MALIGNANT SPINAL CORD COMPRESSION. Kate Hamilton Head of Medical Oncology Ballarat Health Services

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1 MALIGNANT SPINAL CORD COMPRESSION Kate Hamilton Head of Medical Oncology Ballarat Health Services

2 OVERVIEW Background Epidemiology Pathophysiology Diagnosis Investigation Differential Diagnosis Management Prognosis Conclusions

3 BACKGROUND Malignant spinal cord compression is a feared oncological emergency Common complication of cancer Can cause pain May result in irreversible loss of neurological function

4 The natural history of untreated spinal cord compression is relentless & progressive pain, paralysis, sensory loss & sphincter dysfunction Patients with paralysis either at presentation or after treatment have a much shorter life expectancy than ambulatory patients

5 In adults the tip of the spinal cord usually lies at L1 vertebral level Below this the lumbosacral nerve roots form the cauda equina The spinal cord & nerve roots are encased in the thecal sac Spinal cord compression occurs when the thecal sac & it s contents are compressed by an extradural mass The amount of thecal sac compression required for a diagnosis of cord compression is not defined Most specialists consider any radiological evidence of indentation of the thecal sac as diagnostic

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7 EPIDEMIOLOGY OF SCC Incidence of spinal cord compression is unknown Unrecognised/asymptomatic Not investigated Autopsy studies suggest that 5% of patients dying with cancer have malignant SCC

8 CAUSES: Met tumour from any primary site can result in SCC Commonest primaries are: Prostate cancer ~ 20% Breast cancer ~ 20% Lung cancer ~ 20% Other causes include: Renal cell cancer NHL Multiple myeloma/plasmacytoma

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11 PATHOPHYSIOLOGY SOME BASIC ANATOMY: The spinal column is composed of a stack of protective bones (the vertebrae) which enclose the spinal cord The vertebrae consist of the vertebral body anteriorly & the lamina, pedicles & spinous process posteriorly Surrounding the spinal cord is the thecal sac The dura is the outermost layer Between the bone & dura lies the epidural space

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13 At each spinal level nerve roots exit to the side of the spinal cord & behind the vertebral body

14 MECHANICS OF CORD COMPRESSION: 1. Tumour invades the epidural space & compresses the thecal sac: 85-90% are due to met tumour in the vertebral bones (usually the vertebral body) Arterial seeding of bone Seeding via the epidural venous plexus ~10% due to extension of a paraspinal mass into the epidural space via the neural foramen Rarely drop metastases

15 As tumour grows in the epidural space, it tends to take the path of least resistance & encircles the cord/thecal sac obstruction of the venous plexus oedema of the cord & eventually infarction 2. Bone fragments indent cord as the result of fracture Crush fracture may result in retropulsion of bone fragment into the spinal cord itself

16 Mechanism of compression is important Determines the appropriate modality of treatment

17 DIAGNOSIS CLINICAL FEATURES: Early recognition is vital in improving outcome for patients The main determinant of the efficacy of therapy is the patient s neurological status at the start of treatment The goal is to establish the diagnosis before the development of irreversible spinal cord damage

18 Back Pain: Usually the first symptom Present in 83-95% at diagnosis On average, pain is present for up to 7 weeks prior to the onset of other neurological symptoms Pain is often worse on lying down Due to: Nerve compression Distension of epidural venous plexus Disruption of periosteum Pathologic compression fracture May be radicular in nature

19 Motor findings: Weakness is present in 60-85% at diagnosis Distribution depends on the site of compression Tends to produce fairly symmetric lower limb weakness If the cervical spine is involved, the upper limbs may also be weak increasing weakness usually followed by gait disturbance & then paralysis If the lesion is laterally situated then a nerve root may be affected rather than the spinal cord Results in a radiculopathy

20 Sensory findings: Less common than motor changes but still present in the majority of patients at diagnosis Ascending numbness & paraesthesiaes If a spinal sensory level is present it is usually 1-5 levels below the actual level of cord compression Saddle sensory loss is common with cauda equina lesions Sensory loss in a radicular distribution is common

21 Bladder & bowel dysfunction: A late finding Urinary retention Constipation May also result from opiate use May contribute to urinary retention

22 INVESTIGATION Diagnosis of spinal cord compression depends upon the demonstration of a neoplastic mass or bone fragment compressing the thecal sac Careful imaging of the epidural space is mandatory for early diagnosis & optimal treatment Multiple tumour deposits/levels are present in 1/3 rd of patients Imaging MUST include the entire spinal cord/cauda equina

23 The presence of multiple sites of disease significantly affects both prognosis & treatment planning MRI is the imaging modality of choice Accurate evaluation of the extent of disease within the thecal sac & involvement of adjacent soft tissue & bone

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26 CT To evaluate the quality/involvement of adjacent bone CT myelogram For patients unable to have an MRI Rarely used today

27 DIFFERENTIAL DIAGNOSIS Benign causes of back pain Muscle spasm Disc prolapse Spinal canal stenosis Epidural abscess Vertebral body metastasis Not causing cord compression Radiation myelopathy Malignant plexopathy

