title: Does obesity preclude lumbar puncture with a standard spinal needle? The use of computed tomography to measure the skin to lumbar subarachnoid space distance in the general hospital population.
abstract: OBJECTIVE
  Failed lumbar puncture (LP) is a common indication for referral for radiologically guided LP. This study aims to evaluate what percentage of the hospital population would fail an LP using a standard 9-cm needle because of obesity and a skin to subarachnoid space distance greater than 9 cm.
  
  
  METHODS
  Images of 402 consecutive patients undergoing computed tomography of the abdomen and pelvis were reviewed. Skin to subarachnoid space distance was calculated using sagittal images. A survey was conducted among junior hospital doctors to assess their experience of performing lumbar puncture in obese patients.
  
  
  RESULTS
  Four hundred patients were included. Fifty-five patients (13.8 %) had a skin to subarachnoid space distance greater than 9 cm. Intra-abdominal fat, subcutaneous fat and abdominal girth correlated with distance between the skin and subarachnoid space. Among junior doctors, 68.3 % (n = 41) reported LP failure on an obese patient; 78.4 % (n = 47) were unaware of the existence of a longer needle and 13.3 % (n = 8) had experience using a longer needle.
  
  
  CONCLUSIONS
  A significant proportion of the hospital population will fail LP with a standard length spinal needle. Selecting a longer needle may be sufficient to successfully complete LP in obese patients.
  
  
  CONCLUSIONS
  • Lumbar puncture failure commonly leads to referral for an image-guided procedure • Standard lumbar puncture may fail in 13.8 % of patients due to obesity • 78.4 % of trainee doctors are unaware of the existence of longer spinal-needles • Using longer spinal needles may allow successful LP in obese patients.
authors.affiliation: Department of Radiology, Adelaide and Meath Hospitals incorporating the National Children's Hospital, Tallaght, Dublin, Ireland.
authors.forename: Darragh
authors.initials: D
authors.lastname: Halpenny
authors.forename: Katie
authors.initials: K
authors.lastname: O'Sullivan
authors.forename: John P
authors.initials: JP
authors.lastname: Burke
authors.forename: William C
authors.initials: WC
authors.lastname: Torreggiani
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006769:Hospitals, General; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging; D008161:Lumbosacral Region / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009339:Needles / Q000592:standards*; D009765:Obesity / Q000000981:diagnostic imaging*; D015642:Radiology, Interventional / Q000379:methods; D012867:Skin / Q000000981:diagnostic imaging; D013129:Spinal Puncture / Q000295:instrumentation*; D013346:Subarachnoid Space / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*