Cauda Equina Syndrome (CES)
Definition
Cauda equina syndrome (CES) is defined by a constellation of symptoms that result from terminal spinal nerve root compression in the lumbosacral region
Key features
- Dysfunction in bladder, bowel or sexual function (Bladder scan 200-400ml is a strong predictive sign)
- Sensory changes in the saddle or perineal area
Other possible symptoms:
- Back pain – with or without sciatica (CES is possible without back or leg pain)
- Sensory changes or numbness in lower limbs (may or may not be present e.g. if L5/S1 disc)
- Lower limb weakness
- Reduction or loss of reflexes in the lower limbs
- Unilateral or bilateral symptoms
Epidemiology
Peak age 44-48
Common presentation:
Twist in flexion, lift and twist e.g. shovelling snow
Genetic collagen abnormalities can make it familial
Recognition delayed for several reasons
- Bowel, bladder and sexual dysfunction are common presentations and can be part of many different conditions
- Patients will not describe symptoms of incontinence or sexual dysfunction due to embarrassment
- Most patients are on morphine so constipated and therefore do not have normal bowel function
- Incontinence / stress incontinence is common in 50-60 year olds
- 6/7 patients with query CES have functional / psychological issues
Three presentations recognised
Type 1 First presentation of lumbar disc herniation, young patient with severe sudden onset pain
Type 2 End point of long history of chronic back pain with or without sciatica
Type 3 Insidious in a more chronic way with slow progress to numbness and urinary symptoms
Classification [1]:
- CES Incomplete – CE with reduced urinary sensation
- CES with retention
CES results in painless retention of urine so when taking the history asks: If they can feel when their bladder is full e.g. “Can you feel when you need to go for a pee?” “Yes, but I cannot get there is more typical of urge incontinence and is not painless”.
Pathology
Why is the cauda equina vulnerable? Cauda nerve roots are unmyelinated so are very sensitive to compression.
Causes
- Usually large central L4/5 +L5/S1 prolapsed disc
- Congenital narrow canal with superimposed stenosis
- Metastatic
- Trauma
- Post-operative haematoma, most commonly occurs within 24 hours post op
Examination
Perform and document examination of motor, sensation, reflexes and sphincter function.
Motor, sensory and reflex components of lumbar and sacral roots [2]
| Nerve level | Motor innervation | Sensory innervation | Reflexes |
| L2 | Hi[ flexors, thigh adductors | Upper thigh | |
| L3 | Quadriceps (knee extensor) | Anterolateral thigh | |
| L4 | Knee extensors and ankle dorsiflexors | Anteromedial calf | Patellar |
| L5 | Toe extension (EHL) | Lateral calf, dorsum of foot | |
| S1,2 | Foot and toe plantar flexors | Lateral side of foot, sole of foot | Ankle |
| S2, S3, S4, S5 | Spincters (S2,3,4 keeps the sh*t off the floor) | Perianal and saddle | Bulbocavernosus |
Assess fine touch (dorsal column) and pin prick (spinothalamic) sensory modalities.
Assess bladder function with pre and post void residual bladder scan. A post void residual of <200ml has a negative predictive value of 97% of CES [3].
Anal sphincter tone quadruple assessment:
- Resting tone
- Voluntary tone ‘squeeze/bear down’
- Involuntary tone ‘cough’
- Bulbocavernosus reflex
Clinical diagnosis of CES is challenging, in the absence of reliably predictive symptoms and signs, there should be a low threshold for investigation with an emergency scan [4].
Imaging
MRI scan is imaging modality of choice – need to visualise up to the conus
CT myelogram is an alternative in the presence of a non-MRI compatible pacemaker or claustrophobia
Treatment
Emergency discectomy
Technically demanding (compared to an elective discectomy) dura is easy to tear or may be ruptured already
Great care is required to avoid further neurological injury
Start off with segmental decompressions and then move to laminectomies if necessary
Consent for the following risks:
- Dural tear
Routine elective discectomy 5%
Emergency 10-15% because:
1. Dura adherent to the ligamentum flavum
2. Retraction
3. Surgeon error in emergency out of hours circumstances
- Persisting bladder and bowel symptoms
- Neurological injury
- Rare relevant complications (Montgomery)
Blindness
Vascular injury, massive bleeding and death
Urgency of Treatment
Urgency of surgery remains controversial
- No strong evidence to suggest definite timing of decompression
- Incomplete CES – some evidence for early decompression, results suggest better improvement in bladder function
- CES-R poor prognosis, no evidence that urgent decompression improves outcome and therefore surgery can wait until day time when operating conditions are more optimal
- Young patients with clear signs -> image then transfer (or transfer then image if 24-hour access to MRI not available) and decompress early
How urgent is decompression – From BMJ review [2]
Factors that have hindered formation of clear evidence
When there is pressure on the cauda equina causing loss of sphincter control it would be understandable to think that the ideal treatment would be to remove the pressure as soon as possible with surgery. Ethical considerations will not allow this hypothesis to be tested by a randomised study, and it is very difficult to prove by literature review or retrospective and cohort studies for two reasons. Firstly, the time of onset of symptoms is difficult to specify. Thus, it is difficult to define the delay between symptoms and surgery. Secondly, any discussion is muddied by many published (mainly retrospective) series containing a mix of patients with both incomplete CES and CES with retention.
