Deformities of Dural Pouches and Strictures of Dural Sheaths in the Cervical Region Producing Nerve-Root Compression

Abstract

D L'RINC the last decade it has become evident that most cases of sciatica are due to some kind of nerve-root compression, usually the result of a herniation of a lumbar intervertebral disk. Lately attention has been drawn also to the intervertebral disks of the lower cervical spine. I t has been established that a lateral rupture of a disk in this region may produce a compression of the corresponding nerve root in the intervertebral foramen only, without implication of the cord, thus giving rise to the clinical picture of brachial neuralgia (1943: Semmes and Murphey; 6 1944: Bucy and Chenault, 1 Michelsen and Mixter, 4 Spurling and Scoville; 7 1945: Elliott and Kremer; ~ 1946: Eaton, 2 Sahlgren) ~. The isolated involvement of one of the three lowest cervical nerve roots produces an individual clear-cut clinical symptomatology, which enables the surgeon to make a rather accurate preoperative diagnosis as to the level at which the pathologic lesion is to be sought for. During the last four years, in this clinic, several patients presenting signs and symptoms of brachial neuralgia have been operated on in whom the existence of a lateral protrusion of an intervertebral disk was verified at operation. The results of their removal, however, have not been entirely encouraging, partly due, probably, to incomplete decompression or damage of the nerve (luring the operation, and partly, perhaps, to the fact that we have not until recently paid attention to the significance of certain deformities of the dural pouches and dural sheaths which will be described later in this paper. The disks in the cervical region protrude in a dorsal and lateral direction and have a great tendency towards calcification. Simultaneously osteophytes grow out from the edges of the adjoining vertebrae. As a result of the pathologic process the intervertebral foramen is transformed into a narrow osseous canal. The dorsal wall of this canal is formed by the most lateral part of the lamina plus the articular facets, while the ventral wall is formed by the protruded, calcified part of the disk. Consequently it is more adequate, in pathologic cases, to speak of an intervertebral canal instead of an intervertebral forame~. The nerve becomes very tightly fixed in this canal