Sinha et al.’s [1] case report raised several interesting points. Firstly, inadvertent dural puncture with a Touhy needle does not always result in immediate CSF leak and this may lead to significant morbidity [2-3].  As shown by Hollway and Telford, in a series of 29 deliberate dural punctures in non-obstetric patients, spontaneous CSF leak occurred in only 18 cases. In others, the needle had to be rotated or aspirated in order to produce CSF.

As  stated in the article, between 16% and 33% of dural punctures are unrecognised [1]. In our hospital, we audited the incidence of post dural puncture headache (PDPH) in patients having an epidural using a 16G Touhy needle over a 14-year period. Of the 256 patients with PDPH, 33% were unrecognised at the time of the procedure.

Detection of unrecognised dural puncture should be based on symptoms. We feel that there should be a higher index of suspicion of dural puncture in those patients where there have been repeated attempts at epidural insertion. We agree that all patients should be followed up in hospital before discharge to the community, even following a failed procedure.

Postural headache remains the most common symptom of inadvertent dural puncture. However, morbidity following dural puncture may not be limited to headache. Important clinical features that may co-exist include depression, vestibular (e.g. nausea and vomiting), cochlear (e.g. low frequency hearing loss and tinnitus) and ocular symptoms (photophobia) [3].

In addition, two other tests may be used to confirm a PDPH: Gutsche’s test, where manual pressure applied to the right upper quadrant of the abdomen is used to demonstrate a reduction in the severity of the headache; and pure tone audiometry, which is used to detect a low frequency hearing loss [4-6]. In our department, we performed a study involving a series of 118 patients (in press). We found that Gutsche’s test was 73% sensitive, while audiometry and resolution of low frequency hearing loss after epidural blood patch was 100% sensitive in detecting the PDPH syndrome. These two tests may be useful adjuncts when the diagnosis is unclear.

R Kaur, A Barron, S Gowrie-Mahon

Lister Hospital

Stevenage, UK

Email: shan.gowrie-mohan@nhs.net

1. Sinha A, Petkov S, Meldrum D. Unrecognised dural puncture resulting in subdural hygroma and cortical vein thrombosis.

   Anaesthesia 2010; 65: 70–73.

2. Hollway TE, Telford RJ. Observations on deliberate dural puncture with a Touhy needle: depth measurements. Anaesthesia 1991; 

    46: 722-24. 

3. Candido KD, Stevens RA. Post-dural puncture headache: pathophysiology, prevention and treatment. Best Practice & Research    

    Clinical Anaesthesiology 2003; 17: 451-69. 

4. Gutsche BB. Lumbar epidural analgesia in obstetrics: taps and patches. In:Reynolds F, 9ed. Epidural and spinal blockade in 

    obstetrics. London: Balliere Tindall, 1990: 95-106. 

5. Lybecker H, Andersen T, Helbo-Hansen. The effect of epidural blood patch on hearing loss in patients with severe postdural 

     puncture headache. Journal of clinical anaesthesia 1995; 7: 457-464. 

6. Powell E, Gowrie-Mohan S, Fortescue C, Rajamanicam R. Audiometric changes after post dural puncture headache and epidural 

    blood patch. International Journal of Obstetric Anaesthesia 2004; 13: S15.