# CIM Case: Cauda Equina Syndrome ## Clinical Scenario **Patient:** 24-year-old male, 150kg security guard **Presentation:** 2-year history of low back pain with bilateral buttock pain, 2-day history of new right leg pain and weakness of right ankle, presented to ED with new urinary symptoms **Relevant history:** Long-standing LBP worsened 1 week ago after lifting at work, progressive bilateral leg symptoms over 48 hours, difficulty initiating urination since this morning, no bowel symptoms, no trauma, no previous spinal surgery **Examination findings:** - Difficulty walking, requires support - Forward flexed posture (antalgic) - Reduced perianal sensation bilaterally (S2-S4 dermatomes) - Reduced anal tone on PR examination - Bulbocavernosus reflex absent - Right ankle dorsiflexion 2/5 (L5), plantar flexion 4/5 (S1) - Left ankle dorsiflexion 4/5, plantar flexion 5/5 - Knee extension 5/5 bilaterally - Hip flexion 5/5 bilaterally - Right-sided positive straight leg raise at 30° - Crossed straight leg raise positive - Reduced sensation right L5 and S1 dermatomes - Bilateral reduced ankle reflexes - Post-void bladder scan shows 450mL residual urine --- ## Investigations Provided ### Laboratory Results | Test | Result | Normal Range | Interpretation | |------|--------|--------------|----------------| | Hb | 152 g/L | 130-180 g/L | Normal | | WCC | 7.8 ×10⁹/L | 4-11 ×10⁹/L | Normal | | Platelets | 289 ×10⁹/L | 150-400 ×10⁹/L | Normal | | ESR | 6 mm/hr | <15 mm/hr | Normal (no infective/inflammatory cause) | | CRP | 2 mg/L | <5 mg/L | Normal | | Creatinine | 92 μmol/L | 60-110 μmol/L | Normal | | Coagulation | Normal | - | Safe for surgery | ### Imaging **Image 1: MRI Lumbar Spine (performed urgently at 1am)** **MRI findings:** - Large central and right paracentral disc herniation at L4-L5 - Disc fragment measures approximately 15mm × 12mm - Severe compression of the cauda equina - Complete effacement of thecal sac at L4-L5 level - Nerve roots displaced and compressed - Moderate L5-S1 disc degeneration with annular bulge (no prolapse) - No epidural collection or haematoma - No tumour or fracture **Sequences:** - T1-weighted: Demonstrates disc material isointense to native disc - T2-weighted: Compressed CSF signal, loss of normal "horse tail" appearance - STIR: No cord oedema (conus at L1 - normal) - Axial images: Confirm central and right-sided compression ## Questions & Model Answers **Definition:** Cauda equina syndrome (CES) is compression of the lumbar and sacral nerve roots below the conus medullaris (which ends at L1-L2), resulting in characteristic lower motor neuron findings affecting bladder, bowel, and sexual function, as well as lower limb weakness and sensory loss. **Key Clinical Features:** **Cardinal Features (Red Flags):** | Feature | Description | Root Level | |---------|-------------|------------| | **Bladder dysfunction** | Retention (most common), incontinence | S2-S4 | | **Bowel dysfunction** | Faecal incontinence, loss of anal tone | S2-S4 | | **Saddle anaesthesia** | Perineum, buttocks, inner thighs | S2-S4 | | **Sexual dysfunction** | Loss of erection in males | S2-S4 | | **Bilateral leg symptoms** | Weakness, numbness | Multiple roots | **History to Elicit:** | Question | Significance | |----------|--------------| | "Any difficulty passing urine?" | Urinary retention (early sign) | | "Any leaking of urine?" | Overflow incontinence (late sign) | | "Any numbness around your bottom?" | Saddle anaesthesia | | "Any bowel accidents?" | Faecal incontinence | | "Any problems with erections?" (males) | Sexual dysfunction | | "Any weakness in both legs?" | Bilateral motor involvement | **Examination to Perform:** | Examination | Findings in CES | |-------------|-----------------| | **Perianal sensation** | Reduced or absent S2-S4 | | **Anal tone (PR)** | Reduced or absent | | **Bulbocavernosus reflex** | Absent (S2-S4 arc disrupted) | | **Post-void residual** | >100mL suggests retention | | **Lower