Cauda Equina Syndrome
High-yield overview
Emergency Diagnosis | CES-I vs CES-R | Urgent Decompression
0.04%Of LBP presentations
L4/5Most common level
48hSurgery window
S2-S4Bladder innervation
Critical Must-Knows
- CES-I (Incomplete) = altered bladder sensation but control preserved - URGENT surgery to prevent progression
- CES-R (Retention) = painless urinary retention with overflow - poorer prognosis regardless of timing
- MRI is mandatory emergency - do not wait until morning if red flags present
- Post-void residual greater than 500ml is significantly predictive of CES
- Bilateral sciatica + saddle anaesthesia + bladder dysfunction = assume CES until proven otherwise
Clinical Pearls
- "Know Gleave & Macfarlane classification: CES-I vs CES-R distinction is prognostically critical
- "Timing debate: state of patient (CES-I vs R) matters more than exact surgical timing
- "Medico-legal hot topic: 'Better to scan 100 negatives than miss 1 positive'
- "Digital rectal exam is mandatory: assess anal tone AND sensation
Clinical Imaging
Imaging Gallery
Exam Warning - Major Medico-Legal Pitfall
CES-I vs CES-R
CES-I (Incomplete): Altered sensation but voluntary control preserved. URGENT surgery often prevents progression. CES-R (Retention): Painless retention with overflow. Poorer prognosis regardless of timing.
Medico-Legal Trap
"Better to scan 100 negatives than miss 1 positive." Low threshold for MRI. This is the most litigated condition in spinal surgery.
Timing Matters
Decompression in CES-I is time-critical. Once CES-R occurs, recovery is unpredictable. Do not wait for morning if red flags are present.
Exam Strategy
Always define the difference between I and R. Examiners look for this distinction immediately.
Key Mnemonics
Mnemonic
BB-SADDLERed Flags for CES
| B | Bilateral sciatica Pain radiating down both legs (though can be unilateral) |
| B | Bladder dysfunction Retention, hesitancy, or incontinence - the critical symptom |
| S | Saddle anaesthesia Perineal numbness - ask about wiping sensation |
| A | Anal tone loss Reduced voluntary squeeze on DRE - mandatory examination |
| D | Deficit in legs Motor weakness or sensory changes L2-S1 distribution |
| D | Disturbance of bowels Faecal incontinence or loss of awareness |
| L | Lower back pain Severe LBP often present (but not always) |
| E | Erectile/Sexual dysfunction Loss of sensation or function |
| B | Bilateral sciatica Pain radiating down both legs (though can be unilateral) | A | Anal tone loss Reduced voluntary squeeze on DRE - mandatory examination | L | Lower back pain Severe LBP often present (but not always) |
| B | Bladder dysfunction Retention, hesitancy, or incontinence - the critical symptom | D | Deficit in legs Motor weakness or sensory changes L2-S1 distribution | E | Erectile/Sexual dysfunction Loss of sensation or function |
| S | Saddle anaesthesia Perineal numbness - ask about wiping sensation | D | Disturbance of bowels Faecal incontinence or loss of awareness |
Hook:Sitting on a numbness SADDLE - think CES when patients describe perineal symptoms!
Mnemonic
WIPECES Clinical Questions
| W | Wetting accidents? Ask about urinary incontinence or overflow |
| I | Inability to void? Painless retention is ominous - indicates CES-R |
| P | Paper sensation? Can you feel the toilet paper when wiping? Tests S2-S4 |
| E | Erection/Sexual function? Changes in sensation or function |
| W | Wetting accidents? Ask about urinary incontinence or overflow | P | Paper sensation? Can you feel the toilet paper when wiping? Tests S2-S4 |
| I | Inability to void? Painless retention is ominous - indicates CES-R | E | Erection/Sexual function? Changes in sensation or function |
Hook:WIPE - the key questions to ask every patient with red flag back pain!
