Cerebral Venous Sinus Thrombosis with Bilateral Optic Disc Swelling and Bilateral Sixth Nerve Palsies in the Absence of Headache: A Case Report Open Access

Cerebral venous sinus thrombosis (CVST) is relatively rare, occurring in approximately 0.5–1% of all stroke patients [1]. The International Study of Cerebral Vein and Dural Sinus Thrombosis (ISCVT) reported that approximately 78% of patients were younger than 50 years of age and that it was more common in women (male: female, 1:3) [2]. Risk factors include a predisposition to thrombosis, oral contraceptive use, pregnancy, and childbirth [3]. Headache is the most common symptom associated with increased intracranial pressure [4]; however, there are no specific clinical manifestations. The mortality rate within 30 days of onset is 3.4–5.6%, and the cause of death is cerebral herniation associated with extensive intracranial hemorrhage [4]. Most cases of CVST have a good prognosis (complete or partial recovery) if anticoagulation is administered early in the course of the disease; meanwhile, 10–15% have a poor prognosis of death or bedridden status [5]. Herein, we report a case of CVST that developed without headache and presented only with diplopia. The CARE Checklist has been completed by the authors for this case report and is attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000539125).

A 54-year-old woman consulted the Department of Ophthalmology, Toyokawa City Hospital, for binocular diplopia that began approximately 2 weeks earlier. There was no history of headache or vomiting. Her height, weight, and body mass index were 151.0 cm, 55.0 kg, and 24.12, respectively. Her blood pressure was 120/85 mm Hg. She was not pregnant and had not recently given birth or received vaccinations and had no family history of thrombosis.

On clinical examination, visual acuity was 20/20 in the right (OD) and left (OS) eyes, and the intraocular pressure was 19 mm Hg and 20 mm Hg in the right and left eyes, respectively. She exhibited normal pupillary reflexes to light and near objects, with no afferent pupillary defect. The critical flicker fusion frequencies were 41 Hz and 40 Hz in the right and left eyes without attenuation, respectively. The ocular position was mildly esotropic at near; the Hess screen test revealed esotropia and bilateral abduction deficits. No abnormalities were observed in the anterior segment of the eye on slit-lamp biomicroscopy, and the fundoscopic examination showed marked redness and swelling of the optic disc in both eyes (Fig. 1). The degree of optic disc swelling corresponded to Frisén Grade 3 [6], with elevation of the entire circumference of the disc and increased diameter of the nerve head. Optical coherence tomography revealed bilateral optic disc swelling with normal macular morphology. The Goldmann visual field test revealed an enlarged Marriott’s blind spots in both eyes.

Non-contrast computed tomography (CT) of the head revealed no intracranial lesions. Contrast-enhanced magnetic resonance imaging (MRI) of the head revealed no intracranial lesions or enlarged ventricles. However, T2-weighted imaging horizontal sections revealed flattening of the bilateral posterior ocular surfaces and enlargement of the spinal fluid space in the optic nerve sheath, suggesting intracranial hypertension (Fig. 2a), and a high-signal lesion in the superior sagittal sinus, suggesting a thrombus (Fig. 2b). Magnetic resonance venography (MRV) revealed a shadow defect extending from the superior sagittal sinus to the left transverse sinus (Fig. 3). Blood test results, including prothrombin time, activated partial thromboplastin time, D-dimer levels, protein C activity, and protein S activity of the coagulation system, were all within the normal ranges. Autoantibodies, such as antinuclear and anticardiolipin antibodies were negative, and no evidence of thrombophilic predisposition was observed.

Based on these findings, the patient was diagnosed with CVST and consequent intracranial hypertension and bilateral abducens nerve palsies. She was admitted to the Department of Neurology, and anticoagulation therapy was initiated with continuous intravenous heparin (10,000 IU/day) and oral warfarin (4 mg/day). After 1 week of treatment, the diplopia disappeared, and heparin was discontinued. The warfarin dosage was adjusted to maintain a prothrombin time-international normalized ratio of 2.0 (normal: 1.0), and the patient was discharged.

