Cauda Equina Syndrome: Poor Recovery Prognosis Despite Early Treatment

Alexia Planty-Bonjour, MD; Gaelle Kerdiles, MD; Patrick François, MD, PhD; Christophe Destrieux, MD, PhD; Stephane Velut, MD, PhD; Ilyess Zemmoura, MD, PhD; Ann-Rose Cook, MD; Louis-Marie Terrier, MD; Aymeric Amelot, MD, PhD


Spine. 2022;47(2):105-113. 

In This Article


The definition of CES remains unclear: like Gleave and Macfarlane[10] who stressed the importance of categorizing CES into incomplete/complete with urinary resection, other authors studied CES definitions and entities. Ultimately, the weakness in CES's definition has been recently demonstrated in a systematic review of the literature.[2] Indeed, within 61 identified studies, 20 (32.8%) did not define CES, and the rest (41, 67.2%) did so with significant heterogeneity.

Furthermore, in their recent meta-analyses, Srikandarajah et al.[20] highlighted that there existed a significant heterogeneity in the outcomes for patients who had undergone surgery for CES. Moreover, in the literature, no data to this day has established a simple clinical definition of CES, nor prognostic factors for functional outcomes. Due to the heterogeneity of this data, it appears impossible to analyze and edit guidelines for CES management support.

Finally, whether within a department or according to a practitioner there is no consensual definition of CES-I/-C. Thus, all the data collected according to these two pathological subgroups remain unclear with a risk of misdiagnosis to one category or the other. Given these definition weaknesses in qualifying complete/incomplete it seems absurd to separate these two symptom entities and determine different prognosis factors accordingly.

The young age of patients and the high percentage of sequelae makes it a serious mutilating and disabling pathology.[2] Sequalae can be extremely disabling with a significant impact on quality of life; a previously healthy patient may become incontinent (fecal and/or urinary) and lose penile and vaginal sensation, have a major disturbance of sexual function, with a motor deficit and sometimes a sensitive deficit or sciatalgia.[6,11,12,21] Moreover, CES is a surgical emergency, and few authors have demonstrated the need of earlier surgery to limit sequelae.[10,14,22]

Surgical Decompression Timing

Several studies have attempted to define intervention timing following CES onset based on functional outcomes. Historically, following their meta-analyses, Ahn et al.[15] proposed the concept of "within 48 hours" as a guideline for improved outcomes in these patients. However, this dictum has been widely debated.

In resemblance to our findings, some reviews depicted no significant difference in outcomes between early (before 48 h) versus delayed (>48 h) decompression[7,11,23] whilst others argued that early intervention in CES, regardless of the subtype (complete or incomplete), had higher likelihood of improved inpatient outcomes.[13] The odds of getting better were higher, however, this was shown for incomplete CES. In a systematic review and meta-analysis, Chau et al.[7] revisited the impact of timing to intervention on outcomes. They acknowledged the significant "discordance" in the literature relating to an emergency intervention favoring improved outcomes, but concluded on the lack of distinct evidence supporting the 48-hour dictum. DeLong et al.[24] demonstrated a significant improvement of urinary symptoms in patients receiving an intervention within 24 hours in comparison with 72 hours.

To illustrate this 48-hours-dogma, Daniels et al. reviewed the Lexis Nexis Academic Database, which offers information on US Supreme Court decisions from 1983 to 2010. Fifteen lawsuits were identified, and an intervention following a 48-hour time point from symptom onset was associated with an adverse legal decision against the treating surgeon.[25]

To clarify this question, Delamarter et al.[26] explored the relationship between the timing of surgery and the extent of neurologic recovery thanks to a dog-CES experimental model. After induction of 75% of circumferential constriction of the cauda equine, they determined functional neurologic outcomes in recovery for their different subgroups (decompressed immediately or at 1-, 6-, and 24-h or 1-wk intervals). They identified that despite the initial fast improvement in the early-decompression groups, all dogs equally recovered and regained locomotion and bladder function at 6-week FU.[26] Glennie et al.[27] confirmed the recovery of motor function despite the decompression time on rat models, but suggested that an early decompression could improve bladder recovery. The major bias of this previous study was the scale of time-decompression: 1 or 4 hours after compression which is much shorter than the real time of symptom evolution.[27] By cons, it is well established that in patients with CES secondary to trauma, timing to intervention is associated with little or minimal benefit for inpatient outcomes.[13]

The benefit/role of surgery and the prognosis factors of recovery are essentially for patient information about sequelae and postoperative rehabilitation care.[10]

