A 76-year-old man presenting with diplopia, dysarthria, and dizziness was ultimately diagnosed with venous infarction secondary to a hypoglossal canal dural arteriovenous fistula, a rare and diagnostically challenging condition.
Key Findings
Background
The patient presented with a constellation of posterior fossa neurological deficits including left abducens nerve palsy, right lower facial palsy, horizontal nystagmus, and right lower limb paresis.
76-year-old male with 1-month history of worsening binocular diplopia on left horizontal gaze
1 week of progressive dysarthria and dizziness preceding presentation
Neurologic examination revealed left abducens nerve palsy, right lower facial palsy, horizontal nystagmus during right eye adduction, and right lower limb paresis with ipsilateral patellar hyperreflexia
Patient appeared tired with decreased level of alertness
Blood pressure was elevated at 165/91 mm Hg
Background
Laboratory workup revealed elevated inflammatory markers and cerebrospinal fluid protein abnormalities alongside positive oligoclonal bands, initially raising concern for inflammatory or demyelinating etiologies.
C-reactive protein was markedly elevated at 135 mg/L (upper limit of normal 1 mg/L)
Cerebrospinal fluid total protein was elevated at 750 mg/L (reference range 100-450 mg/L)
Cerebrospinal fluid oligoclonal bands were positive
CSF opening pressure was normal at 18 cm H2O, and total nucleated cell count was normal at 3.75/mm3
Extensive serologic workup including anti-aquaporin-4 antibody, anti-DNA antibody, lupus anticoagulant, antinuclear antibody, anti-cardiolipin antibody, and rheumatoid factor all yielded negative results
Results
Brain MRI performed the day after admission demonstrated imaging abnormalities consistent with venous infarction in the setting of a hypoglossal canal dural arteriovenous fistula.
MRI was performed the day after admission to the emergency department
Imaging abnormalities were identified on brain MRI
The final diagnosis was venous infarction secondary to hypoglossal canal dural arteriovenous fistula
Hypoglossal canal dural arteriovenous fistulas are rare lesions and a diagnostically challenging cause of posterior fossa venous infarction
The case is presented in the 'Case of the Day' Radiology format (Case 349), indicating its educational and diagnostic rarity
Background
The patient's relevant past medical history included multiple vascular risk factors and postpolio syndrome, which may have contributed to the clinical presentation and diagnostic complexity.
Past medical history included hypertension, dyslipidemia, insomnia, and hypothyroidism
Patient had postpolio syndrome affecting the right lower limb
Chronic right-sided cervicobrachialgia related to degenerative disk disease was present and improving with oral analgesia
No history of fever, immunosuppressive medication use, intravenous drug use, or congenital abnormalities was reported
No recent or recurrent bacterial or viral infections were reported
What This Means
This research presents a case report of a 76-year-old man who came to the emergency department with double vision, slurred speech, and dizziness. His neurological examination showed several abnormalities pointing to dysfunction in the brainstem and posterior part of the brain. Initial lab tests were confusing — his inflammatory marker (CRP) was very high, his spinal fluid protein was elevated, and he had positive oligoclonal bands (a finding sometimes seen in multiple sclerosis and other inflammatory brain diseases), which initially suggested an inflammatory or autoimmune cause. However, extensive autoimmune and infectious testing came back negative.
Ultimately, brain MRI and further workup led to the diagnosis of a dural arteriovenous fistula (DAVF) located at the hypoglossal canal — a rare abnormal connection between arteries and veins near the base of the skull — which caused venous infarction (a type of stroke resulting from impaired venous drainage rather than blocked arteries) in the posterior fossa of the brain. This is an uncommon location for a DAVF and a particularly rare cause of stroke.
This research suggests that hypoglossal canal dural arteriovenous fistulas should be considered in the differential diagnosis of patients presenting with posterior fossa neurological symptoms, even when laboratory findings initially point toward inflammatory conditions. The case highlights how misleading CSF findings such as elevated protein and positive oligoclonal bands can be, and underscores the importance of advanced vascular imaging in reaching the correct diagnosis. Early recognition matters because dural arteriovenous fistulas are potentially treatable conditions.
Taborda M, Pedro M, Corrêa de Almeida Teixeira B. (2026). Case 349: Venous Infarction Secondary to Hypoglossal Canal Dural Arteriovenous Fistula.. Radiology. https://doi.org/10.1148/radiol.252118