From the Guidelines
Leptomeningeal enhancement is a significant finding that indicates inflammation or infiltration of the meninges, requiring a thorough diagnostic workup, including cerebrospinal fluid analysis, to identify the underlying cause, which can be infectious, malignant, or inflammatory in nature, and treatment should be tailored accordingly to improve morbidity, mortality, and quality of life outcomes. The diagnostic approach to leptomeningeal enhancement involves a combination of clinical evaluation, imaging studies, and cerebrospinal fluid analysis. According to the most recent guidelines 1, high-quality MRI brain and total spine with and without contrast should be performed at the time of diagnosis and for routine disease monitoring. CSF sampling should also be performed in all patients with suspicious leptomeningeal enhancement to confirm the diagnosis and rule out radiographic mimics. Some key points to consider in the management of leptomeningeal metastases include:
- The use of systemic therapies with CNS bioactivity and blood-CSF barrier permeability should be prioritized in all patients with LM, both to treat active disease and prevent leptomeningeal reseeding following local therapies 1.
- Intrathecal chemotherapies are most effective in patients with thin linear LM deposits and unobstructed CSF flow, and ventricular access devices are preferred over lumbar drug delivery due to ease of administration, enhanced drug circulation, and association with superior survival 1.
- CSF biomarkers with improved sensitivity and potential to guide therapeutic decisions, including rare cell capture techniques and circulating tumor DNA, are available at a limited number of tertiary cancer centers, but require validation and CLIA certification before they can be routinely incorporated into clinical practice 1. The prognosis of leptomeningeal enhancement varies significantly based on the underlying cause, with infectious causes generally having better outcomes than malignant causes when treated promptly. However, with the advancement of modern oncologic care and the development of innovative treatment options, the historical survival benchmark of 2-4 months for patients with leptomeningeal metastases is no longer applicable to all patients, and patient counseling and clinical trial design should be individualized based on cancer- and patient-specific factors 1.
From the Research
Significance of Leptomeningeal Enhancement
The significance of leptomeningeal (pia and arachnoid mater) enhancement can be understood through its association with various neurological conditions. Some key points to consider include:
- Leptomeningeal enhancement (LME) is considered an MRI marker of leptomeningeal inflammation in inflammatory neurological disorders, including multiple sclerosis (MS) 2.
- LME is not specific to MS, occurring frequently in non-MS inflammatory neurologic conditions, such as HTLV-associated myelopathy and HIV infection 3.
- The presence of LME can indicate inflammation-related focal disruption of the blood-meninges barrier and associated scarring 3.
- In the context of leptomeningeal disease (LMD), LME can be a challenge for effective diagnosis and management, with the diffuse nature of LMD posing a challenge for drug delivery systems 4.
- LME can also be associated with neoplastic conditions, such as diffuse leptomeningeal glioneuronal tumor, which can be misdiagnosed as other conditions 5.
Clinical Implications
The clinical implications of leptomeningeal enhancement include:
- The need for early and accurate diagnosis of underlying conditions, such as MS, LMD, or neoplastic diseases 2, 4, 5.
- The importance of considering LME in the context of other clinical and radiological findings to guide treatment decisions 3.
- The potential for LME to be affected by treatment, such as autologous hematopoietic stem cell transplantation (AHSCT) in MS patients 2.
- The need for further research into the pathogenesis and treatment of LMD, including the development of new drug delivery systems and combination therapies 4, 6.