CSF leak: symptoms, causes, tests and treatment

The hallmark is an orthostatic headache: one that begins or gets much worse when you sit or stand and improves soon after you lie down. A UK review in Practical Neurology says the delay between becoming upright and the headache starting can be anywhere from immediate to many hours later (a "second-half-of-the-day" headache), but it is usually consistent for any one person.

The same review lists a wide range of other symptoms, shown in the table below. The proportions are pooled estimates from a published meta-analysis and are given by the review as a guide to how often each symptom is reported, not as a prediction for any one person.

The upright pattern can fade over time, so someone seen months or years after the headache began may no longer describe it clearly. A minority of people with the scan changes of SIH have a headache that is not orthostatic (about 5%) or no headache at all (about 3%).

Cerebrospinal fluid circulates around the brain and down the spine. Gloucestershire Hospitals NHS Foundation Trust describes how low pressure in the head can be caused by a leak of this fluid somewhere in the spine. The UK review describes SIH as a clinical and radiological syndrome caused by spinal leakage of CSF due to a dural tear, a leaking meningeal diverticulum or a CSF venous fistula (an abnormal connection between the fluid space and a vein beside the spine).

The trust leaflet says a leak may have happened on its own (spontaneously) or as a result of physical trauma, surgery on the spine, or an injection into the back such as a lumbar puncture or an epidural or spinal anaesthetic. When a leak follows a known procedure, the site is known. In spontaneous cases the site is unknown at first, and that is what makes the search and the treatment more involved.

This guide concentrates on spinal leaks and the low-pressure headache they cause. Clear fluid dripping from the nose or an ear after an injury or operation is a different presentation of CSF leakage and needs prompt assessment by a doctor.

Treatment happens in steps. The first is conservative care: bed rest, good hydration and sometimes caffeine. The Practical Neurology review says symptoms resolve with this alone in about 28% of people, that bed rest is usually the main factor that relieves symptoms, and that other measures such as avoiding straining and heavy lifting are safe but of unknown benefit. Painkillers can be tried, but drug treatment of the headache is rarely effective on its own, so the focus is on finding and treating the leak.

The review says that conservative treatment should not delay an epidural blood patch beyond 2 weeks from symptom onset, because most people do not respond to symptom management alone and early treatment is more likely to work.

An epidural blood patch uses your own blood, taken from a vein in your arm and injected into the epidural space in the back, to seal the leak. For a suspected spontaneous leak the site is unknown, so the review says guidelines recommend a higher volume than for a known puncture, 20 to 40 mL as tolerated, and that a patch is offered to all patients within 2 weeks of symptom onset. If the first patch does not work it may be repeated 2 to 4 weeks later.

People who do not respond to one or two non-targeted patches are referred to a specialist centre. There, scans using contrast (myelography) locate the leak so that a targeted treatment can be used: image-guided blood or fibrin glue patching, surgery for a dural tear, or transvenous embolisation (blocking the abnormal vein connection) for a CSF venous fistula. The review says these have a high chance of success and are best performed where a multidisciplinary team can choose between them.

Diagnosis starts with the story: the posture-related headache, its timing, and any previous lumbar puncture, epidural or spinal surgery. The review says an MRI scan of the brain is the first-line test and typically shows features such as thickened, enhancing coverings of the brain, enlarged venous sinuses and brain sagging. A contrast dye (gadolinium) is ideally used.

A normal scan does not rule it out. The review says as many as 20% of people with SIH have a normal brain MRI, and that lumbar puncture should not be performed solely to check pressure, because only about one-third of people with imaging-confirmed SIH have a pressure at or below the diagnostic threshold and the puncture itself can complicate the picture.

Whole-spine MRI rarely finds the exact site, but it can show a collection of fluid along the spine, which points to the likely type of leak. Locating the leak itself needs dynamic CT myelography or digital subtraction myelography, which the review says are best done by experienced neuroradiologists in a high-volume specialist centre.

Because many headaches get worse upright or on movement, other conditions are often considered first. The review sets out how they differ, and notes that migraine and postural tachycardia syndrome can also coexist with SIH.

Gloucestershire Hospitals NHS Foundation Trust says an epidural blood patch is done under local anaesthetic, so you are awake, and usually takes 20 to 40 minutes. You are asked to lie flat for the first hour and should arrange for someone to collect you because you cannot drive yourself home.

In the days afterwards the leaflet says you may have mild discomfort or bruising at the site, or an increase in your previous symptoms or some new ones, such as headache, pain in another area or tightness around the chest or abdomen, which should get better within a few days. It recommends aiming to lie flat for as long as possible for 1 to 3 days, and minimising bending, straining, stretching, twisting, closed-mouth coughing, sneezing, heavy lifting, strenuous exercise and constipation for the first 4 to 6 weeks.

The review says the effect cannot be judged reliably in the first few days, so follow-up is usually at about 10 to 14 days after a blood patch and at 3 to 6 weeks after a targeted treatment. It also advises MRI follow-up after improvement, because symptoms can improve while the leak persists. The trust leaflet adds that, once symptoms have improved, gradually increasing activity is the most important part of managing symptoms in the longer term.

SIH is described by the UK review as highly disabling but almost always treatable. Recognised complications include collections of fluid or blood over the brain (subdural hygroma or haematoma), blood clots in the brain veins, and superficial siderosis, a late complication of an untreated leak in which iron-containing deposits build up on the brain and spinal cord surface.

The review quotes one study in which none of the patients had developed superficial siderosis or bibrachial amyotrophy (arm muscle wasting) within 4 years, but the rate was around 10% after 8 years, 33% after 12 years and 58% after 16 years. It also says that, rarely, brain sagging can cause a dementia-like syndrome and that coma has been reported.

The NHS headache guidance says to call 999 or go to A&E if a headache started suddenly and is extremely painful, or comes with numbness or weakness in the body or face, a seizure, difficulty speaking, balancing, walking or remembering, drowsiness or confusion, loss of vision, or a very high temperature with a stiff neck or discomfort in bright light. Do not drive yourself.

It advises an urgent GP appointment or NHS 111 for a headache with vision problems, one that is triggered or made worse by coughing, sneezing, bending down or exercise, or one with vomiting.

After a blood patch, the trust leaflet says to attend the Emergency Department urgently for any worsening limb weakness or new loss of bladder or bowel control. New severe back or leg pain, abnormal sensation in the legs or the area between the legs, being unable to pass urine, nausea and vomiting, or fever need assessment by a medical professional the same day, through the anaesthetist contact, your GP, NHS 111 or the Emergency Department.

On the NHS the usual route is a GP referral to a neurologist. The review says guidelines recommend that people with suspected SIH are seen by a local neurologist within 2 to 4 weeks, and that anyone who cannot look after themselves, or who deteriorates rapidly or develops serious complications, needs emergency assessment.

It adds that in most UK hospitals obstetric anaesthetists have the expertise to perform blood patches, and that targeted treatment and myelography are concentrated in specialist neuroscience centres with a multidisciplinary team. A UK survey of clinicians in the review found variable pathways and difficulty accessing investigations such as myelography and treatments such as epidural blood patches, so asking your GP or neurologist how referral works locally is reasonable.

Private neurology and imaging appointments can be arranged by self-pay or insurance. Whichever route you use, the specialist techniques above are delivered by a small number of experienced centres, and the same referral decisions apply.