21st June 2023

Malignant spinal cord compression

Overview of malignant spinal cord compression

Malignant spinal cord compression (MSCC), as the name suggests, is the compression of the spinal cord or cauda equina caused by a malignant process. Although more commonly referred to as ‘metastatic spinal cord compression’, there are several mechanisms by which compression can occur and is not always seen in the presence of metastatic disease.

• Direct invasion – a malignant tumour (either primary or secondary) directly invades into the spinal canal causing resultant compression of the cord/cauda equina.
• Vertebral collapse – a malignant process that causes a compromise in the integrity of a vertebra (typically the vertebral body) causing displacement into the spinal canal, resulting in compression. Again, this can be caused by invasion into the vertebrae, or secondary to a metastatic deposit. Bony metastases are radiologically characterised as sclerotic or lytic. Lytic metastases cause demineralisation of the bone and as such, present a higher risk of destabilisation. These should be differentiated from vertebral collapse secondary to osteoporosis as the approach to management will be different. Clinically, this can pose a challenge as a number of treatments can result in bone demineralisation e.g. aromatase inhibitors for breast cancer, LHRH analogues for prostate cancer and steroids in a variety of applications.
• ‘Spinal canal metastases’ – this describes an umbrella term of metastatic disease found within the canal and can be separated by the location within the canal.
  • Extradural – located outside of the dura mater of the spinal cord. This can be secondary to invasion originating from outside of the vertebral canal.
  • Dural/intradural – located within the dura mater. Less common but is seen in the context of ‘drop metastases’ from primary CNS tumours, above the metastasis.
  • Intramedullary metastasis – located within the spinal cord itself. Technically, this would not be classed as malignant spinal cord compression, but the patient may present and be managed in a similar fashion.

Investigation of suspected MSCC

The approach to managing a patient with suspected MSCC should be standardised and the goal of which is to prevent neurological damage and to further promote neurological function. Typical signs and symptoms which may prompt a clinical review include new onset back pain, particularly non-traumatic back pain with radiculopathy (band-like pain), worsened by movement. Other red-flag signs/symptoms include bilateral lower limb weakness, bilateral shooting leg pains, urinary retention (+/- incontinence due to overflow) and faecal incontinence.

Steps to assessment:

• The patient should be maintained on flat bed rest
• A full neurological examination should be performed including cranial nerves and peripheral nerves.
• Assess for spinal tenderness, using a log-roll technique and perform a digital rectal examination to assess for anal sphincter tone.
• 16 mg Dexamethasone should be administered, either as a STAT dose, or 8 mg BD, ideally morning and lunchtime dosing. This should be co-administered with a PPI.
• A whole spine MRI should be requested, specifically stating that the query is to determine the presence of metastatic spinal cord compression. This must be undertaken within 24 hours of a suspected diagnosis.
• Once a determination of MSCC has been confirmed, treatment should be delivered within 24 hours.
• Spinal Instability Neoplastic Score (SINS) should be calculated to determine the stability of the spine.

Management of MSCC

MSCC may be an acute presentation of metastatic disease. In which case, the underlying diagnosis and stage of the cancer should be ascertained.

The nature of treatment is dependent on a number of patient and biological factors. The Gold standard of treatment for the definitive management of MSCC is anterior direct decompression surgery followed by radiotherapy. However, in practice few patients are suitable for surgery. Factors affecting this include a patient’s comorbidities, perioperative morbidity, life expectancy, burden of disease and degree of spinal instability. Typically, those patients who are young, have a good performance status, have few comorbidities, have a good prognosis, have a single site of disease and for whom surgery might be the best method of tissue diagnosis should be considered for surgery.

In whom surgery is not practical or feasible, palliative radiotherapy is the typical treatment of choice. A single fraction of palliative radiotherapy has been shown to be non-inferior to multiple treatments. In some cases, the underlying biology of the malignancy might be conducive to primary systemic therapy as the treatment of choice e.g. high-grade lymphoma or small cell lung cancer. It is also worth considering that in some circumstances if lymphoma is suspected but a tissue diagnosis has yet to be obtained, if the patient has no neurological deficit, a biopsy may be prioritised over the initiation of steroids due to the exquisite sensitivity of high-grade lymphomas to steroid therapy. However, this should be considered on a case-by-case basis.