuso

Etiology

In general, the cause of occlusions is 30% of cases from embolic events with cardiac starting, usually from the left atrium pockets in patients with atrial fibrillation, when the heart, as it were, starts sinus arithmic and scales blood emboli coagulated in the epiaortic vessels.

In particular they are recognized as emboligene causes:
I. Arteriosclerosis and arterial thrombosis; risk factors: the most important is arterial hypertension; for other risk factors see chap. Ischemic heart disease.
2. Arterial embolisms from the left heart (in the case of mitral vices, rniocardial infarct, cardiac wall aneurysm, atrial fibrillation, bacterial endocarditis) and also from carotid artery and aortic arch plaques.
3. Other causes: rarely dissection of extra-cranial cerebral arteries, vasculitis, frequent causes these in younger patients, for which no other reason can be explained.

Pathogenesis of stroke cerebri

It generally depends on cerebral microangiopathy, that is, pathological facts about the medullary perforating arterioles:
- small lacunar infarcts
- subcortical arteriosclerotic encephalopathy or Binswanger disease, slowly evolving, ev. appearance of dementia.
-macroangiopatia
- macroangiopathy of the intra-cranial cerebral arteries (10%); elective seats: carotid siphon and main trunk of the. average brain
- macroangiopathy of extra-cranial cerebral arteries (90%); only the stenosis / occlusion of the internal carotid artery usually have a significant pathogenetic significance.
The heart attacks by the involvement of the Internal carotid artery mainly come from arterio-arterial embolisms = mobilization of trombogenic material from the internal carotid. Strictures with <75% lumen narrowing are usually asymptomatic. In the case in which the stenosis of the supraortic trunks is particularly sustained, a reduction of the arterial circulation can be obtained and therefore a malaise that often, as in the case of our patient, is framed within the transient ischemic attacks, due in this case to critical reduction of the perfusion pressure, such as to lead to a hemodynamic heart attack if there are no adequate compensatory anastomies. Moreover, if the hematocrit is high, if there is ispissatio sanguinis, if the blood viscosity is high, if dyslipidemia contributes to worsening the picture, then the clinical conditions could be worse until the picture of acute cerebral ischemia that compromises the mechanisms is realized of self-regulation of cerebral perfusion. This results in vasoparalysis with dependence of blood spraying by blood pressure and the viscosity properties of the blood.

In case of ischemia we can have:

- Territorial infarcts due to thrombotic or >> embolic occlusion of the large cerebral arteries at the level of the basal ganglia or at the cortical / subcortical level, with a wedge aspect.
- Extra-territorial infarcts are localized to the periventricular and subcortical medullary tissue; There are 2 types:
the infarcts of the border areas affect the sector at the limit between two vascular districts
• the infarcts of the terminal branches involve medullary arteries without collateral circulation.

Clinic features

The 4 classic stages of the occlusive pathology of extra-cranial cerebral arteries are:

- stage I of asymptomatic stricture
- stage II or TIA = transient ischemic attack with reversible short-term neurological deficit, which regresses within minutes or, at most, within 24 hours. These patients, if not adequately treated, may experience relapses and in 40% of cases the TIA can be presented as a major insult within 5 years: stroke;
- stage III RIND = reversible ischemic neurological deficit (protracted): the complete regression of the neurological deficit requires a period> 24 hours, but not all authors accept this old classification anymore.
-stadio IV: complete cerebral infarction: partial or absent regression of the neurological deficit.

The localization of the occlusion is massive, for example of the average cerebral, a striking symptomatology is determined, in the sense that the ischemia will affect for example the area of the motor-homunculus and it will be possible to have a paresis or paralysis in the opposite territory of whole emiled , the paralysis will be on the opposite side of the lesion due to the intersection of the pyramidal system fibers. The cerebral infarction causes a contralateral sensory-motor hemiparesis with weakening of the reflexes; later, spastic paralysis with increased reflexes and pyramidal signs (Babinski) occurs. In the more extensive infarcts, speech and consciousness disturbances and eventually the deviation of the head and gaze towards the infarct side are also present. If, on the other hand, the occlusion is at the level of the extra-cranial cerebral arteries, then in this case, if for example it affects the a. internal carotid, often at the level of origin; 50% of cases in the presence of a good collateral circulation, the monolateral occlusion of the internal carotid can be asymptomatic. Unilateral amaurosis fugax is typical of internal carotid stenosis. In the case of vertebro-basilar occlusions (15% of cases) we will have rotational vertigo, drop attack, vomiting and visual disturbances, paresis, etc. Again the acute occlusion of the. basic leads to progressive alterations of consciousness. Sudden rotational vertigo, swallowing disorders, bilateral paralysis.

Diagnosis

It certainly uses the brain TAC that is performed in an emergency, first to rule out the dangerous hemorrhagic stroke with spontaneous cerebral hemorrhage (15% of all strokes), most often linked to arterial hypertension with massive hypertensive hemorrhage, more rarely in course of fibrinolytic or anticoagulant therapy. Subsequently, if the hemorrhagic stroke was excluded, the second brain CT scan, performed over time, will give an image of the ictal ischemic event as a hypodense edema area. In the case of strokes affecting the bulb or the medulla oblongata, it is imperative to perform brain encephalography which in these cases can provide further and more valuable information. As always, it takes advantage of the experience of the doctor who examines and performs the neurological examination, to evaluate the side signs, the maneuver of Mingazzini ,. The sign of Babinsky, the bottom of the eye, expression of stasis and papillary edema. It is important to evaluate the patient as a whole, especially if a state of coma and / or psychomotor agitation takes over which represents an unfavorable prognostic sign, especially if convulsive events arise. Arterial pulses are also evaluated, TSA echocolordoppler is performed, arterial pressure can be measured on both arms, to evaluate any difference, in case of aortic arch syndrome, difference between the two sides> 20 mmHg). proceeds with diagnostic imaging: immediate CT is mandatory, which allows the differentiation between ischemic insult, hemorrhage and tumor, and the determination of the localization and extension of the cerebral infarct.

General therapeutic measures:

- ensuring vital functions, ensuring venous access but only in the healthy arm, not in the paralyzed arm, due to the high risk of thrombosis;
- control of respiration, circulation, hydro-electrolyte balance, glycemia, blood gas analysis
- Administration of antiplatelet in ischemic stroke, neurosurgical evaluation in hemorrhagic stroke, 02 when at oximetry the saturation of 02 is <95%. In case of respiratory problems: intubation and assisted breathing;
- control of intestinal and bladder functions (bladder catheter)
- in case of swallowing or conscience disorders with danger of aspiration, feeding with a tube or parenterally. In case of persistent swallowing disorders for more than 2 weeks: percutaneous endoscopic gastrostomy (PEG)
- prophylaxis of decubitus injuries (changing the patient's position at regular intervals, anti-decubitus mattress), prophylaxis of the equine foot and prophylaxis of contractures through adequate posture
- early treatment with rehabilitation gymnastics and speech therapy, respiratory gymnastics
- prophylaxis of thromboembolism for the duration of immobilization (low dose heparin, elastic stockings, motor exercises)

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