Table 1.

Cauda Equina Syndrome (CES) Classification Systems. *indicates preferred classification system of WFNS Spine Committee.

Tandon and Sankaran classification (1967)16	Type 1- A rapid onset of CES symptoms with no history of back problems Type 2- Acute bladder/CES symptoms with a history of back problems and sciatia Type 3- Long-standing back problems and gradually progressive CES, often with spinal stenosis
Gleave and McFarlane (2002)17	CES-I– Incomplete- this represents urinary difficulties of neurogenic origin such as altered urinary sensation, loss of desire to void, poor stream or the need to strain, but there is still executive control of bladder function and voiding is possible even if difficult. CES-R– Retention- this occurs when the bladder is no longer under executive control and there is painless retention of urine with overflow.
Shi et al (2010)18	Group 1 (preclinical) - low-back pain with only bulbocavernosus reflex (BCR) and ischiocavernosus reflex (ICR) abnormalities and no typical symptoms of CES. Group 2 (early) saddle sensory disturbance and bilateral sciatica. Group 3 (middle): saddle sensory disturbance, bowel or bladder dysfunction, motor weakness of the lower extremity, and reduced sexual function. Group 4 (late): absence of saddle sensation and sexual function in addition to uncontrolled bowel function.
Cauda Scoring System (2018)19	(1) Perineal sensation: Graded 0 to 3, where 0 is absent sensation and 3 is normal perineal sensation (2) Anal tone/squeeze: Graded 0 (absent), 1 (reduced), 2 (present) (3) Bladder function: Graded 0 (painless retention >500 mL or painless incontinence), 1 (straining to pass urine with reduced bladder or urethral sensation), 2 (reduced bladder or urethral sensation with normal micturition control), 3 (urgency or hesitancy, but normal bladder sensation and control), 4 (normal bladder function)
Lavy et al modified CESI/CESR system (2022)*	Suspected CES (CESS): No bladder/bowel/genital/perineal symptoms, but bilateral sciatica or motor/sensory loss in legs (clinical CESS) Or Known large disc herniation on existing MRI (radiological CESS) Symptom only CES (Early CES, CESE)- Normal bladder, bowel and sexual function but some sensory loss in perineum or change in micturition frequency Incomplete CES (CESI)- Alteration in bladder/urethral sensation or function, but maintenance of executive bladder control. ± perineal sensory changes, or sexual or bowel sensory or functional changes CES with urinary retention (CESR)- As in 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