Cauda Equina Syndrome

Differentials

Not just large disc bulges don't you know

Classifications & Definitions

A Clinical One

Idealised Concept ¹. But initial definitions in SBNS 2009 Guidelines.

Name	Acronym	Clinical Features	Outcomes
CES-Suspected	CESS	Bilateral Radiculopathy AND/OR subjective sphincter problems AND/OR subjective perineal sensory changes BUT NO objective evidence of CES.	85% Free of sciatica. Normal bladder, bowel & sexual function
CES-Incomplete	CESI	Subjective symptoms and objective signs of CES. Voluntary control of micturition.	Normal/Social bladder & bowel function. Normal or reduced sexual function.
CES-Retention	CESR	Neurogenic retention of urine (Bladder paralysed and insensate)	Often paralysed, insensate bladder & bowel. Often need catheter and manual evacuation. No/reduced sexual function.

Todd¹ points out that a lot of S+S in the guidelines are actually signs of irreversible CES (White flags not Red Flags)
Draws clear lines of operate before there are signs.

- Definite red flags  
    - Bilateral Radiculopathy.  
    - Progressive neuro in legs.   
- Red flag or White flag   
    - Impaired perianal sensation   
    - Impaired anal tone   
    - Non-spec urinary disturbance   
- White Flag   
    - Urinary retention or incontinence   
    - Faecal incontinence.   
    - Perineal sensation.

But states '48-93%' of CESR can show improvement post op with some evidence for surgery within 12-72 hours.
Very hawkish about doing lots of MR:

'MR Imaging of the ? CES patient is part of triage and should be performed at the DGH, 24 hours a day, 7 days a week, prior to discussion with the Regional Centre.'

But, also quotes 'low' rates of CE compression confirmed on MR (14-33%!!) and non-specific nature of S+S means this work should be done in the DGH.

Attempted Definition & Classifications have been ²

Lavy et al ² reviewed 21ys of papers to 2021. n=212.
To find Definition & Classification of CES.
Medicolegal issues are mentioned prominently.
Accept that definitions are uncertain and that there is a role and need for a clinical judgement.

Anatomically the CE is all the roots from the distal spinal cord from L1 to S5.
Roots L1 to S1 are the legs and do not produce the clinical syndrome of 'CES'.

'Cauda equina syndrome is historically used to describe the result of the dysfunction of S2 - S5'

Recommend: as a practical definition.

Cauda equina syndrome is a clinical diagnosis resulting from dysfunction of one or more of the sacral nerve roots S2 and below. One or more of the following symptoms or signs must be present:
- Bladder and/or bowel dysfunction.
- Reduced sensation in the saddle area.
- Sexual dysfunction.
Back and leg pain, and lower limb motor or sensory changes are often present but are not essential to the diagnosis.
Nerve root compression is the commonest cause and MRI scanning is usually needed for confirmation.

Other Classifications

By presentation. Tandon & Sankaran

Type	Description	Notes
Type 1	Rapid onset of CES symptoms with no past history of back problems	Rare in Litigation.
Type 2	Acute bladder / CES symptoms with a history of back pain and sciatica.	Majority in Litigation.
Type 3	Longstanding back problems and gradually progressive CES often with spinal stenosis	"usually non-urgent". Elderly, more tolerant of reduction in bladder/bowel/sexual function.

Multifactorial Classification. Shi et al

Group	Name	Description
1	Preclinical	LBP + only bulbocavernosus reflex & ischiocavernosus reflex abnormalities. NO typical symptoms of CES.
2	Early	Bilateral Sciatica + saddle sensory disturbance & numbness.
3	Middle	Saddle sensory disturbance, numbness, bowel and/or bladder dysfunction, motor weakness of the lower extremities & reduction sexual function.
4	Late	Absence of saddle sensation & sexual function and uncontrolled bladder function.

Not really used - unfortunately - but raises the idea that bulbocavernosus and ischiocavernosus reflexes ought to be assessed.

Bulbocavernosus reflex = Bulbospongiosus reflex = Osinski Reflex.

*Squeeze Glans/Clitoris or Tug on Foley => Anal sphincter contraction. Spinal reflex mediated by S2-S4. Used in ?spinal shock and intra-operatively via neurophysiological measurements.

Comprehensive Classification of CES Gleave & Macfarlane 2002. Todd 2018 The recommended one. Surprise!

Name	Abbreviation	Definition
Suspected CES	CESS	Bilateral sciatica or motor / sensory loss in legs BUT no bladder/bowel/genital/perineal symptoms. OR Known large disc herniation on earlier MRI (='Radiological CESS')
Early CES	CESE	Symptoms only! Some change in perineal sensation or micturition freq BUT normal bladder, bowel & sexual function. a.k.a. 'Symptom-only CES'
Incomplete CES	CESI	Alteration in bladder/urethral sensation or function. But maintain executive bladder function control. +/- Perineal sensory changes, or sexual or bowel sensory or functional changes.
CES with Retention	CESR	As CESI but with painless bladder retention and overflow.
Complete CES	CESC	Insensate bladder with overflow incontinence, no perineal, perianal or sexual sensation. No anal tone.