limb neurology** | LMN signs: weakness, areflexia | **This Patient Has:** - Urinary retention (450mL residual) - Reduced perianal sensation - Reduced anal tone - Absent bulbocavernosus reflex - Bilateral leg weakness (right > left) **Diagnosis: CAUDA EQUINA SYNDROME** - surgical emergency > **Consultant Tip:** Always ask about bladder function in any patient with LBP. Urinary retention is often the earliest sign of CES. Post-void residual >100mL is significant. **Classification of CES:** **1. Timing Classification (Gleave & MacFarlane):** | Type | Definition | Clinical Features | |------|------------|-------------------| | **CES-Incomplete (CES-I)** | Early stage, partial loss | Urinary difficulties (hesitancy, reduced sensation), reduced perianal sensation, may not have retention | | **CES-Retention (CES-R)** | Late stage, complete loss | Painless urinary retention, overflow incontinence, absent perianal sensation | **Prognostic Significance:** | Type | Prognosis | Recovery of Bladder Function | |------|-----------|------------------------------| | **CES-I** | Better | 80-90% regain normal function if decompressed early | | **CES-R** | Worse | Only 50-60% recover bladder function | **2. Timing from Symptom Onset:** | Timing | Bladder Outcome | |--------|-----------------| | Surgery <24 hours | Best outcomes | | Surgery 24-48 hours | Intermediate | | Surgery >48 hours | Poorest outcomes | **This Patient:** - Has urinary retention (450mL residual) - Has reduced (not absent) perianal sensation - May be transitioning from CES-I to CES-R **Classification: CES-Retention (CES-R)** - this is a surgical EMERGENCY **Why Classification Matters:** | Factor | CES-I | CES-R | |--------|-------|-------| | **Urgency** | Urgent (within 24-48 hrs) | Emergency (immediate) | | **Operating list** | Next available | Interrupt current list | | **Counselling** | Good prognosis | Guarded prognosis | | **Medico-legal** | Standard | Heightened scrutiny | **IMPORTANT: CES-I Can Progress to CES-R** Patients with CES-I must be monitored closely or operated urgently as they can deteriorate to CES-R at any time. > **Consultant Tip:** Document the exact time symptoms started and the exact time of surgery. The transition from CES-I to CES-R is a critical event that affects prognosis and has medico-legal implications. **Causes of Cauda Equina Syndrome:** | Category | Causes | |----------|--------| | **Disc prolapse** | Most common (70%), usually massive central herniation | | **Tumour** | Metastases, primary (myxopapillary ependymoma, schwannoma) | | **Trauma** | Fracture-dislocation, burst fracture | | **Infection** | Epidural abscess, discitis | | **Haematoma** | Epidural haematoma (spontaneous or post-procedure) | | **Stenosis** | Severe central stenosis (rare as isolated cause) | | **Iatrogenic** | Post-surgical (haematoma, CSF leak, hardware) | **Disc Prolapse Characteristics Causing CES:** | Feature | Typical CES Disc | |---------|------------------| | **Location** | Central or paracentral | | **Size** | Large (>10mm) | | **Level** | L4-L5 most common, then L5-S1 | | **Type** | Sequestrated or extruded | **MRI Interpretation:** **This Patient's MRI:** | Finding | Significance | |---------|--------------| | Large L4-L5 disc herniation (15 × 12mm) | Cause of CES identified | | Central and right paracentral | Explains bilateral symptoms, right worse | | Complete thecal sac effacement | Severe compression | | Nerve root displacement | Direct compression of cauda equina | | No epidural collection | Rules out abscess, haematoma | | No tumour | Confirms disc as cause | | Conus at L1 | Normal (CES not conus syndrome) | **MRI Sequences:** | Sequence | Use | |----------|-----| | **T1-weighted** | Anatomy, disc vs tumour | | **T2-weighted** | CSF (bright), compression visible | | **STIR** | Oedema, infection, tumour | | **Axial** | Confirms location, laterality | | **Gadolinium** | If tumour or infection suspected | **Differentiating from Conus