MAGNETIC-RESONANCE-IMAGING IN CANCER-RELATED LUMBOSACRAL PLEXOPATHY

Objective: To study the relative utility of computed tomography (CT) a nd magnetic resonance imaging (MRI) of the lumbosacral plexus in patie nts with systemic cancer and plexopathy. Design: In a retrospective st udy, we identified ail patients encountered at Mayo Clinic Rochester b etween 1987 and 1993 with a diagnosis of lumbosacral plexopathy, and w e selected for analysis those with MRT scans of the plexus (an abnorma l finding was not necessary for inclusion) and a clinical and electrop hysiologic appearance consistent with a diagnosis of metastatic lumbos acral plexopathy. Material and Methods: The study group consisted of 3 1 patients (20 men and 11 women), The types of tumor were as follows: prostatic, 10 patients; colorectal, 7; bladder, 3; cervical, 3; and ot her, 8, Eighteen patients had received pelvic radiotherapy before diag nosis of lumbosacral plexopathy, All available MRI scans (in 27 patien ts) were reviewed blinded; the initial imaging report was used if the actual scans mere unavailable (in 4), CT had been done in 22 patients, and results for 16 were available for blinded review, Original report s were available for the other six. Results: Direct involvement of the lumbosacral plexus by tumor was evident on 23 MRI studies, and 6 othe rs showed widespread metastatic disease in the region of the plexus, O n 13 CT examinations, direct involvement of the lumbosacral plexus by tumor was noted, In four patients, MRI findings were abnormal and CT f indings were normal, No patient had abnormal CT findings and normal MR I findings, Conclusion: In this retrospective review, MRI was more sen sitive than CT for diagnosing cancer-induced lumbosacral plexopathy, T hus, use of MRI should be considered in the diagnostic work-up of pati ents with clinical and electrophysiologic evidence of plexopathy and s uspected systemic cancer.