The authors of two recent reviews [1,5] argue that only incomplete cauda equina syndrome requires emergency surgery to try to stem the deterioration in bladder function. They conclude that in patients with CES-R the clinical outcome is poor anyway and bears no relation to timing of surgery. Thus, these patients can wait until an elective surgical list the next morning rather than having a potentially difficult operation in the middle of the night, when circumstances are less than optimal.
Two other recently published UK series [6,7] have found that outcome is independent of the timing of surgery. Incontinence at presentation is a poor prognostic feature in the largest prospective series [7].
Ahn (2000) conducted a meta-analysis that is widely quoted and suggests that intervention less than 48 hours after the onset of symptoms will produce a better outcome than intervention delayed for longer than this [8]. The data included in this meta-analysis have been selectively re-analysed and suggest that the outcome for both types of cauda equina syndrome (with retention, or incomplete) is better with interventions within rather than after 24 hours. In a further analysis of the selected retrospective series, the authors noted that of 47 patients having surgery within 24 hours, 41 (87%) recovered normal bladder function, whereas of 46 patients having surgery later than 24 hours, only 20 (43%) recovered normal bladder function [9].
A recent meta-analysis supports the view that early surgery is related to better results with incomplete cauda equina syndrome, but the case for CES-R is less certain [10].
BASS Standards of Care for CES [4]
The weight of evidence suggests that loss of function in CES is a continuous process; the
longer the cauda equina nerve roots are compressed, the less good the outcome. There are no safe time thresholds (such as 48-hour ‘‘safe’’ time window by Ahn et al.) [8].
Prognosis
- Patients who have suffered CES essentially have suffered a spinal cord injury and require rehabilitation to aid recovery (bladder retraining).
- Historically CES patients have not received the post injury support that’s spinal cord injury patients have
- Improvement is possible up to one year following decompression
Medicolegal implications
Persisting CES has a devastating effect on personal and social life:
Self-catheterisation
Loss of bowel function and control
Lower limb weakness
Mismanagement is one of the commonest causes for litigation in spinal surgery
Most patients are young to middle aged
Tips
An established referral pathway should be in place
Thorough documentation of history and examination is critical
If discharged from ED make sure that you have clearly explained to the patient a safety net of symptoms to look out for and seek medical attention for and document this discussion
Image with MRI early
References
1 Gleave JR, MacFarlane R. Prognosis for recovery of bladder function following lumbar central disc prolapse. Br J Neurosurg 1990;4:205–9.
2 Lavy C, James A, Wilson-MacDonald J, et al. Cauda equina syndrome. BMJ 2009;338:b936.
3 Venkatesan M, Nasto L, Tsegaye M, et al. Bladder Scans and Postvoid Residual Volume Measurement Improve Diagnostic Accuracy of Cauda Equina Syndrome. Spine (Phila Pa 1976) 2019;44:1303–8.
4 Germon T, Ahuja S, Casey ATH, et al. British Association of Spine Surgeons standards of care for cauda equina syndrome. Spine J. 2015;15:S2–4. doi:10.1016/j.spinee.2015.01.006
5 Todd N V. Cauda equina syndrome: the timing of surgery probably does influence outcome. Br J Neurosurg 2005;19:301–6; discussion 307-8.
6 McCarthy MJH, Aylott CEW, Grevitt MP, et al. Cauda equina syndrome: factors affecting long-term functional and sphincteric outcome. Spine (Phila Pa 1976) 2007;32:207–16.
7 Qureshi A, Sell P. Cauda equina syndrome treated by surgical decompression: the influence of timing on surgical outcome. Eur Spine J 2007;16:2143–51.
8 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;25:1515–22.
9 Jerwood D, Todd N V. Reanalysis of the timing of cauda equina surgery. Br J Neurosurg 2006;20:178–9.
10 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;8:305–20.
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