Definition | Diagnostic criteria | Epidemiology | Risk Factors | Pathophysiology | Presentation | Examination | Differential diagnosis | Investigations | Management | Prognosis | Golden Pearls | Quiz | References/Articles/Resources |
Definitions/Diagnostic criteria (Laycock & Goodall, 2019)
"Syringomyelia (sih-ring-go-my-E-lee-uh) is the development of a fluid-filled cyst (syrinx) within the spinal cord. Over time, the cyst can enlarge, damaging the spinal cord and causing pain, weakness and stiffness, among other symptoms." (Mayoclinic, 2021)
Syrinx (pl. syringes) is the collective name given to hydromyelia, syringomyelia, syringobulbia, syringopontia, syringomesencephaly, and syringocephalus. (Radiopaedia)
"Syringomyelia: cavitary lesion within cord parenchyma, of any cause (there are many); located adjacent to the central canal, therefore not lined by ependyma.
In syringomyelia, there is a dissection of the ependymal lining of the central canal and CSF collection within the cord itself. Therefore, the collection does not have an ependymal lining." (Radiopaedia)
Historically, hydromyelia has been used to describe asymptomatic, benign dilatation (syrinx <6 mm size) with no underling cause.
Epidemiology (Laycock & Goodall, 2019; Emedicine 2021)
Prevalence 1.94–8.2 per 100,000. True prevalence may be greater since magnetic resonance imaging (MRI) use increases incidental detection of asymptomatic syringomyelia.
More common in Men than women
Usually appears in 3rd decade of life
Risk factors (UpToDate 2021)
Chiari malformation type 1
Other congenital malformations (e.g. tethered spinal cord)
Postinfectious
Postinflammatory (transverse myelitis and MS)
Spinal neoplasms (ependyoma and haemangioblastoma)
Post-traumatic
Pathophysiology (Laycock & Goodall, 2019)
Syringomyelia, most commonly associated with the Chiari-I malformation (brain material travelling into the spinal column), can also be idiopathic or secondary to conditions including spinal trauma, infection and malignancy
It is a condition located primarily in the cervical or upper thoracic region - but can occur anywhere from brainstem to conus medullaris.
(Chiari malformation (kee-AH-ree mal-for-MAY-shun) is a condition in which brain tissue extends into the spinal canal. It occurs when part of the skull is abnormally small or misshapen, pressing on brain and forcing it downward.)
Presentation (Laycock & Goodall, 2019)
80% of patients are symptomatic
Onset is usually slow and progressive as the syrinx slowly expands
Occasionally an acute episode such as coughing or sneezing can cause it to more rapidly expand leading to rapid onset symptoms
Symptoms vary from headaches to pain, sensory changes, autonomic, and/or motor dysfunction
Sensory symptoms occur in 90% either unilaterally or bilaterally. Usually in the upper limbs (especially when linked with Chiari 1 malformations)
First signs are often loss of temperature sensation in the hands. This is because there is a dissociated sensory loss that affects decussating (crossing) fibres in the dorsal roots that transmit temperature and pain. It often does not affect soft touch, vibration and proprioception. (See image - classical 'cape-like' distribution of symptoms due to decussating fibres)
Facial symptoms can occur if a cranial syrinx moves cephalad. Lower limb symptoms can occur if it moves caudally involving the lateral spinothalamic tract.
Pain occurs in 50% of patients. 40% have neuropathic features and experience dysaesthesiaes including allodynia, hyperalgesia, burning, pins and needles sensations and numbness.
Pain and numbness are the most common - usually in the 'cape like' distribution. Lower limb involvement is rare.
Pain may also be felt in the inter scapular region and/or central cord pain (Todor & Milhorat, 2000).
Pain is thought to come from compression and damage to the spinothalamic tracts, but this doesn't exactly correlate so this is somewhat unclear.
Commonly the early motor signs are in the hands - loss of intrinsic muscle strength and bulk - thought to be due to compression of anterior horn cells. Extension of syrinx can lead to weak arms with low reflexes. Depending on syrinx site, symptoms may be unilateral or bilateral.
Rarely further extension can cause upper motor neuron signs where corticospinal tracts become involved, and rarely patients may develop bowel and bladder symptoms.
Autonomic nervous system involvement can cause trophic changes, pallor, coldness, glossy skin and hyperhidrosis, neurogenic bladder and Horners syndrome.
Examination (Emedicine, 2021)
Clinical examination should focus on motor and sensory function in the upper and lower limbs, and the trunk. Sensory profiling is evaluated using quantitative sensory testing.
Painless ulcers of the hands are frequent. Edema and hyperhidrosis can be due to interruption of central autonomic pathways.
A complete physical examination may reveal diminished arm reflexes, which are sometimes present early in the clinical course of syringomyelia
Dissociated sensory impairment may be noted.
Differential diagnosis (Emedicine, 2021)
AIDP
Central pontine myelinolysis
Diabetic neuropathy
Hydrocephalus
Cervical Spondylosis
Meningioma
Spinal cord injuries (infection, haemorrhage, infarction, tumours)
Vascular AV malformations
Investigations (Laycock & Goodall, 2019)
Diagnostic confirmation is through spinal cord imaging, the most reliable method being MRI. In most cases the syrinx fluid resembles CSF therefore it is hypointense for T1 and hyperintense in T2 weighted images
(Remember: T1 = Fat white / T2 = Water white)
Computed tomography (CT) myelography can help identify spinal cord tethering and additional tests such as electromyography can reveal pathology if the anterior horn cells of the cervical region are involved.
Treatment (Laycock & Goodall, 2019)
Neurosurgical management addresses the cause. Usually a myelotomy (surgical incision of the spinal cord) and placement of shunt in the syrinx to drain CSF - though this often leads to short-lived benefits and complications.
Other surgical techniques looks to remove blockages (e.g. tumour) and correcting CSF flow.
If it is not worsening and symptoms are not severe, conservative management is best
Unfortunately, while surgery can help motor deficits, it is unclear on the benefit for pain. Surgery may even make it worse.
Multimodal multidisciplinary management of pain is best and neuropathic medications such as anticonvulsants and antidepressants are only partially efficacious.
Opioids are not overly helpful
Intrathecal drug and spinal cord stimulators remains experimental
Prognosis
Unclear. Depends upon the cause and therefore the progression
Golden pearls
Quiz
References / Articles / Resources
Laycock H.C., Goodall I.D. (2019) Syringomyelia. In: Abd-Elsayed A. (eds) Pain. Springer, Cham. https://doi-org.ezproxy.library.sydney.edu.au/10.1007/978-3-319-99124-5_269
Todor, D. R., Mu, H. T., & Milhorat, T. H. (2000). Pain and syringomyelia: a review. Neurosurgical focus, 8(3), 1-6.
UpToDate - Disorders affecting the spinal cord (2021)
Emedicine, 2021 - Syringomyelia
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