Leptomeningeal metastases, also know as carcinomatous meningitis, refers to the spread of malignant cells through the CSF space. These cells can be originated both in primary CNS tumours (e.g. drop-metastases), as well as from distant tumours that have metastasized (haematogenous spread).
This article has a focus on the brain's subarachnoid space involvement. Please refer on intradural extramedullary metastases for a particular discussion related to the leptomeningeal metastases in the spine. For other intracranial metastatic locations, please refer to the main article on intracranial metastases.
The demographics will follow those of the underlying malignancy.
Clinical presentation is varied, but most commonly includes a headache, spine or radicular limb pain or sensory abnormalities, nausea and vomiting, and focal neurological deficits 3. Meningism is only present in a minority of patients (13% 3).
The primary intracerebral malignancies that may cause metastases to the subarachnoid space are:
- glioblastoma (GBM) and anaplastic astrocytoma
- choroid plexus carcinoma
The vast majority of leptomeningeal metastases originates from a widespread metastatic disease (haematogenic spread). The most common primary sites are:
- T1: usually normal
- T1 C+ (Gd): leptomeningeal enhancement is the primary mode of diagnosis. Scattered over the brain in a 'sugar coated' manner.
- T2: usually normal
- abnormally elevated signal within sulci 2
- can be performed both non-contrast and post contrast, but is slightly less specific if performed post contrast 1
Treatment and prognosis
Untreated leptomeningeal metastases have a poor prognosis with patients usually succumbing within a few months, whereas, with treatment, that time may be extended up to 6-10 months 2-3. Treatment can consist of 3:
- intrathecal chemotherapy
- leptomeningeal inflammation: leptomeningitis
- slow flow in vessels
- propofol, high oxygen tension, subarachnoid blood can all elevate sulcal FLAIR signal
- 1. Singh SK, Leeds NE, Ginsberg LE. MR imaging of leptomeningeal metastases: comparison of three sequences. AJNR Am J Neuroradiol. 2002;23 (5): 817-21. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 2. Singh SK, Agris JM, Leeds NE et-al. Intracranial leptomeningeal metastases: comparison of depiction at FLAIR and contrast-enhanced MR imaging. Radiology. 2000;217 (1): 50-3. Radiology (full text) - Pubmed citation
- 3. Balm M, Hammack J. Leptomeningeal carcinomatosis. Presenting features and prognostic factors. Arch. Neurol. 1996;53 (7): 626-32. Arch. Neurol. (link) - Pubmed citation