Syringomyelia (‘syrinx’ for short) describes a collection of cerebrospinal fluid within the spinal cord.

Syringobulbia is a similar phenomenon in which there is a fluid-filled cavity within the medulla of the brainstem. This is often an extension of the syringomyelia but in rare cases can be an isolated finding.


  • Incidence: 0.30 cases per 100,000 person-years
  • Peak incidence: 30-40 years
  • Sex ratio: 1:1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


Causes include:
  • a Chiari malformation: strong association
  • trauma
  • tumours
  • idiopathic

Clinical features

The classical presentation of a syrinx is a patient who has a ‘cape-like’ (neck and arms) loss of sensation to temperature but preservation of light touch, proprioception and vibration. Classic examples are of patients who accidentally burn their hands without realising. This is due to the crossing spinothalamic tracts in the anterior commissure of the spinal cord being the first tracts to be affected. Other symptoms and signs include spastic weakness (predominantly of the upper limbs), paraesthesia, neuropathic pain, upgoing plantars and bowel and bladder dysfunction. Scoliosis will occur over a matter of years if the syrinx is not treated. It may cause a Horner’s syndrome due to compression of the sympathetic chain, but this is rare.


Investigation requires a full spine MRI with contrast to exclude a tumour or tethered cord. A brain MRI is also needed to exclude a Chiari malformation.


Treatment will be directed at treating the cause of the syrinx. In patients with a persistent or symptomatic syrinx, a shunt into the syrinx can be placed.