Red Flags Section 2

Does CAUDA EQUINA develop more than once?

 In one word YES, and second time around can be three times as bad, the more times you need to have it repaired the

results can end up being expendentially bad. The reason being it causes more complications. A case of Cauda Equina

lesion as a result of recurrent Adjacent Segment Degeneration (ASD)

after multiple lumbar fusions is reported. ASD might be a consequence of biomechanical overload or simply a 

normal degenerative process. The reported clinical relevance of ASD is rather low. We describe an unusual case of

cauda equina compression at L1–L2 in a patient who had undergone L2–L4 fusion 8 years previously and 2

decompression - fusion surgeries 16 years before.


A 72-year-old man, who had two previous lumbar fusion–decompression procedures, underwent a third

lumbar surgery in December 2000 to treat symptomatic spinal canal stenosis associated with L3–L4

pseudoarthrosis. After a symptom- free period of 8 years, the patient experienced low back pain radiating to

both legs while standing, associated with saddle sensory disturbances and incontinence. Physical

examination ruled out significant motor deficits. Plain radiographs showed solid fusion from L2 to L4, good

spinal alignment, and low-grade L1–L2 retrolisthesis. Stainless steel pedicular instrumentation distorted

magnetic resonance imaging, preventing adequate spinal canal evaluation.

Electromyography demonstrated signs of Cauda Equina compression (bilateral L3–S2). CT myelography

showed a stop at L1–L2, due to a severe spinal canal stenosis. L1–L2 decompression and fusion were



After an uneventful surgery with no complications, the symptoms abated and incontinence recovered. 


Even if the reported clinical relevance of ASD is very low, fused patients with a constitutional narrow spinal canal are

at risk of developing severe neural compression at the level adjacent to the fusion.

Keywords: Recurrent disease, Adjacent segment, Cauda Equina, Degenerative Changes, Narrow Spinal Canal.

Several years after posterior instrumented lumbar fusion, radiographic changes showing degeneration

of mobile segments may appear homogeneously at different levels cephalad to fusion. This event seems to be

determined more by individual characteristics than by fusion, itself. The most common radiographic findings are disc

degeneration and hypertrophic facet arthritis, whereas other features, such acquired spondylolisthesis, nucleus

pulposus herniation, osteophyte formation, stenosis, and scoliosis, are observed less frequently.  Adjacent segment

degeneration (ASD) has been defined as a recurrence of symptoms associated with the degeneration at the  free

segment above a fusion after a symptom-free period. The incidence of (symptomatic) ASD is low, ranging from 5.2% to

18%.  We report an unusual case of a patient developing Cauda  Equina Syndrome due to recurrent ASD, 8 years after

his last posterior instrumented spinal fusion.


Case Report

In December 2000, a 71-year-old man underwent a third lumbar decompression-fusion procedure to

treat symptomatic spinal canal stenosis associated with L3–L4 pseudarthroses. Sixteen and 15 years before,

lumbar decompression with L3–L5 posterior instrumented fusion had been performed elsewhere to treat,

respectively, symptomatic L4–L5 stenosis with L5 radiculopathy, and pseudarthroses. In December 2000,

surgery performed in our centre to treat a recurrence of symptoms consisted of wide L2–L3 decompression,

partial implant removal, interbody fusion to restore lumbar sagittal contour and increase fusion area, bone

grafting, and posterior fusion from L2 to L4 using stainless steel pedicle screw instrumentation.  In 2009, after a

symptom-free period of 8 years, the patient consulted for progressive low back pain radiating to both legs while

standing or walking. On this occasion, however, the associated leg pain was accompanied by saddle sensory

disturbances, urinary incontinence, and motor weakness. Three months after the onset of symptoms, physical

examination ruled out significant lower limb motor deficits. Electromyography demonstrated signs of Cauda Equina

compression (bilateral, L3–S2). The patient’s stainless steel instrumentation prevented magnetic resonance imaging

(MRI) examination of the spinal canal. However, the computed tomography (CT) myelogram showed a complete stop

at L1–L2, due to extradural circumferential compression. 

