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Posttraumatic Syrinx


KEY FACTS

Imaging

  • Fusiform intramedullary hyperintensity tracking cerebrospinal fluid (CSF) signal

    • Myelomalacia precedes overt syrinx formation = “presyrinx state”

  • Cystic expansile cord lesion

    • May appear to be “expansile” lesion, relative finding in presence of cord atrophy

  • Consider cine (“dynamic”) PC CSF flow study if suspected obstruction to CSF flow (e.g., arachnoid adhesions)

Top Differential Diagnoses

  • Gibbs artifact

  • Nontraumatic syrinx

  • Myelitis

  • Myelomalacia

Pathology

  • Current treatment assumes syrinx is related to posttraumatic arachnoid scarring and CSF flow obstruction at trauma level

Clinical Issues

  • Symptoms include spasticity, hyperhidrosis, pain, sensory loss, automotive hyperreflexia

  • Classic presentation: Severe pain unrelieved by analgesics; ascending disassociated sensory loss

  • Surgery reserved from patients with progressive neurological symptoms

    • First-line treatment has moved away from shunting of syrinx to restoring normal CSF flow patterns at traumatic site

      • –

        Untethering of cord

      • –

        Duraplasty

      • –

        Spine realignment or fusion may be added if angulation or stability is problematic

Sagittal images showing extension of syrinx over time into regions of “presyrinx” edema are presented. Initial T2 MR after C3-C4 fusion and prior flexion injury at C5-C6 shows the well-defined syrinx cavity at the C5-C6 level with cord expansion
. T2 hyperintense signal within the cord extends cephalad from the syrinx to the C2 level due to cord edema
.

Sagittal CT myelogram following placement of a syringoperitoneal shunt shows the shunt catheter
within the syrinx cavity, which is decreased in size
.

Follow-up sagittal T2 MR 3 months later shows extension of the syrinx to the C3 level
with slight edema
cephalad to this site. Note the presence of a shunt catheter
, which has not stopped the syrinx progression.

Sagittal T2 MR 6 months later shows expansion of the syrinx at the C3 level
and marked, increased “presyrinx” edema extending cephalad to the medulla
with a small focus of syringobulbia
.

TERMINOLOGY

Abbreviations

  • Post-traumatic syrinx (PTS)

Synonyms

  • Syringomyelia, syringohydromyelia

Definitions

  • Cystic cord cavity that may (hydromyelia) or may not (syringomyelia) communicate with central canal

    • Artificial distinction → syringomyelia is commonly used term

  • PTS implies syrinx formation is related to prior trauma

    • Syrinx may occur in post-trauma patients with complete recovery from trauma, and patients without direct cord injury

  • Cephalad extension to brainstem medulla is termed syringobulbia

IMAGING

General Features

  • Best diagnostic clue

    • Cystic expansile cord lesion with CSF signal intensity on MR

  • Location

    • Rostral to injury site in 81%, caudal in 4%, both directions in 15%

  • Size

    • Average length: 6 cm; range: 5 mm to entire cord

  • Morphology

    • Longitudinal spinal cord cavity with CSF signal/attenuation

    • Frequently has fusiform “beaded” appearance

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