Symptoms of Cauda Equina Syndrome
The most critical early symptoms are bilateral leg pain or weakness, new bladder difficulties with preserved control, and perineal sensory changes—urinary retention and complete saddle anesthesia are late signs indicating irreversible damage and should never be used as triggers for initial evaluation. 1
Early Warning ("Red Flag") Symptoms
These symptoms demand immediate emergency MRI and neurosurgical consultation:
Bilateral radiculopathy – pain, numbness, tingling, or weakness radiating down both legs below the knee, with 90% sensitivity for detecting cauda equina involvement 1, 2
New bladder symptoms with preserved control – hesitancy, poor stream, urgency, or difficulty initiating urination while still able to void 1
Perineal sensory changes – subjective numbness or tingling in the "saddle" distribution (perineum, buttocks, inner thighs) or objective loss of sensation on examination 1, 2
Progressive motor weakness – worsening strength in both lower extremities, particularly foot dorsiflexion or plantarflexion 1
Severe low back pain – often overshadowing leg pain in the acute setting 1
Late ("White Flag") Symptoms
These indicate established, often irreversible neurological damage:
Painless urinary retention – inability to void despite a distended bladder without discomfort, present in 90% of established cases 2, 1
Complete saddle anesthesia – total loss of sensation in the perineal region rather than partial sensory changes 1
Fecal incontinence – loss of bowel control from sphincter dysfunction 2, 3
Loss of anal tone – decreased or absent rectal sphincter tone on digital examination 3, 4
Patulous anus – visibly relaxed anal sphincter 1
Sexual dysfunction – loss of erectile function or genital sensation 3, 5
Clinical Staging and Prognosis
The timing of symptom recognition directly determines outcomes:
Suspected CES (CESS) – bilateral radiculopathy without objective bladder/bowel dysfunction; early treatment at this stage completely prevents progression and preserves normal function 1
Incomplete CES (CESI) – new bladder symptoms with preserved control plus perineal sensory loss; early decompression yields normal or socially normal long-term bladder, bowel, and sexual function 1
CES with Retention (CESR) – painless urinary retention, complete perineal anesthesia, or fecal incontinence; even with urgent surgery, only 48-93% achieve any improvement, and many require lifelong catheterization and manual fecal evacuation 1
Critical Pitfalls to Avoid
Do not wait for urinary retention before referral – this represents a late sign of irreversible damage and should never be the trigger for initial evaluation 1
Do not dismiss unilateral symptoms – while bilateral findings are classic, symptoms may begin asymmetrically and progress rapidly 3, 6
Do not attribute symptoms to common postoperative findings – in postoperative spine patients, back or leg pain refractory to analgesia with urinary retention should raise immediate suspicion for CES 3
Do not rely on a single symptom – no individual sign has high positive predictive value in isolation, making the constellation of symptoms and emergent MRI essential 1
Do not catheterize before assessing post-void residual volume – this obscures whether the patient is in the incomplete or retention stage 1
Temporal Pattern
Symptoms typically develop gradually over weeks to months, though acute presentations can occur with massive disc herniation 1, 3. The gradual onset often leads to attribution of symptoms to more benign causes, delaying appropriate imaging and intervention 1.