cervical myelopathy treatmentdegenerative cervical myelopathycervical compressive myelopathycervical stenosis with myelopathytraumatic cervical myelopathyprogressive cervical myelopathysevere cervical myelopathycervical myelopathy surgeryhoffman sign cervical myelopathycervical spine myelopathyacute cervical myelopathycervical disc disease with myelopathy