Todd makes the point that pain can lead to bladder dysfunction. So, need to see some sensory disturbance to explain a neurogenic cause for the bladder disturbance. But, then says that it is not absolutely mandatory to make a diagnosis and quotes cases of 'MRI-confirmed CES' with normal sensation.
Todd 2017 states the SBNS definition of CESS is too poorly defined 'suggestion of sphincter disturbance' and here changes it to no actual CES symptoms but symptoms suspicious for a large disc herniation and includes patients whose prior MRs put them at risk of progression into CES.

Clinical Features

The literature is more mixed than is apparent.

Ahad et al⁴ looked at RCR clinical criteria for ?CES.
- Conducted in Ninewells and was retrospective and depended on review of the notes. Mean Time to Delay = 149hrs!! The ones who were questionable had OP scans.
- Consecutive patients who 'warranted urgent MRI'. n=79. Age mean ~ 55y
- MR was conducted in 62. Only 33% done in <24h. Only 6% were CES positive and underwent decompression. But 1 was missed and only detected on an OP scan 2w post-admission.
- No clinical features that predicted the presence / absence of a surgical cause of CES.
- But 3% = Discitis. 4% = Malignancy ( only 1 of 3, known about )

And

Fairbank et al⁶ in a 2011 Lit review
- Only found 4 studies of adequate quality and all under 100 patients referred for ? CES.
- Yields on MRI vary from 14 to 48%.
- No symptom or sign has adequate performance to rule in/out CES. - But also say that more research is likely to alter this finding and the clinical importance of these findings.

On the Other Hand...

Zusman et al⁵ says CES is entirely predictable. But..
- 10y study to 2017 based in Academic Tertiary centre in Portland who had an MRI & Ortho consult.
- But, Lumbar MRI from ED = 2751, only n = 509 with Ortho consult, then excluded those without bladder or bowel complaint which could have included CESS etc. Then, excluded 38 cos of trauma / tumour.
- So, only n= 142. And 10 had 'CES diagnosis from MRI'.
- 90% of CES positive = Disc Herniation. 48% of CES Negative.

Finding	Sensitivity	Specificity	PPV	NPV
Rectal Tone	80	86	31	98
Perianal Sensation	60	68	13	96
Bulbocavernosus Reflex	100	100	100	100
Post Void >300ml	80	59	21	96

However they excluded patients with missing data from the analysis. So, the BCR calc is based on only 33 patients. 3 were positive and all CES positive, and 30 were negative and all CES Negative on MRI.

Here Comes the Good Stuff.

Hoeritzauer et al⁷ are a group from Edinburgh neurosciences, neurosurgery and rehab.
- Followed up all patients from NHS Lothian referred for ?CES to Edinburgh over 16 months on EPR andtracked them for at least 18 months.
- Defined ?CES as at least one of acute bladder, bowel, sexual dysfunction or saddle anaesthesia referred to a regional neurosciences centre.
- Assessed Clinical, psychiatric, functional disorders and radiological features.
n= 276. Put the patients into 3 groups defined by the MR findings.

Group	Age	Sex	Result	Functional Disorders	Functional Neuro	Psychiatric Dx
Scan +ve n=78	48y	56% Female	91% Surgery	9%	0%	Depression = 22% Anxiety = 18% PD = 10%
Scan -ve but root compression n=87	43y	68% Female	16% Surgery	30%	11%	Depression = 39% Anxiety = 30% PD = 24%
Scan -ve including roots n=104	42y	70% Female	2% Surgery	37%	12%	Depression = 53% Anxiety = 41% PD = 16%

So presence of Functional disorder co-morbidity, Functional neuro disorder and psychiatric diagnosis were seen at significantly different rates.

Many clinical features assessed but here limited by retrospective and non-systematic assessment so incomplete data sets but the VAST majority are non-significant between groups including:
- Bladder Incontinence or Urgency/Frequency/Hesitancy
- Bladder Retention & reduced awareness & PVR !
- Bowel symptoms including Incontinence, reduced awareness & constipation.
- Reduced anal tone on DRE.
- Change in sexual function.
- Unilateral sciatica. Bilateral and whole leg numbness.
The few that ARE significant are:

Feature	Scan +ve Group	Scan -ve. Root Compression	Scan -ve. No Root Compression	P value
'Mixed' urinary problems	0%	3%	11%	0.01
No urinary symptoms	28%	17%	9%	0.0005
Bilateral Sciatica	41%	20%	21%	0.001
Nerve root distribution pattern numbness	61%	28%	36%	0.001
Saddle Numbness	64%	54%	52%	0.04

State pain is well known as the trigger for functional neuro disorders.
Functional disorders are increasingly diagnosed positively.
- ie Hoovers sign = Weakness of hip extension, which improves with contralateral hip flexion.
- Rx: Tailored physio -> Significant and good improvement.
PathoPhys: Bayesian 'top-down' expectation and abnormal self-directed attention overriding the normal sensory and motor pathways.
The non-significance of urinary symptoms between the groups is counter-intuitive.
Suggest several hypotheses for this. Including Pain -> sympathetic hyperactivity and increased inhibitory signals via the hypogastric & pelvic nerves. Thus, overriding normal relaxation during micturition. Or, the pain -> panic -> exacerbation of underlying dysfunction, especially women. Or, lots of drug interference especially the analgesics for neuropathic pain and opiates -> constipation.

