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Unusual aetiology of malignant spinal cord compression
  1. Jason Boland1,2 and
  2. Adrienne Rennick1
  1. 1Barnsley Hospice, Barnsley, UK
  2. 2Hull York Medical School, University of Hull, Hull, UK
  1. Correspondence to Dr Jason Boland, senior lecturer and honorary consultant in palliative medicine, Hull York Medical School, Hertford Building, University of Hull, Hull HU6 7RX, UK; jason.boland{at}hyms.ac.uk

Abstract

Malignant spinal cord compression (MSCC) is an oncological emergency requiring rapid diagnosis and treatment to prevent irreversible spinal cord injury and disability. A case is described in a 45-year-old male with renal cell carcinoma in which the presentation of the MSCC was atypical with principally proximal left leg weakness with no evidence of bone metastasis. This was due to an unusual aetiology of the MSCC as the renal carcinoma had metastasised to his left psoas muscle causing a lumbosacral plexopathy and infiltrated through the intervertebral disc spaces, initially causing left lateral cauda equina and upper lumbar cord compression, before complete spinal cord compression. This case illustrates the varied aetiology of MSCC and reinforces the importance of maintaining a high index of suspicion of the possibility of spinal cord compression.

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Introduction

Malignant spinal cord compression (MSCC) is a relatively common emergency seen by palliative medicine physicians and oncologists which requires rapid diagnosis and treatment to prevent irreversible spinal cord injury and disability.1 It is most often caused by haematogenous infiltration of the vertebrae and less frequently by direct tumour invasion into the spine or by deposition of tumour cells causing compression of the spinal cord. Metastases to the spinal column occur in 3%–5% of all patients with cancer and may cause pain, vertebral collapse and MSCC. In the USA, 3.4% of patients dying from cancer are hospitalised with MSCC.2

Presentation of MSCC is generally with spinal pain, which may be localised or radicular (including limb radiation), and can be accompanied by numbness or paraesthesia. Weakness might also occur, and in advanced stages bladder and bowel control can be lost (table 1). In a population-based data analysis of over 15 000 cases of MSCC from the USA, the most prevalent underlying diagnoses in patients with MSCC were lung cancer (25%), prostate cancer (16%) and multiple myeloma (11%).2 A Scottish prospective observational study of 319 patients also showed breast cancer to be a common underlying diagnosis.1 In this study, the majority of patients diagnosed with MSCC already had an established diagnosis of cancer (77%), but in 23% of patients MSCC was the first presentation of malignancy.1 At diagnosis, 82% of patients with MSCC were unable to walk or needed assistance. In all, 94% had pain (84% severe pain), which was present for a median duration of 3 months, and had a nerve root distribution in 79%.1

Table 1

Comparison of the main differentiating factors among spinal cord compression, cauda equina compression and peripheral lumbosacral plexopathy

We present and discuss a rare cause of MSCC in a patient with renal cell carcinoma, which metastasised to the psoas muscle and tracked through the intervertebral space to compress the lateral cauda equina and spinal cord.

Case

A 45-year-old male with renal cell carcinoma, lymph node and lung metastases diagnosed 6 months earlier was referred to the hospice with back pain and decreased mobility. Although he had a past medical history of chronic back pain this had significantly increased over the previous week. He was usually independently mobile but his mobility had decreased over the preceding 3 days to such an extent that on presentation he was bedbound. The pain was in his lower back which radiated to his left hip and anterior thigh and was worse at night. He reported that his legs felt cold, but denied pins and needles. There were no urinary symptoms and he had a long history of constipation which was unchanged. He had intermittent stabbing pain in his rectum, which was not related to defecation. Both legs had become increasingly swollen over the previous month.

On examination he had tenderness over his upper lumbar spine. Neurological examination demonstrated normal tone in both legs and no clonus. His left leg was weak proximally with power 2/5 in his hip flexors and 2+/5 in his knee extensors. There was also a mild reduction in power (4/5) in his distal left leg and diffusely (4/5) in his right leg. The left knee reflex was absent and the left ankle reflex was reduced. The right lower limb reflexes were brisk. Both plantar responses were down going. Sensation to light touch was intact with no saddle anaesthesia.

