Spontaneous Intracranial Hypotension (SIH)

How a CSF leak causes symptoms

Cerebrospinal fluid surrounds and cushions the brain and spinal cord. When fluid leaks from the spinal dura (the protective membrane), CSF volume drops. When you stand up, the brain sags downward, stretching pain-sensitive structures and nerves, which causes the headache and other symptoms. Lying flat relieves the pull.

Despite the name, CSF pressure measured by lumbar puncture is often normal. It is the volume loss that matters.

Types of spinal CSF leaks

Symptoms

• orthostatic headache: worse within minutes to hours of being upright, better lying down. Usually at the back of the head
• headaches may become less positional over months
• neck pain or stiffness
• nausea and vomiting
• tinnitus, muffled or echoing hearing, ear fullness
• dizziness and imbalance
• blurred or double vision
• sensitivity to light and noise
• cognitive slowing or brain fog
• rarely, severe brain sagging causing memory and behavior changes

Causes and risk factors

• spontaneous leaks without trauma, often due to bone spurs or weak dura
• connective tissue disorders: Ehlers-Danlos syndrome, Marfan syndrome
• minor trauma: coughing, sneezing, lifting, chiropractic manipulation, a fall
• most common in people aged 30 to 50, more often in women

Leaks after lumbar puncture, epidural anesthesia or spine surgery are not spontaneous, but cause the same symptoms. See headache after lumbar puncture.

Diagnosis

1. Brain MRI with contrast: may show thickened, enhancing brain linings, brain sagging, subdural fluid collections and engorged veins. A normal MRI does not rule it out
2. Spine MRI: looks for fluid outside the dura
3. Leak localization: CT myelography, dynamic or digital subtraction myelography, or decubitus CT myelography, especially for CSF-venous fistulas
4. Lumbar puncture opening pressure, which is often low but may be normal, is not always needed

Treatment

Conservative measures

• bed rest and lying flat
• generous fluid intake and caffeine
• pain relief
• avoiding straining, heavy lifting and bending

Some leaks heal with these measures alone, but many need further treatment.

Epidural blood patch

A sample of your own blood is injected into the epidural space of the spine, where it seals the leak and raises pressure. A non-targeted patch is often tried first. Targeted patches, placed at the site of the leak, have higher success. More than one patch may be needed.

Other procedures

• fibrin glue injection at the leak site
• transvenous embolization for CSF-venous fistulas
• surgical repair for leaks that do not respond, particularly ventral tears from bone spurs

Complications

• subdural hematoma or fluid collections from brain sagging
• rebound high pressure after treatment: a headache worse lying down, often with blurred vision, usually short-lived and treatable
• chronic daily headache when untreated

Outlook

Many people improve significantly after successful treatment, though recovery can take weeks to months and some leaks recur. Delayed diagnosis is common, and long-standing leaks can be harder to treat. Specialist centers with experience in CSF leak imaging and treatment offer the best outcomes.

Frequently asked questions

What does a spinal CSF leak headache feel like?

It typically starts or gets worse within minutes to hours of sitting or standing and eases after lying flat. It is often felt at the back of the head and neck, and may come with nausea, ringing in the ears, muffled hearing and dizziness.

What causes spontaneous intracranial hypotension?

It is caused by spinal fluid leaking through a tear in the dura, often from a bone spur or calcified disc, through weak spots at nerve root sleeves, or through abnormal connections to veins called CSF-venous fistulas. Connective tissue disorders raise the risk.

How is a CSF leak diagnosed?

A brain MRI with contrast may show typical signs such as thickened brain linings and brain sagging. Spine imaging, including specialized myelography, is used to find the exact leak site. Some people with SIH have normal scans, so clinical history matters.

What is an epidural blood patch?

It is a procedure in which a small amount of your own blood is injected into the epidural space of the spine. The blood forms a seal over the leak and increases pressure, often relieving the headache within hours to days.

Can a CSF leak heal on its own?

Some spontaneous leaks heal with rest, fluids and caffeine. Many, however, need an epidural blood patch or other targeted treatment. If symptoms persist beyond a couple of weeks, see a specialist.