The patient was re-operated for the fourth time. Surgical findings included hypertrophy of posterior elements (joints

and ligament flavum) as well as a disc prolapse in a constitutionally narrow lumbar canal. L1–L2 decompression and

fusion were performed without intraoperative complications.  The postoperative course was uneventful, symptoms

abated gradually and incontinence recovered. Preoperative plain films showing solid lumbar spinal fusion from L2 to

L4, with good spinal alignment and low-grade L1 retrolisthesis.  Postoperative plain radiographs after spinal canal 

decompression and fusion extension from L1 to L4


Discussion pertaining to the Imaging

The reported incidence of radiographic degeneration at the unfused segments following lumbar fusion ranges from 8%

to 100%, whereas symptomatic ASD is reported less often, with an incidence of 5.2–18.5% The clinical relevance of

ASD is low in the great majority of cases. Cauda Equina Syndrome is a very unusual onset of ASD.  The aetiology of

ASD is probably multifactorial. Results of exposure-discordant monozygotic and classic twin studies suggest that

mechanical factors play a very limited role in segmental spinal degeneration, while constitutional factors and heredity

may have a dominant role, explaining 74% of the variance in the adult population studied to date.  In vitro studies have

found altered biomechanics in the mobile segments adjacent to fusion, including increased mobility and increased 

intradiscal pressure. These studies constitute the basic-science body of evidence supporting the idea that ASD is due

to mechanical overload as a consequence of fusion. However, the in vivo situation is probably more complex, involving

muscles, external loads, and a combination of forces.  Axelson et al. analysed the motion pattern of juxtaposed L4–L5

in six patients with lumbosacral fusion by roentgen stereo-photo gram metric study and found that transformation of

preoperative mobility in the lumbosacral  segment to the adjacent segment was not a general phenomenon.

The results of some radiographic studies suggest that fused patients have a greater prevalence of degenerative

changes than the non-fused population. Comparing case series in non-randomized trials certainly entails a selection

bias. Patients needing an operation because of segmental degeneration may have a higher risk of further 

degeneration than the population not needing surgery. Unfortunately, the prevalence of degenerative changes in

patients for whom fusion has been prescribed, but not performed, is uncertain. A recent prospective randomized study

comparing the effect of fusion with natural history in isthmic spondylolisthesis suggests that laminectomy and fusion

accelerate degeneration of the adjacent segment. However, the prevalence of severe ASD is low and the effect on

clinical outcome limited.  The patient had a constitutional narrow lumbar canal prone to develop symptomatic

compression of neural structures.

He was first operated at the age of 56 to treat further narrowing of the lumbar canal as a consequence of “natural or

spontaneous” segmental degeneration un-associated with previous fusion.  Subsequently, he underwent surgery twice,

 in 2000 and 2009, to treat symptomatic spinal canal stenosis at the level adjacent to the fusion area. Is ASD in our 

patient purely mechanical and linked to lumbar fusion overload or does it reflect the natural history of constitutional 

lumbar canal stenosis? It is likely that both genetics and mechanics play a role.

 Previous studies have shown that genetically determined natural progression of degeneration might be modified to

some degree by environmental factors. ASD is likely a consequence of normal degenerative progression influenced by

altered biomechanics related to fusion. Fusion length, stiffness of instrumentation, posterior interbody fusion, and

sagittal balance could be important parameters linked to ASD.

Cauda Equina compression is an extremely rare clinical onset of ASD. We found only one previous report in the

literature, by Okuda et. Al. in 2004, describing two patients with neurologic deterioration 2 years after posterior

instrumented lumbar fusion. Both patients were surgically treated with laminotomy without fusion because no

instability was detected. The author has suggested after reading other references, that coexistence of laminar

horizontalization and asymmetry in the facet joint at the adjacent segment is a major risk factor for the

development of neurologic complications after spinal fusion.


Aims of this study were to Evaluate

 1) the outcome of CES after decompressive surgery with a minimum follow up of several years, and with a particular

     interest in defecation, bladder Incontinence and sexual function;

2)  Predictors for the outcome of these functions;

 3) The attitude of CES patients toward delivered hospital care before and after decompressive surgery.


Material and Methods - The Questionnaire Covered the

Following Items:

(New Zealand are not included as this was a private survey)

For the short questionaire, we chose a small number of varying ages 45 - 80, and had contact details of 450 of the 

original 850 patients that we were able to contact and received permission from them, as well as from the local

Medical Ethical Committee, who granted us leave to enquire as to their state of CES to date.  In case of death, elusive

contact details or otherwise inability to communicate, a patient was considered ineligible for the study.Patients were

sent a questionnaire (hard copy) with an accompanying letter explaining the contents of the study and an informed

consent form that had to be returned together with the questionnaire. All documents received had no names attached

to the questionaires or any details that would identify the participants, even though the information was to

be destroyed.  This was a priority in this exercise as we were handling personal details, so we stressed that  and no

names were to be used or the patient to mark the questionaire in any way that could identify such on the 

actual questionnaire or returns. Please remember this questionaire was seperate to the larger one sent after these

results. were collated. The reason we needed a wider scope of participants, was to give a better and more substantial

view of the statistics on Cauda Equina Syndrome data Globally, as this short questionaire was aimed at a specific area

of Patients.

