To determine the detection of large intracranial artery thrombosis by CT angiography (CTA) in patients with acute ischemic stroke, depending on the severity of neurological symptoms at the international NIHSS score.

Materials and methods. Study population are patients, hospitalized to the M.P. Konchalovsky City clinical hospital in Moscow during 2019 with ischemic stroke and underwent CTA scans of extra-and intracranial arteries: total 173 patients (94 women (54.3%), man 79 (45,7 %), average age – 70 years) with a diagnosis of acute ischemic stroke, who were in all cases, NIHSS scale was used to assess the severity of neurological symptoms. Intravenous fibrinolytic therapy (FT) or intra-arterial mechanical thrombectomy (TE) was performed in all cases. The Spearman rank correlation was used to measure the correlation.

Results. In 63 of 173 patients (36%) NIHSS score was 6 points or less. Occlusions of large intracranial arteries were detected in 27.7% (n=46) of cases, of which only 61% (n=28) patients reached the stage of TE. FT was performed in 54% of cases (n=94). Of 46 cases with occlusion of large intracranial arteries only 2 patients (4%) had NIHSS score 6 or less. Of all patients, who underwent the CTA, only 2 (1.2%) had NIHSS score 6 or less. There was a significant positive correlation between NIHSS score and the detection of intracranial artery thrombosis. Spearman's rank correlation coefficient Rs is 0.55 (p<0.0001). For one patient brought to the TE stage, there were 6 CTA of extra-and intracranial arteries.

Conclusion. There is a strong relationship between NIHSS score and the detection of intracranial artery thrombosis by CTA. With the low values of the NIHSS score (less than 6), the probability of detection of thrombosis is extremely small. It is advisable to prescribe CTA for patients with NIHSS score of 7 or more only.