28 MANAGEMENT Goals of treatment: Pain control Avoidance of complications Preservation of or improvement in neurological function Need to take into account: Patient s burden of disease Life expectancy Patient s values

29 The most important prognostic factor for the ability to walk after treatment for cord compression is the pretreatment neurological status Education of patients, families & health care providers about symptoms requiring immediate investigation may improve outcome Unexplained back pain is of particular concern

30 MANAGEMENT MODALITIES: Glucocorticoids Symptomatic management Definitive therapy: Surgery EBRT (radiotherapy) Stereotactic radiotherapy Chemotherapy

31 SYMPTOMATIC MANAGEMENT: Pain management Anticoagulation Prevention of constipation Chest physio

32 GLUCOCORTICOIDS: Standard management for cord compression Limited evidence however High dose (96mg) v moderate dose (16mg) dexamethasone Cochrane meta-analysis concluded that available data provided insufficient evidence as to the role of corticosteroids & appropriate initial dose Higher initial doses were not associated with better outcomes but were associated with a higher incidence of serious adverse events» George et al Cochrane Database Syst Rev 2008

33 Standard practice would indicate that Dexamethasone should be commenced immediately there is suspicion of cord compression Especially if neurological changes are present Generally recommend 8mg immediately followed by 4mg qid sc = iv = oral Consider gastric protection with a PPI

34 DEFINITIVE THERAPY: choice of treatment modality depends on: Presence/absence of spinal instability Degree of spinal cord compression Extent of vertebral disease Duration of symptoms Relative radiosensitivity of the tumour

35 Assessment of spinal stability vital when deciding on definitive therapy EBRT will not relieve the pain of an unstable spine There is no widely accepted definition of an unstable spine Radiological» Subluxation» Bilateral facet joint destruction Pain on motion

36 SURGERY: Aim is to relieve the pressure on the spinal cord & stabilise the spine Indications for surgery: Spinal instability Bony compression Single site of compression Neurological progression after EBRT Unknown primary site Radioresistant tumours Careful selection of patients is essential: Otherwise fit Minimal burden of disease Life expectancy > 6 months

37 Posterior decompression by laminectomy Little access to the bulk of tumour May further destabilise spine Anterior approach, with curetting tumour out of the vertebral body & epidural space & then stabilisation Significant improvement over EBRT alone Ambulatory rate 84% v 57%» Patchell et al Lancet 366:643, 2005 All patients should receive post-op EBRT

38 EBRT (EXTERNAL BEAM RADIOTHERAPY): Following surgical decompression patients should receive EBRT Patients who are not surgical candidates should receive EBRT alone as their definitive therapy EBRT portal covers: the vertebral body All areas of paravertebral tumour extension with a margin Extends at least 1 vertebra above & below the involved area

39 Generally well tolerated GI toxicity Bone marrow suppression Dexamethasone should be continued Commencement of EBRT may result in a worsening of oedema neurological deterioration Effective for palliation of pain & local tumour control Pretreatment neurological function is the most important predictor of posttreatment outcome Only 1/3 rd of nonambulatory patients regained the ability to walk Of paraplegic patients only 2-6% show any improvement

40 A variety of doses & schedules used Depends on the setting Commonest is 20 Gy in 5# Also see 30 Gy in 10# Longer courses used in patients who are having areas re-irradiated

41 STEREOTACTIC BODY RADIOTHERAPY: Effectiveness of conventional EBRT is limited by the spinal cord s tolerance of radiation SBRT utilises precisely targeted radiation to a tumour while minimising radiation to adjacent normal tissue Allows treatment of small- or moderate-sized tumours in close proximity to the spinal cord High doses can be delivered but normal tissue constraints are always respected

42 SBRT may be particularly useful for relatively radioresistant tumours Renal cell carcinoma Melanoma

43 CHEMOTHERAPY: Suitable for patient s with cord compression due to a chemosensitive malignancy: Hodgkin s disease NHL Germ cell tumours Breast cancer (rarely) Hormonal therapy may be considered (but rarely used) for patients with cord compression but no neurology due to: Breast cancer Prostate cancer

44 PROGNOSIS Median survival is 6 months Neurological status pretreatment: Survival of ambulatory patients 8-10 months Survival of nonambulatory patients 2-4 months For patients who remain nonambulatory after treatment the median survival is 1 month

45 CONCLUSIONS Unfortunately for many situations in which spinal cord compression occurs there is very little if any evidence about the most appropriate management The main thrust in improving outcomes for patients with cord compression is to detect problems early to prevent permanent neurological deficits

46 Patients with any symptoms suggestive of spinal cord compression must be managed to minimise treatment delay: Delay in diagnosis will lead to neurological decline Initiate dexamethasone immediately Immediate discussion with the appropriate oncologist Urgent whole spine MRI Definitive therapy: Surgery EBRT

47 Don t forget to manage: Pain Anticoagulation Especially if bedbound Bowel management Chest physio Especially if paraparetic If the patient has a limited life expectancy comfort measures alone may be appropriate