Title : Alexia without agraphia in cerebral venous thrombosis: A case report
Abstract:
Objective: We present a rare case of alexia without agraphia in the setting of cerebral venous thrombosis and review the neuroanatomical basis, diagnostic considerations, and clinical relevance of this uncommon presentation.
Background: Alexia without agraphia is a rare disconnection syndrome in which visual input from the right visual cortex cannot reach the language-dominant left hemisphere. It typically arises from lesions involving the left occipital lobe and the splenium of the corpus callosum. Acquired pure alexia due to hereditary thrombophilia is exceptionally rare.
Case Presentation: A 60-year-old Caucasian female with no significant past medical history presented with two days of word-finding difficulty and a two-week history of left-sided headache. Neurological examination revealed alexia without agraphia: she was unable to read printed or handwritten material, including her own writing, while spontaneous writing and speech remained intact.
Non-contrast CT of the head demonstrated a left temporal intraparenchymal hemorrhage, and CT venography revealed a left transverse sinus thrombus extending into the left jugular vein. Further evaluation revealed extensive thromboembolic disease, including right lower extremity deep vein thrombosis (common femoral, popliteal, and gastrocnemius veins) and bilateral pulmonary emboli without hemodynamic compromise. Hypercoagulable testing identified a prothrombin gene mutation, consistent with a positive family history of thrombosis.
The patient was managed with anticoagulation in the neuro-ICU, initially with heparin and later transitioned to therapeutic enoxaparin, with close monitoring. Serial CT scans showed no hematoma expansion, and neurosurgical intervention was not required. The patient improved clinically, had no functional limitations on physical or occupational therapy evaluation, and was discharged on therapeutic anticoagulation with outpatient hematology and neurology follow-up.
Discussion: Alexia without agraphia is classically caused by lesions in the left occipital cortex and splenium, producing a disconnection between visual input and the language-dominant hemisphere. More recent evidence emphasizes the role of the ventral occipitotemporal cortex, including the visual word form area (fusiform gyrus), as a critical node for reading. Cerebral venous thrombosis can also cause venous congestion, further disrupting interhemispheric visual-linguistic connections. This case illustrates that temporo-occipital lesions, even when temporal-predominant on CT, can clinically manifest as alexia without agraphia. To our knowledge, alexia without agraphia as a manifestation of thrombophilia-associated cerebral venous thrombosis with temporal-predominant involvement is extremely rare, emphasizing the importance of considering CVT in atypical cognitive presentations.
Conclusion: This case highlights a rare manifestation of cerebral venous thrombosis presenting as alexia without agraphia due to left temporo-occipital involvement. It underscores the importance of recognizing venous infarction in focal disconnection syndromes, illustrates the neuroanatomical basis of reading pathways, and emphasizes the limitations of the NIH Stroke Scale in detecting subtle cognitive deficits.