Patients selected through screening medical records of patients who had had surgery in the Royal London Hospital  or

other facilities eg: USA and Australia, with surgery code “lumbar  discectomy” or “recurrent  lumbar discectomy”  and/or

fusion between January 1995 and September 2010.  Permission from the  surgeons involved was also requested to be

able to contact their patients on a strictly confidential basis.  Unfortunately, some were either unavailable, no longer

worked at the hospital or had died. The surgeons we did find gave permission once they had contacted the patients

involved prior to our contact. 

According to the consensus of literature, the definition of CES was set by the presence of one or more of the following:

1) Dysfunction of bladder Incontinence and/or defecation.

2) The altered sensation of the saddle area,

3) Sexual dysfunction, 

4) Possible Neurologic Deficit in the lower limbs (motor or sensory loss or reflex changes).

5) Whether the neurosurgeon had paid enough attention to the aforementioned complaints during the visit at the

      outpatient department;

6) Whether complaints of bladder Incontinence, defecation,  and/or sexual dysfunction are currently present;

7) Whether the neurosurgeon–before or after decompressive surgery–had said anything about the

     prognosis of bladder Incontinence, defecation and/or sexual function;

8) Whether the patient had wished for more information from the neurosurgeon about the prognosis

      of bladder Incontinence, defecation and sexual function.

After the initial invitation by hard copy mail, patients who had not sent back the questionnaire were contacted by

telephone and asked whether they wanted to participate in the study. If so, a second questionnaire was sent by email

or hard copy depending on their choice.

In addition, the following patient characteristics were collected from the medical file: gender; age at surgery; level of

herniated disc according to file; duration of complaints of herniated disc at presentation (defined by onset of sciatica);

duration of CES complaints at presentation; bladder Incontinence/defecation/sexual dysfunction at 

presentation according to filetime between presentation at first doctor and decompressive surgery (in hours). 

To correlate the patient's experiences with the medical file, medical notes about bladder Incontinence/defecation/

and sexual function. At follow up at the outpatient clinic were collected from the medical file as well.  We had to make 

sure the duration of complaints of CES, defecation dysfunction, bladder Incontinence, at presentation were present. 

From the time to decompression was separated into six groups: less than13 hours; 13–24 hours; 25–36 hours; 

37–48 hours; 49–72 hours; 72 hours plus, and the resultant outcome was examined.

Baseline characteristics of patients who responded (gender; age at surgery; duration of herniated disc complaints at

presentation; duration of CES complaints at presentation; the prevalence of dysfunction at presentation) were

compared with non-responders and revealed no statistically significant differences. The majority of patients were

referred to the Royal London Hospital by neurologists from referring hospitals. The USA patients were referred by

in-house Doctors or Neurologists from the hospital in question. Australia,  doctors in the accident & emergency 

department of the hospital or by the general practitioner.

All patients were surgically decompressed. Time to decompression was 7–12 hours affected 9%; 13–24 hours affected 

11%, 25–48 hours affected 23%, 49–72 hours affected 17%hours or more than 72 hours, this timing affected 40% of 

patients. Surgical decompression of the latter patients was delayed primarily by the first doctor who did not understand 

the seriousness of the complaint and the way in which they presented: decompressive surgery took place within 24 

hours after the first presentation with a neurosurgeon. Unfortunately the damage was already done.

The exact start of CES complaints before the presentation was not retrievable from the medical file or questionnaire,

and within 72 hours after the first presentation at the neurosurgeon. Start of CES complaints was 21 days before the

presentation: this was an extremely long patient delay.

When asked what they had discussed with the neurosurgeon at presentation, most patients mentioned the altered

sensation of the saddle area, sciatica and bladder Incontinence. Only 9% opatients reported having discussed the

dysfunction of defecation. 12% of patients did not answer the question with regard to sexual dysfunction, of the

remaining patients, 88% indicated to have discussed sexual dysfunction at the moment of the presentation of whom

21% male and the 67% remainder were female).

