Whereas most authors describe deposits of calcium in the cerebrospinal meninges, including psammomas and osteophytes, as of not uncommon occurrence, all are agreed that osteomas and chondromas are rare. Burle and Morel,1 in reporting an osteoma of the dura, quoted Devay as being able to find reports of only ten cases in the literature in 1908, when the latter reported a case at the Société Nationale de Médecine.
In Lewandowsky's Handbuch,2 Flatau made a careful classification of 213 cases of tumor of the spinal cord, using Schlesinger's statistics, but did not mention osteomas. Ernst, in Aschoff's Treatise,3 stated that chondromas are rare but did not mention osteoma. Oppenheim,4 in his large series, did not mention the osteoma, though he spoke of the psammoma as a comparatively rare tumor of the spinal cord. Ziegler5 described psammomas as a calcareous degeneration occurring in sarcoma of the pia.
RAEDER OJ. OSTEOMA OF THE SPINAL ARACHNOID WITH PSAMMOMATOUS DEGENERATION. Arch NeurPsych. 1929;21(5):1079-1086. doi:10.1001/archneurpsyc.1929.02210230093005