Reply to the letter to the editor of N. V. Todd concerning “Cauda Equina Syndrome treated by surgical decompression: the influence of timing on surgical outcome” by A. Qureshi, P. Sell (2007) Eur Spine J 16:2143–2151

Abstract

The author of this letter is correct in stating that our paper is the only prospective study. It also includes validated outcome measures relevant to the condition. The reason for embarking upon the study was to attempt to dispel some of the myths that have evolved and become established in surgical and medico-legal thinking. These have been based upon experiential evidence and narrative reviews that are sometimes represented as a meta-analysis. Quality systematic meta-analysis can really occur only with level one or occasionally with good level two evidence. The reviews by Ahn and Todd contain level three and level four evidences. The debate regarding timing is particular to those indulging themselves in medical negligence activity. All spinal specialists recognise the need for urgent expeditious management and perceived ‘time thresholds’ for outcome are artificial. Mr Todds’ suggestions of principles are his own views. The concept that once the bladder is paralysed a spinal decompression can be carried out as a routine, is not accepted by this author or supported by any evidence. It is a stance that cannot be in the best interests of patient care. The limited available evidence suggests that age and incontinence at presentation are the main determinants of outcome. However, despite age over 55 and incontinence at presentation half the patients in this group in our study recovered bladder function with surgery. Half did not. Sub group analysis is not valid with such small numbers, if it was, we would have undertaken it. The partitioning of an analogue spectrum of a disorder into ‘digital’ compartments of convenience displays a lack of practical wisdom and common sense. In our study, we found both clinicians and patients were unable to be precise about the moment of transition from incomplete cauda equine syndrome to cauda equine syndrome with neurogenic retention of urine. Verifiable logic suggests that from an empty bladder to a full bladder with a urine production rate of between 40 and 100 mls per hour, could result in a significant variance of timing. Factors relating to neurogenic retention of urine are multiple. The precise definition of its onset is elusive. Mr Todd would be welcome to repeat our study, perhaps obtaining larger numbers. Yours sincerely, Mr Philip Sell