**1. Introduction**

Cerebral venous thrombosis is a relatively rare, however life-threatening condition. Current studies show that around 10% of the patients die. Earlier works proved that most of the thromboses originated secondarily, as a consequence of local or systemic infection, more than 30% of the cases were considered to be idiopathic. More recent studies also mention other risk factors, which may contribute to the onset of thrombosis. These include thrombophilic states or use of oral contraceptives. A number of hypercoagulation states or thrombophilic conditions, which contribute to the onset of thromboembolic disease, have been discovered and described in the recent years.

Thrombophilia is a congenital or acquired disorder of the haemostatic mechanism, characterized with an increased tendency towards blood clotting and thrombotization. Typical manifestations of the condition include frequent occurrence of lower extremities thromboses in young age, with frequent recurrence, or localization in unusual places. Congenital forms of the disorder are characterized with family occurrence. The most frequent conditions associated with congenital form of the disease are mutation of genes coding VLeiden factor (Leiden mutation), prothrombin G20210A, hyperhomocysteinemia and furthermore also autosomal inheritance of antithrombin III (AT III), protein C and protein S deficit.

The point mutation of the factor V gene usually occurs in the place of protein C binding, which results in its cleavage and inactivation. The changes are associated with substitution of guanine with adenine at the 1691st nucleotide of the factor V, this substitution results in further substitution of glutamine with arginine on the 506th position of the factor V chain (FV Q506). The mutation is also known as "Leiden mutation", based on the place of its discovery (Leiden, Holland). Substitution of amino acids in the factor V chain causes resistance against the activated protein C, resulting in a higher tendency towards thrombosis. The mutation is considered to be autosomal dominant hereditary. It affects 5-9% of the European population. The mechanism of resistance against the activated protein C (APC resistance) was first described by Dahlbäck in 1993 in Sweden.

Another possible predisposition factor of venous thrombosis is a mutation of gene for prothrombin - G20210A variant. It is present in about 2% of the population. The mutation

Cerebral Venous Thrombosis in Patients Using Oral Contraceptives 115

APC resistance was tested with the use of factor V deficient plasma (Coatest® APC resistance Chromogenix). The test presents almost 100% sensitivity and specificity in detection of factor V mutations (Leiden). Patients with APC ratio below 1.86 were tested with PCR analysis for the presence of FV:Q506 allele. We have also chromatogenously determined the levels of protein C, antithrombin III (AT III), prothrombin, heparin II cofactor and plasminogen. Protein S was

In order to determine the complex mutations of FV 1691 G-A, prothrombin 20210 G-A and MTHFR 677 C-T, we used specific, polymerase chain reaction (MS PCR), according to the works of Austrian authors Endler et al. This method is a single-tube PCR technique based upon the use of allele-specific primers, differing mutually in 8-10 pairs of bases (bp). The subsequent amplification was carried out in accordance with the protocol, which was optimised for thermocycler Perkin Elmer 2400. Following the initial 10-minute denaturation at 95°C, 34 cycles follow, consisting of separation of DNA chains for 1 min at 95°C , annealing primers for 2 min at 56°C and DNA synthesis for 1 min at 72°C. After completion, final elongation was carried out for 7 min at 72°C, followed with cooling to 4°C. To separate the PCR products we used electrophoresis on Spreadex 400 gel (Elchrom Scientific), which enables separation of products up to 400 pb, with high resolution. The results were reviewed on UV review table at 254 nm, the photo documentation was obtained using a

**3.1 Case Report of CVT – Application of local fibrinolysis in 24-year patient using HAK**  24-year-old female patient with a negative history, including pregnancy or thromboembolism used third-generation gestagen as oral contraceptives. The patient was admitted to Neurology ICU, suffering from a strong headache, localized retroaurically, lasting for the period of one week. During the previous two days, the pain was associated with vomiting. Neurological findings included IV-degree somnolence, apathy, dysarthria, nuchal rigidity with 12 points on the GCS (Glasgow Coma Scale) on admission. A CT examination and conventional DSA were carried out in the evening. Angiography showed a partial thrombotic closure of the superior sagittal sinus and complete closure of right-hand lateral and sigmoid sinus, Galen's vein and direct sinus with stagnation of venous drainage in thalamus and basal ganglia. CT examination confirmed hypodensity in the right side of the thalamus and basal ganglia, oedema in right-hand temporal-occipital area and a minor

The examination showed left-hand hemiparesis, divergent strabismus, bilateral miosis, nuchal rigidity and tachycardia 120/min. Oedema of the papillae was not present. Considering the progreding disorder of consciousness gradating into coma, the patient was intubated and left on artificial ventilation. Consequently, the patient was taken to Anaesthesiology-Resuscitation Department. We introduced anticoagulation treatment with dalteparine 1000 IU/hr and antibiotic therapy with amoxyciline with clavulanic acid 1,2 g/ 8 hrs and ciprofloxacine 100 ml/12 hrs. The ventilation was maintained with FiO2 0,3, tidal volume (Vt) 550 ml and positive end-expiratory pressure (PEEP) of 5 cm H20. ECG was normal, without any ischemic signs, frequency 120/min. Magnetic resonance and magnetic resonance venography (MRV) confirmed vasogenic inflation, blood hypovolemia of the right mesencephalum, right thalamus and basal ganglia, as well as thrombosis of deep

determined immunologically, as a free form of protein S.

yellow filter with Mitsubishi camera enabling digital recording.

haemorrhage in the area of right lateral and sigmoid sinus.

**Neurological examination** 

cerebral veins and venous sinuses.

causes an increase of the prothrombin level and contributes to elevation of the risk of thrombosis up to threefold level.

Deficit of the antithrombin III is a disorder with most prothrombotic effects. The risk of developing a thromboembolic disease during life is 70-80% in carriers in the heterozygous form (homozygous carriers suffer from a lethal thromboembolic event usually already during childhood). AT III is a polypeptide synthetized in hepatocytes with an increased half-time (65 hours). Apart from its effect on thrombin, AT III is also able to activate factors Xa, IXa, VIIa and plasmin. The activation of antithrombin III is increased up to 40 000 times with heparin binding. The deficit of AT III is caused by numerous point mutations, deletion and insertion, and the inheritance is mostly autosomally dominant.

Homocysteine is contained in plasma at concentrations of 5 – 16 mol/l. Congenital hyperhomocysteinemia may be caused by a number of enzymatic defects. Clinical manifestations may be strengthened with a deficit of B6 and B12 vitamins, folic acid or during a treatment with methotrexate. Thrombophilia caused by hyperfibrinogenemia and dysfibrinogenemia is observed significantly less frequently.

Large population studies aimed at the relations between hormonal contraceptives and deep vein thrombosis have been performed. The increased risk was described mainly in patients using third-generation gestagens. Moreover, the identified risk of thrombosis in patients using hormonal contraceptives with thrombophilia is higher than what would correspond with a simple addition of risks. This finding confirms the theory that the procoagulation mechanisms are mutually strengthened in these women.

The problems of cerebral venous thrombosis in women in fertile age, who are the users of hormonal contraceptives have been studied in several trials including only a small number of patients. The results are in many cases misleading and inconsistent.

The aim of our study was to analyse cases of CVT in relation to sex, age, use of hormonal contraceptives and thrombophilic states, in correlation with CT, MRI and DSA findings and with clinical neurological findings.
