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Intradural Extramedullary Spinal Metastases of Non-neurogenic Origin: A Distinct Clinical Entity or a Subtype of Leptomeningeal Metastasis? A Case-Control Study

Knafo, Steven MD‡,*; Pallud, Johan MD§,¶,*; Le Rhun, Emilie MD; Parker, Fabrice MD#; Iakovlev, Gueorgui MD**; Roux, François-Xavier MD§,¶; Page, Philippe MD§,¶; Meder, Jean-François MD§,‡‡; Emery, Evelyne MD§§; Devaux, Bertrand MD§,¶; the Club de Neuro-oncologie of the Société Française de Neurochirurgie

doi: 10.1227/NEU.0000000000000132
Research-Human-Clinical Studies

BACKGROUND: Leptomeningeal metastases from carcinoma are still poorly understood.

OBJECTIVE: To better define the management of unique intradural extramedullary spinal metastases (IESM) from solid cancers of non-neurogenic origin, in particular regarding leptomeningeal metastasis (LM).

METHODS: We conducted a retrospective, multicenter, case-control study including 11 patients with IESM matched with 11 patients with LM. Primary endpoint was overall survival; secondary endpoints were diagnostic criteria and prognostic factors.

RESULTS: Descriptive analysis showed a clinically significant difference between IESM and LM patients regarding preexisting neurological deficit (45.5% vs 90.1%, P = .06) and malignant cells in cerebrospinal fluid (0% vs 54.5%, P = .03). The median overall survival was significantly higher for IESM patients (732 days) than for patients with LM (53 days; P < .0002). Multivariate analysis showed that preexisting neurological deficit was a negative prognostic factor for overall survival (hazard ratio: 10.2; 95% confidence interval: 1.88-102; P = .04), in contrast to functional improvement with treatment (hazard ratio: 0.01; 95% confidence interval: 0.00-0.52; P = .04). We propose the following diagnostic criteria for IESM: (1) a solid lesion located within the intradural extramedullary space, (2) the absence of other leptomeningeal lesion seen on full-spine injected magnetic resonance imaging, (3) the absence of malignant cells in cerebrospinal fluid, and (4) a histological confirmation of the metastatic nature of the lesion.

CONCLUSION: The significant difference in survival between IESM and LM suggests that they are 2 distinct evolutions of the metastatic disease. Distinguishing IESM also has therapeutic consequences because patients can benefit from a focal surgical treatment with functional improvement and extended survival.

ABBREVIATIONS: IESM, intradural extramedullary spinal metastases

LM, leptomeningeal metastasis

Department of Neurosurgery, Pitié-Salpétrière Hospital, Université Pierre et Marie Curie, Paris, France;

§Department of Neurosurgery, Sainte-Anne Hospital Center, Paris, France;

University Paris Descartes, Paris, France;

Centre de Lutte contre le Cancer Oscar Lambret, Lille, France;

#Department of Neurosurgery, Bicêtre Hospital, University Paris Sud, Le Kremlin-Bicêtre, France;

**Department of Neurosurgery, Beaujon Hospital, University Paris Diderot, Paris, France;

‡‡Department of Neuroradiology, Sainte-Anne Hospital Center, Paris, France;

§§Department of Neurosurgery, Caen Hospital, Caen, France

Correspondence: Johan Pallud, MD, Service de Neurochirurgie, Hôpital Sainte-Anne, 1 rue Cabanis, 75674 Paris cedex 14, France. E-mail:

* Drs Knafo and Pallud contributed equally to this work.

Received February 13, 2013

Accepted August 01, 2013

Copyright © by the Congress of Neurological Surgeons