Medullaris Syndrome:** | Feature | CES | Conus Syndrome | |---------|-----|----------------| | **Level** | Below L1-L2 | At L1-L2 | | **Symptoms** | Asymmetric, radicular | Symmetric, perianal | | **Motor** | LMN (flaccid) | Mixed UMN/LMN | | **Reflexes** | Absent | Variable (may have Babinski) | | **Bladder** | Atonic (retention) | Spastic | | **Progression** | Can be gradual | Often sudden | > **Consultant Tip:** Always review the MRI yourself. Look at axial cuts to determine laterality and plan surgical approach. A right paracentral disc may be approached from the right side. **Management: SURGICAL EMERGENCY** **Immediate Actions (in ED):** | Action | Rationale | |--------|-----------| | **Insert urinary catheter** | Decompress bladder, monitor output | | **Document neurological status** | Baseline before surgery | | **Keep NBM** | Prepare for surgery | | **IV access and bloods** | Preoperative preparation | | **Contact on-call spine surgeon** | Immediate escalation | | **Book emergency theatre** | Interrupt current list if necessary | | **Consent** | Discuss risks, uncertain outcome | **Surgical Planning:** | Factor | This Patient | |--------|--------------| | **Timing** | Emergency (tonight/immediately) | | **Procedure** | L4-L5 discectomy | | **Approach** | Posterior, midline or paramedian | | **Side** | Right-sided approach (right paracentral disc) | | **Decompression** | Adequate visualisation of traversing and exiting roots | **Surgical Technique - Discectomy:** | Step | Details | |------|---------| | **Position** | Prone on Wilson frame/Jackson table | | **Level** | Confirm with fluoroscopy | | **Incision** | Midline over L4-L5 | | **Approach** | Subperiosteal muscle elevation | | **Laminotomy** | Partial laminotomy L4, flavectomy | | **Retract thecal sac** | Gently medially | | **Identify disc** | Remove sequestered fragment | | **Explore canal** | Ensure no residual fragment | | **Haemostasis** | Bipolar, haemostatic agents | | **Closure** | Layered closure | **Intraoperative Considerations:** | Issue | Management | |-------|------------| | **Tense dura** | Careful retraction | | **Large fragment** | May require wider decompression | | **CSF leak** | If dura breached - primary repair | | **Residual compression** | May need bilateral approach | **Postoperative Care:** | Issue | Management | |-------|------------| | **Catheter** | Leave in, trial of void at 24-48 hours | | **Neurology** | Monitor closely for recovery | | **VTE prophylaxis** | Mechanical ± chemical | | **Mobilisation** | Early as tolerated | | **Pain** | Multimodal analgesia | > **Consultant Tip:** Document the time of symptom onset, time of diagnosis, time of surgical decision, and time of surgery. This is crucial for prognosis and medico-legal purposes. **Intraoperative CSF Leak (Dural Tear):** **Diagnosis:** - Sudden rush of clear fluid during discectomy - Clear fluid pooling in wound - Dura visibly torn - May see nerve roots **Incidence:** 1-17% of primary lumbar discectomy (higher in revision surgery) **Management of Dural Tear:** **Immediate Actions:** | Action | Purpose | |--------|---------| | **Stay calm** | Controlled management | | **Identify the tear** | Visualise extent | | **Control bleeding** | May obscure repair | | **Complete discectomy** | May need to complete procedure first | | **Primary repair if possible** | Watertight closure preferred | **Repair Technique:** | Method | Indication | |--------|------------| | **Primary suture** | Small, accessible tear, healthy dura | | **Patch graft** | Larger tear, thin dura | | **Fibrin sealant** | Adjunct to repair | | **Muscle/fat graft** | Augment repair | | **Dural substitute** | If patch needed (collagen matrix, etc.) | **Primary Suture Technique:** | Step | Details | |------|---------| | **Suture material** | 5-0 or 6-0 non-absorbable (e.g., Prolene) | | **Technique** | Running or interrupted | | **Needle** | Tapered, non-cutting | | **Watertight closure** | Goal of repair | | **Test repair** | Valsalva manoeuvre | **If Primary Repair Not Possible:** | Scenario | Management | |----------|------------| | **Large defect** | Patch with fascia lata, dural substitute | | **Inaccessible tear** | Fibrin glue, bed rest | | **Root entrapment** | Must release root before closure | **Postoperative Management After Dural Tear:** | Measure | Duration | |---------|----------| | **Flat bed rest** | 24-48 hours (controversial) | | **Adequate hydration** | Maintain CSF production | | **Wound monitoring** | Watch for CSF leak | | **Neurology monitoring** | Root damage may occur | | **Avoid straining** | Stool softeners | **Complications of Dural Tear:** | Complication | Management | |--------------|------------| | **Pseudomeningocele** | Observation, may need repair | | **CSF fistula** | Wound leak - may need repair | | **Meningitis** | Antibiotics, urgent exploration | | **Chronic headache** | CSF hypotension - blood patch | | **Root damage** | From retraction or repair | **Prognosis:** - Most dural tears managed well with primary repair - Long-term outcomes similar to uncomplicated cases if repaired adequately > **Consultant Tip:** Don't panic if you see CSF. Complete the decompression first if safe, then repair the dura. A watertight primary repair with period of flat bed rest usually results in good outcome. **Prognosis in CES:** **Factors Affecting Outcome:** | Factor | Better Prognosis | Worse Prognosis | |--------|------------------|-----------------| | **Type** | CES-Incomplete (CES-I) | CES-Retention (CES-R) | | **Time to surgery** | <24 hours | >48 hours | | **Bladder function preop** | Incomplete retention | Complete retention | | **Duration of symptoms** | Shorter | Longer | | **Severity of compression** | Less severe | Complete cauda compression | **Expected Outcomes by Domain:** | Domain | CES-I (early surgery) | CES-R (late surgery) | |--------|----------------------|---------------------| | **Bladder function** | 80-90% recover | 50-60% recover | | **Bowel function** | 70-80% recover | 50-60% recover | | **Sexual function** | 60-70% recover | 40-50% recover | | **Motor function** | 70-80% improve | 50-60% improve | | **Sensory function** | Variable | Variable | **This Patient's Prognosis:** - CES-R (has retention) - Symptoms 2 days (48 hours) - Surgery planned tonight Prognosis: Guarded - 50-60% chance of bladder recovery - Higher chance of motor improvement - May have permanent deficits **Counselling Points:** **1. What has happened:** - "The disc has ruptured and is pressing on the nerves controlling your bladder and legs" - "This is a serious condition that needs emergency surgery" **2. Surgery:** - "We need to operate tonight to remove the disc pressure" - "The operation is called a discectomy - removing the disc fragment" - "This is done through a small incision in your back" **3. Risks of surgery:** | Risk | Approximate Rate | |------|------------------| | Infection | 1-2% | | Dural tear | 1-5% | | Nerve damage | 1% | | Recurrent disc | 5-10% | | DVT/PE | 1-2% | | No improvement | 10-20% | | Worsening | <1% | **4. Prognosis:** - "Even with surgery, there is no guarantee your bladder will return to normal" - "About 50-60% of patients with your level of symptoms recover bladder function" - "Your leg weakness is more likely to improve than your bladder" - "Recovery takes months - we won't know the final outcome for 12-18 months" **5. If no surgery:** - "Without surgery, you will almost certainly have permanent paralysis and incontinence" - "Surgery gives you the best chance of recovery" **6. Follow-up:** - "You will need a catheter for now - we'll trial removing it after surgery" - "Urology may need to be involved for bladder management" - "Physiotherapy will help with rehabilitation" - "I'll see you regularly to monitor your recovery" **7. Work and lifestyle:** - "You may not be able to return to heavy manual work" - "We'll discuss this once we see how you