Wednesday, 11 June 2008

How can you confirm a cerebrospinal fluid leak in a base of skull fracture?

Basilar skull fractures (i.e. base of skull fractures) have a high incidence of dural tears and thus a higher than average risk of meningitis - although it is controversial whether or not to give prophylactic antibiotics. The basics to know about this condition are as follows:

Firstly, skull X-rays are almost never of any help in diagnosing basilar skull fractures. You need to go by clinical signs.

Clinical signs include:
  • Raccoon eyes - this refers to a periorbital (around the eyes) bruising, and is a result of blood tracking down from the skull fracture site to the soft tissue around the eyes.

  • Battle's sign - named after a guy (unsurprisingly) called Battle, this is bruising around the mastoid process (behind the ears). As with raccoon eyes, this bruising is due to blood tracking there from the skull fracture, not from damage directly to the mastoid process.

  • Cerebrospinal fluid (CSF) otorrhoea -this is leakage of CSF out your ear, via a combination of a ruptured tympanic membrane and nearby basilar skull fracture.

  • CSF rhinorrhoea - similar to the otorrhoea story, this is leakage of CSF out your nose. Usually (but not exclusively) the ethmoid cribriform plate is the part fractured.

  • Cranial nerve palsies - many of the cranial nerves run nearby enough to be injured or compressed by a fractured base of skull.

A good question that might now arise is how you tell if fluid coming out the nose or ears is CSF - it could be pure blood, or it (in the case of nasal discharge) it could be the normal nasal secretions. There are a number of tests you can do.

Firstly, CSF should have glucose in it, whereas this is unlikely in normal nasal secretions, and so measuring the glucose (initially on dipstix, and then formally) is helpful.

Secondly, if you are dealing with a bloody fluid, you could try to look for the halo sign (or ring sign). Dab some of the blood on a tissue. If there is CSF mixed with the blood, it will move by capillary action further away from the centre than the blood will. You'll get something like this:

These tests are helpful pointers, but they aren't wholly accurate. If you want to be more sure, measure the level of beta-2-transferrin in the fluid. This protein is only found in CSF, so if you are finding it in fluid coming from the nose or ears, you have a CSF leak.

If you have any of these signs present, you may be dealing with a basilar skull fracture. To confirm your diagnosis, you need to organise a CT scan of the area. This is more or less the diagnostic procedure followed in most hospitals.


  1. I got a good follow-up question to this post:

    "hello doc,

    Thank you very much for the answer.
    I am not that clear with the halo sign. If blood was present, would there not also be a yellow ring? Blood would clot and appear in the center. If it is so, we will have to compare the normal blood and
    blood and csf on tissue paper. The sample with CSF would have a wider ring. Does that sound way too crazy?"

  2. I think you're on the right track there. When blood clots, there can certainly be a separation of the solid constituents (mainly red blood cells) from the plasma. The plasma would then be capable of spreading out on the tissue/blotting paper quicker than the rest, which could cause a halo sign of sorts.

    But I think this effect:

    (1) takes time - the halo sign is usually present in the case of CSF long before the blood fully clots

    (2) is quite minimal. CSF produces a much more marked effect.

    But you nonetheless bring up a really good point that is worth emphasising again. The halo sign is NOT hugely specific or sensitive - it simply isn't a diagnosis-clincher. It's simply a sign that is an improvement on a random guess.

    Don't take my word for it though. For those interested in a little more detail, there's a nice article here about CSF rhinorrhoea. The relevant passage about the halo sign is:

    Most of us have read about the halo sign. CSF will separate from blood when the mixture is placed on filter paper resulting in a central area of blood with an outer ring or halo. Dula et al studied this ring sign and found that mixtures of CSF and blood will produce a clinically detectable ring with CSF:blood ratios of 30%-90%. Blood alone does not produce a ring. The best ring was obtained with a 50: 50 mix of blood and CSF. More importantly, they found that the presence of a ring was not exclusive for CSF. Blood mixed with tap water, saline, and rhinorrhea fluid also produced a ring. The halo sign does occur, but clearly does not clinch the diagnosis.

  3. Thank you very much. It helps me a lot with my finals. It saves my time, reading the textbook.

  4. excellent job...keep helping us...tnx

  5. Thank you very much.

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  7. Thanks for the tips. I have had fluid leaking out of my ears for 4 1/2 years--been to 3 ENTs, GP, neuro-ENT, 4 neurologists. NONE took samples of the fluid. NONE. All said "Your ears look fine." I have positional tremors, can't walk heel-to-toe without falling, tinnitus (buzzing, humming, beeping), tingling in my spine, electric current sensations--if I press my ears in different areas, it will cause these sensations in various parts of my body--my buttocks, my toes, my thighs, etc.