Mnemonic
S2-3-4Bladder Innervation
| S2 | Sensory afferents Bladder fullness sensation travels via S2-S4 |
| S3 | Sphincter control External urethral sphincter innervation |
| S4 | Somatic pudendal Voluntary control of micturition reflex |
| S2 | Sensory afferents Bladder fullness sensation travels via S2-S4 |
| S3 | Sphincter control External urethral sphincter innervation |
| S4 | Somatic pudendal Voluntary control of micturition reflex |
Hook:S2, 3, 4 keeps the wee off the floor - and the poo out of the shoe!
Clinical Significance
Definition
Cauda equina syndrome (CES) is compression of the cauda equina nerve roots (L2-S5) below the conus medullaris, causing a constellation of lower back pain, unilateral or bilateral sciatica, saddle anaesthesia, and motor/sphincter dysfunction. It represents a surgical emergency requiring urgent decompression.
Demographics and Incidence
- Incidence: 0.04% of all lower back pain presentations
- Rarity: 1-2 per 100,000 population annually
- Age: Any age, peak 40-60 years
- Gender: Equal distribution
- Most common cause: Large central lumbar disc herniation (L4/5 or L5/S1)
- Other causes: Tumour, infection (epidural abscess), haematoma, trauma
Despite rarity, high index of suspicion is essential due to catastrophic consequences of missed diagnosis.
Clinical Impact
- Permanent bladder dysfunction: Up to 50% in CES-R
- Permanent bowel dysfunction: 30-40%
- Sexual dysfunction: Up to 50%
- Chronic pain: Very common
- Litigation: Extremely common for delayed diagnosis
- Quality of life: Severely impacted
Economic and personal burden is substantial. Delayed diagnosis is the leading cause of spine-related litigation.
Anatomy of the Cauda Equina
Cauda Equina ("Horse's Tail"):
- Collection of nerve roots distal to conus medullaris (which ends at L1/L2 in adults)
- Contains nerve roots L2 to S5
- Provides motor and sensory innervation to legs, perineum, and sphincters
- Contains parasympathetic bladder supply (S2-S4 - "S2, 3, 4 keeps the wee off the floor")
Pathophysiology of Compression:
- Nerve roots are tethered within the spinal canal and have less protective connective tissue than peripheral nerves
- Compression compromises intraneural blood flow (venous congestion leading to arterial ischaemia)
- Autonomic fibres to bladder (S2-S4) are most vulnerable due to small diameter and peripheral location
- Sensory fibres affected before motor fibres in early stages
CES Staging - Critical for Prognosis
CES-I vs CES-R Classification
The Critical Distinction
CES-I patients have altered bladder sensation but can still voluntarily void. They often describe needing to strain to urinate, incomplete emptying, or loss of normal desire to void. However, they retain control.
CES-R patients have a paralysed bladder. They develop painless urinary retention (bladder fills without sensation) and overflow incontinence (dribbling when bladder is overfull). This represents established neurological damage.
The transition from CES-I to CES-R is often irreversible - hence the urgency to operate while still CES-I.
Differential Diagnosis
Many conditions mimic CES (so-called "scan-negative" or pseudo-CES, where up to 60-70% of emergency MRIs for suspected CES show no compressive lesion). Distinguishing true compressive CES from mimics avoids both missed diagnoses and unnecessary night-time operating.
CES and its Mimics
Conus vs Cauda Equina
The conus medullaris (T12-L2 vertebral level) produces an early, symmetrical, mixed UMN/LMN picture with prominent early bladder involvement and sometimes preserved reflexes. The cauda equina produces an asymmetrical, purely LMN, areflexic picture with radicular leg pain. Both are emergencies, but examiners frequently test the anatomical distinction.
History
Key Questions:
- Onset: Acute vs gradual deterioration
- Back pain: Severity, radiation pattern
- Leg symptoms: Unilateral vs bilateral, dermatomal distribution
Bladder Questions (CRITICAL):
- "Can you feel when your bladder is full?"
- "Can you start and stop urinating normally?"
- "Have you had any wetting accidents?"
- "Have you noticed you're not passing urine as often?"
Bowel Questions:
- "Can you feel the paper when wiping?" (S2-S4 sensation)
- "Any change in bowel control?"
- "Can you feel when you need to pass a motion?"
