What is the cause of intermittent clear watery fluid dripping from one nostril when bending over, accompanied by a history of headaches and hypermobility (hypermobility syndrome)?

Suspected CSF Rhinorrhea

This patient most likely has cerebrospinal fluid (CSF) rhinorrhea, and you should confirm the diagnosis with β-2-transferrin testing of the nasal fluid followed by high-resolution CT imaging of the paranasal sinuses. 1

Clinical Presentation Strongly Suggests CSF Leak

The constellation of clear watery fluid dripping from one nostril when bending forward, occurring intermittently over months, with associated headaches is classic for CSF rhinorrhea. 1 Key diagnostic features in this case include:

• Positional nature: CSF leaks characteristically worsen with leaning forward or Valsalva maneuvers 1
• Unilateral clear rhinorrhea: The fluid is from the left nostril only, which is typical for CSF leaks 2
• Absence of congestion: This patient is not congested, making allergic or infectious rhinitis unlikely 2
• Chronicity without URI symptoms: Persistent clear rhinorrhea without fever, myalgia, or other viral symptoms argues against infectious causes 2
• Associated headaches: Headaches commonly accompany CSF leaks due to intracranial hypotension from CSF volume loss 2

The Hypermobility Connection

The patient's history of hypermobility syndrome is particularly relevant here. Connective tissue disorders like hypermobility syndrome/Ehlers-Danlos hypermobility type are associated with weakened dura and can predispose to spontaneous CSF leaks. 3 While these patients do have higher rates of migraine 4, the specific symptom pattern here—positional clear rhinorrhea—points toward CSF leak rather than primary headache disorder.

Diagnostic Workup

Immediate Step: Confirm CSF in Nasal Fluid

• Order β-2-transferrin testing of the nasal fluid, which is the most sensitive and specific test to confirm CSF presence 2, 1
• This is superior to glucose testing, which has poor specificity 1

Imaging Protocol Once CSF Confirmed

1. Start with high-resolution CT (HRCT) of paranasal sinuses without IV contrast as the first imaging study 1

   • Provides superior bony detail to identify skull base defects 2
   • Sensitivity of 88-95% for detecting osseous defects 1

2. Add MRI with heavily T2-weighted sequences (MR cisternogram) 1

   • Complementary to CT with higher sensitivity (67-93%) compared to CT cisternography (33-72%) 2, 1
   • Better for soft tissue characterization and identifying the exact leak site 2

3. Consider CT cisternography only if multiple osseous defects are found and you need to determine which specific site is actively leaking 2

Important Clinical Pitfalls

Do not dismiss this as "sinus headache" or allergic rhinitis. Even though nasal symptoms can accompany migraine 5, and this patient has hypermobility with associated migraine risk 4, the positional clear watery rhinorrhea is pathognomonic for CSF leak until proven otherwise. 1

Do not wait for a history of trauma or recent surgery. Spontaneous CSF leaks occur without preceding trauma, particularly in patients with connective tissue abnormalities. 2, 1, 3 The three main causes of spontaneous CSF leaks are dural defects, leaking meningeal diverticula, and CSF-venous fistulas. 3

The spine is the most common source. Most symptomatic CSF leaks originate from the spine rather than intracranially due to pressure dynamics, so imaging investigation should be directed primarily toward the spine if initial sinonasal imaging is negative. 2

Why This Matters

Persistent CSF leaks require surgical treatment because of the significant risk of ascending meningitis. 2 Accurate localization of the leak site is essential for successful surgical repair. 2 The combination of positional symptoms, chronicity, and hypermobility history makes this a high-probability CSF leak that warrants immediate diagnostic confirmation.