CLINICAL-SIGNIFICANCE OF DIFFUSE DURAL ENHANCEMENT DETECTED BY MAGNETIC-RESONANCE-IMAGING

This study was performed to determine the clinical significance of dif fuse dural enhancement (DDE) detected by magnetic resonance (MR) imagi ng and to typify enhancing patterns related to inflammatory or metasta tic causes. The authors retrospectively evaluated the clinical, imagin g, and laboratory characteristics of 20 consecutive patients with DDE. Those with DDE and an underlying neoplastic disease (13 patients) wer e compared to 11 consecutive patients with cytological evidence of neo plastic leptomeningeal metastasis evaluated by MR imaging. The DDE was often associated with an underlying malignancy (13 (65%) of 20 patien ts) but it coexisted with leptomeningeal metastasis in only one patien t. Skull metastases were evident in 10 (77%) of 13 patients and crania l nerve palsies in six (46%) of 13. Other causes of DDE were related t o cerebrospinal fluid (CSF) leak or shunting (five (25%) of 20), with or without symptoms of intracranial hypotension, and to dural sinus th rombosis and pachymeningitis. Dural biopsies obtained in two patients with DDE showed a narrow rim of granulation-like tissue adherent to th e dural surface facing the inner skull table. Magnetic resonance subtr action, diffusion, and perfusion studies revealed unique characteristi cs in patients with metastatic causes as compared to those with DDE se condary to CSF leak. None of the patients with proven leptomeningeal m etastasis had DDE, but four of them presented with focal dural enhance ment and two displayed apparent leptomeningeal enhancement. The findin gs indicate that DDE is not a radiographic hallmark of leptomeningeal metastasis in spite of the similarities in clinical manifestations (fo r example, headache and cranial polyneuropathy). Nonetheless, DDE is m ost frequently associated with metastatic malignancies and particularl y with skull metastases and CSF leak. Special MR techniques can discer n the underlying cause and elucidate the disparity in the pathophysiol ogical mechanisms leading to DDE.