Pathological basis of spinal cord cavitation in syringomyelia: analysis of 105 autopsy cases

Abstract

This report summarizes neuropathological, clinical, and general autopsy findings in 105 individuals with nonneoplastic syringomyelia. On the basis of detailed histological findings, three types of cavities were distinguished: 1) dilations of the central canal that communicated directly with the fourth ventricle (47 cases); 2) noncommunicating (isolated) dilations of the central canal that arose below a syrinx-free segment of spinal cord (23 cases); and 3) extracanalicular syrinxes that originated in the spinal cord parenchyma and did not communicate with the central canal (35 cases). The incidence of communicating syrinxes in this study reflects an autopsy bias of morbid conditions such as severe birth defects. Communicating central canal syrinxes were found in association with hydrocephalus. The cavities were lined wholly or partially by ependyma and their overall length was influenced by age-related stenosis of the central canal. Non-communicating central canal syrinxes arose at a variable distance below the fourth ventricle and were associated with disorders that presumably affect cerebrospinal fluid dynamics in the spinal subarachnoid space, such as the Chiari I malformation, basilar impression, and arachnoiditis. These cavities were usually defined rostrally and caudally by stenosis of the central canal and were much more likely than communicating syrinxes to dissect paracentrally into the parenchymal tissues. The paracentral dissections of the central canal syrinxes occurred preferentially into the posterolateral quadrant of the spinal cord. Extracanalicular (parenchymal) syrinxes were found typically in the watershed area of the spinal cord and were associated with conditions that injure spinal cord tissue (for example, trauma, infarction, and hemorrhage). A distinguishing feature of this type of cavitation was its frequent association with myelomalacia. Extracanalicular syrinxes and the paracentral dissections of central canal syrinxes were lined by glial or fibroglial tissue, ruptured frequently into the spinal subarachnoid space, and were characterized by the presence of central chromatolysis, neuronophagia, and Wallerian degeneration. Some lesions extended rostrally into the medulla or pons (syringobulbia). Although clinical information was incomplete, simple dilations of the central canal tended to produce nonspecific neurological findings such as spastic paraparesis, whereas deficits associated with extracanalicular syrinxes and the paracentral dissections of central canal syrinxes included segmental signs that were referable to affected nuclei and tracts. It is concluded that syringomyelia has several distinct cavitary patterns with different mechanisms of pathogenesis that probably determine the clinical features of the condition.

Natural and surgical history of Chiari malformation Type I in the pediatric population

“…The pathophysiological underpinnings of syrinx formation in children with CM-I has been previously descr ibed, 3,7,[9][10][11]15,18,20,21,26,38 and the presence of a syrinx is considered an indication for surgical intervention at many neurosurgical centers. [12][13][14] A recent meta review of 145 operative series of patients with CM-I (30% of series included patients ≤ 18 years of age) noted an incidence of syringomyelia of 65%, which improved or resolved in 78% of patients.…”

Idiopathic syringomyelia: retrospective case series, comprehensive review, and update on management

“…32 The procedure performed by Gardner and Angel has also been reported to work just as well without closure of the obex. In their review of pathological specimens, Milhorat et al 29 reported that syringes that communicated with the fourth ventricle were mostly found in children with hydrocephalus. This included an association with postmeningitic and posthemorrhagic hydrocephalus along with CMs Type II and Dandy-Walker cysts.…”

“…For noncommunicating syringes, symptoms can include spastic weakness of the lower extremities, paresthesias, or dysesthesias and segmental sensory loss. 29 Bogdanov and Mendelevich 4 reported that the pace of neurological deterioration in syringomyelia is initially rapid but slows down after neurological signs become well established. Table 2 provides a review of the key literature regarding idiopathic syringomyelia.…”

Disproportionately Large Communicating Fourth Ventricle Associated With Syringomyelia and Intradural Arachnoid Cyst in the Spinal Cord Successfully Treated With Additional Shunting

“…3,14) Classification of syringomyelia based on pathological findings and MR imaging includes communicating syringomyelia, noncommunicating syringomyelia, atrophic cavitations, and neoplastic cavitations. 8) Our case was suggested to be communicating syringomyelia based on the findings of MR imaging. The observation that the size of syringomyelia changed according to the fourth ventricle size reinforced this hypothesis.…”