Sexual Function:
- Sensation changes
- Erectile dysfunction (males)
- Loss of genital sensation (both sexes)
Examination
Neurological Examination:
- Full lower limb motor exam (L2-S1 myotomes)
- Full lower limb sensory exam (L2-S1 dermatomes)
- Reflexes: knee (L3/4), ankle (S1), Babinski
Perineal Examination (MANDATORY):
- Light touch sensation in saddle area (S2-S5)
- Pin-prick sensation perineum
- Compare both sides for asymmetry
Digital Rectal Examination (MANDATORY):
- Resting anal tone: Assess baseline sphincter tone
- Voluntary squeeze: Ask patient to squeeze examiner's finger
- Perianal sensation: Light touch around anus
- Document findings: Essential for medico-legal purposes
Bladder Assessment:
- Palpate suprapubically for distended bladder
- Bladder scan: PVR greater than 200ml suspicious, greater than 500ml highly predictive
Bladder Sensation Warning Sign
Loss of bladder sensation (desire to void) is often the earliest sign of autonomic dysfunction in CES-I, occurring before painless retention. Ask specifically about alteration in sensation, not just ability to urinate.
Clinical Pearl: Subjective change in urinary function is a RED FLAG - do not dismiss.
Emergency Imaging
MRI Lumbar Spine:
- Gold Standard investigation for suspected CES
- Must be performed urgently (day or night) if red flags present
- Whole lumbar spine with sagittal and axial T2-weighted sequences
- Look for: Canal occlusion (usually greater than 50-75%), disc herniation level, nerve root compression, other pathology (tumour, abscess)
CT Myelogram:
- If MRI contraindicated (pacemaker, severe claustrophobia)
- Requires lumbar puncture and intrathecal contrast
- Second-line but still diagnostic
Bladder Ultrasound:
- Post-void residual (PVR) measurement
- PVR greater than 200ml: suspicious
- PVR greater than 500ml: highly predictive of CES
- Quick, non-invasive, can be performed at bedside
MRI Imaging Gallery
Algorithm
Management Algorithm
On Presentation:
- Full history and examination (including DRE)
- Bladder scan for PVR
- Catheterise if retention confirmed (document volume - medico-legal)
- Keep nil by mouth in anticipation of surgery
- Analgesia (avoid masking neurological progression)
- Request EMERGENCY MRI - do not wait until morning
MRI Confirms CES:
- Contact on-call spine surgeon immediately
- Book emergency theatre
- Consent for surgery (high risk of permanent dysfunction despite surgery)
- Thromboprophylaxis
Evidence Base
Decompression within 48 hours - Ahn meta-analysis
Ahn UM, Ahn NU, Buchowski JM, et al. • Spine (Phila Pa 1976) (2000)
Key Findings:
- Meta-analysis of 322 patients with CES secondary to lumbar disc herniation (42 studies)
- No significant difference between surgery under 24h versus 24-48h
- Significant advantage for decompression within 48h versus after 48h for sensory, motor, bladder and bowel recovery
- Pre-operative chronic back pain and rectal dysfunction predicted worse urinary outcome
Clinical Implication: The most-cited timing meta-analysis. It supports the widely quoted 48-hour benefit window but found no extra gain from operating inside 24h, underpinning the 'as soon as safely possible' (not 'within X hours') doctrine.
CES-R vs CES-I should not be analysed together - DeLong meta-analysis
DeLong WB, Polissar N, Neradilek B • J Neurosurg Spine (2008)
Key Findings:
- Meta-analysis of 16-27 observational cohorts of CES with retention (CES-R)
- Later surgery predicted a worse (Fair/Poor) urinary outcome (relative risk 1.77 to 2.19 across breakpoints)
- CES-R carried a worse outcome than incomplete CES (relative risk 2.58)
- Concluded CES-R and CES-I must be reported separately, not pooled
Clinical Implication: Methodologically reframed the timing debate: prognosis hinges on whether the patient is incomplete (CES-I) or in retention (CES-R) at presentation, and earlier surgery still favours bladder outcome.
