Patho phsiology of pdph

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Patho phsiology of pdph

  1. 1. PATHOPHYSIOLOGY OF PDPHA (POST DURAL PUNCTURE HEADACHE)Dr Ashok Jadon, MD DNB MNAMSSenior Consultant & HOD Anaesthesia,Tata Motors Hospital, Jamshedpur-831004Address for Correspondence:Duplex-63, Vijaya Heritage, Kadma, Jamshedpur-831005Jharkhand (India)Mobile: 09234554341E-mail: ashok.jadon@tatamotors.comIntroduction:In 1898 Karl August Bier probably gave the first spinal anaesthetic and described symptomsof a post-dural puncture headache (PDPHA). Bier postulated that CSF (Cerebrospinal fluid)leak through dural opening was the cause of these symptoms which was substantiated lateron by many scientific studies. Post-dural puncture headache (PDPHA) is a frequentcomplication of dural puncture whether performed for therapeutic purposes oraccidentally, as a complication of anesthesia.Pathophysiology:About 500 ml of CSF is produced each day (21ml per hour or 0.3ml/kg/hr), mainly (90%)coming from the choroid plexus, and 10% from the brain substance itself. The total CSFvolume in an adult is about 150 ml, with 50% in the cranium. The normal CSF pressure inthe lumbar region when supine is between 5 and 15 cmH20 and over 40 cmH20 when erect.The spinal needle while giving spinal anaesthesia (or epidural needle during accidental duralpuncture) makes a hole in dura which allows leak of CSF in epidural space due to pressuregradient between subarachnoid space (positive pressure) and epidural space (potentialnegative pressure). The rate of CSF loss through the dural perforation (0.084-4.5 ml/sec)may be greater than the rate of CSF production (0.35 ml/minute) especially with larger
  2. 2. needles/holes.1, 2 As little as 10% loss of CSF volume can cause an orthostatic headache.Two mechanisms have been proposed for the cause of the headache.First, Excessive loss of CSF leads to intracranial hypotension. Intracranial hypotension maycause downward displacement of the brainstem and traction on pain sensitive intracranialstructures. The traction on the upper cervical nerves like C1, C2, and C3 causes the pain inthe neck and shoulders. Traction on the fifth cranial nerve causes the frontal headache. Painin the occipital region is due to the traction of the ninth and tenth cranial nerves.3Second, Loss of CSF produces a compensatory adenosine mediated intracranialvenodilatation (Munro-Kellie doctrine). The venodilatation is then responsible for theheadache. CT scan and MRI may show abnormal, intense, dural venous sinus enhancement,indicating a compensatory venous expansion.4The amount of CSF leak depends upon various factors.a. Size of needle: larger the size of needle (smaller SWG) will result in increased CSF leak5 and incidence of headache (Table-1).b. Type or design of needle: incidence of PDPHA is higher with cutting tip design (Quincke) spinal needles than pencil point needles.6 Spinal needles with cutting tip design cuts the dural fibers and may cause prolonged CSF leak. Pencil point needles split the fibers therefore chances of CSF leak is minimized (Fig-1).c. Thickness of dura at puncture site: Recent measurements of dural thickness have demonstrated that the posterior dura varies in thickness within the individual and between individuals.3 Dural puncture in a thick area may be less likely to lead to a CSF leak. This in part may explain the unpredictable consequences of a dural puncture.d. Direction of needles’ bevel: bevel insertion parallel to dural fibers will result in lower incidence of PDPHA then bevel in perpendicular to dural fibers.7In parallel direction it splits the dural fibers and allows immediate closure of entry wound but parallel entry cuts the dural fibers and results in leak of CSF for longer period. With recent understanding of dural fiber configuration this theory is being questioned now.e. Reinsertion of stylet: a small fragment of arachnoids’ may come out through dural puncture while removing the spinal needle and it may lead to PDPHA due to persistent
