A 26‑year‑old woman with isolated ACTH deficiency on hydrocortisone presents with migraines, upper‑field visual loss, left ptosis, intermittent right‑sided CSF rhinorrhea and an empty‑sella appearance on non‑contrast MRI; what is the most likely diagnosis and how should it be confirmed and managed?

Spontaneous Intracranial Hypotension with CSF Leak

This patient most likely has spontaneous intracranial hypotension (SIH) with CSF rhinorrhea secondary to a dural defect at the skull base, and the diagnosis must be confirmed with contrast-enhanced MRI of the brain and spine plus MR myelography to localize the leak site. 1

Clinical Presentation Strongly Suggests SIH

The constellation of findings in this patient is pathognomonic for spontaneous intracranial hypotension:

• Empty sella appearance – The flattened pituitary gland with CSF filling the sella turcica is a cardinal imaging sign of intracranial hypotension, resulting from downward brain sagging and loss of CSF buoyancy 1
• Intermittent CSF rhinorrhea – Direct evidence of CSF leakage through a skull base dural defect, typically occurring when upright and resolving when supine 1, 2
• Orthostatic headaches with pressure symptoms – Migraines that worsen with upright posture and improve with recumbency are the hallmark symptom, occurring in nearly 90% of SIH cases 1, 3
• Visual field defects (upper field loss) – Result from downward traction on the optic chiasm as the brain sags in response to decreased CSF volume 1
• Ptosis – The left eyelid drooping reflects cranial nerve dysfunction from mechanical traction 1
• "Bursting sounds" with eye pressure – Suggests communication between the CSF space and paranasal sinuses 2

The empty sella in this context is not primary empty sella syndrome but rather a secondary finding caused by chronic CSF volume depletion. 1, 4

Diagnostic Confirmation Protocol

Immediate imaging requirements:

• MRI brain and orbits WITH contrast – Essential to visualize pachymeningeal enhancement (a key secondary sign of SIH), assess the degree of brain sagging, and evaluate venous sinus engorgement 1

  • The non-contrast MRI already performed is insufficient because it cannot demonstrate meningeal enhancement or adequately characterize the sella 1
  • Specific findings to document: pituitary height, pontomesencephalic angle, midbrain descent, and venous-hinge angle 1

• MRI complete spine WITH contrast – Required to identify the spinal leak source, which is present in the majority of symptomatic SIH cases 1

  • Look for epidural fluid collections (direct evidence of CSF leak), dilated epidural venous plexus, subdural hygromas, and dural enhancement 1

• MR myelography – If initial spine MRI does not localize the leak, this invasive study provides the highest sensitivity for detecting CSF-venous fistulas and meningeal diverticula 1

  • The spine represents the anatomical source of most symptomatic CSF leaks, not intracranial structures 1

Critical pitfall: Do not attribute the empty sella to primary empty sella syndrome or idiopathic intracranial hypertension without first ruling out SIH, as the treatment approaches are diametrically opposed. 1, 3

Addressing the Dyspnea Question

Yes, dyspnea can be related to this condition through two mechanisms:

1. High hemoglobin with fluid retention – The combination of elevated hemoglobin (suggesting hemoconcentration) with fluid retention from hydrocortisone creates a paradoxical state that may impair oxygen delivery and increase work of breathing 5

2. Positional component – If dyspnea worsens when upright and improves supine (mirroring the headache pattern), this strongly suggests it is part of the SIH syndrome, as reduced cerebral perfusion pressure can trigger compensatory hyperventilation 1

The normal mineralocorticoid function makes primary volume depletion less likely, but the hydrocortisone-induced fluid retention may be masking underlying CSF volume depletion. 5

Management Algorithm

Step 1: Confirm diagnosis and localize leak

• Obtain contrast-enhanced brain MRI and complete spine MRI immediately 1
• If leak not identified, proceed to MR myelography 1

Step 2: Initial conservative management

• Strict bed rest in Trendelenburg position (head down 30 degrees) 1
• Aggressive hydration (2.5–3 L/day) to increase CSF production 1
• Caffeine supplementation (300–500 mg twice daily) to promote cerebral vasoconstriction 1

Step 3: Targeted intervention based on leak location

• Epidural blood patch – First-line invasive therapy for spinal leaks; inject 15–20 mL autologous blood at the leak site under fluoroscopic guidance 1
• Percutaneous fibrin glue injection – Alternative for refractory cases or when blood patch fails 1
• Surgical dural repair – Reserved for large structural defects or failed conservative/minimally invasive approaches 1
• Endovascular embolization – Specifically for CSF-venous fistulas identified on myelography 1

Step 4: Address skull base defect

• Transsphenoidal repair of the sellar floor defect to prevent recurrent rhinorrhea 2
• This requires otolaryngology and neurosurgery collaboration 2

Hormonal Considerations

Do not discontinue hydrocortisone replacement:

• The isolated ACTH deficiency is a separate, pre-existing condition requiring lifelong glucocorticoid replacement 5
• Morning cortisol below 3 μg/dL is virtually diagnostic for adrenal insufficiency and mandates continued therapy 5
• Stress-dose steroids (100 mg hydrocortisone IV) will be required if surgical repair is undertaken 6, 5

Monitor for evolving hypopituitarism:

• Approximately 30% of patients with empty sella develop additional pituitary hormone deficiencies over time 1, 6
• Repeat comprehensive pituitary axis testing (TSH, free T4, IGF-1, prolactin, sex hormones) every 6–12 months 6

Red Flags Requiring Urgent Intervention

• Progressive visual field loss – Signals the need for immediate CSF pressure restoration via epidural blood patch or temporary lumbar drain placement 1, 3
• Worsening ptosis or new diplopia – Indicates increasing traction on cranial nerves III and VI 1
• Severe orthostatic headache unresponsive to bed rest – May require hospitalization for IV hydration and urgent blood patch 1
• Signs of meningitis (fever, nuchal rigidity) – CSF rhinorrhea creates a direct pathway for ascending infection requiring immediate antibiotics and neurosurgical consultation 2

Common Diagnostic Pitfalls

• Mistaking SIH for idiopathic intracranial hypertension (IIH) – Both can present with headache and empty sella, but SIH causes orthostatic headaches that improve when lying down, whereas IIH headaches worsen supine 1, 3
• Assuming normal CSF pressure excludes SIH – CSF pressure can be normal in up to 30% of SIH cases, especially if measured in the supine position 1
• Attributing all symptoms to the known ACTH deficiency – While fatigue and hypotension can occur with adrenal insufficiency, the visual symptoms, rhinorrhea, and orthostatic headaches are not explained by isolated hypocortisolism 5
• Performing lumbar puncture without imaging – This can worsen SIH by creating an additional leak site and may cause the empty sella to temporarily disappear, confounding diagnosis 4

Prognosis and Follow-Up

• Most patients achieve complete resolution with targeted epidural blood patch (success rate 70–90% after 1–2 attempts) 1
• Surgical repair of skull base defects has excellent long-term outcomes for preventing recurrent rhinorrhea 2
• Careful long-term endocrine follow-up is mandatory, as the flattened pituitary may develop additional hormone deficiencies even after CSF leak repair 6, 7