CES classification and the timing controversy
Gleave JRW, Macfarlane R • Br J Neurosurg (2002)
Key Findings:
- Articulated the incomplete (CES-I) versus retention/overflow (CES-R) distinction now in routine use
- CES-I: subjective bladder symptoms with volitional control preserved
- CES-R: painless retention with overflow incontinence and a paralysed bladder
- Authors argued that once retention with overflow is established, urgent decompression confers no additional benefit
Clinical Implication: The conceptual basis for the modern CES-I/CES-R split. Its pessimistic view of established CES-R reinforces why the true window is catching and decompressing patients while still CES-I.
UCES - UK prospective cohort (Woodfield)
Woodfield J, Hoeritzauer I, Jamjoom AAB, et al. • Lancet Reg Health Eur (2022)
Key Findings:
- Prospective multicentre cohort of 621 surgically treated CES patients with 1-year follow-up
- Median time to surgery 3 days; only 32% operated within 48h
- No association between time to surgery (or radiological compression) and Oswestry Disability Index or urinary outcome at 1 year
- Functional improvement occurred even in those presenting in retention; 65% needed extra healthcare services during follow-up
Clinical Implication: The largest modern prospective CES dataset. It tempers the 'every hour counts' framing for established CES, while highlighting the heavy long-term morbidity and rehabilitation burden that counselling must address.
Long-term micturition, defecation and sexual outcome (Korse)
Korse NS, Pijpers JA, van Zwet E, et al. • Eur Spine J (2017)
Key Findings:
- Cohort of 75 surgically decompressed CES patients; L5-S1 most common level
- At presentation: micturition dysfunction 92%, saddle sensory change 93%, defecation dysfunction 74%
- At follow-up: micturition dysfunction 48%, defecation dysfunction 42%, sexual dysfunction 53%
- Recovery is slow and incomplete in the majority despite decompression
Clinical Implication: Provides realistic prognostic figures for consent: roughly half of patients retain bladder, bowel or sexual dysfunction long after surgery, irrespective of how promptly they were treated.
Red flags versus 'white flags' - rethinking triage (Todd)
Todd NV • Br J Neurosurg (2017)
Key Findings:
- Systematic review of 7 guideline sources, 37 recommendations
- Up to two-thirds of so-called 'red flags' actually describe late, often irreversible CES ('white flags' of defeat)
- Only ~32% of features were true early warning signs that allow avoidable damage to be prevented
- Calls for low-threshold MRI as part of triage at the district general hospital
Clinical Implication: Reframes red-flag teaching: waiting for saddle anaesthesia or painless retention means waiting for damage already done. The exam-relevant message is early scanning of suspicious back pain, not absolute clinical certainty.
BASS / SBNS national standards for suspected CES
British Association of Spine Surgeons & Society of British Neurological Surgeons • Standards of care for suspected and confirmed CES (2018)
Key Findings:
- Emergency MRI mandatory for suspected CES, day or night, where the patient presents
- Confirmed CES should be transferred and decompressed on an emergency basis
- No arbitrary hour limit - operate as soon as safely feasible
- Meticulous documentation of bladder, bowel, perineal and DRE findings is mandatory
Clinical Implication: Joint UK national standard. Emphasises emergency imaging, networked transfer pathways and documentation given that delayed diagnosis is the leading source of spinal litigation.
Controversies and Areas of Uncertainty
Does the exact hour matter?
Retrospective meta-analyses (Ahn 2000, DeLong 2008) suggest benefit from decompression within 48h and a graded relationship with timing. The largest modern prospective cohort (Woodfield/UCES 2022) found no association between time to surgery and 1-year disability or urinary outcome. The likely truth: timing matters most for patients still CES-I, whilst once CES-R is established the damage is largely fixed.
Scan-negative CES
A majority of emergency MRIs for suspected CES show no compressive lesion. Operating on imaging without correlation, or conversely dismissing genuine early CES, are both errors. Imaging must match the clinical picture.
The 'white flag' problem
Todd (2017) argues many classic red flags (painless retention, established saddle anaesthesia) are signs of late, irreversible CES. Triaging on these alone guarantees late presentation; earlier, subtler symptoms should trigger MRI.
