Clinical manifestations of CVT result from impaired venous drainage and focal brain injury secondary to venous infarction. These factors obviously overlap, and clinical findings are often attributable to both. Headache is the most common symptom of increased intracranial pressure and occurs in up to 90 % of patients. It may present as a progressive dull pain or as a thunderclap headache [8–11]. Concomitant findings in up to 25 % of the patients include papilledema or other signs of increased intracranial pressure, such as a sixth nerve palsy [12]. A high index of suspicion for CVT is needed in patients with known risk factors, but insufficient clinical findings.

Focal neurological findings vary according to the location of CVT. Superior sagittal sinus thrombosis is the most common, and often presents with headache and papilledema. Bilateral cortical venous infarctions may cause visual field defects, weakness, and speech disturbances [13, 14]. Thalamic or basal ganglionic infarcts may occur with involvement of the deep cerebral veins such as the internal cerebral vein or the vein of Galen in about 16 % of patients (Fig. 8.1a–c). These patients classically present with depressed levels of consciousness and difficulty with upward gaze [13, 15]. In patients with involvement of the lateral sinuses such as the transverse and sigmoid, ear pain and headache are the most common presenting features.

Seizures occur in about 40 % of patients with CVT [4]. These may or may not secondarily generalize, and may occur early or later in the disease process. Seizures are most commonly seen in patients with superior sagittal sinus thrombosis or cortical vein thrombosis due to involvement of cortical gray matter [4, 29]. The incidence, risk factors, and treatment of epilepsy in CVT are discussed in detail later.

Certain clinical findings differentiate CVT from other cerebrovascular diseases. First, the occurrence of seizures in CVT is frequent. Second, CVT often results in bilateral hemispheric damage and bilateral motor signs. Third, CVT can present with slowly progressive symptoms that may account for delays in diagnosis.

The American Heart Association/American Stroke Association (AHA/ASA) published a Scientific Statement in 2011 to help streamline diagnosis and management of CVT [16]. Their recommendations regarding clinical and laboratory workup were as follows:

Brain CT is a quick and easy neuroimaging test employed to screen patients with new-onset neurological signs and symptoms. However, brain CT without contrast is abnormal only in 30 % of patients with CVT [21]. Acute CVT may be identified on a non-contrast CT as a hyperdense cortical vein or dural sinus [22]. A “delta sign” has been described on CT scans in patients with clot at the torcula or confluence of the venous sinuses [23, 24].

Magnetic resonance imaging (MRI) is superior to CT in identifying patients with CVT [25]. MRI assists not only in the diagnosis but also in staging the thrombus based on varying T1- and T2-weighted signals that result from evolution of the paramagnetic blood products within the thrombus. While diffusion-weighted and gradient-echo sequences of MRI assist in the diagnosis of hemorrhagic infarcts, the two-dimensional time-of-flight venogram or the contrast-enhanced venogram can directly visualize the site and extent of thrombosis. MR venogram is preferable to a CT venogram due to the lack of radiation exposure and risk of allergy to iodinated contrast [26, 27].

Seizures occur either before or soon after the diagnosis of CVT in 35–40 % of patients [28, 29]. In prospectively conducted population studies of all ages, seizures have been reported in 37 % adults, 48 % children, and 71 % newborns with CVT [30]. The ISCVT reported that 245 of 624 (39.3 %) patients experienced seizures, including 43 (6.9 %) early seizures within 2 weeks of diagnosis [31]. Of these subjects, 9.3 % had focal seizures without generalization, 19.7 % had generalized seizures from onset, and the remaining 10.3 % had both types.

Masuhr et al. reported seizures in 86 of 194 patients during hospitalization with CVT [32]: Twenty-one (24.4 %) presented with focal seizures without generalization and 65 (75.5 %) with secondary generalization. Seizures that occurred early (44.3 %) in the course of the disease (< 2 weeks) were further studied. Multivariate logistic regression analyses identified intracranial hemorrhage, cortical vein thrombosis, and motor deficits as independent predictors of early seizures [32]. As expected, 12.8 % patients who developed status epilepticus required prolonged intensive care unit (ICU) stays and had greater mortality and morbidity compared to those who had fewer than 3 seizures.

In the Cerebral Venous Thrombosis Portuguese (VENOPORT) Collaborative Study Group [29], 91 patients with CVT were prospectively studied for the development of seizures. Of these, 31 (34 %) had early symptomatic seizures: 29 (31.9 %) as a presenting feature and two (2.1 %) after admission. Early symptomatic seizures were associated with sensory and motor deficits as well as an identifiable parenchymal lesion on CT or MRI. Late seizures occurred in patients with early symptomatic seizures and in those with hemorrhage or hemorrhagic infarcts on CT/MRI. Patients presenting with early seizures had a greater incidence of seizure recurrence within 2 weeks.

Pooled analyses of the VENOPORT [29], ISCVT [4], and other studies [32] confirm that focal motor deficits, cortical venous thrombosis, and supratentorial parenchymal lesions are associated with an increased risk of early seizures. Treatment and/or prophylaxis are hence important clinical decisions that may require risk stratification of patients based on available literature.

Pregnancy and puerperal CVT have been associated with a very high percentage of seizures in some studies, but not others [7, 33]. Data regarding seizures associated with CVT in the pregnant or postpartum state are scarce. Possible confounders are young age and concurrence of preeclampsia. Thus, further studies are needed to determine the prevalence of seizures and CVT in this select population.

Diagnosis and treatment of seizures in patients with CVT is in line with standard practice. Seizures necessitate brain imaging (CT or MRI) to rule out parenchymal hemorrhage if initial imaging is negative or has not been performed. Electroencephalography (EEG) is helpful in patients with altered mental status to rule out nonconvulsive seizures.