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Responses to dural puncture during institution of combined spinal-epidural analgesia: a comparison of 27 gauge pencil-point and 27 gauge cutting-edge needles.

Nausea, hypotension and post-dural puncture headache (PDPH) are iatrogenic morbidities commonly associated with spinal analgesia (1). Compared with cutting-edge spinal needles, those with a pencil-point cause less cerebrospinal fluid (CSF) leak from the dural puncture site (2), less PDPH (3) and are recommended for spinal and combined spinal-epidural (CSE) analgesia techniques in anaesthetic practice. During the performance of CSE techniques, iatrogenic morbidity has been reported. Between 37% (4) and 81%5 of parturients experience paraesthesia or dysaesthesia at the moment of dural puncture during 'needle through needle' insertion of 26 and 27 gauge pencil-point spinal needles, following the use of either air or saline (4) or an air-saline combination5 to determine loss of resistance and facilitate placement of the epidural needle.

These observations provide clinical evidence contradicting opinion held during the last century that dural puncture is painless (6) and confirms animal studies showing sensory nerve endings in the lumbar peridural membrane and dura mater (7,8). The presence of pain, pressure or stretch receptors in the lumbar meninges raises the possibility that dural puncture with pencil-point needles, which indent and stretch the meninges prior to perforation, and cutting-edge needles, which pierce the meninges with less indentation and stretch, may induce different sensory responses at the moment of dural puncture.

This audit was undertaken to compare the effects of a 27 gauge pencil-point and a 27 gauge cutting-edge spinal needle on the incidences of involuntary movement, grimacing, spontaneous vocalisation and patient acknowledgement of experiencing a sensation at the moment of dural perforation, associated with 'needle through needle' CSE analgesia.


A protocol detailing the prospective audit9 was presented to the Committee for the Protection of Human Subjects of the University of Texas in Houston and to the Research and Ethics Committee of the Memorial Hermann Hospital in Houston, Texas and authority obtained to prospectively collect outcome data associated with routine performance of CSE techniques with verbal, not written, patient consent, maintenance of patient confidentiality and written consent for anaesthesia and/or surgery.

Successive patients presenting to the investigators for elective caesarean section or labour analgesia were consented and included in the audit. Those scheduled for caesarean section were visited by one of the investigators on the morning of surgery, suitability for CSE anaesthesia was assessed and premedication with oral ranitidine 150 mg, oral sodium citrate 30 ml and EMLA[R] topical skin cream to the non-dominant hand prescribed. Patients referred for or requesting labour analgesia were visited in the labour ward by one of the investigators and similarly assessed for suitability for CSE analgesia. Parturients were excluded if they had any contraindication to neuraxial block or relevant drug allergy.

The sample size was calculated as 38 patients per group using the formula for a two-sided comparison on the basis that a 33% difference in incidence of any subjective or objective patient response would indicate a significant outcome, with confidence limits of 95% and 80% power. As is customary in a clinical audit (9), the investigators (the primary investigator, four trainee anaesthetists and a visiting assistant professor of anaesthesia) used the spinal needle of their choice and the audit continued until data on at least 38 patients per group had accumulated.

In the operating room or delivery suite, following application of non-invasive monitoring devices (ECG, NIBP, [S.sub.a][O.sub.2]), insertion of an intravenous (IV) cannula and IV administration of ondansetron for prophylaxis of emesis, each patient was advised to anticipate skin cleansing, application of sterile drapes and injection of 3 to 5 ml lignocaine 2% containing adrenaline 1:200,000 (to reduce bleeding from the epidural puncture site) at a suitable L2/3 to L4/5 interspace. A 17 gauge Weiss (Tuohy-type) epidural needle (Portex Regional Anesthesia Tray, Smiths Medical ASD Inc., Keene, NH, USA) was inserted using loss of resistance to preservative-free normal saline to identify the epidural space. After advising the patient that sensation might be experienced, either a 27 gauge Whitacre pencil-point spinal needle (Portex Regional Anesthesia Tray, Smiths Medical ASD Inc., Keene, NH, USA) or a 27 gauge Quincke cutting-edge spinal needle, according to the personal preference of the anaesthetist, was inserted 'needle through needle' and gently advanced until the 'click' (6) or 'give' (10) of dural penetration was determined.

