Answer of July 2008

 

Clinical History:


A 49-years-old man who had a history of colonic carcinoma complicated by disseminated lymph node metastasis, presented with repeated episodes of loss of consciousness.  Contrast CT brain and EEG were unremarkable.  MRI brain (axial T1W +C, coronal T1W +C, coronal T2W FLAIR) was obtained.


Jul 08 - Pic 1 Jul 08 - Pic 2

Jul 08 - Pic 3 Jul 08 - Pic 4

Jul 08 - Pic 5 Jul 08 - Pic 6

 

Diagnosis:


Leptomeningeal metastasis.


Discussion:


MRI brain showed hyperintense signas filling up the sulci of cerebellum and bilateral cerebral hemispheres near the vertex on FLAIR sequence. Mild leptomeningeal enhancement is demonstrated in the post-contrast coronal T1-weighted imaging. With the clinical context of colonic cancer, the radiologic features were compatible with diffuse leptomeningeal metastasis.

The typical radiographic features of leptomeningeal metastasis are leptomeningeal enhancement, subependymal enhancement and hydrocephalus. These findings are most pronounced on gadolinium-enhanced T1WI and FLAIR sequences than CT.  Contrast enhanced CT scan of the brain is not sensitive in depicting the disease with a false-negative rate of more than 50%.

The survival rate of patients with malignant leptomeningeal metastasis is between 1 to 2 months without treatment. With palliative treatment (radiotherapy and/or intrathecal chemotherapy), survival rate can be increased up to 6-10 months. Early detection of leptomeningeal metastases is not only crucial to the overall prognosis but also allows early institution of appropriate therapy to preserve neurologic function.