A likely cause of the discordance in findings of all these studies could be the discrepancy between clinical examination, patient's subjective feelings and the evaluation scales for intimate impairments such as urinary, bowel, and sexual symptoms, especially for women.[21,28] In many studies, urinary and bowel symptoms are only evaluated by score questionnaires but not objective examinations. Recent studies show that a bladder scan measuring post-void residual volume improves the diagnostic of CES with a sensitivity of 94% and predictive negative value at 98.7% if post-void residual volume is > 200 mL. These simple examinations could be very useful in enhancing diagnosis precision and for patient health care.[29,30]

Furthermore, we suggest that many patients ignored their first sign of CES, and therefore consulted too late, once CES was installed. Hence, many symptoms progressed quietly and were unnoticed by patients. Thus, in our study, the median evolution time of CES symptoms was 4 days, a finding confirmed by König et al. who identified a median CES evolution time of 10 days.[31–33]

Genito-urinary and Bowel Recovery

In our series, at the end of FU, 47.5%, 67.8%, and 35.6% kept urinary, genital, and bowel dysfunctions respectively. Our data was comparable with that found by Korse et al. who reported at the final FU for 75 patients with CES: 36% with urinary dysfunctions, 52% sexual dysfunctions, and 41% bowel dysfunctions.[6,28,34] Unfortunately, in our series, data on erectile or vaginal disorders could not be collected. In another study, Hazelwood et al.[35] reported for their 46 patients a higher percentage of urinary sequelae: 76%, 39% genital dysfunction, and 43% bowel dysfunction at 43 months of FU. McCarthy et al.[11] thanks to an important FU of 5 years demonstrated 43% with urinary dysfunction, 30% sexual dysfunction, and 57% bowel dysfunction. Finally, our data are comparable with those reported in previous smaller series.

We found that anal incontinence represented a prognosis factor in keeping genital and sphincter sequelae. This factor was identified in other studies. Moreover, urinary catheterization is also reported as a prognosis factor, but we did not collect this data.[6,11,36] In our study, as evocated by Korse et al.[28] dysuria was a risk factor in keeping genital and sphincter deficits, but it was not significant in multivariate analysis.

Complete saddle anesthesia was reported by two studies as a risk factor of sphincter sequels, but we did not demonstrate a significant difference, maybe due to the absence of difference in our criteria according to partial and complete saddle anesthesia.[7]

Motor and Sensitive Recovery

There are very few studies about motor and sensitive recovery after CES, probably because it was not clearly defined in the syndrome and moreover, the studies focused on urinary and bowel symptoms. Despite experimental studies demonstrating complete motor recovery at FU,[26,27] a large portion of patients kept a motor deficit: 32% in our study against respectively 52%, 20%, and 48% for McCarthy et al., Olivero et al., and König et al. studies.[11,37] The differences in results can be explained by numbers of patients (140 for our series, 56 for McCarthy's, 31 for Olivero's, and 73 for Konig), severity/percentage of initial motor deficit, and length of FU (15 mo to 5 yrs). In comparison with series that studied an isolated motor deficit secondary to a herniated lumbar disc, motor sequelae varied from 36% to 75% of patients, which is higher than rates found for CES.[38] In our series, most of the motor deficits were light (Levels 3–4 for 74% of patients) and were described as a better prognosis for recovery.[38] Thereby, we identified that a bilateral motor deficit and an initial deep deficit (0–2) were risk factors in keeping motor sequelae. Furthermore, in CES we wondered if the first appearance of a genito-sphincterian dysfunction allowed an earlier diagnosis, thus limiting motor impairment. Concerning sensory deficit, it was rarely studied: in our series, 18% of patients kept their sensitive deficit against 46% in the McCarthy et al.[11] study. These physical examinations and evaluations remain very subjective as highlighted by Suri et al.[39]


In our study, 31% of patients could return to work after CES. In others studies, percentages were better (51%)[35] and (70%).[36] Cauda equina syndrome is a disabling condition, rates in returning to work are lower than those found for a simple herniated lumbar disk pathology where 80% of patients can go back to work at 3 months.[40] CES significantly impacts socioeconomic costs, with important additional funding. Implicitly, final motor and sphincter dysfunctions were identified as risk factors of not being able to return to work. We did not identify other studies, which dealt with the prognosis factor of going back to work: however, it seems to be very important in view of the socioeconomic cost of this pathology.

In the United Kingdom and United States, CES sequalae is one of the major causes of litigation due to the resulting disabilities, invalidity, handicap, and the necessity to cease work.[2,41] Likewise, Gardner et al. reviewed the database of the Medical Protection Society in the United Kingdom. A 5-year analysis revealed that the mean payment per CES litigation amounted to £117,331 (maximum recorded settlement being £584,000–£20,100,077).[42,43]