During insertion of the spinal needle each patient was closely observed by the attending midwife (who was stationed facing the patient, was familiar with the protocol of the audit but blinded to the nature of the spinal needle being tested) for any involuntary movement, grimace or spontaneous vocalisation during thecal penetration. Immediately after dural puncture was confirmed, irrespective of whether involuntary movement or spontaneous vocalisation had occurred, the patient was asked "Did you feel that?" by the anaesthetist.

In those undergoing caesarean section, when free flow of CSF was observed, 1.2 to 2.5 ml 0.75% (7.5 mg/ml) hyperbaric bupivacaine plus 25 [micro]g fentanyl was injected slowly intrathecally, with intermittent barbotage (10), an epidural catheter inserted in a cephalad direction, routine tests performed on the epidural catheter to exclude intrathecal or intravenous misplacement and, following a test dose of 3 ml lignocaine 2% containing adrenaline 1:200,000, a definitive dose (7 to 10 ml) of bupivacaine 0.5% (5.0 mg/ml) was injected epidurally. In those receiving labour analgesia, after flow of CSF from the spinal needle was observed, 1.0 ml lignocaine 1% (10 mg/ml) plus fentanyl 15 to 25 [micro]g was injected intrathecally with intermittent barbotage. After testing the epidural catheter, an epidural infusion of ropivacaine 0.2% (2.0 mg/ml) containing fentanyl 1 [micro]g/ml was commenced at 4 to 12 ml/hour. In patients undergoing caesarean section, an epidural infusion of bupivacaine and fentanyl was continued for up to 48 hours after surgery.

Complaints of sustained or severe paraesthesia or dysaesthesia during spinal needle insertion or intrathecal injection were regarded as indications to remove and re-site the epidural and spinal needles at an alternative lumbar interspace, but transient complaints were not.

After delivery the patients were visited daily by one of the investigators, who, after cessation of the epidural infusion in those having had surgery, removed the epidural catheter and enquired as to residual sensory or motor impairment. Patient demographics (age, weight, height, parity and American Society of Anesthesiologists status), subjective or objective responses during dural puncture and the patient's answer to the anaesthetist's question were recorded on a customised data sheet and details of neurological sequelae, following cessation of the postoperative epidural infusion, were added if present.

Statistical analyses were performed using the chi-square and Student's t-tests to compare demographic data and the chi-square test to compare nonparametric data. A P value of <0.05 was considered to indicate statistical significance.


The population audited (n=115) comprised two groups of pregnant women presenting for either caesarean section (n=30) or labour analgesia (n=85) under a CSE technique. Of those undergoing caesarean section, 18 (60%) and 12 (40%) patients (P <0.001) had CSE analgesia instituted using pencil-point and cutting-edge needles respectively. Of those having labour analgesia, 59 (69%) and 26 (31%) patients (P <0.0001) had CSE analgesia with a pencil-point or cutting-edge needle respectively. The characteristics (age, weight, height, American Society of Anesthesiologists status) of the patients in the two cohorts of patients were comparable, as were the characteristics within the two sub-groups receiving a pencil-point or cutting-edge needle (Table 1). During the audit, accidental dural puncture occurred in five patients. These patients were excluded from the study and five extra patients enrolled.

Among the entire population audited, grimacing or involuntary movement during dural penetration occurred in 17 (22%) and 2 (5%) of patients (P <0.025), spontaneous vocalisation occurred in 4 (5%) and 1 (3%) (P=NS) and patient acknowledgement of having perceived dural puncture occurred in 13 (17%) and 3 (8%) of patients (P=NS) in whom pencil-point and cutting-edge needle were used, respectively. A total of 34 and 6 (P <0.005) subjective and objective responses to dural puncture were noted in parturients in whom pencil-point and cutting-edge needles were used, respectively (Table 2).

On no occasion was the spinal needle withdrawn, re-directed or re-sited because of complaint by the patient of severe paraesthesia or dysaesthesia during insertion of the test spinal needle or subsequent intrathecal injection of local anaesthetic. In addition, on the days following cessation of epidural therapy and removal of the epidural catheter, no patient complained of residual paraesthesia, dysaesthesia or neurological deficit.