  8. Tiger, have you had cranial/cervical MRIs?

  9. hey guys. The last 4 days I've been experiencing a fluid leaking from in the back of my throat that it feels like its coming from my left nostril. The first two days I didn't experience any headaches or anything else the could imply CSF leak. But the past two I've have had migraines and when I woke up the left side of my head felt kinda numb. I went to the doc yesterday and she put a camera in my nose and down my throat but couldn't find anything. oh note also that I've hit my head on a door,in fact my forehead,about a month ago. Now the doc said that if it keeps going I can do a ct scan to make sure if its CSF leaking or not. Unfortunately here in Greece testing of the fluid happens only in Athens and because it just started to happen it might cost a fortune and might have to even travel there. So do you guys think a ct scan is reliable enough? Or is the test of the fluid better?

    Thank you for reading

    1. Did you ever get confirmation of CSF leak?

  10. Thanks this was beyond helpful

  11. I have had clear drainage from my right nostril for several days now. It started as a few drops when I would bend over. In the last two days the drops have increased to 10-15 drops each time I bend over. I was seen in the ER last night and CT came back as sinusitis. MD wanted me to leave with just that. I protested and had them test the fluid for glucose and protein. Both came back positive, though glucose was a little low. They sent me home with Abx and a follow up to ENT. Should I be more concerned? I know Meningitis is life threatening, but the drainage is intermittent. Should I get another opinion? See another ER doc?

  12. لدينا مميزات في خدمات كشف تسربات التي تقدمها شركة ركن البيت التي تكون متخصصة فيها فتعاملك مع شركة كشف تسربات المياه بالدمام لديها امكانيات جيدة يساعدك علي التخلص من مشاكل التسريب التي توجد لديك بسهولة دون التعرض للخطر حيث نمتلك في شركة كشف تسربات بالدمام الامكانيات والفنين المتميزين الذين يقدمون الخدمة بتميز فاذا كنت فى حيرة من امر التسريب الذي يوجد لديك فعليك ان تعلم ان خدماتنا منتشرة في جميع انحاء المملكة مثل خدمات شركة كشف تسربات المياه بالرياض التي تحل لك المشاكل المتكررة المتعلقة بالتسربات فلا داعى للقلق من الان لانك سوف تملك فني جيد منزلك يحل لك كل مشاكل التسربات و كيفية القيام بهذه الخدمة وتذكر ان الحل الامثل فى شركة كشف تسربات بالرياض ان توفر كل الامكانيات التى تساعدك علي حل مشكلاتك

  13. How can I tell it's CSF, mine started draining from my left ear, then this last 2 weeks I started waking up with my left nostril seemed to be coated with a sticky substance in side. Then it started pouring out the left nostril. At first I thought I had a bloody nose. But the fluid is yellowish and very sticky.

  14. I have had a positional head/neck/mid upper back severe ache for the last 5 days. severe pain when vertical, completely gone after a few mins of repositioning prone to supine position. I originally suspected musculoskeletal process when it was just between the scapula but when is spread to neck and head over the course of 4 hours and became severe I was more concerned (9-10 pain scale). I tried flexeril at first, but did not help. after 1 urgent care and 4 ER visits, several pain medications with no relief, head, neck, spine MRI with and without contrast, VQ scan to R/O PE and lumbar puncture to check CSF pressure (was very low), and r/o meningitis, I was unable to convince the MDs that it may be a CSF leak. They had never heard of a spontaneous leak and have no answers for me. I really wanted anesthesia to try a blood patch, but was only told to follow up with my primary doc and put in a referral for a neurologist. I am at home and have been on bedrest, today is getting better and although I am able to stand without the severe pain, I am remaining very cautious for now and continuing with rest and hydration. Minimal caffeine because I sometimes have episodes of SVT. I noticed that I am having some clear drainage from my right nostril only, and have been having some drainage that I previously didn’t think much of until now. I also had been to my doc this last year with c/o a feeling of ICP when bending forward, lying in the prone position, coughing, laughing, sneezing, etc. I am now thinking that perhaps I did have ICP which may have led to a spontaneous CSF leak. Please let me know what you think, as none of the physicians I have seen have heard of a spontaneous leak, like I said. It is very frustrating.
    Thank you!

    1. Pseudotumor cerebri. Can be dangerous. Need to have your optic nerves and discs looked at asap. See a neurologist.

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  16. I hit my head running full tilt into a cupboatd door, was knocked off my feet and saw stars.As my head was bleeding and I am on warfarin (longterm for blood clotting disorder),I was sent to A & E, UK NICE guidelines, for a CT scan.
    I was told this was negative,given a leaflet about minor head injury/concussion and released.
    Four weeks on...still off work,with leaking nose,which increases if I bend over;headaches that increase in severity if I try to do more,only alleviated by resting, plus other minor symptoms.
    Went back to A & E, Dr said based on symptoms 'csf leak',had a repeat CT which was normal so released with no advice except bedresthe, and "caffeine can help" bed.
    GP has referred for a neurology consult but earliest appointment end of December.
    I am still feeling very unwell and incredibly frustrated - I know I would not cope at work at present (++driving and ++computer work) and my boss says doesn't want me back until I am "better" anyway, but I want to get to work asap emotionally and financially!
    Any advice please!