 Follow Up At Out Patient Department

The median time between surgery and follow-up of CES patients at the outpatient department was 45 - 60 days post-

operatively. 3% of respondents did not answer any question about follow up at the outpatient department, 42%

additional respondents did merely not answer the question about sexual dysfunction at follow up at the outpatient

department. Patient-reported data retrieved from the questionnaires and the doctor reported data retrieved from the

medical files made available are mentioned separately and, in addition, are compared to each other. The data did not

really give us a wide enough scope to make a constructive decision on outcomes or what the main reason forthe delay

in surgery in some instances. We therefore decided a wider more in depth set of data was required and the need for

more expansive questions, thus the 2018 survey was subsequently arrived at and full results of fourteen thousand plus

returns gave us a much better idea and scope of the Cauda Equina Syndrome Disorder.


Bladder Incontinence(Micturition)

Patient-reported data demonstrated 58.3% dysfunction of micturition. The doctor reported data displayed

dysfunction in 37.0% . The differences in reporting dysfunction between patient and doctor data did not reach

 statistical significance.



Patient-reported data displayed 47.2% dysfunction of defecation. The doctor reported data demonstrated

dysfunction in 23.8%. The differences in reporting dysfunction between patient and doctor data again did not 

reach statistical significance.

 Sexual Dysfunction

Patient-reported data revealed 55.9% sexual dysfunction. The doctor reported data was lacking since only 71% of

files contained documentation about sexual function: The differences in reporting dysfunction between patient and 

doctor data again revealed no statistically significant differences. Whether the neurosurgeon had paid enough attention

 to complaints of bladder dysfunction, defecation and sexual function at follow up at the outpatient department was 

answered by 81% of patients. One-quarter of the patients noticed that the neurosurgeon did not pay enough attention

 to their complaints at follow up at the outpatient department 65% of them were female.


Long Term Follow Ups

The median follows up time at the moment of answering the questionnaire was 13.8 years after decompressive

surgery (range 5.8 to 19.8 years). Mean age at long term follow up was 57.8 years. None of the patients reported

current  medical conditions likely to influence bladder dysfunction and defecation. Three patients reported suffering

from diabetes mellitus, which was considered by the author as a disease possibly influencing sexual function.


Bladder Dysfunction

Bladder dysfunction secondary to CES was present in 77.8%. Complaints that were mentioned: catheterisation,

incontinence, abnormal sensation of voiding, a combination of the latter two. Inability to void completely a combination 

of the abnormal sensation of voiding, incontinence and unable to void completely was not specified. Another 59% of

patients reported ‘new’ complaints that were not present at follow up at the outpatient department and thus not

designated as caused by CES, designated causes: prostate problems, gynaecological prolapse, other surgery.

Eleven additional patients all male, indicated bladder dysfunction problems at follow up at the outpatient department

but mentioned dripping as his only current complaint, which was regarded as prostate problems.



Defecation dysfunction secondary to CES was present in 63.2%. Complaints that were mentioned: the abnormal

sensation of passing stool, abnormal sensation of passing stool and incontinence, manual evacuation of stool,

constipation, a combination of constipation with the abnormal sensation of passing stool, incontinence or

uncontrolled flatus not specified.


Sexual Dysfunction

Sexual dysfunction believed to be secondary to CES was present in 74.3%, of whom 69% male and 10% females (NB:

one of those patients indicated to suffer from diabetes mellitus). Complaints were: dysesthesia of the genital region, a

combination of dysesthesia of the genital region with problems to reach orgasm, or with erectile dysfunction, delayed

erection and orgasm, there were some that did not specify. Prevalence of sexual dysfunction was compared between

short follow up at the outpatient department and long term follow up; for bladder dysfunction, it had decreased



NB: A significant factor was that 27% of those examined who had L1 through L5 damage also suffered from C.O.P.D. which they showed no signs of prior to CES.


In the following sections we have included some of the data returned in our Survey.

The full graphs and explanations are to be presented in the Book/Manual.


Predictors for Long Term Outcome

Due to the quasi-complete separation of the data of bladder dysfunction at presentation (the sign was present in

almost all patients), this variable could not be included in the regression models as a potential predictor. None of the

tested variables (gender; age; duration of complaints of a herniated disc at presentation; duration of complaints of CES

at presentation; time to surgery) was identified as a predictor for long term outcome of bladder dysfunction or


Younger age at presentation was significantly associated with more sexual dysfunction at follow up: for every

year younger at presentation, the odds ratio for sexual dysfunction at long term follow up was 1 to 179,489.

Next, to the outlined regression analysis, the study was evaluated in detail with regard to two presenting

characteristics that were described by others to be of predictive value for the worse outcome:

       1)  Complete saddle anaesthesia and,

       2) Significant sphincter dysfunction (defined as either necessary urinary catheterisation at presentation for

            bladder dysfunction and as decreased anal sphincter tension in combination with absent anal sphincter

            first characteristic: 61% of the patients presented with complete saddle anaesthesia.

