Persistent Occipital Neuralgia as the Initial Presentation of a Cognard Type V Hypoglossal Canal Dural Arteriovenous Fistula

Background

Occipital neuralgia is a common cause of posterior head pain, typically associated with musculoskeletal strain, cervical degenerative disease, trauma, or nerve entrapment. However, persistent symptoms despite appropriate therapy and atypical clinical features should prompt evaluation for secondary causes. Hypoglossal canal dural arteriovenous fistulas (HC-dAVFs) are rare vascular lesions that may present with nonspecific symptoms, leading to delayed diagnosis.

Methods / Case Presentation

A previously healthy 24-year-old woman developed intermittent right-sided occipital pain following presumed neck strain. Symptoms progressed despite treatment with acetaminophen, nonsteroidal anti-inflammatory drugs, muscle relaxants, gabapentin, transcutaneous electrical nerve stimulation, chiropractic care, and physical therapy. Neurological examinations remained normal. Initial CT imaging of the head and cervical spine was unrevealing, and cervical MRI showed only mild degenerative changes and moderate right C4-C5 foraminal narrowing, findings insufficient to explain symptom severity. The patient continued to be diagnosed with cervicalgia, occipital neuritis, and occipital neuralgia. Approximately five months after symptom onset, she developed right-sided pulsatile tinnitus, prompting further vascular evaluation. MRI/MRA demonstrated abnormal vascular enhancement near the craniovertebral junction. Digital subtraction angiography confirmed a high-grade Cognard type V HC-dAVF supplied predominantly by the right ascending pharyngeal artery, with venous drainage into the condylar venous system and spinal venous plexus.

Results / Findings

Given the high-risk spinal venous drainage pattern and potential for neurological complications, multidisciplinary evaluation by vascular neurosurgery and neurointerventional radiology recommended endovascular intervention. The patient underwent successful transarterial embolization with angiographic resolution of the arteriovenous shunting. Following treatment, her occipital pain and pulsatile tinnitus resolved, allowing return to normal daily activities.

Discussion & Conclusion

This case highlights the importance of reassessing the diagnosis when symptoms fail to follow an expected course. Treatment-refractory occipital neuralgia, particularly when accompanied by pulsatile tinnitus, should raise suspicion for secondary vascular etiologies and prompt consideration of advanced vascular imaging. Cognard type V dAVFs are clinically significant due to their association with spinal venous hypertension, progressive myelopathy, and neurological deterioration if untreated. Avoiding premature diagnostic closure and maintaining a broad differential diagnosis can facilitate timely recognition and definitive treatment of rare but potentially serious vascular lesions.