recover" **Documentation:** - Document the discussion, prognosis, and that patient understands uncertain outcome > **Consultant Tip:** Be honest about prognosis but not nihilistic. Patients with CES-R can still have meaningful recovery. Document your discussion carefully. --- ## Key Teaching Points ### Pattern Recognition **This pattern suggests Cauda Equina Syndrome:** - Low back pain with bilateral leg symptoms - Urinary retention or incontinence - Saddle anaesthesia (perineal numbness) - Reduced anal tone - Absent bulbocavernosus reflex - Large central disc herniation on MRI **Red Flags for CES (MUST Ask/Examine):** | Feature | How to Assess | |---------|---------------| | Bladder function | "Any trouble passing urine?" | | Bowel function | "Any accidents with your bowels?" | | Saddle anaesthesia | Test S2-S4 dermatomes | | Anal tone | Digital rectal examination | | Sexual function | "Any problems with erections?" | ### Critical Management Points 1. **CES is a surgical EMERGENCY** - operate within 24-48 hours, ideally immediately 2. **CES-I vs CES-R determines prognosis** - retention has worse outcomes 3. **Time is critical** - document symptom onset precisely 4. **Large central disc is most common cause** - confirm on MRI 5. **Dural tear is manageable** - don't panic, repair primarily if possible 6. **Prognosis is guarded** - counsel honestly about uncertain outcomes --- ## Common Examiner Follow-ups **Q: "What is the evidence for timing of surgery in CES?"** Evidence for early surgery: - **Ahn et al. (2000):** Better outcomes with surgery <24 hours - **Kohles et al. (2004):** Meta-analysis showed <48 hours better than later - **Todd (2005):** CES-I to CES-R transition is critical event - **British Association of Spine Surgeons (BASS) guidelines:** Surgery as soon as reasonably practicable, ideally within 48 hours of onset Current consensus: - CES-I: Operate within 24-48 hours (urgent) - CES-R: Operate immediately (emergency) - Transition from CES-I to CES-R can occur at any time --- **Q: "What if surgery is delayed due to theatre availability?"** If surgery cannot be performed immediately: - **Document reason for delay** (e.g., theatre in use, surgeon travel time) - **Monitor neurology** closely - any deterioration escalates urgency - **Keep NBM** and ready for theatre - **Inform patient** of situation and reason for delay - **Escalate** to hospital management if needed to access theatre Medico-legal considerations: - Delays in CES surgery are a leading cause of spinal litigation - Every hour of delay should be justified and documented - "Waiting for morning theatre" is not acceptable for CES-R --- **Q: "How do you differentiate CES from conus medullaris syndrome?"** | Feature | CES | Conus | |---------|-----|-------| | Level | Below L1-L2 | At L1-L2 | | Presentation | Often asymmetric | Symmetric, perianal predominant | | Motor findings | LMN only (flaccid) | Mixed UMN/LMN | | Reflexes | Absent | Variable, may have Babinski | | Bladder | Atonic, painless retention | Spastic, may have urgency | | Pain | Severe radicular | Less severe | | Onset | May be gradual | Often sudden | Pure conus syndrome is rare - most lesions at thoracolumbar junction cause mixed picture. --- **Q: "What is your follow-up plan after surgery?"** Follow-up protocol: - **24-48 hours:** Trial of void, remove catheter if able - **1-2 weeks:** Wound check, remove sutures - **6 weeks:** Neurology assessment, return to light activity - **3 months:** Full assessment, physiotherapy review - **6-12 months:** Final outcome assessment If bladder doesn't recover: - Urology referral for long-term management - Intermittent self-catheterisation training - Consider urodynamic studies If motor function doesn't recover: - Physiotherapy for gait training - Consider AFO if foot drop persists - Vocational rehabilitation --- ## Related Topics - Lumbar Disc Herniation - Spinal Stenosis - Spinal Cord Injury - Lumbar Discectomy - Dural Tear Management - Neurogenic Bladder