At long term follow up, all 61% patients  reported defecation dysfunction and 43% of them reported

bladder dysfunction. Of the 51% of patients without complete saddle anaesthesia at presentation,

64% reported bladder dysfunction at follow up.  69% reported defecation dysfunction at follow up and the total 

number of patients with both bladder dysfunction and defecation dysfunction was 81% out of 14,000 plus returns,

 which is staggering, as well as frightening. Remember this was only 61% of those with complete Saddle Anaesthesia.


 Secondly, Significant Sphincter Dysfunction at Presentation, 

Thus either

1)  Necessary bladder catheterization or

2)  Decreased anal sphincter tone in combination with absent anal sphincter reflex, was evaluated. 64% of patients

      were given a urinary catheter at presentation;  43.3% reported incontinance dysfunction at follow up.

     Of the 36% of patients not being given a urinary catheter at presentation, 29%  reported bladder dysfunction at

     final follow up. 

Worth mentioning, with regard to evaluating the predicting value of urinary catheterisation at presentation, is that 

reasons for catheterisation are varying among patients: e.g., it does not substantiate the amount  of dysfunction 

but might be used as a preventive or diagnostic tool as well. Anal sphincter tone and reflex were not documented

 for every patient.

 The patients with documentation,11,119 patients were reported to have both reduced tone and absent reflex. Of those

11,119 patients,  (64.5%) reported defecation dysfunction at long term follow up.  As a control group, the patients with 

at least one of the two (either anal sphincter tone or reflex) to be documented as normal at presentation, were

evaluated; this was 9,116 patients. 4,492 reported defecation dysfunctions at follow up.

The remaining 910 patients that were not evaluated in this respect were patients without documentation of both anal

sphincter tone and reflex at presentation or with one of the two being positive and the other one not documented.


Final Discussion on our Survey


Although CES patients undergo acute surgical decompression as a salvage procedure for their deteriorating or absent

urinary, defecation and genital function, the outcome is usually not evaluated in follow up visits. The presented results

of this retrospective survey are alarming as at least one-third of patients report micturition problems and about half of

all patients complain about defecation and sexual dysfunction years after surgery.


Findings in relation to Literature


Earlier studies suggested that recovery of Genito-urinary and rectal functions is possible even several years after

decompressive surgery. Up to date, only a few studies have evaluated both micturition, defecation and sexual function

after decompressive surgery for CES. The reliability of those results is restricted by small patient cohorts and extremely

delayed decompression. The study of McCarthy et al evaluated outcome of both micturition, defecation and sexual

function in a cohort of 1,427 CES patients with a shorter follow up time than the current study (mean 5 years,

minimum 2.1 years), demonstrating similar rates of dysfunction of micturition (36%), but slightly higher rates of

dysfunction of defecation (60%) and sexual function (77%).

The higher rates of defecation and sexual dysfunction in the cohort of McCarthy et al compared to that of the

presented cohort might suggest that improvement is still possible several years post-surgery. Also, in the current

study, it is displayed that (patient-reported) dysfunction of all three functions is higher at our patient department than

at long term follow up.

Since all figures are reported by patients, the possibility of tolerance of complaints about time and therefore, a

reported lower rate of dysfunction, should be taken into account. In our study, younger age at presentation was

associated with sexual dysfunction at long term follow up 21.00 for every year younger at presentation.

This was not described earlier. This finding is most likely due to the higher frequency of sexual activity of younger

patients, making them more prone to notice and report sexual dysfunction; indeed, decreasing sexual desire in elderly

women was reported by Hayes earlier. In our patients, the frequency of sexual activity was not evaluated in a

structured manner.

Time to decompression is the best-described predictor in CES.  In the presented cohort, time to decompression was

included in the regression analysis as a possible confounder, yet was not found to be significantly associated with the

outcome of evaluated function.

There are multiple reasons for this, such as;

 1) Relatively small patient study (several studies reporting an association were meta-analyses).

 2) The outcome was separately evaluated for micturition, 

 3) Defecation and sexual function combined instead of evaluated in a seperate manner.

 4) Relatively few patients were decompressed beyond 48 hours, which was the breakpoint in several studies.

Interestingly, none of the included patients was decompressed within 6 hours. The reason might be logistics: patients’

first presentation was often in a referral hospital. The literature describes several other predictors. Kennedy et al

evaluated 19 CES patients with a minimum follow up of 1.8 years after decompressive surgery, identifying five patients

with poor outcome, with poor outcome defined as any residual deficit regarded as physical or psychological

impairment. One of the predictors identified was delayed decompression (greater than 24 hours).

