[Proposal for the definition of "foramen magnum syndrome"--foramen magnum tumor and abnormalities].

The clinical appearance of foramen magnum tumor is protean and, even at the stage when serious neurological deficits are present, the lesions are often misdiagnosed as another disease, especially cervical spondylosis and multiple sclerosis, and patients may undergo improper concervative or even surgical treatments. The best guarantee against misdiagnosis, we believed, was to establish a definition of "Foramen Magnum Syndrome" to facilitate the recollection of its peculiar clinical findings. "Foramen Magnum Syndrome" is composed of: 1. Cape distribution of sensory loss; 2. Atrophy of the intrinsic muscles of the hands; 3. Neck or suboccipital pain; 4. Dysesthesia of the hands (numbness, tingling, and cold sensation); 5. Eleventh cranial nerve palsy; 6. Stereoanesthesia. (Remember the mnemonic CANDES or DESCAN) Among these, cape distribution of sensory loss, eleventh cranial nerve palsy and cold dysesthesia (not numbness or tingling sensation) are of great importance for topological diagnosis. We also pointed out the similarities between the clinical picture of syringomyelia and that of the advanced stage of foramen magnum tumor. The syringomyelic syndrome, often seen in Arnold-Chiari malformation and basilar impression, has been attributed to the concurrent syrinx of cervical cord. But the clinical analysis of foramen magnum tumors showed that this is not always true and that compressive lesions at the foramen magnum alone can cause syringomyelic syndrome.