According to Carrie and Collins  post dural puncture headache (PDPH) is "a headache occurring after dural puncture and has a significant effect on the patient's post operative well being i.e. headache which is not only postural but also continues for more than 24 hours at any level of intensity or so severe at any time that the patient is unable to maintain upright position.According to the International Headache Society, the criteria for PDPH  include a headache that develops less than seven days after a spinal puncture, occurs or worsens less than fifteen minutes after assuming the upright position, and improves less than thirty minutes in the recumbent position with at least one of the following (neck stiffness, tinnitus, hypacusia, photophobia, and nausea). The headache should disappear within fourteen days after a spinal puncture; if it persists, it is called a CSF fistula headache.The incidence of PDPH is estimated to be between 30-50% following diagnostic or therapeutic lumbar puncture,0-5% following spinal anaesthesia and up to 81% following accidental dural puncture during epidural insertion in the pregnant woman.Other than spinal anaesthesia the procedures leading to PDPH include,diagnostic lumbar puncture( where a big sized needle is used) labour analgesia with accidental dural puncture and therapeutic epidural steroid injections.
Do the needle size and type matters? Of course, researchers of the past 100 years have found that there is a definite relationship between the incidence of PDPH and needle size. Reducing the size of the spinal needle has made a significant impact on the incidence of post‐spinal headache. The incidence is approx 40% with a 22G needle; 25% with a 25G needle; 2%–12% with a 26G Quincke needle; and less than 2% with a 29G needle. With needles of 29G or smaller, the technical difficulties may lead onto a failure of the procedure and multiple attempts may be required causing multiple dural puncture which in fact increase the incidence.Pencil point whitacre needles are now preferred.If the needle bevel is oriented parallel to the nerve fibres during spinal anaesthesia the incidence can be lowered further.PDPH is rare in children owing to their low CSF pressure
Characteristic features of head ache: Ninety per cent of headaches will occur within 3 days of the procedure,and 66% start within the first 48 h. Rarely, the headache develops between 5 and 14 days after the procedure.The head ache is commonly distributed over the frontal and occipital areas radiating to the neck and shoulders and sometimes the temporal, vertex and nuchal areas also may be affected.Neck stiffness may be present. The pain is exacerbated by movements of the head, standing position and relieved by supine position.Other symptoms include nausea,vertigo,tinnitus,visual disturbances and rarely cranial nerve palsies.The headache is usually relieved in seven days but cases were reported where it lasted upto 3 months.The cause for the head ache is CSF leak leading to intracranial hypotension
Diagnosis: Mainly by clinical features and history of possible dural puncture.Additionally a diagnostic CSF tap may show, a low CSF opening pressure, minimally raised CSF protein, and a rise in CSF lymphocyte count.The MRI may demonstrate diffuse dural enhancement, with evidence of a sagging brain or descent of the brain. Cisternography or CT myelography may be used for diagnosing a CSF leak.Untreated cases may develop intracranial hematoma due to rupture of bridging veins following intracranial hypotension.
Treatment:1) Bed rest: No use at all  but along with other measures very effective in reducing headache.
2) Simple analgesics: Paracetamol and other NSAIDs for mild pain.
3) Posture: Supine position helps to maintain the CSF pressure and prone position increases intra abdominal pressure and the CSF pressure and gives instantaneous relief. However prone position may not be comfortable for the patient.Supine position helps to avoid complications like intracranial hemorrhage and seizures due to low CSF pressure.
4) Abdominal binders: Should be tight enough to increase the intra abdominal pressure.
5) Caffeine : Caffeine is a CNS stimulant and cerebral vasoconstrictor.The recommended dose is 300-500 mg of oral caffeine once or twice in a day It is assumed that caffeine acts through vasoconstriction of dilated cerebral vessels.Caffeine is associated with some adverse events like cardiac arrhythmias and maternal seizures and necessary precaution may be taken. High doses of the drug may reach the baby through breast milk and can cause neonatal irritability
6) Sumatriptan: Sumatriptan is a 5‐HT1D receptor agonist that promotes cerebral vasoconstriction,acts in a similar way to caffeine. It increases the cerebral vascular tone.
7) Synthetic ACTH: was first reported to be effective for treating PDPH in the 1990s. Postulated
mechanisms include CSF retention through increased mineralocorticoid mediated sodium reabsorption,
and a direct analgesic effect via its glucocorticoid activity. A randomised controlled trial in 2004 found no effect of a single intramuscular injection of Synacthen compared with an intramuscular injection of normal saline.ACTH has been administered as an infusion  1.5 microgram per kilogram.