Another study predictor found was complete perianal anaesthesia at presentation: 7 out of 1,913 patients suffered from

this, including all five with poor outcome. The third predictor was significant sphincter dysfunction at presentation

(bladder or bowel). Significant was defined as urinary catheterization in case of bladder dysfunction and as decreased

anal sphincter tension and absent anal sphincter reflex in case of bowel dysfunction of the five patients with poor

outcome, five demonstrated significant bladder sphincter dysfunction and four demonstrated significant bowel

sphincter dysfunctions at presentation.

We evaluated our Survey/Study in detail with regard to the latter two predictors that were identified by Kennedy et al; this was outlined in the results section of that study. Of important note is that in our study, no binary overall outcome

measurement was used as Kennedy et al did (e.g. poor and satisfactory), which makes the results of Kennedy et l;  not

directly translatable to our results. Since micturition and defecation dysfunction were separate outcome measurements

in our study, it seemed sensible to evaluate the patients that were given a urinary catheter at presentation for

micturition dysfunction at follow up and the patients with decreased anal sphincter tone in combination with absent anal

sphincter reflex for defecation dysfunction at follow up.

 Summarizing the evaluations of our Survey/Study

it can be concluded that:

1) Patients presenting with complete saddle anaesthesia do seem more at risk for micturition and defecation

    dysfunction at follow up (66.7% versus 32.3% and 91% versus 32.3%, respectively);

 2) Patients being catheterized at presentation do not seem to be more at risk for micturition dysfunction at follow up

    (33.3% versus 40.0%) not unlikely due to the fact that catheterization at presentation is not a distinctive                     

    characteristic of dysfunction.

3) Patients with reduced anal sphincter tone and absent anal sphincter reflex do seem more at risk for defecation

    dysfunction fllow up (54.5% versus 25%). However, no firm conclusions can be drawn from these figures since they

    were not analysed through statistics.

This was not done because it would create unreliable regression models: adding the parameters complete perianal

anaesthesia at presentation, catheterization at presentation and reduced anal sphincter tension plus absent reflex at

presentation to our regression models for the outcome of micturition and defecation dysfunction would lead to

overfitting i.e. when a model consists of more parameters than events.

The univariate analysis would be inappropriate due to the high risk of confounding which risk is significantly reduced

by using (multivariate) regression models, as was done in this study). Only in a larger cohort of patients (with thus

more events), more parameters can be reliably added to the regression model.

Buchner et al presented a cohort of 22 CES patients with a mean follow up of 3.8 years postoperatively and

mentioned absence of complete perianal anaesthesia at presentation and female gender both being predictors of a

better postoperative outcome. Postoperative outcome was graded by level of micturition and divided into four groups:

excellent, good, fair or poor. In the study of Buchner et al, the outcome was regarded as “better” when the outcome

shifted in the direction of excellent, regardless where it came from and how much it shifted in that direction.

Doubtless, this is a completely different outcome measurement than the one that was used in the current cohort, and

therefore not unlikely, inducing different correlations. In addition, the analysis by Buchner et al was univariate, which is

more prone to confounding than the use of multivariate analysis as was done in the current study.

 McCarthy et al evaluated 42 CES patients with a mean of 5 years after decompressive surgery and demonstrated

1) Female gender to be a predictor of urinary incontinence at follow up and

2) Bowel dysfunction at presentation to be a predictor of sexual dysfunction at follow up. With regard to the first

    finding: in our regression analysis, no differentiation was made between urinary incontinence and other micturition

    problems at follow up.

Evaluating the outcome for micturition in our study closer displays that the 40% patients with urinary incontinence at

long term follow up, were all female; of the remaining 60% patients with micturition problems but without incontinence,

25% were female and 15% were male. Thus, indeed, female gender seems to be associated with urinary incontinence

at follow up in our study as well, however, no association was seen for the total group with micturition dysfunction.

McCarthy et al identified bowel dysfunction at presentation as a predictor of sexual dysfunction at follow up, which was

not demonstrated in our study.

The use of univariate models instead of multivariate models could, however, be an explanation of identifying a

predictor which was not found in our study. We think that the multivariate regression analysis used in our study

diminished the risk of confounding. So our survey study was quite comparative to the above two studies on the

ratio of numbers.