Out-of-hours operating
Decompression at night by a fatigued team without the full set of staff and equipment may add morbidity (a point Gleave and Macfarlane raised). "As soon as safely possible" balances urgency against operating under suboptimal conditions; many networks transfer to a 24/7 spinal centre rather than operate locally at 3am.
Long-term Outcomes and Complications
Long-term Outcomes by CES Type
Surgical Complications:
- Wound infection (1-2%)
- CSF leak/dural tear (2-5%)
- Haematoma requiring return to theatre (rare)
- Recurrent disc herniation (5-10%)
- Wrong level surgery (rare but documented)
Guidelines, Registries & Global Practice
Global epidemiology
- Incidence approximately 1-3 per 100,000 population per year; roughly 0.04% of low back pain presentations and around 2-6% of lumbar disc operations.
- Most common cause is a large central lumbar disc herniation (L4/5 then L5/S1); other causes include tumour (primary or metastatic), epidural abscess, spontaneous or post-operative epidural haematoma, spinal stenosis decompensation and trauma.
- True compressive CES is confirmed on only about 30-40% of emergency MRIs performed for suspected CES, so a high false-positive clinical rate is expected and acceptable.
Society Guidance Compared
Registry and audit notes
- CES is not an arthroplasty/implant condition, so there is no implant registry; instead, national audit data (e.g. the UK UCES prospective cohort) provide the best contemporary outcome benchmarks.
- Across these datasets, median time from symptom onset to surgery is measured in days rather than hours, and only about a third of patients reach theatre within 48 hours - a reminder that real-world pathways lag behind the textbook ideal.
High- vs limited-resource practice variation
- High-resource settings: 24/7 MRI access, dedicated spinal on-call rotas and rapid inter-hospital transfer allow same-day decompression.
- Limited-resource settings: MRI may be unavailable out of hours, so CT myelogram or even clinical judgement with urgent referral becomes necessary; transfer distances and theatre availability commonly delay surgery, increasing the proportion presenting as CES-R. Early urinary catheterisation and intermittent self-catheterisation teaching remain universally available and important interim measures.
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
CLINICAL SCENARIOAdvanced
Classic CES Presentation
CLINICAL PROMPT
"A 45-year-old man presents to ED at 2am with severe back pain and bilateral sciatica. He mentions he hasn't passed urine since the morning (16 hours ago) but 'doesn't feel the need to go'. DRE reveals reduced anal tone. What do you do?"
PRACTICAL APPROACH
This is a classic presentation of **Cauda Equina Syndrome**.
**Immediate Actions:**
1. **Clinical Assessment:** Determine if retention is present - palpate bladder, perform bladder scan. He has painless retention and lost sensation, indicating **CES-R (Retention)**.
2. **MRI:** Request **Emergency MRI Lumbar Spine** immediately. Do not wait for the morning - this is a surgical emergency (hospital protocol dependent, but clinically this requires urgent imaging).
3. **Preparation:** Keep nil by mouth, provide analgesia, catheterise if retention confirmed (document volume for medico-legal purposes).
**MRI confirms large central disc at L4/5.**
**Management:**
- **Consent:** High risk of permanent bladder/bowel/sexual dysfunction despite surgery. Surgery attempts to halt progression and aid recovery.
- **Surgery:** **Emergency Decompressive Laminectomy and Discectomy**.
- **Timing:** "As soon as safe". If team and theatre available at night, proceed. If not, first on morning list (within hours).
- **Post-op:** Monitor voiding trials (TWOC). Repeat MRI if new symptoms develop.
**Prognosis Discussion:**
- Since he is already CES-R (painless retention), his prognosis for full bladder recovery is guarded (approximately 50-60% have permanent issues).
- If he was CES-I, I would emphasise even greater urgency to prevent progression to CES-R.
KEY CLINICAL POINTS
Painless retention = CES-R (poor prognostic sign)
Reduced anal tone = S2-S4 compromise
MRI is mandatory emergency investigation
Decompress ASAP (aim within 24-48h of symptom onset)
COMMON PITFALLS
Sending home for outpatient MRI in morning (potential negligence)
Failing to check anal tone and sensation
Not documenting bladder volume pre-catheterisation
Promising full recovery - outcomes are guarded in CES-R
FURTHER QUESTIONS
"What defines the difference between CES-I and CES-R?"