Review of previous chest, abdomen and pelvic CT scans 1 month earlier and a bone scan 3 months earlier showed no evidence of bony disease, but a left psoas metastasis, which along with the focal neurological signs made spinal cord compression an unlikely diagnosis. However, in view of the very high clinical suspicion, an urgent whole spine MRI scan was performed which showed diffuse malignant infiltration of the left psoas muscle, with penetration through the intervertebral disc spaces, causing compression of the spinal cord at L1 and also the left lateral aspect of the superior cauda equina (figure 1). As there was no surgical option he was administered 16 mg dexamethasone daily (commenced on presentation) and five fractions of radiotherapy (which started within 18 h of presentation), but despite this his leg weakness steadily progressed, such that by a week later he had lost all power in both legs. These treatment modalities, along with polymodal pharmacotherapy, have been previously advocated.3 The back pain progressed to involve both legs and increased significantly in intensity. It was initially responsive to oxycodone, pregabalin and oral ketamine, but soon became so severe that he needed duloxetine, clonazepam and subcutaneous ketamine adding and titrating to achieve pain relief. He developed anaesthesia for light touch in the left L1 and L2 dermatomes which further progressed to involve the L3 and L4 dermatomes over the following 2 weeks. He also became incontinent of urine and faeces during this time and required catheterisation and regular bowel intervention.

Figure 1

Spinal cord compression from malignant psoas muscle infiltration. (A) T1 sagittal MRI image showing tumour infiltration through the L1 and L2 intervertebral spaces; (B) T2 transverse (axial) MRI image showing the left renal cell carcinoma, psoas muscle metastasis and tumour invasion into the spinal cord.

Discussion

This patient had an atypical presentation of spinal cord compression which was caused by an unusual aetiology. The diagnosis could have been impeded as he did not have evidence of spinal metastases on recent imaging. By having a high level of suspicion, in view of the rapidly progressive weakness and severity of the back pain, exclusion of MSCC was paramount. Clear goals of care were established and reviewed with the patient and family, and after discussion with the radiologist and oncologist his management was optimised. The mixed clinical presentation and medical need for a definitive diagnosis had to be balanced with transferring a patient with severe pain to the nearest oncology centre.

This is a rare presentation of spinal cord and cauda equina compression secondary to renal cell carcinoma metastasising to the left psoas muscle (causing a lumbosacral plexopathy) which then penetrated through the L1/L2 intervertebral spaces to compress the left lateral aspect of the superior cauda equina and lumbar spinal cord, before causing complete cord compression (table 1). Neoplastic lumbosacral plexopathy is caused by malignant infiltration of the L1–L4 and L5–S5 nerve roots as they traverse the psoas muscle, leading to pain and sensorimotor deficits. However, muscle involvement by cancer is rare as movement, high lactate and low pH inhibit neoplastic infiltration3 and there is only a very limited literature of psoas muscle metastasis from renal cell carcinoma.3 ,4

The management options of spinal cord compression due to tumour penetrating through the intervertebral spaces include surgery, radiotherapy, steroids, opioids, non-steroidal anti-inflammatory drugs and adjuvant drugs for neuropathic pain; muscle relaxants such as benzodiazepines or baclofen may be needed to treat the muscle spasm.3 There has been a previous report of three patients with psoas muscle metastases in non-small cell lung cancer where radiotherapy was effective.5

In this rare cause of spinal cord compression, a detailed history and examination along with a high level of suspicion and urgent investigation enabled rapid diagnosis and treatment, which unfortunately, in this case, did not impact on the patient's functional ability.

Acknowledgments

The authors would like to acknowledge Jane Alty, Neurology SpR, Leeds Teaching Hospitals NHS Trust and Ingrid Jolley, Consultant Radiologist, Sheffield Teaching Hospitals NHS Trust for their assistance with writing the case report.

  • Received 25 September 2012.
  • Revision received 8 February 2013.
  • Accepted 7 March 2013.

References

View Abstract

Footnotes

  • Contributors Both authors have made a substantial contribution to this article.

  • Competing interests None.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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