Title: Unexplained fitting in patients with post-dural puncture headache. Risk of iatrogenic pneumocephalus with air rationalizes use of loss of resistance to saline
Abstract: Editor'The report of unexplained fitting in three parturients suffering post-dural puncture blockade (PDPH) by Drs Oliver and White1Oliver CD White SA Unexplained fitting in three parturients suffering postdural puncture headache.Br J Anaesth. 2002; 89: 782-785Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar failed to mention the relationship between seizures and pneumocephalus secondary to the injection of air to detect loss of resistance (LOR). Omission, too, by the authors to describe which medium was used to test for LOR was especially significant to us, as we recently presented an incident to our morbidity and mortality meeting of a convulsion in a 29-yr-old parturient who, after an uneventful epidural for labour using air for LOR, developed PDPH. A blood patch was performed 10 days later, again using air for LOR. Regrettably, a dural tap complicated the blood patch, which otherwise was successful until the following day when the patient failed to observe strict bed rest orders, got out of bed and the headache recurred. The severity of the headache resulted in her remaining hospitalized, and being treated with fluids, bedrest, analgesics and i.v. caffeine. However, the headache continued, the patient became emotionally labile and 2 days after the blood patch, she suffered a generalized convulsion. A neurological examination revealed no deficit, but a magnetic resonance imaging (MRI) scan revealed ‘pneumocephalus’ and ‘features suggestive of postpartum microvascular angiopathy’. The patient was transferred to the hospital's stroke unit, received continued conservative treatment, improved and was discharged 10 days thereafter. These events drew the attention of the obstetric anaesthestists at our hospital to the question of which medium is best used to test for LOR. A literature search revealed no reports, other than anecdote, supporting the contention that LOR is more easily determined using air.2Howell TK Prosser DP Harmer M A change in resistance? A survey of epidural practice amongst obstetric anaesthesists.Anaesthesia. 1998; 53: 228-243Crossref Scopus (31) Google Scholar 3Goodyear P Identification of the epidural space using air and normal saline.Anaesthesia. 2001; 56: 397-398Crossref PubMed Scopus (2) Google Scholar Furthermore, the claim by proponents of the air technique that air more easily allows detection of cerebrospinal fluid (CSF) leaking from the epidural needle after inadvertent dural puncture is challenged by reports advocating either the use of a ‘dipstick’ for testing emitting fluid for pH and protein, or assessing its warmth by allowing the fluid to drip onto the dorsum of the anaesthestists's hand or arm.4el-Behesy BAZ James D Koh KF Hirsch N Yentis SM Distinguishing cerebrospinal fluid from saline used to identify the extradural space.Br J Anaesth. 1996; 77: 784-785Crossref PubMed Scopus (18) Google Scholar However, of much greater importance than reports that use of normal saline for detection of LOR is associated with a better endpoint,5Macdonald R Dr. Doughty's technique for the location of the epidural space.Anaesthesia. 1983; 38: 71-72Crossref PubMed Scopus (16) Google Scholar 6Reynolds F Identifying the epidural space.in: Norris MC Obstetric Anaesthesia. 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A. A. van den Berg L. Nguyen M. von-Maszewski H. Hoefer Houston, USA Editor'We would like to thank van den Berg and colleagues for their interest in our case reports. We acknowledge that pneumocephalus secondary to using a loss of resistance to air technique can be a cause of seizures. However, a loss of resistance to saline technique was used in all three of our cases. Indeed in 1998 a UK survey of obstetric anaesthetists showed 52.7% used a loss of resistance to saline technique and 57.2% taught this technique.2Howell TK Prosser DP Harmer M A change in resistance? A survey of epidural practice amongst obstetric anaesthesists.Anaesthesia. 1998; 53: 228-243Crossref Scopus (31) Google Scholar We note that i.v. caffeine was used to treat this patient's PDPH and she subsequently suffered a generalized convulsion. I.V. caffeine is known to cause seizures,29Cohen SM Laurito CE Curran MJ Grand mal seizure in a postpartum patient following infusion of caffeine sodium benzoate to treat persistent headache.J Clin Anesth. 1992; 4: 48-51Abstract Full Text PDF PubMed Scopus (34) Google Scholar and thus would need to be considered as a differential cause of this patient's convulsion. C. D. Oliver S. A. White London, UK