"Describe the micturition reflex and which spinal levels control it"
"Which disc levels are most commonly affected and why?"
CLINICAL SCENARIOChallenging
Early CES-I Recognition
CLINICAL PROMPT
"A 38-year-old woman presents with 3 days of worsening back pain radiating to both legs. She mentions her bladder 'feels strange' - she has to strain to start urinating and doesn't feel like she empties fully. On examination, she has reduced perineal sensation but intact anal tone. What are your concerns?"
PRACTICAL APPROACH
This presentation is concerning for **CES-I (Incomplete)** - which represents a critical window for intervention.
**Key Features Suggesting CES-I:**
- Bilateral sciatica (red flag)
- Subjective bladder symptoms (altered sensation, straining, incomplete emptying)
- Reduced perineal sensation
- **Crucially:** She retains volitional control - no overflow, can still initiate voiding
**Why This is Critical:**
CES-I represents the **window of opportunity**. She still has bladder control but has early autonomic dysfunction. Urgent decompression can prevent progression to CES-R (retention) with its much poorer prognosis.
**Management:**
1. **Complete examination:** Full neuro exam, DRE (her anal tone is preserved - good sign)
2. **Bladder scan:** Check PVR - if elevated (greater than 200ml), adds urgency
3. **Emergency MRI:** Today, not tomorrow
4. **Surgical planning:** If MRI confirms compression, book emergency theatre
**Counselling:**
- Emphasise urgency - we want to operate before she develops retention
- Good prognosis if decompressed while still CES-I
- Without intervention, high risk of progression to CES-R
**Key message:** Altered bladder sensation with preserved control is CES-I - the time to act is NOW.
KEY CLINICAL POINTS
Straining to void + incomplete emptying = early autonomic dysfunction
Preserved volitional control = CES-I (not yet CES-R)
This is the critical window - surgery can prevent CES-R
Reduced perineal sensation confirms S2-S4 involvement
COMMON PITFALLS
Dismissing symptoms as 'just back pain' without full assessment
Waiting for retention to develop before acting
Not recognising that subtle bladder symptoms precede retention
Failing to perform DRE because patient is young female
FURTHER QUESTIONS
"What is the prognosis for bladder function in CES-I vs CES-R?"
"What surgical approach would you use?"
"How would you counsel this patient pre-operatively?"
CLINICAL SCENARIOChallenging
Scan-negative suspected CES
CLINICAL PROMPT
"A 29-year-old woman presents with 2 days of bilateral leg pain, a feeling of numbness 'down below' and urinary urgency. DRE shows normal anal tone and normal perianal sensation to pinprick. Emergency MRI of the whole lumbar spine shows a small L5/S1 disc bulge but no significant canal compromise and free-floating nerve roots. How do you proceed?"
PRACTICAL APPROACH
This is suspected CES that is **scan-negative** - the clinical picture raised the alarm but MRI does not show a compressive lesion that explains a true cauda equina compression.
**Interpretation:**
- It was entirely correct to image her urgently; a low threshold for MRI is the standard of care and most emergency CES scans are negative.
- Her examination is reassuring: normal anal tone, normal perianal pinprick, and non-dermatomal symptoms. The MRI shows no canal-filling lesion.
- This does not fit compressive CES. Differentials include a functional/scan-negative presentation, early radiculopathy, or a non-spinal cause of urinary urgency.
**Management:**
1. **Do not operate** - there is no surgical target. Operating on a small disc bulge that does not correlate would be wrong.
2. **Reassess** - repeat the focused neurological and perineal examination, and re-take the bladder history (urgency is different from painless retention).
3. **Bladder scan** for post-void residual; if normal, true retention is unlikely.
4. **Safety-net** - clear written advice to return immediately if she develops painless retention, worsening saddle numbness, or loss of anal/perineal sensation.
5. **Onward care** - analgesia, physiotherapy, and referral to neurology or urology if symptoms persist, rather than spinal surgery.
