A leptomeningeal metastasis revealed by sciatica.

Meningeal metastatic disease usually occurs as a complication of a brain tumor and is exceptionally isolated in patients with solid tumors. We report the case of a 74-year-old woman admitted for mechanical S1 sciatica refractory to drug therapy. She had been treated for breast cancer three years earlier. Physical findings were pain upon hyperextension of the lumbar spine and absence of the ankle jerks. Analysis of cerebrospinal fluid sampled during an intrathecal glucocorticoid injection showed 1 g/L of protein and 11 normal cells per mm3. Grade 3 L5-S1 spondylolisthesis was seen on plain radiographs, computed tomography scans, and magnetic resonance imaging scans. At that point, the patient developed sphincter dysfunction and motor loss in the left lower limb in the distribution of several nerve roots. Findings were normal from a myelogram and a magnetic resonance imaging study of the brain. A repeat cerebrospinal fluid analysis showed 1.1 g/L of protein and 5 cells/mm3. Because of the discrepancy between the clinical and imaging study findings, the patient was transferred to a neurology department. A third cerebrospinal fluid study showed numerous adenocarcinoma cells, and a repeat magnetic resonance imaging demonstrated a mass in the dural sac opposite L2. A program of monthly intrathecal methotrexate injections was started. A fatal meningeal relapse occurred eight months later.

CONCLUSIONS

This case shows that a leptomeningeal metastasis can cause isolated nerve root pain, and demonstrates the diagnostic value of magnetic resonance imaging and cerebrospinal fluid cytology in patients with atypical symptoms, particularly when there is a history of malignant disease.