Makindo Medical Notes

Related Subjects: |Spinal Cord Anatomy |Acute Disc Prolapse |Spinal Cord Haematoma |Foix-Alajouanine syndrome |Cauda Equina

A patient presenting with acute low back pain accompanied by disturbances in bladder or bowel function and/or saddle sensory disturbances should be suspected of having Cauda Equina Syndrome (CES). The cauda equina begins at the L2 vertebra and contains lower motor neuron (LMN) motor fibers from the lower lumbar and sacral roots, as well as sphincter control and afferent sensory fibers from the perianal and saddle areas. It lies below the spinal cord, which ends at the L1 vertebra. Upper motor neuron (UMN) signs are typically absent unless the spinal cord itself is also involved, suggesting multiple lesions or a lesion at the filum terminale.

About

• CES results from damage to nerve roots below the L1/L2 level where the spinal cord ends.
• The most common cause is a prolapsed lumbar disc.
• Compression affects both lumbar and sacral nerve roots.
• CES is classified as a compressive radiculopathy, involving nerve root compression.

Aetiology

• Degenerative Spinal Disease/Spinal Stenosis: Narrowing of the spinal canal due to age-related changes.
• Spinal Fractures: Traumatic injuries leading to fractures that compress nerve roots.
• Central Lumbar Disc Herniation (L4/5 or L5/S1): Prolapse of intervertebral discs centrally, pressing on the cauda equina.
• Spinal Metastatic Bone Disease: Cancers spreading to spinal bones causing compression.
• Malignancies: Such as ependymoma of the filum terminale.
• Lipoma with Spina Bifida: Fatty tumors associated with congenital spinal defects.
• Arteriovenous (AV) Malformations and Bleeding: Abnormal blood vessel formations causing hemorrhage.
• Dural AV Fistulas: Abnormal connections between dural arteries and veins.
• Mass Effects: Caused by infections, hematomas, or bone fragments from vertebral insufficiency fractures.

The most common cause of urinary difficulties in patients with lumbar degenerative disorders is pain rather than CES. However, pain does not exclude the possibility of CES.

Clinical Features

• Sudden Bilateral Sciatica and Lower Back Pain: Acute onset of pain radiating down both legs.
• Loss of Bladder Control: Typically presents as overflow incontinence.
• Loss of Anal Sphincter Control: Results in fecal incontinence.
• Flaccid LMN Weakness: Weakness in the legs without UMN signs.
• Sensory Loss: Over the perianal region, saddle area, and genitals.
• Reduced Anal Sphincter Tone: Leads to incontinence.
• Reduced Ankle Jerks: Indicative of LMN involvement.
• No UMN Signs: Plantar responses are typically down-going, and reflexes are normal or reduced unless the spinal cord is also involved.
• Loss of Normal Sexual Function: Due to autonomic and motor nerve involvement.

Anatomy with Vertebrae

Anatomy with Central Disc Compression of Cauda

Patients at High Risk of CES

• Bilateral radicular pain and/or bilateral sensory disturbances.
• Bilateral motor weakness and/or bilateral loss of reflexes.
• Note: These patients do not have CES but are at high risk and should be carefully evaluated.

Investigations

• Blood Tests: Full Blood Count (FBC), Urea & Electrolytes (U&E), Liver Function Tests (LFTs), Erythrocyte Sedimentation Rate (ESR), Calcium levels (Ca), Chest X-Ray (CXR), Prostate-Specific Antigen (PSA), and Myeloma screen.
• Malignancy Screening: Breast examination and mammogram, exclude melanoma if malignancy is suspected.
• Imaging:
  • Ultrasound (USS) of the Bladder: Assesses residual bladder volume post-voiding. Commonly used in emergency settings but its validity in diagnosing CES is not well established.
  • Magnetic Resonance Imaging (MRI): Preferred imaging modality to visualize soft tissue structures, including nerve roots and any compressive masses. Urgent MRI is essential for diagnosis.
  • Computed Tomography (CT) Scan: Used if MRI is unavailable or contraindicated. Provides detailed bone anatomy but is less effective for soft tissue assessment.
  • Plain Radiographs: Not useful for diagnosing CES.
• Neurological Assessment: Comprehensive evaluation of motor and sensory functions, reflexes, and autonomic signs.

The Four Stages of CES

• CESS Suspected:
  • Bilateral radicular pain.
• CES I: Incomplete:
  • Urinary difficulties of neurogenic origin.
  • Altered urinary sensation.
  • Loss of desire to void.
  • Poor urinary stream.
  • Need to strain to micturate.
• CES R: Retention:
  • Neurogenic retention of urine.
  • Painless urinary retention and overflow.
  • Incontinence due to loss of bladder control.
• CES C: Complete:
  • Objective loss of continence and erectile function.
  • Absent perineal sensation.
  • Patulous anus (spread open).
  • Paralyzed insensate bladder and bowel.

Outcomes from Imaging

• Cauda Equina Compression Confirmed: Immediate referral to an appropriate surgical service is necessary.
• Cauda Equina Compression Excluded: If a structural explanation for pain is identified, provide appropriate advice about potential future CES symptoms and consider referral via local spinal pathways during working hours.
• Non-Compressive Pathology Identified: Such as demyelination, requires referral to the appropriate specialist service.
• No Explanation of Symptoms: Develop an appropriate management plan, which may include a cervicothoracic MRI and referral to continence services.

Management

• CES is a devastating condition affecting quality of life, potentially leading to permanent loss of bladder, bowel, and sexual function, along with significant neurological pain. It requires rapid and effective assessment, diagnosis, and treatment to achieve the best possible outcomes. Despite optimal medical care, many patients with CES may suffer long-term disabilities.
• High-Risk Patients Without CES: Patients identified as high risk but not currently exhibiting CES should undergo urgent MRI. If a large central disc prolapse is present, urgent surgery may be necessary to prevent the development of CES.
• Referral and Surgery: Even though few referred as CES will need emergency surgery, escalate all cases for expert opinion. Patients diagnosed with CES need urgent MRI and consultation with a spinal team, aiming for surgery within 48 hours of onset. Procedures may include laminectomy and decompression.
• Rehabilitation: Spinal neurorehabilitation should be initiated to address bowel and bladder function, mobility, and the use of mobility aids, depending on the extent of neurological damage.

References

• Greenhalgh, S., Finucane, L., Mercer, C., & Selfe, J. (2018). Assessment and Management of Cauda Equina Syndrome. Musculoskeletal Science and Practice, 37, 69-74. ISSN 2468-7812.
• Standards of Care for Investigation and Management of Cauda Equina Syndrome.
• Todd, N. V. (Year). An Algorithm for Suspected Cauda Equina Syndrome. [Journal Name], [Volume(Issue)], [Page Numbers].