The study was a prospective clinical audit, which is suggested as an appropriate means of assessing outcomes of current practices in clinical anaesthetic practice9. The audit revealed that, compared with patients in whom a cutting-edge spinal needle was used, significantly more patients in whom a pencil-point spinal needle was inserted 'needle through needle' either responded to, or acknowledged having perceived, sensation at the moment of dural and arachnoid puncture at the time of a CSE technique. In the audit a larger number of patients accrued in the pencil-point group because these were more popular than cutting-edge needles, because of the reduced risk of CSF leak and PDPH (1-3).

Cognisant of the medical definitions (11) of paraesthesia (an abnormal sensation such as burning, pricking, tickling or tingling) and dysaesthesia (an abnormal, unpleasant sensation such as burning, pricking, tickling or tingling) and of descriptions in authoritative anaesthetic texts (12) of paraesthesia (an abnormal sensation, whether spontaneous or evoked) and dysaesthesia (an unpleasant abnormal sensation, whether spontaneous or evoked), we did not enquire into the nature of the sensation occurring at the moment of dural penetration and considered the simple question "Did you feel that?" adequate to cover the fleeting sensations experienced. In addition, although it is recommended that elicitation of paraesthesia or dysaesthesia during performance of regional blocks is an indication to remove and re-site the needle (13,14), we concur with the alternative opinion that the available data does not consistently link elicitation of paraesthesia or dysaesthesia with subsequent nerve damage (15,16). The latter opinion has recently received greater creditability by demonstration that puncture of peripheral nerves and apparent intraneural injection of local anaesthetic during axillary plexus blockade does not invariably lead to neurologic injury (17). Accordingly, we did not routinely remove and re-site the spinal needle in parturients in whom transient sensation or responses occurred during dural penetration.

The onset of hypotension, nausea and shivering shortly after intrathecal injection of local anaesthetic drugs and later development of PDPH and backache are iatrogenic morbidities commonly seen after spinal analgesia (18). The occurrence of iatrogenic paraesthesia or dysaesthesia at the moment of dural puncture during performance of a 'needle through needle' CSE technique has been described more recently (4,5,19,20). Of these symptoms however, only paraesthesia and dysaesthesia accompanying dural puncture and later onset of PDPH are related to the technique of neuraxial block (spinal or epidural) and to the nature (cutting-edge or pencil-point) and gauge of the spinal needle used. It is likely therefore, that the incidence and severity of iatrogenic paraesthesia and dysaesthesia occurring during thecal penetration may also be related to the nature and gauge of the spinal needle. Sensation experienced during dural puncture when performing a CSE technique is usually transient and mild and its frequency is reduced by injection of lignocaine 3 ml into the epidural space one minute before insertion of the spinal needle5. Although this complaint may be less frequent with smaller gauge pencil-point spinal needles, a consideration which awaits investigation, the dura mater covering the brain is especially sensitive to traction and stretch (21). Our findings that more patients in whom pencil-point spinal needles are inserted either respond to or acknowledge having experienced sensation at the moment of thecal penetration provides strong clinical evidence that the lumbar meninges are well supplied with sensory stretch receptors.

Despite more frequent responses to dural puncture with the 27 gauge pencil-point needle, we still favour this needle rather than alternative cutting-edge needles because dural puncture responses are usually transient and mild compared with the potentially more protracted and debilitating complication of PDPH, which is more likely from cutting-edge needles. However, to reduce the incidence of paraesthesia and dysaesthesia accompanying their use, we now routinely inject lignocaine through the epidural needle prior to 'needle through needle' insertion of the needle.

The limitations of our findings are that the study was conducted as a prospective, observational audit of the routine practice of multiple proceduralists and is not a randomised, double-blinded study. This means that other factors may have resulted in more responses in the pencil-point group. However, the findings suggest that these data warrant consideration when selecting a spinal needle, and that, pending a confirmatory formal investigation, the greater potential for dural puncture response associated with this pencil-point needle be recognised and communicated to patients when instituting CSE anaesthesia or analgesia.


The authors wish to thank Mrs Robyn Mitchell and Moira Priestnal-van den Berg for typographical assistance and Dr Tadgh Lynch (anaesthesia registrar, The Mayo General Hospital, Co. Mayo, Castlebar, Co. Mayo, Ireland) for academic assistance.


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(21.) Raskin NH, Peroutka SJ. Headache, including migraine and cluster headache. In: Braunwald E, Faua AS, Kasper DL, Hauser SL, Longo DL, Larry JJ, eds. Harrison's Principals and Practice of Internal Medicine 15th ed. New York: McGraw Hill, 2001: p. 70-79.

