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Pathophysiology of primary spinal syringomyelia.
J Neurosurg Spine. 2012 Nov; 17(5):367-80.JN

Abstract

OBJECT

The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression.

METHODS

To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing.

RESULTS

In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space.

CONCLUSIONS

These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245.

Authors+Show Affiliations

National Institute of Neurological Disorders and Stroke, Surgical Neurology Branch, National Institute of Health, Bethesda, Maryland, USA. heissj@ninds.nih.govNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Intramural

Language

eng

PubMed ID

22958075

Citation

Heiss, John D., et al. "Pathophysiology of Primary Spinal Syringomyelia." Journal of Neurosurgery. Spine, vol. 17, no. 5, 2012, pp. 367-80.
Heiss JD, Snyder K, Peterson MM, et al. Pathophysiology of primary spinal syringomyelia. J Neurosurg Spine. 2012;17(5):367-80.
Heiss, J. D., Snyder, K., Peterson, M. M., Patronas, N. J., Butman, J. A., Smith, R. K., Devroom, H. L., Sansur, C. A., Eskioglu, E., Kammerer, W. A., & Oldfield, E. H. (2012). Pathophysiology of primary spinal syringomyelia. Journal of Neurosurgery. Spine, 17(5), 367-80. https://doi.org/10.3171/2012.8.SPINE111059
Heiss JD, et al. Pathophysiology of Primary Spinal Syringomyelia. J Neurosurg Spine. 2012;17(5):367-80. PubMed PMID: 22958075.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Pathophysiology of primary spinal syringomyelia. AU - Heiss,John D, AU - Snyder,Kendall, AU - Peterson,Matthew M, AU - Patronas,Nicholas J, AU - Butman,John A, AU - Smith,René K, AU - Devroom,Hetty L, AU - Sansur,Charles A, AU - Eskioglu,Eric, AU - Kammerer,William A, AU - Oldfield,Edward H, Y1 - 2012/09/07/ PY - 2012/9/11/entrez PY - 2012/9/11/pubmed PY - 2013/2/12/medline SP - 367 EP - 80 JF - Journal of neurosurgery. Spine JO - J Neurosurg Spine VL - 17 IS - 5 N2 - OBJECT: The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression. METHODS: To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing. RESULTS: In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space. CONCLUSIONS: These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245. SN - 1547-5646 UR - https://www.unboundmedicine.com/medline/citation/22958075/Pathophysiology_of_primary_spinal_syringomyelia_ L2 - https://thejns.org/doi/10.3171/2012.8.SPINE111059 DB - PRIME DP - Unbound Medicine ER -