Intradural extramedullary spinal metastases of non-neurogenic origin: a distinct clinical entity or a subtype of leptomeningeal metastasis? A case-control study.
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.


CONCLUSIONS
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.
‡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.
Steven
S
Knafo
Johan
J
Pallud
Emilie
E
Le Rhun
Fabrice
F
Parker
Gueorgui
G
Iakovlev
François-Xavier
FX
Roux
Philippe
P
Page
Jean-François
JF
Meder
Evelyne
E
Emery
Bertrand
B
Devaux
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D055756:Meningeal Carcinomatosis / Q000175:diagnosis* / Q000401:mortality; D008875:Middle Aged; D009369:Neoplasms / Q000401:mortality / Q000473:pathology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013125:Spinal Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000556:secondary*