A. A. van den BERG *, S. GHATGE ([dagger]), G. ARMENDARIZ ([double dagger]), D. CORNELIUS ([double dagger]), S. WANG ([double dagger])

Department of Anesthesiology, University of Texas, Houston, Texas, United States of America

* M.B., Ch.B., F.F.A.R.C.S., E.C.F.M.G., Specialist Anaesthetist.

([dagger]) M.B., B.S., F.R.C.A., Consultant Anaesthetist, Department of Anaesthetics, University Hospital of North Staffordshire, Hartshill, Stoke on Trent, Staffordshire, England.

([double dagger]) M.D., Anesthesiology Resident.

Address for correspondence: Dr A.A. van den Berg, Department of Anaesthetics, Port Hedland Regional Hospital, Kingsmill Street, Port Hedland, WA. Email:

Accepted for publication on November 9, 2010.
Characteristics of patients undergoing lower uterine segment caesarean
section or labour analgesia (and combined) in whom pencil-point
((Whitacre) and cutting-edge (Quincke) spinal needles were used

 LUSCS (n=30)

 Pencil- Cutting- P value
 point edge

Patient numbers 18 (60%) 12 (40%) <0.001
Age, y 25 (6) 27 (9) NS
Weight, kg 82 (17) 85 (21) NS
Height, cm 162 (7) 164 (7) NS
ASA grade
 I 2 1 NS
 II 16 11 NS

 Labour analgesia (n=85)

 Pencil- Cutting- P value
 point edge

Patient numbers 59 (69%) 26 (31%) <0.0005
Age, y 25 (7) 24 (7) NS
Weight, kg 86 (20) 84 (19) NS
Height, cm 160 (8) 163 (7) NS
ASA grade
 I 5 4 NS
 II 54 22 NS

 Overall (n=115)

 Pencil- Cutting- P value
 point edge

Patient numbers 77 (67%) 38 (33%) <0.0005
Age, y 25 (7) 25 (7) NS
Weight, kg 85 (19) 85 (19) NS
Height, cm 170 (7) 164 (7) NS
ASA grade
 I 7 5 NS
 II 70 33 NS

LUSCS=lower uterine segment caesarean section, NS=non-significant,
ASA=American Society of Anesthesiologists. Values given as whole
numbers (percentages), or mean (standard deviation).

Numbers of patients undergoing lower uterine segment caesarean section
or labour analgesia (and combined) in whom pencil-point and cutting-
edge spinal needles were used, and who grimaced or involuntarily
moved, spontaneously vocalised or acknowledged feeling sensation at
the moment of dural puncture

 LUSCS (n=30)

 Pencil- Cutting- P value
 point edge

No. patients per test group 18 (60%) 12 (40%) <0.001

No. patients grimacing or 5 (28%) 0 (0%) <0.05

No. patients vocalising 2 (11%) 0 (0%) NS

No. patients acknowledging 0 (0%) 1 (8%) NS

Total number of responses 7 (39%) 1 (8%) NS

 Labour analgesia (n=85)

 Pencil- Cutting- P value
 point edge

No. patients per test group 59 (69%) 26 (31%) <0.0005

No. patients grimacing or 12 (20%) 2 (7%) <0.025

No. patients vocalising 2 (3%) 1 (4%) NS

No. patients acknowledging 3 (5%) 1 (4%) NS

Total number of responses 17 (29%) 4 (15%) NS

 Overall (n = 115)

 Pencil- Cutting- P value
 point edge

No. patients per test group 77 (67%) 38 (33%) <0.0005

No. patients grimacing or 17 (22%) 2 (5%) <0.025

No. patients vocalising 4 (5%) 1 (3%) NS

No. patients acknowledging 13 (17%) 3 (8%) NS

Total number of responses 34 (44%) 6 (16%) <0.005

LUSCS=lower uterine segment caesarean section, NS=non-significant.
Data given as patient numbers (n) and percentage (%). Anaesthesia and
Intensive Care, Vol. 39, No. 2, March 2011
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Article Details
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Author:van den Berg, A.A.; Ghatge, S.; Armendariz, G.; Cornelius, D.; Wang, S.
Publication:Anaesthesia and Intensive Care
Article Type:Report
Geographic Code:8NEWZ
Date:Mar 1, 2011
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