.

      A chronic cerebrovascular ischemia most often manifests itself in signs of a dyscirculatory encephalopathy (DEP) characterized by diffuse-type headaches, vertigo, tinnitus, memory derangements, emotional lability, increased fatigability and performance impairment, sleep disorder. In DEP, general symptoms prevail without focal neurologic symptoms: severe headaches (77%), increased fatigability (68%), hypomnesia (44%) [17]. Decreased learning capacity is typical for such children.

      Regarding the specific features of the clinical course of some types of the pathology, it should be mentioned that clinical manifestations of stenosis and occlusion of major cerebral vessels do not have any specific features and can manifest themselves as various ischemic cerebrovascular diseases. A moderate decrease of the cerebral blood flow usually does not manifest itself clinically (asymptomatic disease course), or it may be accompanied by some unspecific complaints.

      At the onset of the moyamoya disease and syndrome, their clinical manifestations are rather diverse, and they may resemble the clinical manifestations of cerebrovascular disturbances in pathologic deformations of major cerebral vessels, thrombosis and atherosclerosis of intracranial arteries as well as the manifestations of other diseases (epilepsy, malformations of cerebral vessels, subarachnoid and intra-cerebral hemorrhages of various genesis [192; 196; 270].

      Headache is mentioned as a manifesting symptom in a variety of studies on the moyamoya disease occurring in children too. In literature, there is even an individual notion – a headache associated with the moyamoya disease (HAMD) [141; 233; 238; 288]. Headache is often the only symptom at the onset of this disease. The headache is supposed to be caused by a compensatory dilatation of meningeal and leptomeningeal arteries, which can stimulate nociceptive receptors of dura mater of brain (DMB). The headache may have a migraine-like nature and be resistant to a drug therapy. However, this symptom usually is not considered as a fatal sign. In most patients, the headache regresses after the surgery [71; 136; 238].

      The subsequent joining of transient focal neurologic symptoms is often considered by neurologists as a manifestation of sub- or de-compensation of residual organic background under the effect of school loads, intense sports activities, viral infections, vaccinations, etc. They are acknowledged as TIAs most often retrospectively, after the verification of the moyamoya disease. A short-term and transient nature of symptoms in children, often combined with the inability to describe their «unusual» complaints verbally, result in delayed help-seeking and late hospitalization. According to literature data, the delayed diagnosing is noted in all patients, and it may exceed two years. The moyamoya disease is usually identified only after the child has suffered a typical IS, which is followed by various neuroimaging examinations. Clinical manifestations in children with the moyamoya disease are distributed in the occurrence rate as follows: ischemic symptoms – 80% of cases (including strokes – 40% and transitory ischemic attacks – 41%) [21; 80; 224; 242; 254]; epilepsy – 5%, intracranial hemorrhages – 2.5%; other symptoms – 12.5% of cases (headache, motor disturbances, or combined symptoms) [72; 80; 224; 242; 254].

      5. Diagnostics of pediatric stroke

      A nation-wide Russian recommended list of diagnostic procedures aimed at differential diagnostics of a CVD at an early age does not exist. It is actively discussed and formed in some individual centers. The variability of the CVD causes considerably hinders the diagnostic search. During the most acute and acute disease periods, the efforts are focused on identifying the pathogenic variant of the CVD, primarily, on identification of the most frequent diseases, whose therapy can be started immediately (cardiac pathology, congenital clotting disorders, congenital and acquired pathology of cerebral vessels) with due regard for the age [22; 34]. If the cause has not been determined, it is recommended afterwards to rule out consecutively other, less common, causes of the CVD at an early age [7; 9; 22; 24; 134].

      It is known that, despite a rather well-defined organization of the diagnostic process in foreign clinics, about 20% of ischemic strokes remain etiologically unexplained. The similar national indicator reaches 65 – 70% [161; 174; 280]. Despite the high cost of a laboratory-based instrumental examination and its long duration, such an examination must be held. The earliest clarification of the cause of an ACVD in a child is considered a high-priority and the most important mission of a diagnostic search at any phase of the disease. The accurate clarification of the etiology of an ischemic ACVD determines the focus of the corrective drug therapy, the system of preventive measures and the prognosis regarding the further course and recurrence of the disease.

      Based on the FSBEI of Higher Professional Education «Urals State Medical University», a list of diagnostic activities, which are due to be held for examination of children with IS and TIA at an emergency (inpatient) stage, was developed and implemented into a routine practice (Table 3).

      It must be noted that a consecutive clinical, laboratory-based and instrumental examination with the fulfillment of all items proposed above should be held even in the cases, when the cause of a stroke or TIA seems evident. This is due to the fact that, beside an evident cause, the presence of other, equally important, risks may be possible, which could lead to a pathology of the blood coagulation system. It is just these individual risk combinations, which, under the effect of the initiating agents, facilitate the realization of genetically determined prothrombotic readiness and lead to the formation of a focal spot of an infarction or TIA in children.

      All stated above is aimed at the clarification of the ACVD causes as well as at the further prevention of recurring strokes. However, regarding the determination of indications for surgical treatment held, when the conservative therapy is not effective, or in addition to it, as well as when a surgical intervention method is selected, some additional tests are required to assess the state of major vessels and the cerebral circulation system. As distinct from adults, the algorithm of instrumental examination of children with cerebrovascular diseases is not developed yet.