Metastatic spinal cord compression (MSCC) is a medical emergency which necessitates immediate assessment and treatment.
It can occur as a first presentation of malignancy, or during treatment (representing disease progression or relapse). The two most common cancers to cause spinal cord compression are:
- Myeloma – neoplastic plasma cells proliferate within the marrow itself
- Prostate cancer – metastatic spread to vertebral bodies.
Breast, lung, kidney and thyroid cancers also frequently metastasise to bone. Ultimately, compression of the spinal cord by direct pressure of a growing tumour, or via vertebral collapse, will lead to permanent neurological deficit unless relieved.
In this article, we will review the relevant spinal anatomy and explore an approach to assessment and diagnosis of the patient with metastatic spinal cord compression.
- 5% of cancer patients are affected by MSCC
- In ~20% of those with malignant MSCC, this is the first presentation of the cancer (1)
- Back pain is a near universal component of the presenting complaint, but may be accompanied by a variety of other symptoms
The spinal cord is part of the central nervous system and extends from the base of the midbrain to the conus medullaris at the level of L1, with the cauda equina continuing below this level.
It travels through the vertebral column via the vertebral foramina, in a space termed the spinal canal. Three meningeal layers surround the spinal cord:
- The pia mater closely adheres to the spinal cord
- The subarachnoid space contains CSF and lies between the pia mater and arachnoid mater
- The arachnoid mater closely adheres to the thicker dura mater (or thecal layer) which is separated from the surrounding bone by the epidural space.
The Bilsky score is often used to grade MSCC with reference to how many layers of the meninges are involved.
The spinal cord carries several ascending and descending nerve fibres, which enter/exit the spinal cord at each vertebral level via the intervertebral foramen. These are termed spinal nerves and they leave the spinal cord above the vertebral body from C1-7, with C8 leaving below the C7 vertebra, and all remaining nerves leaving below the vertebral body.
The two main clinical features of metastatic spinal cord compression are back pain and neurological symptoms:
Back pain – the most common initial symptom associated with MSCC. There are features of this pain which tend to distinguish it from many other conditions:
- Doesn’t relieve with rest, even at night – this may result in sleep disturbance
- Exacerbated by exertion – e.g. coughing, straining, moving
- Thoracic spine location – (~70% of all cases present in this spinal region) or Cervical spine
- Multi-level location – i.e. discrete pain felt in c-spine and thoracic spine with pain free regions in between
- In cancer patients progressive or severe and unremitting lumbar spinal pain or localised spinal tenderness
Neurological deficit – the constellation of deficits observed in a case of SCC depends on the exact nature of the compression, as discussed in table 1. However, the main symptoms which can manifest include:
- Muscle weakness – often presenting as an inability to weight bear or ambulate
- Altered sensation
- Bladder or bowel dysfunction – either retention or incontinence
There are four clinical syndrome variants of MSCC, each arising from slight differences in the way a tumour impacts upon spinal anatomy:
|Compression||Sensory Deficit||Motor Deficit||Autonomic function|
|Complete||Sensory level can be identified, with all modalities affected.||Bilateral weakness with signs corresponding to an UMN lesion||Bladder and bowel dysfunction (either retention or incontinence)|
Spinothalamic and corticospinal tracts affected
|Loss of pain and temperature below the level of the lesion sensation||Bilateral weakness with signs corresponding to an UMN lesion||Bladder and bowel dysfunction|
Dorsal column affected
|Loss of vibration and position sense below the level of the lesion||Potentially intact motor function||Intact|
|Contralateral loss of pain and temperature
Ipsilateral loss of vibration and position sense
|Ipsilateral weakness with signs corresponding to an UMN lesion||Intact|
Table 1 – the four clinical syndromes which can occur with spinal cord compression. Adapted from Oxford Handbook of Oncology
“In any cancer patient, the presentation of new onset back pain which is atraumatic should be met with a high index of suspicion. This often includes those who are in remission, as MSCC can represent relapse.”
The differential diagnosis for suspected spinal cord compression includes:
- Benign musculoskeletal conditions such as muscle spasm, osteoarthritis, spinal stenosis
- Epidural abscess
- Brain metastasis resulting in sensori-motor deficit
Another possible diagnosis is cauda equina syndrome. The spinal cord ends at the L1/L2 vertebral level. Nerve roots for L2-S5 run in a bundle below this known as the cauda equine. As spinal nerves contain lower motor neurons only, it is characterised by:
- Flaccid paralysis and hyporeflexia (LMN signs)
- “Saddle” or perianal/sacral anaesthesia
- Bowel and bladder dysfunction
“In a case of suspected cauda equina syndrome, performing an examination of sensation in the perianal area as well as a digital rectal examination to assess anal tone can aid in diagnosis.”
Assessment & Management
After a focused history and examination, the gold-standard investigation of choice is an MRI spine. However, there are practical steps which can minimise risk during the process of ordering an MRI, transferring the patient and waiting for radiological report:
- Keep the patient flat and log roll (until spinal stability assessed by imaging)
- Dexamethasone – this reduces the inflammation and oedema which surrounds cancerous tissue in the hope of reducing the pressure placed on the spinal cord.
- Analgesia – e.g. paracetamol, weak or strong opioids depending on the degree of pain
- VTE prophylaxis – this is crucial as the patient will be immobile and their underlying cancer may contribute as a pro-thrombotic factor
- Blood tests – FBC, U&E, LFT, bone profile
“When prescribing high-dose corticosteroids, always check the patient’s blood sugar and monitor it for elevation. Additionally, always co-prescribe omeprazole to protect the stomach mucosa.”
Surgery is the definitive treatment option and is typically performed by a spinal orthopaedic or neurosurgeon.
- Operability is determined by the findings on MRI and the patient’s general fitness for surgery.
- If this is not opted for initially, close monitoring of lower limb neurological status is key to identify deterioration and reconsideration of surgery
For those deemed unfit for surgery, external beam radiotherapy can be considered.
- Most effective for “radio-sensitive” tumours but it is also often offered when surgery is deemed inappropriate as a palliative measure
- Radiation can induce oedema – patients are warned pain may flare for 24-48 hours after radiotherapy before improving and they may require additional analgesia in this time. Following radiotherapy patients should follow a weaning dose reduction protocol for their corticosteroids but steroid dose can be increased again if symptoms worsen
- Chemotherapy be an alternative treatment to radiotherapy or surgery in very chemosensitive tumours (eg. lymphoma, myeloma, small cell lung cancer).
Best Supportive Care
- This refers to the use of treatments which manage a patient’s symptoms, without attempting to alter the course of disease progression.
- Post-treatment physiotherapy and rehabilitation are also important to help patients maximise limb function.