Syringomyelia and Related Diseases

Abstract

Syringomyelia is an uncommon medical condition in which a cyst (syrinx) develops in the spinal cord. Untreated, the syrinx will displace, injure and destroy the spinal cord, resulting in neurological deterioration in the affected region of the body. The Chiari I malformation is the most frequent cause of syringomyelia. Symptoms of paralysis, sensory loss and chronic pain usually develop during the second through the fifth decades of life in these patients. Syringomyelia may also develop months to years after trauma or meningitis. The natural history of syringomyelia is typically one of gradual, stepwise neurological deterioration over many years. The objective of surgical treatment of syringomyelia is to eliminate the syrinx and prevent progression of spinal cord dysfunction, known as myelopathy. Syringomyelia usually resolves after surgical treatment that eliminates the effects of the underlying condition by opening the CSF (cerebrospinal fluid) pathways at the foramen magnum or spinal canal.

Key concepts:

  • Syringomyelia is a cyst within the spinal cord that results in dysfunction of the spinal cord, which is known as myelopathy.

  • The fluid within the syrinx is chemically identical to normal cerebrospinal fluid (CSF) when there is an associated condition that obstructs the CSF pathway at the foramen magnum or within the spinal canal.

  • The fluid within the syrinx has a protein content that is in excess to that of normal CSF when the syrinx is associated with a tumour within the spinal cord (an intramedullary tumour).

  • The syrinx injures sensory nerve cell bodies (posterior horn cells) near the centre of the spinal cord and results in loss of sensation, uncomfortable sensations known as dysesthesias and perception of pain in the anatomic region supplied by the sensory nerves.

  • The syrinx injures motor nerves cell bodies (anterior horn cells) near the centre of the spinal cord and results in loss of strength and atrophy in the muscles supplied by those nerves.

  • The syrinx may expand over time to compress the long tracts of neurons that pass to the inferior part of the spinal cord and disrupt their function, resulting in spasticity, paralysis and loss of sensation in the lower extremities.

  • Treatment of syringomyelia requires a surgical procedure that successfully addresses the condition that causes syringomyelia, by opening obstructed CSF pathways or by removing a spinal cord tumour.

  • Successful treatment of syringomyelia arrests the progression of syringomyelia but results in limited improvement in signs and symptoms of spinal cord injury.

  • Because treatment of syringomyelia can prevent disease progression, but cannot restore neurons lost to the disease, early diagnosis and treatment is the key to maintain optimal function.

Keywords: spinal cord diseases; nervous system malformations; cerebrospinal fluid; neurosurgical procedures; paralysis; intractable pain

Figure 1.

Cross‐sectional anatomy of (a) a normal spinal cord in the cervical portion. The sensory nerves for pain and temperature enter the dorsal nerve root and synapse within the dorsal horn before crossing to the other side of the spinal cord and ascending (upward arrow) to the brain. The downward arrow indicates the motor fibres from above that pass through the cervical spinal cord to synapse more inferiorly with the lower motor neurons supplying the muscles of the lower extremities. In (b), as a syrinx develops, cerebrospinal fluid (CSF) enters the spinal cord through the Virchow–Robin spaces around the vascular supply. In (c) the small collections of extracellular fluid within the grey matter have coalesced into a syrinx. (d) The posterior fossa contents and the cervical spinal cord are shown in sagittal as a cross‐sectional view. The subarachnoid space is partially occluded at the foramen magnum, partially entrapping the CSF in the spinal canal and preventing the normal rapid movement of CSF from the head to the spine during the cardiac cycle. The large arrows indicate the inferior movement during cardiac systole of the cerebellar tonsils and medulla on the partially enclosed cervical subarachnoid space. This movement creates elevated waves of pressure in the CSF within the spinal subarachnoid space, which drive the CSF into the spinal cord (as shown in (b)), compress the spinal cord and syrinx and propel the syrinx fluid inferiorly.

Figure 2.

(a) Normal anatomy and flow of cerebrospinal fluid (CSF) in the subarachnoid space at the foramen magnum during the cardiac cycle in a normal healthy volunteer. (b) Obstructed flow of CSF in the subarachnoid space at the foramen magnum resulting in the cerebellar tonsils acting as a piston on the cervical subarachnoid space, creating cervical subarachnoid pressure waves that compress the spinal cord from without and propagating syrinx fluid movement. (c) Relief of the obstruction of the subarachnoid space at the foramen magnum, eliminating the mechanism of progression of syringomyelia. Reproduced from Heiss et al..

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References

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Further Reading

Barnett HJM, Foster JB and Hudgson P (1973) Syringomyelia. In: Walton JN (Series ed.) Major Problems in Neurology, vol. 1. Philadelphia, PA: WB Saunders.

Batzdorf U (ed.) (1991) Syringomyelia: Current Concepts in Diagnosis and Treatment. Baltimore, MD: Williams and Wilkins.

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How to Cite close
Heiss, John D, and Oldfield, Edward H(Feb 2010) Syringomyelia and Related Diseases. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002208.pub2]