Detection of occult spinal cord compression with magnetic resonance imaging of the spine

Spinal cord compression (SCC) is the most significant complication due to skeletal metastasis from prostate cancer. The early detection of SCC is essential as the neurological status before treatment is the major determinant influencing outcome. The aim of this investigation was to determine the role of magnetic resonance imaging of the spine in detecting SCC or occult SCC in patients with metastatic prostate cancer with no functional neurological deficit (FND).

A retrospective analysis of the clinical data of 150 consecutive patients with metastatic prostate cancer and no FND, who had MRI of the spine from January 2001 to May 2005, was carried out. 'Overt SCC' on MRI was defined as the involvement or compression of either the spinal cord or the cauda equina by an epidural or intramedullary mass lesion and 'occult SCC' as metastatic disease causing impingement, indentation or loss of definition of the thecal sac, which were considered together for statistical purposes as radiological spinal cord compromise (rSCC).

Twenty-four (16%) patients had overt SCC, whereas 17 (11.3%) patients had occult SCC. Seven patients had rSCC at multiple non-contiguous sites. The significant clinical determinants of rSCC on univariate analysis were extensive bone metastasis (P=0.005) and back pain (P=0.002). On multivariate analysis, both back pain (P=0.012) and extensive bone metastasis (P=0.047) significantly predicted for rSCC.

A significant proportion (27.3%) of patients with metastatic prostate cancer may harbour overt or occult SCC in the absence of FND. MRI of the spine for the early diagnosis of SCC may be considered useful in patients with extensive skeletal metastasis and back pain.