**Key message:** Imaging must correlate with the clinical picture. A negative scan in a patient with normal anal tone and no painless retention does not warrant decompression, but it does warrant careful safety-netting because early CES can evolve.
KEY CLINICAL POINTS
Most emergency MRIs for suspected CES are negative - this is expected, not a failure
Normal anal tone, normal perianal pinprick and a normal post-void residual argue strongly against compressive CES
Urinary urgency is not the same as painless retention with overflow
Surgery requires a compressive lesion that correlates with the clinical picture
COMMON PITFALLS
Decompressing a small incidental disc bulge that does not explain the symptoms
Failing to safety-net a scan-negative patient who could still evolve into true CES
Calling urinary urgency 'retention' without measuring a post-void residual
Dismissing the patient entirely instead of arranging neurology/urology follow-up
FURTHER QUESTIONS
"What proportion of emergency MRIs for suspected CES are positive?"
"How do you distinguish conus medullaris syndrome from cauda equina syndrome?"
"What safety-netting advice would you document for this patient?"
Cauda Equina Quick Reference
Clinical summary
Red Flags (BB-SADDLE)
- •Bilateral sciatica (though can be unilateral)
- •Bladder dysfunction - THE critical symptom
- •Saddle anaesthesia (perineal numbness)
- •Anal tone loss on DRE
- •Deficit in legs (motor/sensory)
- •Disturbance of bowels
- •Lower back pain (severe)
- •Erectile/Sexual dysfunction
Classification (Gleave & Macfarlane)
- •CES-I (Incomplete): Altered bladder sensation, volitional control PRESERVED - URGENT
- •CES-R (Retention): Painless retention, overflow incontinence - POORER PROGNOSIS
Investigation
- •Gold Standard: Emergency MRI Lumbar Spine
- •Bladder scan: PVR greater than 500ml highly predictive
- •CT Myelogram if MRI contraindicated
Management
- •Emergency surgical decompression
- •Laminectomy +/- discectomy
- •Timing: As soon as safely possible (within 24-48h)
- •Goal: Operate while CES-I to prevent CES-R
References
- Gleave JRW, Macfarlane R. Cauda equina syndrome: what is the relationship between timing of surgery and outcome? Br J Neurosurg. 2002;16(4):325-328. PMID 12389883. doi:10.1080/0268869021000032887
- Ahn UM, Ahn NU, Buchowski JM, et al. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. Spine (Phila Pa 1976). 2000;25(12):1515-1522. PMID 10851100. doi:10.1097/00007632-200006150-00010
- DeLong WB, Polissar N, Neradilek B. Timing of surgery in cauda equina syndrome with urinary retention: meta-analysis of observational studies. J Neurosurg Spine. 2008;8(4):305-320. PMID 18377315. doi:10.3171/SPI/2008/8/4/305
- Korse NS, Pijpers JA, van Zwet E, et al. Cauda equina syndrome: presentation, outcome, and predictors with focus on micturition, defecation, and sexual dysfunction. Eur Spine J. 2017;26(3):894-904. PMID 28102451. doi:10.1007/s00586-017-4943-8
- Woodfield J, Hoeritzauer I, Jamjoom AAB, et al. Presentation, management, and outcomes of cauda equina syndrome up to one year after surgery: a multi-centre prospective cohort study. Lancet Reg Health Eur. 2022;24:100545. PMID 36426378. doi:10.1016/j.lanepe.2022.100545
- Todd NV. Guidelines for cauda equina syndrome. Red flags and white flags. Systematic review and implications for triage. Br J Neurosurg. 2017;31(3):336-339. PMID 28637110. doi:10.1080/02688697.2017.1297364
- Korse NS, Veldman AB, Peul WC, Vleggeert-Lankamp CLA. The long term outcome of micturition, defecation and sexual function after spinal surgery for cauda equina syndrome. PLoS One. 2017;12(4):e0175987. PMID 28423044. doi:10.1371/journal.pone.0175987
- British Association of Spine Surgeons and Society of British Neurological Surgeons. Standards of care for established and suspected cauda equina syndrome. 2018.