8) Desmopressin(DDAVP): injection intramuscularly before spinal injection has also proven to be effective but more reasearch is required to prove its efficacy.
9)Adequate hydration: was found to be helpful but overhydration must be avoided.
10)Epidural Blood Patch: Perhaps the most effective treatment for PDPH is epidural blood patch(EBP).the concept of EBP has developed following the observation that bloody taps were associated with reduced incidence of headache.The first epidural blood patch was performed in 1960 by theAmerican surgeon, Dr James Gormley.The mechanism is that once blood is introduced into the epidural space it coagulates and form a seal occluding the puncture site preventing further CSF leak.The procedure is associated with high success rate and low incidence of complications and has become the standard mode of treatment for PDPH.Before initiating the treatment one has to look for the contraindications like coagulopathy, local infections, fever or patient refusal.A sample of the patient's blood may be sent to lab for culture.If symptoms of PDPH persist after 24-48 hours,or the headache is disabling,consider an epidural blood patch.
Guidelines for placement of epidural blood patch (St.George Hospital, London)
The procedure must be carried out in theatre. Two anaesthetists are required, one of whom should be a consultant.
1. Written, informed consent should be obtained from the woman following a careful explanation of the procedure. The discussion should also include the chances of success, significant side effects and the possibility of requiring a second blood patch(approximately 1 in 5).
2. The epidural space is located with a Tuohy needle, by the first anaesthetist, at the level of the supposed dural puncture, or an intervertebral space above or below. CSF may be present in the epidural space. 20 – 30 ml of the patient’s blood (provided by the second anaesthetist) is then injected into the epidural space over 30 – 60 seconds. Dull, lower back pain may limit the volume injected, although pausing for a few seconds or slowing the rate of injection may allow the full amount to be injected.
3. The second anaesthetist is responsible for drawing blood from the patient. As with the epidural, vene puncture must also be carried out using a full aseptic technique. After cleaning and draping the skin of the antecubital fossa, the skin should be anaesthetized with local anaesthetic prior to the insertion of a 14 or 16 gauge cannula. This should be done when the epidural needle is sited.
4. It has previously been thought that samples of the blood should routinely be sent for culture. This is an area of much controversy, and is backed up by little evidence,however until we have a definitive answer to this question it would seem prudent to continue to send blood for screening purposes. There is no evidence for the routine use of prophylactic antibiotics following blood patch.
5. The epidural blood patch should be carried out in the Obstetric theatre. Immediately following the procedure the patient should be taken to the recovery area for close observation. The patient is encouraged to lie still for one to two hours. After this time she can be transferred to the ward where she should be encouraged to walk.
6. It is important that the patient has repeated clinical assessment while an inpatient,although she may well go home the same day. Prior to going home, advice must be given regarding the need to contact labour ward or present to an Accident and Emergency department in the case of any complications. Specifically patients should be told about presenting features of cauda equina syndrome and epidural abscess.Where
possible written information should also be given. " During placing of EPB thus patient always should be asked about any acute occurrence of new pain, radiating pain and sharp shooting pain. Thus in EPB always a test dose of 2-3 ml of blood should be injected and patient should be evaluated. The total volume should be injected in increments of 2-3 mls".
Mechanism of action of EBP: After injection the patient should remain supine and immobile for
30 minutes to 2 hours to allow the blood to form a clot.Once injected the blood is distributed caudally and cephalad regardless of the direction of the bevel of the Tuohy needle. The blood also finds its distribution circumferentially around to the anterior epidural space. This has been proved  by using radiolabelled red cells or by MRI.There is evidence of thecal space compression and escape of blood through the intervertebral foramina and into the paravertebral space.The injected blood spreads up about six spinal segments cephalad and three segments caudad.The procoagulat property of CSF accelerates clotting of blood and the puncture site is sealed followed by an immediate relief of headache.At 7–13 h, there is clot resolution leaving a thick layer of mature clot over the dorsal part of the thecal sac.
Efficacy of blood patch: EBP is likely to be most effective if performed at least 24 hours after the onset of PDPH.The success rate varies between 75-90% and about 40% patients may need second EBP.The technique is safe and the rare transient complications include radiculopathy,backache, neckache and bradycardia.Major complications are rare,and may include meningitis, subdural haematoma, seizures, arachnoiditis, spastic paraparesis, dural puncture,cauda equina syndrome etc.If an epidural blood patch fails to relieve a PDPH, it is advisable to consider radiological imaging of the head to exclude other pathology prior to repeating the blood patch.