  3. 3. CSF leak. If stylet is reinserted while needle is withdrawn after spinal procedure, results in low incidence of PDPHA because it repositions the archanoid at its place (Fig-2).8f. Dural response to trauma: after perforation of the dura, dural repair is facilitated by fibroblastic proliferation from surrounding tissue and blood clot. The experimental study9 noted that dural repair was promoted by damage to the pia-arachnoid, the underlying brain, and the presence of blood clot. It is therefore possible that a spinal needle carefully placed in the subarachnoid space does not promote dural healing; as trauma to adjacent tissue is minimal. Indeed, the observation that blood promotes dural healing agrees with Gormley’s original observation that bloody taps were less likely to lead to a postdural puncture headache as a consequence of a persistent CSF leak.10CSF leak is inevitable during spinal procedures however; every patient does not developPDPHA after spinal. Therefore it has been postulated that other factors along with CSF leakmight be contributing for variable incidence of PDPH in similar set of clinical situation. Theplausible factors 11 are:i. Hormonal influence: higher incidence of PDPHA in young females is probably due to higher levels of progesterone which sensitize the brain for PDPHA.ii. Hydration: although aggressive hydration does not prevent PDPHA however, maintaining good hydration during conservative management decreases the intensity of symptoms in established case of PDPHA.iii. Body mass index: Women who are obese or morbidly obese may actually have a decreased incidence of PDPH. This may be because the increase in intra-abdominal pressure may act as an abdominal binder helping to seal the defect in the dura and decreasing the loss of CSF.iv. Dural fiber elasticity: the incidence is greater in younger women because of increased dural fiber elasticity that maintains a patent dural defect compared to a less elastic dura in older patients.v. History of Headaches and motion sickness: patients with a headache before lumbar puncture and a prior history of PDPH are also at increased risk. There may be some correlation between history of motion sickness and PDPH.
  4. 4. vi. Other receptors: efficacy of various agonist and antagonist for the treatment of PDPHA shows that 5HT and opioid receptors along with adenosine receptors might have some role is causation of PDPHA.12Summary & Conclusions:CSF leak occurs after dural puncture. If it is in excess to its formation, may cause intracranialhypotension and results in PDPHA. The exact pathophysiology of PDPHA is not wellestablished as even with best of precautions to prevent CSF loss does not guarantee againstPDPHA. The two possible hypotheses for the symptoms are traction on pain sensitive areasof brain and venodilatation by Adenosine receptor activation has recently been proposeddue persistent leak and resultant low pressure of CSF. The concept of adenosine receptoractivation has been substantiated by treating PDPHA with Adenosine receptor antagonist;caffeine and Methylxanthines.References:1. Cruickshank RH, Hopkins JM. Fluid flow through dural puncture sites. An in vitro comparison of needle point types. Anaesthesia 1989; 44: 415-18.2. R. W. Evans. “Complications of lumbar puncture,” Neurologic Clinics 1998;16: 83–105.3. Turnbill DK, Shepherd DB. Postdural puncture headache: pathogenesis, prevention and treatment. Br J Anaesth 2003:91:718-29.4. Settipani N, Piccoli T, La Bella V, Piccoli F. Cerebral venous sinus expansion in post-lumbar headache. Funct Neurol 2004;19:51-2.5. Ready et al. Spinal needle determinants of rate of transdural fluid leak. Anasthesia and Analgesia 1989;69:457-60.6. Halpern S. et al. Postdural Puncture Headache and Spinal Needle Design: Meta-analyses. Anesthesiology1994; 81: 1376-1383.
  5. 5. 7. Flaaten H. et al. Puncture technique and postural postdural puncture headache. A randomised, double-blind study comparing transverse and parallel puncture. Acta Anasthesiology Scandanavia 1998;42:1209-14.8. Strupp M, Brandt T, Muller A. Incidence of post-lumbar puncture syndrome reduced by reinserting the stylet: a randomized prospective study of 600 patients. J Neurol 1998; 245:589-592.9. E. B. Keener. An experimental study of reactions of the dura mater to wounding and loss of substance. Journal of Neurosurgery1959; 16: 424–447.10. J. B. Gormley. Treatment of post-spinal headache. Anesthesiology1960; 21: 565–566.11. Ghaleb A. Postdural Puncture Headache. Anesthesiology Research and Practice. On line avilable at http://www.hindawi.com/journals/arp/2010/102967.cta.html .12. D Bezov. Post-Dural Puncture Headache: Part I Diagnosis, Epidemiology Headache 2010; 50:1144-1152.
  6. 6. Table-1Table shows CSF flow rates with different size of needleFigure-1The effect of dural puncture by Quincke andPencil point needle
  7. 7. Figure-2Figure shows the effect of reinsertion of stylet on archanoid

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