The ocular manifestations of cerebral venous sinus thrombosis: An uncommon form of stroke

Dear Editor, Cerebral venous sinus thrombosis (CVST), a rare form of stroke, represents 0.5%–3% of all stroke cases.[1] In various studies on CVST, the most common presentations are headaches, followed by seizures, focal neurological signs, altered sensorium, blurred vision, and vomiting.[2] Due to its variable presentation, CVST can be challenging to diagnose without a high level of suspicion. We performed a study that aimed to analyze the complete neuroophthalmological spectrum of CVST. In our experience, headache was the most prevalent clinical complaint in 93.33%, followed by papilledema in 40.0%, cranial nerve involvement in 10.0%, and diplopia in 6.66% of the patients. The neuro-ophthalmological symptoms are due to intracranial hypertension occurring in CVST. A rise in intracranial pressure (ICP) causes axoplasmic flow stasis in the optic nerve fibers in the prelaminar area of the optic nerve head, which in turn causes disc edema in papilledema. When papilledema was assessed using Friesen's grading, the majority of patients belonged to Grades 4 and 5. Vision is normally unaffected in the early stages of papilledema unless there is an exudation, retinal hemorrhage, or macular edema. Newer diagnostic methods, such as optical coherence tomography, have made it easier to identify papilledema patients that are subclinical. In as many as 31% of cases, untreated papilledema can result in secondary optic atrophy, leading to permanent vision loss.[3] Thereby, prompt diagnosis and early intervention in patients with CVST presenting with visual manifestations can result in a better prognosis. In our study, 43.3% of patients presented with blurring of vision. The majority (63.33%) of patients had a presenting visual acuity less than or equal to 0.5 log MAR. The most frequent visual field defect found in subjective visual field tests in various studies is the concentric enlargement of the physiologic blind spot. In our study, it was detected in 22.72% of patients. There are two basic theories as to why the physiological blind spot enlarges: first, it can be due to acquired peripapillary hyperopia caused by the elevation of the retina with subretinal fluid, or second, it can be due to compression and lateral displacement of the peripapillary retinal nerve fiber layer.[4] Sixth nerve palsy, which is particularly susceptible to elevated ICP because of its extensive path to the orbit, is the common cause of diplopia, which was observed in 6.66% of the patients. To conclude, we therefore recommend that all identified cases of CVST confirmed on magnetic resonance venography undergo an early and comprehensive ophthalmological examination on presentation, along with serial monitoring, to prevent permanent visual damage. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.