Differences in Reporting between Doctor and Patient


Micturition and defecation dysfunction at follow up outpatient’s department were more often reported by the patient

than by the doctor did not reach statistical significance, probably due to small patient numbers. For sexual dysfunction,

the patient and doctor reported data are much more similar. Reason for this might be that doctors find it easier to

discuss micturition and defecation and thus also get to know and document about non-symptomatic patients.

Sexual dysfunction, however, is more difficult to discuss and therefore, is not often discussed when the patient doesn’t

bring up the subject him or herself. The obvious reason for a patient to bring up this topic is because complaints are

present. Consequently, the doctor's notes about sexual function are relatively more often about dysfunction than the

notes about micturition and defecation, suggesting that discussing sexual dysfunction is a barrier, not only for the

patient but for the doctor as well.




Apart from a younger age which was associated with sexual dysfunction at follow up, no predictors were identified.

The average age was between 24 to 38. This urges the clinician to be attentive to dysfunction during the presentation

and follow up in all CES patients, bearing in mind the presented results of alarmingly high rates of dysfunction still

years after surgery. The presented CES patients indicated to be in dire need of recovery prospects. The fact that the

majority did not receive any information of this kind, marks the lack of prognostic data in CES literature. With the

presented data as best available evidence, it is now possible to start informing CES patients properly.

Despite recommendations from the Consortium of Spinal Cord Medicine (2010) to identify threats to sexual

wellbeing in high-risk spinal patients, discussing sexual dysfunction in CES patients did not get a foothold in current

practice yet, which is highly regrettable considering the presented prevalence of dysfunction. The authors advocate

identifying sexual dysfunction in CES patients at an early stage. Bringing up the subject cannot be left to the patient

and is the solemn responsibility of the doctor: too often, the patient is unaware of the link of CES with sexual

dysfunction and is too ashamed to ask.




This study might seem minimal of CES patients with long term results which were presented up to now, however, the

total number of patients is still relatively small compared to evaluation studies of other neurological diseases. This

restricted study/survey size prevents a good intervention-prognostic variable analysis to predict the outcome. Like all

surveys, this questionnaire study/survey faced the problem of non-responding. This study achieved a response rate of

91% with a fully completed conclusion rate of 78%. To accommodate for the best response rate possible, postal

surveys were sent instead of web-based surveys and telephone reminders were used as a proven method to improve

response rate. The average response rate for patient surveys is about 60%, which figure is deducted from studies

published in 1991, 1996, 1999, 2007 and 2011, whereas it is well-known that the response rates have been decreasing

ever since, especially for surveys sent by healthcare professionals. 

More importantly, surveys about sensitive subjects such as sexual dysfunction are proven to be prone to lower

response rates and display a decreasing response rate over the years as well.  Worth mentioning, the current study

has an extremely long time up to more than 25 years is the longest period of CES sufferer, which makes it more likely

that patients are less prone to participate. Baseline characteristics of responders and non-responders were not

significantly different, making response bias unlikely. The other problem which must be taken into account is the

differential in what questions were asked and the length of the studies. As well we looked at the history of the previous

studies and tried to evaluate the way in which our questions were worded and try to envisage what replies were likely

to be returned.

Of course, long term follows up creates risks for recall bias; i.e., patients report events differently from the true course

of events due to loss of memory on the concerning item. This is something that cannot be corrected for in the current

study design; any evaluation of long-term outcome will introduce a risk of recall bias. Obviously, because of the

considerable long follow up period, the mean age of included patients has increased substantially during follow up

(from 44.6 to 57.8 years old). Increasing age changes the prevalence of problems of micturition, defecation and sexual 

function in the general population, this might have also influenced the prevalence of the dysfunction in the study

population. The effort was taken to correct where possible: current medication use and co-morbidity were taken into

account wherever dysfunction was reported, and where necessary, the correction was used: a correction was used

for reported complaints that were thought not to be caused by CES but by other diseases such as urological prostate

or gynaecological prolapse problems.

The author believes that the risk of bias was therefore minimized in this respect. A further survey would be of benefit

in 5 years, with a wider expanse of participants, in various age groups such as  25 - 35, 40 - 55, 60 - 75 and 80+.

Although we have not included the full amount of statistics from the returns  here (which are fully contained with the

Book/Manual) we have in brief given a wide overview of the rariry of Cauda Equina Syndrome and it's after effects.




This study presents data about long term outcome of micturition, defecation and sexual function in CES after

decompression and is unique in three aspects,

1) Markedly large Study

2) Lengthy follow up

3) Integral evaluation of defecation and sexual function next to micturition.

