Dysesthetic pain in patients with syringomyelia.

Dysesthethic pain is a common complaint of patients with syringomyelia, traumatic paraplegia, and various myelopathic conditions. Because cavitary lesions of the spinal cord can be defined with good resolution by magnetic resonance imaging, syringomyelia provides a potential model for examining anatomic correlates of central pain. In this study, a syndrome of segmental dysesthesias, characterized by burning pain, hyperesthesia, and a variable incidence of trophic changes, was described by 51 of 137 patients (37%) with syringomyelia at the time of clinical presentation. Complete magnetic resonance scans, including axial images, demonstrated extension of the syrinx into the dorsolateral quadrant of the spinal cord on the same side and at the level of pain in 43 of 51 patients (84%). Surgical treatment of syringomyelia resulted in the relief or improvement of dysesthetic pain in 22 of 37 patients (59%), but 15 patients (41%) reported no improvement or an intensification of pain despite collapse of the syrinx. Postoperative dysesthetic pain was often a disabling complaint that responded poorly to medical therapy, including analgesics, sedatives, antiepileptics, antispasmodics, and anti-inflammatory agents. In most cases, there was a gradual improvement of symptoms, although six patients continued to complain of pain 24 to 74 months postoperatively. Prompt but transient relief was achieved in two of two patients with regional sympathetic blocks, and prolonged relief was achieved in one patient by stellate ganglionectomy. We conclude that painful dysesthesias can be caused by a disturbance of pain-modulating centers in the dorsolateral quadrant of the spinal cord and have certain causalgia-like features that respond in an unpredictable way to surgical collapse of the syrinx.

Clinicopathological correlations in syringomyelia using axial magnetic resonance imaging.

Axial magnetic resonance (MR) images of non-neoplastic spinal cord cavities were reviewed in 115 patients with otherwise complete neurological and neuroradiological findings. The variations in axial morphology revealed three distinct cavitary patterns. These patterns were as follows: 1) symmetrically enlarged central cavities (28 patients); 2) central cavities that expanded paracentrally in one or more focal areas (36 patients); and 3) eccentric cavities that were off-center, frequently irregular, and sometimes associated with myelomalacia (51 patients). The radiological patterns of spinal cord cavitation correlated well with recently reported histopathological findings that distinguish simple dilations of the central canal, dilations of the central canal that dissect paracentrally, and primary cavitations of the spinal cord parenchyma (extracanalicular syringes). Like histologically confirmed central canal syringes, MR-defined central cavities were associated with pathogenic factors that affect the dynamics of the cerebrospinal fluid, including hindbrain malformations, hydrocephalus, and extramedullary obstructive lesions. Eccentric cavities resembled extracanalicular syringes and occurred typically with disorders that damage spinal cord tissue (e.g., trauma, infarction, meningitis/arachnoiditis, spondylosis/disc herniation, radiation necrosis, and transverse myelitis). Analysis of clinical findings at the time of MR imaging established the following correlations. 1) Symmetrically enlarged central cavities were asymptomatic or produced nonspecific neurological signs. 2) Central cavities that expanded paracentrally were associated with segmental signs referable to the paracentral component. 3) Eccentric cavities produced various combinations of long tract and segmental signs that could usually be related to the level, side, and specific quadrant of spinal cord cavitation.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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.