Syringomyelia is a condition characterized by the formation and enlargement of fluid filled cavities within the spinal cord
Ollivier d'Angers (1827 ) introduced the term syringomyelia , to describe pathological dilatation of the central canal, after the Greek συριγξ (syrinx), meaning pipe, tube, or channel and μυελος (myelos), meaning marrow
Stillings in 1856, used hydromyelia to describe a dilatation of the central canal, and syringomyelia referred to a cystic cavity separate from the central canal.
To avoid confusion, syringohydromyelia and hydrosyringomyelia have been used to encompass all syrinxes.
Other terms used include progressive posttraumatic cystic myelopathy for post-traumatic syrinxes, and pseudosyringomyelia for cysts occurring in association with tumours, haemorrhage, or necrosis.
In 1891, Chiari’s description of cerebellar malformations included two types (I and II) that were associated with syringomyelia.
In the Chiari type I malformation, 57–65% of patients will develop syringomyelia
Syringomyelia occurs in association with a wide array of congenital and acquired conditions
Most cases are associated with an abnormality at the craniocervical junction or a localized spinal abnormality.
Syrinxes develop in 35% of patients with occult spinal dysraphism, 37–53% of patients with diastematomyelia, and 24% of patients with a tethered cord
Syringomyelia may be seen with virtually any intramedullary tumour
Two thirds of patients with haemangioblastomas and half those with spinal ependymomas have an associated syrinx
Syringomyelia in association with an extramedullary mass is not common but may be seen with neoplasms, cysts, lipomas, cervical disc disease, or spondylosis
Non-traumatic arachnoiditis of the posterior fossa or spine may be associated with syringomyelia
Syringomyelia affects mainly children and young adults, presenting on average before the 29th year
In patients suffering a spinal injury (between one and thirty years after injury) , 21–28% of them will be found to have a syrinx and 30–50% will have a degree of spinal cord cystic change
However, symptomatic syringomyelia is reported in only 1–9% of the spinal injury population
3 primary theories:
A defect in neural tube closure predisposes the development of a syrinx
A disturbance of CSF outflow from the third ventricle, a “pre-syrinx” condition associated with alteration of CSF flow and Valsalva contribution to syrinx expansion
Disturbed blood supply, blockage of perivascular spaces, microhemorrhage with tissue atrophy (autolysis) and physical tissue compromise
PATHOLOGY OF SYRINGOMYELIA
Syrinxes most commonly occur in the low cervical and upper thoracic spinal cord
The syrinx wall is formed by compressed glial tissue surrounded by gliosis
There is evidence of Wallerian degeneration, macrophage infiltration, demyelination in the surrounding white matter, and central chromatolysis and neuronophagia in the grey matter
PATHOLOGY OF SYRINGOMYELIA
Enlargement of perivascular spaces may be present.
Vascular changes may be seen around the syrinx, including hyalinized and thickened vessels, oedema, and haemorrhages.
Syrinx enlargement often affects the crossing spinothalamic tracts.
PATHOLOGY OF SYRINGOMYELIA
Arachnoiditis, or spinal leptomeningeal inflammation and thickening, is often found in conjunction with post-traumatic syringomyelia.
In these cases the dura is firmly affixed to the underlying spinal cord due to a proliferation of collagen in the subarachnoid compartment.
The collagen may form a thick layer embedding the damaged spinal cord remnants, and entrapping nerve roots and vessels.
There is some neovascularisation, osseous metaplasia may occur.
Milhorat et al. have classified syrinxes according to pathological and MRI features into:
d) atrophic cavitations; and e) neoplastic
The first clinical correlation was made by Portal (1804) recognized that progressive sensory loss and paralysis of the limbs of a servant was associated with post-mortem findings of cystic spinal cord cavitation.
Schultze (1882) described the classic dissociated sensory syndrome of pain and temperature loss with preservation of light touch and proprioception
Symptomatic progression is usually gradual.
The commonest initial symptoms include segmental pain and sensory loss
Pain is dull, aching, or burning in nature, reflecting injury to spinothalamic pathways
Compromise of crossing fibers of the spinothalamic tract is one of the earliest clinical features of central cord cavitation.
The pain is often at or above the level of injury, and may be mild or severe, constant or intermittent
Coughing, sneezing, straining, or sitting can exacerbate the pain
Dissociated sensory loss in ascending segments is more common than complete loss of sensation
Progressive asymmetrical weakness tends to occur after the onset of sensory symptoms
Patients will generally report a gradual loss of motor function above the level of previous injury.
There is also evidence that spasticity is worse in spinal cord injury patients with a syrinx than in those without syrinxes
Other associated symptoms and signs include asymmetrical reduction in reflexes, hyperhydrosis, autonomic dysreflexia, Horner’s syndrome, dysphagia, and cardiorespiratory dysfunction
In rare cases, the syrinx can extend into the brain stem and cause bulbar symptoms and signs
Progressive intramedullary cavity expansion can lead to compromise of the anterior horn cell region, resulting in a lower motor neuron presentation in the upper extremity.
Lateral expansion resulting in corticospinalk tract compromise leads to varying degrees of lower extremity spastic paraparesis
Dysautonomia may occr secondary to compromise of sympathetic fibers
Neurogenic arthropathies are seen in the older individual.
Cauda equina syndrome may be the only presentation in patients with cavitation primarily in conus medullaris
Dr Patrick Schweder Department of Paediatric Neurosurgery Starship National Children’s Hospital Auckland, New Zealand
10 years experience in the management of syringomyelia in the paediatric population (180 patients)
Dr Patrick Schweder Department of Paediatric Neurosurgery Starship National Children’s Hospital Auckland, New Zealand 10 years experience in the management of syringomyelia in the paediatric population (180 patients)
The natural history of syringomyelia is not well established
Symptoms may progress for a few years and then remain static, or there may be a slow and intermittent or continuous deterioration
Most patients demonstrate slow progression of symptoms and signs
A few progress more rapidly, sometimes immediately after myelography or from haemorrhage into the syrinx from vessels in the wall of the cavity
In small observational series, 17%–50% of patients remained static without treatment over 10 years or more
There are reports of spontaneous resolution in adults and children, which may be due to decompression of the syrinx into the subarachnoid space