This report demonstrates dysfunction to be extremely common years after surgery and communicates a clear demand

from CES patients for more information about their prognosis on those functions. Without a doubt, the presented

information collected with this survey and questionnaire as well as the help from those who supported the Study/Survey

substantially to the current knowledge about CES.

It gives the clinician in spinal care the opportunity to inform CES patients realistically about long term recovery of

micturition, defecation and sexual function after decompressive surgery. With regard to the seriousness of Genito-

urinary and defecation dysfunction and impact on the quality of life, a prospective study is necessary to evaluate

the risk of permanent deficit and to identify predictive variables, which can be influenced by intervention and

personal guidance in rehabilitation.


Key Elements 

Cauda Equina Syndrome is a grey area and there is no consensus on which signs and symptoms should be acted on.

However, it can have life-changing consequences and it is important to act quickly if it is even suspected.




The scale and impact of claims for negligence against clinicians treating people with CES are significant and

rising. Whilst it is difficult to accurately collate international statistics, there are robust data for the UK, which are

presented below. These are taken from national agencies dealing with litigation against medical professionals (Medical

Defence Union- MDU, and the National Health Service Litigation Authority-NHSLA). Taylor et. al. analysed claims

made to the MDU between 2005 and 2016 related to CES. In that period there were 1500 claims made 92% against

GPs. The majority of these were successfully defended (70%) through the MDU paid out £350 000 pounds ($456,340

NZD) in legal costs. Over the same time period, £8 million ($10.4mNZD) was paid out on settled claims, most of which

were under £100 000 ($130 000 NZD). £4.5m of this was in solicitors’ fees. Around 12% of claims were for more than

£500 000 pounds ($650 000 NZD).

        The NHSLA (2016) examined claims for CES from 2010-2015. Of the 293 cases identified, 232 were still under 

investigation and unsettled; 20 had settled with agreed damages; 41 had concluded with no damages awarded.   

Overall  £25 million had been paid out. The survey identified that 76% of patients involved in claims were aged 

between 31-50.

Other data suggests that average pay-outs for CES claims in the UK are around £336 000 ($436 800 NZD), with

around £133 000 of that going to the patient and the remainder on legal costs. US data suggests average pay-outs are

$549 427USD (£422 636).  Although not specifically focused on CES, a study by Taylor et. al. in 2014 of litigation

cases in the USA against neurosurgeons, found that they were more likely to be sued following spinal surgery than

cranial surgery, with the average claim being around USD$278 362. A similar study, relating to neurosurgical litigation

in the UK, found that the highest number of claims related to spinal surgery (44%) and that 87.5% of claims relating to

CES were successful.

 It is clear that litigation for CES is only likely to increase, and equally clear that as treating healthcare

professionals, we need to ensure that we examine patients fully and appropriately, that we warn, or “safety net” them

where we have concerns, and that we have robust pathways in place to ensure rapid access to MRI scanning and

spinal surgical specialists. The largest to date ( May 2020) that we have found is Euro - €7,345,675 plus legal costs.

In New Zealand there is NO Litigation law due to the Accident Compensation Corporation a Government backed

insurer and the maximum payout as at 2018 was $135,000 approx, with between 15 to 25% of that going in legal

fees, as the ACC does not cover those, only when the claim is reviewed or overturned. Court can be an option to fight

the system but as to what will be ordered to pay has a capping. It is also rare that a surgeon will be sued because of

the ACC. 

See Claims Page For More Details


Clinical Bottom Line

 Cauda Equina Syndrome is rare, dangerous and a serious disorder that can have life-changing consequences

if not acted upon in a timely manner. If surgical intervention is delayed irreversible damage can occur to the bladder,

bowel and sexual function. Relevant symptoms include unilateral or bilateral radicular pain and/or dermatomal reduced

sensation and/or myotomal weakness with any suggestion of a change in bladder or bowel function however minor

should be investigated. Nothing is to be gained by delaying surgery and should be carried out as soon as is practically



Safety Netting

Not all patients with back pain will develop CES and it is not necessary to warn all patients. Those patients whom you

suspect may go onto develop CES should be given the appropriate information and know what to do should they go on

to develop symptoms.



Patients need to understand the relevance of the questions the Doctor asked as they may not fully appreciate the

importance and subsequent consequences if not explained properly. Doctors also need to listen and take the time to

explain in plain language what exactly the problem is. The excuse "we are too busy" does not cut it with a serious

condition such as CES.



It is important that a patient signs and symptoms are fully documented in accordance with your governing

bodies standards of practice so there is a clear record of the patient's journey. This is important for the Patient's benefit

as well as the Doctor's






Cauda Equina Syndrome Sufferers Global Support Group