Summary

Cauda Equina Syndrome (CES) is a rare but devastating neurosurgical emergency caused by compression of the cauda equina nerve roots (L1-S5) within the lumbar spinal canal. The classic cause is a massive central disc herniation (L4/5 or L5/S1). If untreated, it leads to permanent paralysis, bladder/bowel incontinence, and sexual dysfunction. The definitive management is Emergency MRI followed by Urgent Surgical Decompression (Discectomy/Laminectomy). The critical window for decompression is generally quoted as <48 hours from onset of autonomic symptoms, but earlier is better ("Time is Spine"). [1,2,3]

Key Facts

• Definition: Compression of multiple nerve roots in the cauda equina bucket.
• Most Sensitive Sign: Urinary Retention (Painless). A post-void residual volume >200ml is highly suspicious.
• Most Specific Sign: Loss of Anal Tone (S3/4).
• The "White Flag": Painless urinary incontinence is a sign of established damage (CES-R). At this point, recovery is poor. We must catch them at the "Incomplete" (CES-I) stage (retention/hesitancy).

Clinical Pearls

"Painless is Worse than Painful": A patient screaming in agony with sciatica is usually safe. A patient whose pain has suddenly gone numb and who wet themselves without feeling it is in big trouble.

"Bilateral Sciatica": Most disc prolapses cause unilateral leg pain. If it goes down BOTH legs, the disc is massive and central, threatening the whole cauda bucket.

"Don't Trust the Rectal Exam Alone": Anal tone is subjective. A Bladder Scan is objective. If they have >500ml in the bladder and "didn't feel the urge", that is CES until proven otherwise.

                 SUSPECTED CAUDA EQUINA
               (Red Flags + Back Pain)
                        ↓
             BLADDER SCAN + NEURO EXAM
             ┌──────────┴──────────┐
         NORMAL                 ABNORMAL
    (<200ml, No S/S)       (>200ml or S3-5 Signs)
         ↓                         ↓
    CLOSE OBSERVATION        EMERGENCY MRI
    (Warn Patient)           (Within 4 hours)
                                   ↓
                           COMPRESSION CONFIRMED?
                           ┌───────┴───────┐
                          NO              YES
                           ↓               ↓
                  TREAT CAUSE        URGENT SURGERY
                (Pain/Sciatica)     (Decompression)
                                   (Target <48h)

1. Surgical Decompression

• Operation: Wide Lumbar Decompression / Discectomy.
• Timing:
  • CES-I (Incomplete): IMMEDIATE. (Day or Night). Goal is to save the bladder.
  • CES-R (Retention): URGENT. (Next list). The damage may be done, but decompression prevents worsening.
  • The "48 Hour Rule": Meta-analyses show outcomes significantly worse if decompressed >48h after onset of symptoms.

2. Medical (While waiting)

• Catheterisation: If in retention, insert a catheter to prevent bladder wall damage (atony).
• Analgesia: Sparing opioids if possible (constipation masks history).
• Dexamethasone: High dose steroids ONLY if tumour suspected. Not for discs.

The BASS Standards (2018)

• MRI: Must be performed at the referring hospital BEFORE transfer to spinal center (unless no scanner).
• Scan Timing: "Emergency" basis.
• Surgery: As soon as possible, ideally <24h.

Todd & Todd Meta-Analysis (2002)

• Showed that decompression <48h gave significantly better bladder/bowel recovery compared to >48h.
• Decompression <24h was even better.

What is it?

The nerves at the bottom of your spine are like a horse's tail. A large piece of disc has popped out and is strangling these nerves.

Why is it an emergency?

These nerves control your bladder, bowels, and legs. If we don't take the pressure off quickly, the nerves will die. Once they die, they do not grow back, and you could be left needing a catheter and nappies for life.

The Surgery

We will cut away the bone at the back of the spine to make space, and pluck out the loose disc material.

Recovery

Leg pain usually goes away quickly. Numbness and bladder function take much longer (up to 2 years) to recover, and sometimes recovery is incomplete.

Q1: Differentiate CES-I from CES-R. A:

• CES-I (Incomplete): Altered urinary sensation, loss of desire to void, poor stream, BUT retention is not established and overflow incontinence has not occurred. Control is preserved. Surgery is limb/organ SAVING.
• CES-R (Retention): Established painless urinary retention with overflow incontinence. The bladder is mechanically paralyzed. Surgery is salvage.

Q2: What is the significance of the "Bulbocavernosus Reflex"? A: Squeeze the glans penis (or clitoris) or tug on the Foley catheter: the anal sphincter should contract. Absence of this reflex indicates disruption of the S2-S4 reflex arc (Conus Medullaris or Cauda Equina damage).

Q3: Why is "Bilateral Sciatica" such a strong red flag? A: Standard disc herniations are paracentral, affecting one nerve root (e.g., Left L5). For a disc to hit BOTH L5 roots (Left and Right), it must be a massive CENTRAL herniation. A central mass that big is inevitably compressing the sacral roots (S1-S4) that sit in the middle of the canal.

(End of Topic)