Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Perineural Root Sleeve Cyst


KEY FACTS

Terminology

  • Dilatation of arachnoid and dura of spinal posterior nerve root sheath, containing nerve fibers

  • a.k.a. Tarlov cyst

Imaging

  • Occur anywhere along spine

    • Most common in lower lumbar spine and sacrum

    • S2 and S3 nerve roots most commonly involved

  • Thin-walled cyst mass

    • Contents follow cerebrospinal fluid (CSF) density/signal intensity

    • No enhancement

  • ± neural foraminal widening (bone remodeling)

Top Differential Diagnoses

  • Facet synovial cyst

  • Nerve sheath tumor

  • Spinal nerve root avulsion

  • Meningocele

Pathology

  • Nabors classification of spinal meningeal cyst (MC)

    • Type I: Extradural MC without spinal nerve root fibers

      • –

        IA: Extradural MC

      • –

        IB: Occult sacral meningocele (outdated term)

    • Type II: Extradural MC with spinal nerve root fibers

    • Type III: Intradural MC

Clinical Issues

  • Majority asymptomatic: > 80%

  • Symptoms may worsen with postural changes, Valsalva maneuvers

  • Cyst rupture → spontaneous intracranial hypotension

  • Symptoms simulate disc herniation and spinal stenosis

Diagnostic Checklist

  • CSF intensity mass enlarging neural foramen or sacral canal characteristic of perineural root sleeve cyst

Axial T2WI MR demonstrates a focal, well-circumscribed, hyperintense perineural cyst
within the left C6-7 foramen. Subtle linear low signal
within the cyst represents the exiting nerve within it.

Sagittal T2WI MR confirms focal expansion of the left C6-7 foramen by a large perineural root sleeve cyst
. Note hyperintense cyst signal compared with the normal dorsal root ganglia
within the adjacent level neural foramina.

Axial CT myelography shows multiloculated bilateral T1 nerve root contrast-filled cysts
confirming contiguity with the contrast-filled dural sac. Only part of the right cyst contains contrast.

Axial T2WI MR of the thoracic spine demonstrates bilateral, well-circumscribed cerebrospinal fluid intensity perineural cysts
extending through the neural foramina.

TERMINOLOGY

Synonyms

  • Spinal nerve root diverticulum

  • Tarlov cyst

  • Perineural cyst

Definitions

  • Dilatation of arachnoid and dura of spinal posterior nerve root sheath, containing nerve fibers

IMAGING

General Features

  • Best diagnostic clue

    • Thin-walled cerebral spinal fluid (CSF) density/intensity masses extending into/through neural foramina

  • Location

    • Anywhere along spinal axis

      • –

        Most common in lower lumbar spine and sacrum

      • –

        S2 and S3 nerve roots most commonly involved

  • Size

    • Variable

  • Morphology

    • Well circumscribed

    • Thin-walled cystic mass

    • Round, lobular, multiloculated

    • Often multiple and bilateral

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts