Bilateral Lower Leg Tingling and Memory Fog as Red Flags for Leptomeningeal Metastasis

Clinical Presentation and Diagnosis

The combination of mental changes and sensorimotor deficits of extremities should raise suspicion for leptomeningeal metastasis (LM) in patients with known cancer, according to the European Society for Medical Oncology 2, 3, 4
Key features of LM include mental changes (such as cognitive fog), radicular signs (including weakness, voiding problems, and cauda equina syndrome), and gait difficulties, as reported by the European Society for Medical Oncology 2, 3, 4
Cerebrospinal MRI without and with contrast is the gold standard for diagnosing LM, with sensitivity 66-98% and specificity 77-97.5%, as stated by the European Society for Medical Oncology 3
Characteristic MRI findings for LM include sulcal enhancement, linear ependymal enhancement, cranial nerve root enhancement, and leptomeningeal enhancing nodules of the cauda equina, according to the European Society for Medical Oncology 3

A detailed neurological examination focusing on pattern of sensory loss, motor weakness, reflexes, and gait is recommended for initial evaluation, as suggested by the European Society for Medical Oncology 2, 3
Assessment for cancer history is crucial, as LM occurs primarily in patients with known malignancy (breast, lung, melanoma most common), according to the European Society for Medical Oncology 2, 4
If cancer history exists, MRI brain with gadolinium AND complete spine MRI with contrast should be performed to evaluate for leptomeningeal disease, as recommended by the European Society for Medical Oncology 3 and the American College of Radiology 6

Glioblastomas typically present at the subcortical gray-white junction with irregular ring enhancement and surrounding vasogenic edema, as described by the American Association of Neurological Surgeons 1

Cognitive decline occurs in up to 90% of patients with brain metastases and 30-40% of patients with primary malignant brain tumors, but this is typically accompanied by other localizing signs, as reported by the Society for Neuro-Oncology 5