leptomeningeaux

Leptomeningeaux, commonly written leptomeninges in English, refers to the leptomeninges, the two innermost membranes that enclose the brain and spinal cord: the arachnoid mater and the pia mater. These membranes lie beneath the dura mater (the pachymeninges) and envelop neural tissue. The subarachnoid space, located between the arachnoid and pia, contains cerebrospinal fluid and blood vessels and serves as a conduit for CSF circulation and exchange of nutrients and waste.

In health, the leptomeninges provide a protective covering and a barrier interface with the CSF. Pathology affecting them can lead to meningitis, an inflammation of the leptomeninges caused by bacteria, viruses, fungi, or parasites. Clinically, meningitis may present with headache, fever, neck stiffness, and altered mental status. Diagnostic workup typically includes analysis of cerebrospinal fluid obtained by lumbar puncture and magnetic resonance imaging with contrast. Findings vary by cause but may include pleocytosis, elevated protein, and, in bacterial infections, low glucose with characteristic meningeal enhancement on MRI.

A related condition is leptomeningeal carcinomatosis, which denotes the dissemination of malignant cells to the leptomeninges from systemic cancers such as breast, lung, or melanoma. This infiltration can cause multifocal neurologic symptoms reflecting widespread meningeal involvement and is typically assessed with CSF cytology and neuroimaging. Management depends on the underlying etiology and may involve antimicrobial therapy, oncologic treatment, or palliative measures; prognosis is generally guarded in leptomeningeal disease.