Prophylactic blood patch: The beautiful explanation in this regard is by Dr Nicola Jane Campbell FRCA, Effective management of post dural puncture headache Anaesthesia tutorial of the week 181, 31st may 2010.He says,
A potentially attractive option in the face of a recognised dural puncture with a Tuohy needle is to resite the epidural so that a prophylactic epidural blood patch (PEBP) can be provided in the hope of preventing a subsequent PDPH. The popularity of this technique has diminished recently for a number of reasons including the limited evidence that PEBP reduces the requirement for a therapeutic EBP, the increasing use of intrathecal catheter placement following dural puncture which may itself reduce the risk of subsequent PDPH and the recognition that some dural punctures don’t result in a PDPH and many PDPHs do not require a therapeutic EBP. Administering a PEBP to patients following duralpuncture may therefore expose these patients to an unnecessary procedure with associated risks.
Epidural saline and Dextran: theoretically a suitable alternative to EBP and thought to be safe as they are sterile solutions.These techniques are very useful in Jehovah witnesses patients or patient with bacteremia and HIV infection .They increase the CSF pressure by mass effect but formation of a coagulum and subsequent sealing effect over the dura are doubtful.Regimens include (i) 1.0–1.5 litre of epidural Hartmanns solution over 24 h, starting on the first day after dural puncture; (ii) up to 35 ml h–1 of epidural saline or Hartmanns solution for 24–48 h, or after development of the headache; (iii) a single 30 ml bolus of epidural saline after development of headache; and (iv) 10–120 ml of saline injected as a bolus via the caudal epidural space.The tamponade effect of epidural dextran is also transient and similar to saline offering no advantage over saline.In neither of these an aseptic inflammatory response over the dura was found.
Epidural Morphine: Administration of epidural morphine soon after inadvertent dural puncture as prophylactic measure to prevent PDPH has been advocated by many authors but evidence lack due to absence of large controlled trials.
Fibrin glue: As an alternetive to blood patch fibrin glue injection into the epidural space was found to be helpful..The procedure may be done blindly or by CT guided percutaneous injection.The failure rates are high. Chance of development of aseptic meningitis makes the procedure less acceptable to many.
Intrathecal catheters:An alternative method of managing ADP by passing an epidural catheter through the needle into the subarachnoid space was described by Cohen in 1989. Since then, several studies have claimed a reduction in incidence of PDPH if the epidural catheter is inserted intrathecally at the time of dural puncture and removed after at least 24 h. Injection of a 10 ml bolus of normal saline into the intrathecal catheter before its removal further reduced the incidence of PDPH. It was postulated that placement of
a spinal catheter through the perforation may provoke an inflammatory reaction that will seal the hole. However, neurological complications, such as cauda equina syndrome and infection, should preclude the use of intrathecal catheters and keeping the catheter for more than 24 hours is also not advocated
Surgical closure: Surgical closure of the dural perforation is the last resort to treatment
Preventing PDPH; Preventive measures like smaller needle size, shape of needles and direction of needle bevel in relation to dural fibers, should always be considered.For spinal blocks, pencil point needles of 25 G or smaller should be used, especially in the obstetric population.While performing Epidural anaesthesia Loss of resistance to saline performed with continuous pressure on the syringe plunger may have the effect of
moving the dura anteriorly as the needle approaches thereby reducing the likelihood of dural puncture
compared with an intermittent pressure technique with air.Other precautions should include ensuring an optimal patient position, slow controlled advancement of the needle and limiting patient movement during the procedure by using adequate local anaesthetic infiltration.When there is difficulty use of ultrasound guidance for epidural placement may be considered.
Differential diagnoses: for PDPH:Tension Headache,Migraine Headache, Caffeine Withdrawal, Lactation Headache, Hypertension, Pneumocephaelus, Meningitis, Subarchnoid Heamorrahge, Spontaneous Intracranial Hypotension and eclampsia.
PDPH is the most distressing experience for post operative patient and can lead on to significant morbidity and death..Apart from increasing the duration of hospitalisation, it can cause auditory and visual disturbances, nausea, vomiting ,cranial nerve palsy and intracranial hemorrhage due to low CSF pressure.The treatment should be aggressive with conservative methods initially and in severe and resistant cases with CNS involvement EBP may be tried..Mostly the headache is benign and will be resolved spontaneously in 5-7 days
A current review about PDPH by Steve Schwalbe, MD is found to be interesting in this context..http://www.soap.org/media/newsletters/fall2000/pathophysiology_management.htm
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