They follow up these findings in later papers including Hoeritzauer et al⁹

Prospective paper (published in Neurology, so not available)
Says the same things though with scan -ve ones more likely to have
- Worst pain ever
- Panic symptoms at presentation
- More positive features of functional neuro disorders.
- Less likely to have reduced bilateral ankle jerks.
No difference in terms of reduced anal tone nor urinary retention.

Also this paper which is more a review about Functional Neuro in the CES population. In it they state lots about the Scan -ve CES and the complex functional neurology behind it.

Surgical Treatment

Does it work?

Well it is a complex condition which the neurosurgeons like to limit to as simple a pathway as possible so that they can so they can understand it. So, patients in the CES positive group, who are the ones who will be operated on, there is no attempt to prospectively identify the ones who are 'functional', thus any functional patient with a large enough disc bulge will have it decompressed but of course will not benefit from it.
To prove this hypothesis then note the rates of functional abnormality in the scan positive group are still worse than in the universal population.

Lam et al¹⁰ Followed up 71 of 135 patients operated on emergently for CES who responded to telephone interview.
Had significant increase in degree of limitation from back pain. - Also severe increase in urinary, bowel and sex function after, whilst small percentage before.

Radiological Techniques

Gnanasekaran et al ³ thought most were a waste of time so created a short sequence of just lumbrosacral spine for patients <55y lasting mean of 9.9 minutes. At Stoke Mandeville. 2017-8. n=188 patients. 196 MRI scans. Consecutive ?CES patients under 55.
14 = CES and all had emergency decompression. (= 7%) 0 = Missed CES.

Todd NV. Guidelines for cauda equina syndrome. Red flags and white flags. Systematic review and implications for triage. British Journal of Neurosurgery. 2017;31(3):336–339. doi: 10.1080/02688697.2017.1297364. ↩↩
Lavy C, Marks P, Dangas K, Todd N. Cauda equina syndrome—a practical guide to definition and classification. Int Orthop. 2022;46(2):165–169. doi: 10.1007/s00264-021-05273-1. ↩↩
Gnanasekaran R, Beresford-Cleary N, Aboelmagd T et al Limited sequence MRI to improve standards of care for suspected cauda equina syndrome. Bone Joint J 2020;102(4) https://doi.org/10.1302/0301-620X.102B4.BJJ-2019-0645.R2 ↩
Ahad A, Elsayed M, Tohid H. The accuracy of clinical symptoms in detecting cauda equina syndrome in patients undergoing acute MRI of the spine. Neuroradiol J. 2015;28(4):438-442. doi:10.1177/1971400915598074 ↩
Zusman NL, Radoslovich SS, Smith SJ, Tanski M, Gundle KR, Yoo JU. Physical Examination Is Predictive of Cauda Equina Syndrome: MRI to Rule Out Diagnosis Is Unnecessary. Global Spine J. 2022;12(2):209-214. doi:10.1177/2192568220948804 ↩
Fairbank J, Hashimoto R, Dailey A, Patel AA, Dettori JR. Does patient history and physical examination predict MRI proven cauda equina syndrome? Evid Based Spine Care J. 2011;2(4):27-33. ↩
Hoeritzauer I, Pronin S, Carson A, Statham P, Demetriades AK, Stone J. The clinical features and outcome of scan-negative and scan-positive cases in suspected cauda equina syndrome: a retrospective study of 276 patients. J Neurol. 2018;265(12):2916-2926. doi:10.1007/s00415-018-9078-2 ↩
Hoeritzauer I, Stanton B, Carson A, Stone J. ‘Scan-negative’ cauda equina syndrome: what to do when there is no neurosurgical cause. Practical Neurology. 2022;22(1):6-13. doi:10.1136/practneurol-2020-002830 ↩
Hoeritzauer I, Carson A, Statham P, et al. Scan-Negative Cauda Equina Syndrome: A Prospective Cohort Study. Neurology. 2021;96(3):e433-e447. doi:10.1212/WNL.0000000000011154 ↩
Lam J, deSouza RM, Laycock J, et al. Patient-Reported Bladder, Bowel, and Sexual Function After Cauda Equina Syndrome Secondary to a Herniated Lumbar Intervertebral Disc. Top Spinal Cord Inj Rehabil. 2020;26(4):290-303. doi:10.46292/sci19-00065 ↩