🧠 Low CSF Pressure Headache (also called CSF leak headache or intracranial hypotension) occurs when cerebrospinal fluid (CSF) pressure falls below normal. This usually results from a spinal CSF leak, either spontaneous or iatrogenic. The hallmark is a postural headache-worse upright, relieved by lying flat.

📌 About

Results from a reduction in CSF volume/pressure due to leakage.
Leads to brain sagging within the skull, causing pain, cranial nerve stretch, and venous engorgement.
Most often linked to lumbar puncture or spontaneous dural tear, but also seen after trauma or surgery.

🧬 Aetiology

Spontaneous CSF Leak: Small dural tear, often thoracic or cervical spine. Associated with connective tissue disorders (e.g., Marfan, Ehlers–Danlos).
Post-Lumbar Puncture: Commonest iatrogenic cause; dural puncture may not fully seal.
Trauma: Spinal or head trauma tearing the dura.
Post-Surgical: Especially after spinal/neurosurgical procedures.
Connective Tissue Disorders: Weakened dura predisposes to leaks.

💡 CSF circulation: Produced by the choroid plexus in ventricles → flows via aqueducts & foramina → circulates in subarachnoid space → absorbed by arachnoid granulations → venous system. A leak disrupts this balance → ↓ intracranial pressure.

🩺 Clinical Features

Headache: Diffuse, throbbing, often occipital. Worsens upright, relieved supine (orthostatic headache).
May be worse in the morning and improve with rest.
Associated symptoms: nausea, vomiting, neck stiffness, tinnitus, hearing changes.
Cranial nerve palsies (esp. CN VI → diplopia) due to traction.
Rare: cognitive slowing, encephalopathy, or coma in severe untreated cases ⚠️.

🔍 Investigations

MRI brain with gadolinium: Shows diffuse meningeal enhancement, “brain sagging,” or subdural hygromas.
Spinal MRI or CT myelography: To locate the leak (contrast extravasation).
Intrathecal contrast MRI: High sensitivity for pinpointing leaks.
Radioisotope cisternography: Rarely used now.

💊 Management

Conservative: Bed rest, oral/IV fluids, caffeine (vasoconstrictor, ↑CSF production).
Epidural Blood Patch: Standard treatment for post–lumbar puncture headache. Injected autologous blood seals leak; success rates >90%.
Surgical Repair: Required for persistent or recurrent leaks (direct dural closure or fibrin glue).
Symptomatic: Analgesics, antiemetics, avoidance of straining.
Monitoring: Recurrence possible, esp. in connective tissue disorders.

📈 Prognosis

Most post-LP leaks resolve with an epidural blood patch.
Spontaneous leaks may require repeat interventions but often respond to targeted patches or repair.
Untreated, chronic CSF hypotension can lead to subdural haematomas or permanent neurological deficits.

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Low CSF pressure Headache