Two months after discharge, the optic disc swelling was reduced. Six months after discharge, optical coherence tomography findings were improved. The patient continued to receive warfarin on an outpatient basis during follow-up. Her visual acuity was 20/20 in both eyes, and there was no recurrence of papilledema, headache, or other symptoms of intracranial hypertension.

CVST can lead to stroke even in younger individuals. Although headache, a nonspecific symptom, is an initial or early feature in approximately 90% of patients with CVST [4], its absence may delay the correct diagnosis. Similarly, the absence of optic disc swelling, which is observed in only 54% of patients [7], can also delay diagnosis. The causes of optic disc swelling include intracranial space-occupying lesions, such as brain tumors and brain hemorrhage; intracranial inflammation, such as encephalitis; and elevated intracranial pressure caused by CVST.

Abducens nerve palsy is the most common form of external ophthalmoplegia, with an incidence of 11.3 per 100,000, accounting for 43.8–57% of all external ophthalmoplegia cases [8]. Causes include brain tumors, trauma, vascular disorders, cerebral aneurysms, and demyelinating diseases, with approximately 30% being attributed to vascular disorders. Approximately half of the vascular disorders are associated with ischemic lesions caused by diabetes mellitus or hypertension [9]. The abducens nerve takes an angular course over the clivus through Dorello’s canal, making it more susceptible to mechanical stresses such as intracranial pressure fluctuations and arteriosclerosis, resulting in abducens nerve palsy [10]. In the present case, CVST was thought to have caused impaired venous return, resulting in increased intracranial pressure. Moreover, esotropia and bilateral abduction deficits were thought to be caused by the same mechanism; therefore, when bilateral abducens nerve palsies are accompanied by bilateral optic disc swelling, intracranial hypertension should be considered, even in the absence of headaches or other neurological findings.

The patient had no subjective symptoms such as headache or vomiting, except for binocular diplopia. Although optic disc swelling was observed in both eyes, there was no history of hypertension, inflammation in the anterior segment, or obvious lesions on CT of the head. Since blood tests indicated no evidence of thrombotic predisposition, we initially suspected idiopathic intracranial hypertension (IIH) [11] and requested a cerebrospinal fluid examination from a neurologist. In this case, contrast-enhanced MRI of the head revealed bilateral posterior ocular flattening and enlargement of the spinal fluid space in the optic nerve sheath, suggesting intracranial hypertension [12]. The neurologist decided that lumbar puncture should be withheld because the intracranial hypertension on the head MRI was obvious, and MRV suggested that the cause was probably CVST.

Differentiating between CVST and IIH is important. Treatment for CVST involves anticoagulation with heparin and warfarin, whereas treatment for IIH involves weight loss and oral acetazolamide. Previously, cerebral angiography and cerebrospinal fluid examination have been conventionally used for a definitive diagnosis; however, MRV allows for the detection of the site of venous obstruction, making the diagnosis of this disease relatively easy and useful [11]. MRV is the most preferred diagnostic modality for CVST [13], while CT venography is a reliable alternative and may be less susceptible to artifacts [14]. In case of delayed therapeutic intervention for CVST, papilledema may lead to optic atrophy and irreversible visual impairment if it persists for a long time [15]. In addition, complications such as cerebral hemorrhage may occur or even death due to cerebral herniation. Therefore, prompt diagnosis and therapeutic intervention are crucial, and intracranial hypertension must be relieved.

CVST is a rare disease with no specific symptoms and may be overlooked. In the differential diagnosis of the causes of intracranial hypertension, CVST should be considered when bilateral optic disc swelling and abducens nerve palsy are observed, particularly in the absence of headache or other neurological findings.

We would like to thank Editage (www.editage.com) for English language editing.

This study was conducted in accordance with the Declaration of Helsinki of the World Medical Association. The study protocol was reviewed, and the need for approval was waived by the Ethics Committee of Toyokawa City Hospital. Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

The authors have no conflicts of interest to declare.

This study was not supported by any sponsor or funder.

D.N.: patient examination, clinical data collection, and writing – original draft. H.O. and K.U.: patient examination and clinical data collection. Y.S. and A.T.: writing – editing. M.H. and Y.I.: writing – review. All the authors have read and approved the final version of the manuscript.

All data generated or analyzed during this study are included in this article and its online supplementary material. Further inquiries can be directed to the corresponding author.